Hydrology [H]

H53A MCC:level 2 Friday 1340h

Water Quality of Hydrologic Systems Posters

Presiding:J W Kirchner, University of California, Berkeley; E W Boyer, State University of New York College of Environmental Science and Forestry

H53A-1191 1340h

Determination of Optimal Velocity Ranges Based on the Shape Profiles of Two Passive Surface Water Flux Meters

* Padowski, J C (JCPadowski@ifas.ufl.edu) , University of FLorida, Soil and Water Science PO Box 110290, Gainesville, FL 32611 United States
Klammler, H (haki@gmx.at) , University of Florida, Civil and Coastal Engineering PO BOX 116580, Gainesville, FL 32611 United States
Jawitz, J W (JWJawitz@ifas.ufl.edu) , University of FLorida, Soil and Water Science PO Box 110290, Gainesville, FL 32611 United States
Hatfield, K (khatf@ce.ufl.edu) , University of Florida, Civil and Coastal Engineering PO BOX 116580, Gainesville, FL 32611 United States
Annable, M (annable@ufl.edu) , University of Florida, Environmental Engineering Sciences PO BOX 116450, Gainesville, FL 32611 United States

A method is presented for direct measurement of cumulative surface water flux (discharge) and solute flux using a Passive Surface Water Flux Meter (PSFM). Both the water velocity and the shape, or bluntness, of the device are important for determining the flow profile around a submerged body. Theoretically, the PSFM should provide the most precise cumulative flux measurements when the shape of the device is as blunt as possible without creating a separation region or a downstream wake. This study examined how the shape of the PSFM affects the accuracy of the cumulative flux data and determined the optimal velocity ranges under which each shape profile could be used. In this experiment, blunt (cylindrical) and streamlined (Joukowsky profile) shapes were tested. Both of these devices were examined under a range of velocities in a laboratory flume. Results showed that the blunt shape provided more accurate water and solute flux measurements at lower velocities, whereas the streamlined shape provided more accurate measurements at higher velocities. These findings indicate that the shape profile of the PSFM may be adjusted to provide the most accurate cumulative water and solute flux measurements when deployed in known flow regimes.

H53A-1192 1340h

Groundwater Nutrient Flux Meter Application for Determination of Phosphorus Flux: Application in Lake Okeechobee Basin, FL

* Hamilton, M K (khammi@ufl.edu) , Soils and Water Science, 2169 MCCarty Hall PO Box 110290, Gainesville, FL 32611 United States
Cho, J (jaehyunc@ufl.edu) , Environmental Engineering, 353 NEB P.O. Box 116450, Gainesville, FL 32611 United States
Jawitz, J W (jawitz@ufl.edu) , Soils and Water Science, 2169 MCCarty Hall PO Box 110290, Gainesville, FL 32611 United States
Annable, M D (annable@ufl.edu) , Environmental Engineering, 353 NEB P.O. Box 116450, Gainesville, FL 32611 United States
Hatfield, K (khatf@ufl.edu) , Civil Engineering, 580 WEIL HALL PO BOX 116580, Gainesville, FL 32611 United States

As part of a larger study of phosphorus (P) movement within cow-calf agricultural systems, nutrient flux meters (NFM's) were deployed around several isolated wetlands to monitor and determine P flux. Phosphorus loading is a recurring problem in agricultural systems as excess phosphorus concentrations drive P-limited systems to a eutrophic state. The (NFM) is a cylindrical, permeable unit of variable length containing a sorbent that fits tightly into a well casing and was designed to use a variety of sorbents depending on application. A strongly basic anion exchange resin was used to retain phosphate present in groundwater while a separate sorbent was used to hold a tracer to determine water flux. Lab experiments were conducted for the selection of an appropriate sorbent that was suited for low concentrations of P and other parameters. The NFM was deployed in several monitoring wells to determine the mass flux of P present in the groundwater resulting from cow-calf operations at the Larson Ranch in Okeechobee, Florida. Several NFM's were deployed in groundwater monitoring wells surrounding the isolated wetlands and in the artificial drain from the wetlands. Phosphorus fluxes were determined by extraction from the anion exchange resin. From the deployment of the NFM for a pre-determined amount of time, P mass flux was found to be higher in the wells that were upgradient of the wetland and reduced at the exit point. Groundwater flux was also determined to be toward the wetland based on the observed gradients. The NFM is a useful tool for measuring groundwater nutrient movement in groundwater around wetlands and in general for TMDL applications.

H53A-1193 1340h

Incorporating Real Time Fiber Optic Detection into a Newly Developed in-situ Passive Groundwater Contaminant Flux Meter

* Wang, H (whuaguo@ifas.ufl.edu) , Soil and Water Science Department University of Florida, 2169 McCarty Hall, Gainesville, FL 32611 United States
Jawitz, J W (jwjawitz@ifas.ufl.edu) , Soil and Water Science Department University of Florida, 2169 McCarty Hall, Gainesville, FL 32611 United States

Quantification of contaminant mass flux is essential for characterizing the risks to humans and the environment from groundwater contaminants. Traditionally, the contaminant mass flux has been indirectly obtained by integrating point contaminant concentrations. A new passive contaminant flux meter (PFM) that can simultaneously measure the contaminant mass flux as well as the ground water flux at the same location has been recently introduced. It is expected that the system can significantly increase the accuracy of contaminant flux estimation when temporal or spatial variability of water flux exists. Here, in-situ, real time fiber optic measurements are incorporated into the PFM. Fluorescent dyes are applied as tracers in the permeable matrix of a PFM. Water flux is quantified by measuring the dye behavior by a fiber optic sensor. Both excitation and emission light are carried in and out the sensor through optic fibers. Signal analysis is conducted using a miniature fiber optic spectrometer that is driven and controlled by a notebook computer, enabling real-time, in-situ field measurement.

H53A-1194 1340h

Field Deployment of Novel Approach in Acquiring Deep Groundwater Samples at Sandia National Laboratories; Nevada Test Site; and Nye County, Nevada

* Murray, P (paul.murray@aeatech.com) , AEA Technology Engineerin Services, 184B Rolling Hill Road, Mooresville, NC 28117 United States
Russell, C E (chuck@dri.edu) , Desert Research Institute, 755 E. Flamingo, Las Vegas, NV 89119 United States

Groundwater sampling is routinely conducted at hundreds of wells at numerous U.S. Department of Energy facilities to monitor changes in the groundwater that occur over time. Some of these wells are very deep (greater than 600 meters), consequently presenting unique problems that must be overcome in order to obtain representative, undisturbed samples. Samples are being collected at these facilities using current technology, including submersible pumps, discrete bailers, and various manufactured systems. Each system or method has particular advantages and special uses. One of the greatest limitations to routine groundwater sampling is the cost associated with acquiring samples. Thus, innovations that allow purging and collection of groundwater at minimal expense are highly desirable. A novel solution for economically collecting groundwater samples is presented. In this approach, a pneumatic sampler employs compressed air to force a polyurethane pig up and down a borehole. This sampler employs two moving parts and is completely automated. Purge rates between 3-4 liters per minute have been demonstrated thus far, and greater purge rates are possible. Successive prototypes of the sampler have been deployed in wells at Sandia National Laboratories; Nevada Test Site; and Nye County, Nevada, adjacent to Yucca Mountain. A functionality test was conducted during the Sandia deployment. The initial prototype of the sampler was improved during deployment to the Nevada Test Site where rudimentary comparisons were made between tritium samples collected by the pneumatic sampler and samples collected through pumping and bailing operations. In the Nye County deployment, various types of groundwater samples were collected and compared to those collected using established groundwater sampling techniques. In addition, durability of the sampler will be assessed over long periods during the Nye County deployment.

H53A-1195 1340h

The Impact of Mass Transfer on the H-3/He-3 Dating Method

* Neumann, R B (rneumann@mit.edu) , Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 77 Massachusetts Ave., Cambridge, MA 02139 United States
Harvey, C F (charvey@mit.edu) , Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 77 Massachusetts Ave., Cambridge, MA 02139 United States

Estimates of groundwater age allow researchers to resolve surface water recharge rates, ascertain an aquifer's susceptibility to contamination, and calibrate complex flow models. The H-3/He-3 groundwater dating method is unique because it does not require exact knowledge of the timing, location, and concentration of an aquifer's highly transient tritium input. In this investigation the impact of mobile-immobile domain mass transfer on the H-3/He-3 dating method is assessed in order to improve age interpretation and bound uncertainty. A finite difference model was constructed to simulate the decay of tritium, production of helium, and the transport of both species through aquifers with a range of parameters. Resulting concentrations were used to calculate H-3/He-3 ages which were compared to corresponding average water ages (the expected value of the water age distribution) and mobile water ages (the age associated with the mobile water velocity). Findings show that the H-3/He-3 method does provide a reasonable approximation of the average water age for heterogeneous, porous aquifers, but that H-3/He-3 measurements must be carefully interpreted for fractured aquifers. Interestingly, the different diffusion coefficients for tritium and helium, suspected to cause inaccuracies in the H-3/He-3 method, have a minimal impact on the H-3/He-3 age.

H53A-1196 1340h

Isotope Of Discharge Water From The July 1st Glacier In China

* Sakai, A (shakai@ihas.nagoya-u.ac.jp) , Nagoya University, Graduate School of Environmental Studies, Nagoya University, Hydrospheric Atmospheric Research Center, Chikusa-ku,, Nagoya, 464-8601 Japan
Fujita, K (cozy@ihas.nagoya-u.ac.jp) , Nagoya University, Graduate School of Environmental Studies, Nagoya University, Hydrospheric Atmospheric Research Center, Chikusa-ku,, Nagoya, 464-8601 Japan
Matsuda, Y (s030117d@mbox.nagoya-u.ac.jp) , Nagoya University, Graduate School of Environmental Studies, Nagoya University, Hydrospheric Atmospheric Research Center, Chikusa-ku,, Nagoya, 464-8601 Japan
Nakawo, M (nakawo@chikyu.ac.jp) , Research Institute for Humanity and Nature, Research Institute for Humanity and Nature, 335 Takashima-cho, Kamigyo-ku,, Kyoto, 602-0878 Japan
Duan, K (kqduan@ ns.lzb.ac.cn) , Cold and Arid Regions Environmental and Engineering Research Institute, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, 260 Donggang West Road,, Lanzhou, 730000 China
Pu, J , Cold and Arid Regions Environmental and Engineering Research Institute, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, 260 Donggang West Road,, Lanzhou, 730000 China
Yao, T (tdyao@itpcas.ac.cn) , Cold and Arid Regions Environmental and Engineering Research Institute, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, 260 Donggang West Road,, Lanzhou, 730000 China

Glacier melt water has an important role for water cycle in the arid region, northwest China, since the amount of precipitation in the mountains is much larger than those in the lower desert area. Historically ground water in the desert has been irrigated by meltwater from glaciers and seasonal snow in the mountains. Isotope ratio of the discharge from glaciers provides good information to understand the history of ground water in desert area. The purpose of this study, therefore, is to understand the composition of isotope ratio in the present discharge from glacier taking into account the isotope ratios of the glacier ice and precipitation. Observation has carried out at July 1st Glacier in Qilian mountain, China from June to September in 2002. Sample of the precipitation, discharge water, surface snow and ice on the glacier have been taken to analyzed the delta 18O. We also observed the discharge and mass balance of the glacier. Average delta 18O of the discharge water, precipitation at the altitude 3800 m a.s.l., and glacier surface ice were -10.3 permil, -7.4 permil, -11.4 permil, respectively during the observation period. Altitudinal effect on the delta 18O in the precipitation was -0.16 permil/100m. Older ice, which has accumulated at upper part of the glacier, was exposed at the ablation area at present. delta 18O in the surface ice at ablation area changes from -14.0 permil at the terminal to -10 permil near the equilibrium line altitude, those isotope ratio was smaller than that in the present precipitation falling on the ablation area. We calculated the delta 18O of discharge water by taking into account isotope in rain, snow and melt ice in the ablation area. Calculated result of isotope in discharge was almost equal to the observed delta 18O in the discharge water.

H53A-1197 1340h

Natural Radioactivity in Groundwater from the Negev, Israel

* pery, N (peryn@bgumail.bgu.ac.il) , Department of geological and enviromental sciences , Ben gurion university of the negev, P.O.B 653, Beer sheva, 84105 Israel
Vengosh, A (Avnerv@bgumail.bgu.ac.il) , Department of geological and enviromental sciences , Ben gurion university of the negev, P.O.B 653, Beer sheva, 84105 Israel
Haqin, G (Gostavu@soreq.gov.il) , Soreq nuclear research center, Yavne 81800, Yavne, 81800 Israel
Paytan, A (apaytea@pangea.stanford.edu) , Department of geological and enviromental sciences Stanford university, Broun hall, CA, 94305-2115 United States
Elhanani, s (sarael1@water.gov.il) , Water commition, Hamasger 14 P.O.B 20365, Tel aviv, 61203 Israel
pankratov, I (irenap60@water.gov.il) , Water commition, Hamasger 14 P.O.B 20365, Tel aviv, 61203 Israel
Broshi, L (N.A.) , Soreq nuclear research center, Yavne 81800, Yavne, 81800 Israel
Yungreiss, Z (N.A.) , Soreq nuclear research center, Yavne 81800, Yavne, 81800 Israel
Gazit-Yaari, N (N.A.) , Soreq nuclear research center, Yavne 81800, Yavne, 81800 Israel

As most of the groundwater basins in the Middle East are being diminished or contaminated, exploitation of the deep aquifers referred as the "Nubian Sandstone" from the Paleozoic and Lower Cretaceous sandstone units is increasing. In many basins across the Sahara and Sahel regions, the Arabian peninsula, Gulf States, Jordan, and Israel the fossil groundwater are the only available water resource. Natural radioactivity is an important water quality factor of groundwater from this aquifer.Systematic analyses of radium isotopes ($^{226}$Ra,$^{228}$Ra,$^{224}$Ra,$^{223}$Ra) in over sixty groundwater samples from the Negev and Arava Valley, Israel, reveal that a large number of the pumping wells exceeds the international drinking water regulations as regulated by the USEPA and the European Community (EU). In the Lower Cretaceous Nubian sandstone (Kurnob Group) aquifer 26 out of the 29 (90%) investigated wells are having radium activity above the EU and the EPA regulations. Excluding the activity of the shorted-live $^{224}$Ra isotopes (half life of 3.6 days) the fraction of wells with activity above the EU regulation reduces to 79%. In the overlying Upper Cretaceous carbonate (Judea Group) aquifer the numbers of wells with activity exceeding the EU and EPA drinking regulations are 9 (39%) and 11 (48%) out of 23. In the carbonate aquifer we observed a linear correlation between $^{226}$Ra activity and salinity whereas in the sandstone aquifer the $^{228}$Ra isotopes is predominated and no relationship with salinity was found. Our results clearly indicate that high activity of radium, even low saline groundwater, play a key role in exploitation and water utilization for domestic and agriculture applications.

H53A-1198 1340h

Studying the anthropogenic radionuclides in Puerto Rico: Preliminary Result

* Ithier-Guzman, W (ithiergu@marine.usf.edu)
Pyrtle, A J (apyrtle@marine.usf.edu)
Smoak, J (smoak@stpt.usf.edu)

Local introduction of anthropogenic radionuclides to Puerto Rico's terrestrial and aquatic environments began in 1962 as a result of US government-sponsored research activities. Some of the earlier experiments examined the effects of radiation in tropical rainforests and the potential of superheated boiling nuclear reactor technology. More recent activities involved the use of depleted uranium during military exercises on Vieques. While the presence of radionuclides in Puerto Rico is documented, little research has been done to assess the environmental impact of this anthropogenic material. After entering Puerto Rico's environment, it is likely that some radionuclides are transported away from initial introduction sites. It is important that the distributions and behavior of radionuclides in Puerto Rico be determined. As such an investigation of this material throughout Puerto Rico was initiated. Sediment Cs-137 and Pb-210 activities, as well as ancillary geochemistry data are presented. These preliminary findings will be utilized as part of an ongoing study to determine radionuclide distributions and behaviors, with respect to aquatic geochemistry and dominant transport processes.

H53A-1199 1340h

Extraction and Analysis of PAHs in Surface Soils Near Freeways in Los Angeles

* Mannino, I (imannino@altrionet.com) , California State University Los Angeles, Department of Civil Engineering 5151 State University Drive, Los Angeles, CA 90032 United States

Large urban areas such as Los Angeles are characterized by high levels of motor vehicle traffic. A by-product of this traffic is the emission of a group of compounds known as polycyclic aromatic hydrocarbons (PAHs). PAHs are a global-scale persistent environmental hazard, many of which are considered to be carcinogenic. This study investigated the prevalence of 16 PAHs in surface soils near major Los Angeles highways. The first phase of the study was the development of a methodology for efficiently extracting PAHs from soil. Preliminary findings suggested that the most efficient extraction method using an accelerated solvent extractor employed a mixture of acetone and hexane and a static extraction time of 5 minutes (completed in 2 cycles). Extraction efficiency was measured by spiking clean sand with a known amount of a PAH standard and extracting and analyzing the sand. The addition of an extra static cycle produced a significant increase in extraction efficiency. For example, utilization of 2 static cycles recovered 99.6% of the spiked phenanthrene compared to a 44% efficiency for the 1 cycle run. Preliminary results from a field sampling campaign indicated that significant concentrations of PAHs are deposited onto and accumulate in surface soils. Specifically, we found 12.13 $\mu$g/kg of anthracene, 15.82 $\mu$g/kg of benzo(a)pyrene, 23.42 $\mu$g/kg of phenanthrene, and 23.43 $\mu$g/kg of pyrene in surface soils, including soils from a public park. These results indicate that background levels of PAHs in soils may pose a significant health risk to humans. For example, the California preliminary remediation goal for benzo(a)pyrene in residential soils is 62 $\mu$g/kg, slightly greater than our reported background values. A more detailed field sampling campaign will be pursued to elucidate the role of different environmental variables (i.e., time of day, sun intensity, traffic congestion, etc.), on the accumulation of PAHs in soils.

H53A-1200 1340h

Geochemical Factors Affecting Release of U(VI) from Soils

* Zheng, Z (zzuoping@lbl.gov) , Lawrence Berkeley National Laboratory, One Cycltron Road, Berkeley, CA 94720 United States
wan, j (jwan@lbl.gov) , Lawrence Berkeley National Laboratory, One Cycltron Road, Berkeley, CA 94720 United States

Abstract: The retention, mobility, and bio-availability of U(VI) in contaminated soils depend strongly on release of U(VI). In this study, laboratory batch experiments were performed to evaluate the factors controlling the release of U(VI) from contaminated soil at the U.S. Department of Energy' Oak Ridge site. We found that the ionic strength of the extraction solution strongly affects release of U(VI). Increase in ionic strength shows a strong effect on U(VI) release as indicated by the increase in release rates and associated release mass of U(VI). We also found that the ratio of solution volume to solid mass (V/M) has a significant impact on the release of U(VI). Increase in the V/M ratio shows a negligible effect on the U(VI) release in a short period (4-day period). However, in the longer time (from 30 to 120 days), larger V/M ratios yield greater U(VI) release. The maximum U(VI) concentrations observed in the release experiments are in the range of schoepite solubility estimated under conditions relevant to the experiments, suggesting that schoepite solubility primarily controls the U(VI) release, but that solubilization and desorption effects cannot be distinguished using macroscopic methods.

H53A-1201 1340h

Selenium Speciation, Solubility, and Mobility in Agricultural Evaporation Ponds in California

* Ryu, J (jiryu@ucdavis.edu) , Department of Land, Air and Water Resources University of California, Davis , One Shields Avenue, Davis, CA 95616
Gao, S (sgao@fresno.ars.usda.gov) , USDA-ARS, SJVASC-Water Management Research Lab, 9611 S. Riverbend Avenue, Parlier, CA 93648
Tanji, K K (kktanji@ucdavis.edu) , Department of Land, Air and Water Resources University of California, Davis , One Shields Avenue, Davis, CA 95616
Alemdar, C (calemdar@ucdavis.edu) , Department of Land, Air and Water Resources University of California, Davis , One Shields Avenue, Davis, CA 95616
Dahlgren, R A (radahlgren@ucdavis.edu) , Department of Land, Air and Water Resources University of California, Davis , One Shields Avenue, Davis, CA 95616

Constructed evaporation ponds are an important and economic disposal option for subsurface drainage water to sustain irrigated agriculture in the southern portion of the San Joaquin Valley of California. The trace element of most concern in disposing of agricultural drainage water is selenium due to its potential toxicity in the aquatic food chain of evaporation ponds. We investigated selenium biogeochemistry at the Tulare Lake Drainage District's South Evaporation Basin consisting of ten ponds covering a surface area of 7.26 km$^{2}$. The ten ponds represented a wide range of water salinity due to its evapoconcentration sequence. Aqueous selenium speciation was determined for both inorganic species (Se(VI) and Se(IV)) and organic species (org-Se) at representative sites in the ponds. Total selenium concentration was determined in sediments at different depths. The redox environment affecting selenium speciation in the evaporation ponds was evaluated. To understand biological activity and its potential effect on selenium accumulation and speciation in the evaporation ponds, we determined organic carbon, nutrients (N and P), chlorophyll-a, and water temperature. The results from this study have important implications for understanding selenium behavior in natural and managed environments such as evaporation basins, playas and wetlands.

H53A-1202 1340h

Characterization of Selenium Pollution in the Western United States by Coupling Soil Moisture with Geochemical Transport

* Zhao, M (zhao@berkeley.edu) , Civil and Environmental Engineering, 2108 Shattuck Ave. Rm 419 , Berkeley, CA 94720 United States
Liang, X (liang@ce.berkeley.edu) , Civil and Environmental Engineering, 2108 Shattuck Ave. Rm 419 , Berkeley, CA 94720 United States
Guo, J (jzhguo@berkeley.edu) , Civil and Environmental Engineering, 2108 Shattuck Ave. Rm 419 , Berkeley, CA 94720 United States

Due to the arid conditions of the Western United States, selenium released from sandstone and shale hillslopes is transported by overland runoff and is shown to cause fish and aquatic bird death and reproductive failure. Precipitation in contact with exposed seleniferous soils, carry dissolved and particulate forms of selenium in runoff and groundwater to the valley floor to be redistributed throughout the hillslope and alluvial fan. Impervious clay soils and the arid climate impede the flushing of selenium below the groundwater table so that selenium is continually cycled in the alluvial fan. A physically based model that couples hydrologic land surface interactions and geochemical transport based on soil moisture was developed to characterize the loading, transport, and distribution of selenium. The soil moisture distribution and overland flow patterns determined by the hydrologic model for the watershed are factors that control soil chemical movement and transformation. The main geochemical and physical transport mechanisms of selenite and selenate, dissolution from soil, speciation, adsorption, advection, and mass transfer from pore water to overland form, are characterized as functions of surface flow and the soil moisture of the fifteen centimeter deep soil layer for each model grid. The movement of overland flow within each grid is routed to the outlet of the watershed. Flow patterns and measured selenium concentrations at two sites; the Panoche/ Silver Creek watershed in Central California, and the Leach Creek watershed in Colorado, are compared to model results. Selenium pollution characterization at a watershed scale will add to the understanding of the cycling of selenium within and across watersheds and aid in the mitigation of selenium pollution.

H53A-1203 1340h

The Release of Chromium in Aquifers Underlying the Western Mojave Desert

Khachikian, C S (ckhachi@calstatela.edu) , California State University Los Angeles, Department of Civil Engineering 5151 State University Drive, Los Angeles, CA 90032 United States
* Plotkin, C (CPlotkin@dtsc.ca.gov) , California State University Los Angeles, Department of Civil Engineering 5151 State University Drive, Los Angeles, CA 90032 United States
Monterrosa, A (atmonterrosa@yahoo.com) , California State University Los Angeles, Department of Civil Engineering 5151 State University Drive, Los Angeles, CA 90032 United States
Ramirez, P (pramire@calstatela.edu) , California State University Los Angeles, Department of Geological Sciences 5151 State University Drive, Los Angeles, CA 90032 United States

Recent studies suggest that chromium (Cr) in aquifers underlying the western part of the Mojave Desert may be naturally occurring, resulting from the release of this element from aquifer materials in oxic ground water with pH $>$ 8.0. In order to test this hypothesis, we studied the kinetic release of Cr from aquifer material collected from the Sheep Creek fan near Victorville, CA. Pulverized and untreated aquifer material were incubated in 15mL Falcon tubes with water at three different pH values (2, 7, and 9) for 227 days. Duplicate samples were incubated in a heating bath at temperatures 20$^{o}$C above ambient, in order to accelerate the kinetics of Cr release. Samples from each tube were collected, filtered through a 0.22 $\mu$m filter, and analyzed using a graphite furnace atomic absorption photospectrometer using EPA Method 7199. Due to the heterogeneity of the aquifer material an accurate measure of Cr release kinetics was not possible; results presented here represent equilibrium values at the end of the incubation period. For untreated aquifer material incubated at ambient temperatures, Cr was found at concentrations of 26.0 $\pm$ 8.0 ppb at pH = 2, 5.2 $\pm$ 0.6 ppb at pH=7, and 9.1 $\pm$ 0.9 ppb at pH=9. As expected, the highest value of Cr was found for the samples incubated at pH=2. Pulverization of the samples resulted in an increase in Cr release by a factor of 1.5, 2.4, and 1.6 at pH values of 2, 7, and 9, respectively. Heating the pulverized samples at pH 7 and 9 resulted in an increase in the concentration of Cr released (by 25% and 9% respectively). However, heating the pulverized sample at pH=2 resulted in an almost 95% decrease in the concentration of released Cr (from 37.8 ppb to 2.2 ppb). The reason for this decrease is not known at this point. Our results indicate that significant concentrations of Cr are released naturally in Western Mojave Desert aquifers under various geochemical conditions. Additional studies are underway to study the kinetic release of Cr in packed columns.

H53A-1204 1340h

A "Tail" Of Two Mines: Determining The Sources Of Lead In Mine Waters Using Pb Isotopes

* Cousens, B L (brian_cousens@carleton.ca) , Earth Sciences, Carleton University 1125 Colonel By Dr., Ottawa, ON K2E5S4 Canada
Allen, D M (dallen@sfu.ca) , Earth Sciences, Simon Fraser University, Burnaby, BC V5A1S6 Canada
Lepitre, M E , Earth Sciences, Simon Fraser University, Burnaby, BC V5A1S6 Canada
Mortensen, J K , Earth and Ocean Sciences, University of British Columbia, Vancouver, BC V6T1Z4 Canada
Gabites, J E , Earth and Ocean Sciences, University of British Columbia, Vancouver, BC V6T1Z4 Canada
Nugent, M , Earth Sciences, University of Ottawa, Ottawa, ON K1N6N5 Canada
Fortin, D (dfortin@science.uottawa.ca) , Earth Sciences, University of Ottawa, Ottawa, ON K1N6N5 Canada

Acid mine drainage can be a significant environmental problem in regions where mine tailings are exposed to surface water and shallow groundwater flow. Whereas high metal concentrations in surface waters and groundwaters indicate that metals are being mobilized, these data do not uniquely identify the source of the contamination. The isotopic composition of Pb in mine waters is a superb tracer of Pb sources, because the isotopic composition of ore Pb is usually significantly different from that of host rocks, other surficial deposits, and aerosols. We have investigated metal mobility at two abandoned Pb-Zn mines in different geological settings: the sediment-hosted Sullivan Mine in southeastern British Columbia, and the New Calumet Mine of western Quebec that is hosted in metamorphic rocks of the Grenville Province. Ores from both mines have homogeneous Pb isotopic compositions that are much less radiogenic than surrounding host rocks. At Sullivan, the Pb isotopic compositions of water samples define a mixing line between Sullivan ore and at least one other more radiogenic end-member. Water samples with high Pb concentrations (0.002 to 0.3 mg/L) generally are acidic and have Pb isotope ratios equal to Sullivan ore, whereas waters with low Pb contents have near-neutral pH and have variably more radiogenic Pb isotope ratios. Thus not all the waters collected in the study area originate from Sullivan ore or mining operations, as previously thought. The dominant source of ore Pb in mine waters are the waste rock dumps. Based on their isotopic compositions, host shales or aerosols from the local Pb smelter are potential sources of non-Sullivan ore Pb; local glacial tills are an unlikely source due to their heterogeneous Pb isotopic composition. Similarly, at the New Calumet mine, water samples collected in direct contact with either ore at the surface or tailings have high Pb concentrations (up to 0.02 mg/L) and Pb isotope ratios equal to New Calumet Pb-Zn ore. However, all water samples collected downstream from the mine site have low Pb concentrations and variably more radiogenic Pb isotope ratios. Water samples from a well on the mine site and a pipe discharging water from below the tailings dam also have non-ore Pb isotope ratios. The isotopic compositions of low-Pb samples do not lie on a mixing line between ore and local host rocks, but rather lie on a mixing line between agricultural ditch and stream waters upstream of the mine and New Calumet ore. These waters may form a groundwater system flowing under the mine site that is virtually uncontaminated by the overlying ores and tailings. Compared to the Sullivan case, metals from the New Calumet ore and tailings are only weakly mobilized into local waters, probably due to buffering of waters by carbonate-bearing host rocks. We are impressed with the fingerprinting ability of Pb isotopes to track the sources of heavy metals in water systems, and suggest that other radiogenic isotopes (Sr, Nd) may also be useful in environmental studies.

H53A-1205 1340h

Complexation of Inorganic Mercury in Freshwaters: Spatial Variability and Ligand Sources

* Black, F J (black@etox.ucsc.edu) , University of California, Santa Cruz, 1156 High Street Department of Environmental Toxicology, Santa Cruz, CA 95064 United States
Flegal, A (flegal@etox.ucsc.edu) , University of California, Santa Cruz, 1156 High Street Department of Environmental Toxicology, Santa Cruz, CA 95064 United States

The speciation, bioavailability, and toxicity of mercury in aquatic systems are substantially influenced by complexation with natural ligands. Wetlands, waste water treatment plants, and other sub-oxic environments serve as important sites for the methylation of inorganic mercury (Hg[II])to its more toxic form, monomethyl mercury (MMHg). These environments are also sources of sulfide, polysulfides, thiols, and other reduced sulfur ligands which can form strong complexes with Hg(II) and MMHg. This complexation can affect the biogeochemical cycling of mercury by altering its bioavailability, transport, and mineral phase dissolution rates. This project aims to better understand the role these unique reducing environments play in the aquatic chemistry of mercury in oxic receiving waters. A technique employing competitive ligand exchange followed by solid phase extraction (CLE-SPE) is being used to characterize the concentration and binding strengths of ligands in natural freshwaters which complex inorganic Hg(II) at environmentally relevant dissolved mercury levels. Sampling has been designed to evaluate the role of wetlands, seasonally anoxic lakes, and other reducing environments as potential sources of ligands. Their effects on the complexation of Hg(II) at downstream sites with elevated mercury levels are also investigated. The concentration, stability, and transport of these complexes, and their possible effects on the methylation and mobility of mercury, are being examined in various freshwater lakes and steams.

H53A-1206 1340h

Mercury Benthic Flux: A Comparison Between 3 Mining-Impacted Water Bodies in the Western United States

* Topping, B R (btopping@usgs.gov) , U.S. Geological Survey, 345 Middlefield Rd., Menlo Park, CA 94025 United States
Kuwabara, J S (kuwabara@usgs.gov) , U.S. Geological Survey, 345 Middlefield Rd., Menlo Park, CA 94025 United States
Marvin-Dipasquale, M C (mmarvin@usgs.gov) , U.S. Geological Survey, 345 Middlefield Rd., Menlo Park, CA 94025 United States
Agee, J L (jlagee@usgs.gov) , U.S. Geological Survey, 345 Middlefield Rd., Menlo Park, CA 94025 United States
Kieu, L H (lhkieu@usgs.gov) , U.S. Geological Survey, 345 Middlefield Rd., Menlo Park, CA 94025 United States
Flanders, J R (jflander@usgs.gov) , U.S. Geological Survey, 345 Middlefield Rd., Menlo Park, CA 94025 United States
Parchaso, F (parchaso@usgs.gov) , U.S. Geological Survey, 345 Middlefield Rd., Menlo Park, CA 94025 United States

The legacy of mining in the Western United States has left an indelible environmental imprint on terrestrial and aquatic systems. On both sides of the Sierra Nevada mountain range (Sierras), mercury was used copiously in the amalgamation of gold and silver. Mercury deposits in close proximity to San Francisco Bay (e.g., the New Almaden mining district) provided much of the mercury for these processes. To evaluate mercury benthic flux, three geographically distinct water bodies were studied: Lahontan Reservoir (NV) on the eastern side of the Sierras, affected by historic gold and silver mining; Camp Far West Reservoir (CA) on the western side of the Sierras, down stream of historic hydraulic gold mining and processing; and South San Francisco Bay (CA), the estuarine component down stream of the New Almaden Mercury Mines. Average benthic flux of total-dissolved mercury was highest in Lahontan Reservoir ($\sim$1400 pmol/m$^{2}$/hr), followed by Camp Far West Reservoir ($\sim$180 pmol/m$^{2}$/hr), and lowest in South San Francisco Bay ($\sim$50 pmol/m$^{2}$/hr). In spite of this wide range of values, and the unique character of each watershed (e.g., forested vs. urbanized), all three systems exhibited quantitatively significant mercury benthic fluxes relative to riverine inputs. That is, areally averaged benthic fluxes (thus, expressed as annual loads) were of similar or greater magnitude relative to riverine loads. System-averaged values of dissolved methylmercury fluxes were similar for South San Francisco Bay (undetectable) and Camp Far West Reservoir (average of $\sim$0 pmol/m$^{2}$/hr; some fluxes undetectable), and only slightly higher in Lahontan Reservoir ($\sim$2 pmol/m$^{2}$/hr). Similarly, system averaged potential rates of methylmercury production (by sulfate-reducing bacteria; as assessed by $^{203}$Hg(II) radiotracer studies) in the surficial sediment were not significantly different among the three locations. However, within-system variability was approximately an order of magnitude in each case. The interactions between bottom sediment and overlying water chemistry appears to consistently play an important role in dissolved-mercury distribution, transport and trophic transfer, and should therefore be considered when numeric targets are developed for remediation and restoration programs.

H53A-1207 1340h

Natural Versus Anthropogenic Remediation of Streams Impacted by Acid Mine Drainage in Southeast Ohio

* Clinton, T (tc279803@ohio.edu) , Ohio University, 316 Clippinger Laboratories Deparment of Geological Sciences, Athens, OH 45701 United States
Lopez, D L (lopezd@ohio.edu) , Ohio University, 316 Clippinger Laboratories Deparment of Geological Sciences, Athens, OH 45701 United States

Three streams that have been affected by acid mine drainage in southeast Ohio have been investigated (Sulphur Run in the Federal Creek watershed, Rock Run in the Monday Creek watershed, and Buffer Run in the Raccoon Creek watershed). Sulphur Run neutralizes acidic inputs naturally due to its strong buffering capacity acquired from water-rock interactions with the abundant carbonate lithology surrounding the stream. Rock Run and Buffer Run have been anthropogenically remediated using successive alkalinity producing wetlands, open limestone channels, and alkaline capping of adjacent coal refuse piles. The objective of this study is to compare the water quality evolution of the three streams. For this purpose, water and sediment samples were collected for chemical analysis and in-situ flow rate, alkalinity, acidity, pH, dissolved oxygen, and conductivity were measured. Preliminary results reveal that the pH of Sulphur Run, which never drops below 6.7, increases steadily along the flow path. Downstream of the remediation sites, the pH of Rock Run and Buffer Run is always below 4 and declines along the flow path, possibly due to a combination of additional acidic inputs downstream from the main source and the oxidation of metals, leading to hydrolysis reactions that produce additional hydrogen protons. The net alkalinity of Sulphur Run increases steadily downstream, reflecting the effectiveness of a continuous supply of alkaline material at neutralizing acidic inputs. Both Buffer Run and Rock Run are net acidic, suggesting that armoring of the open limestone channels by metal precipitates is impeding the recovery of water quality. The early results indicate that remediation schemes that do not mimic nature by providing a long term, steady supply of alkaline material appear to be ineffective.

H53A-1208 1340h

Effects of Coal-Bed Methane Discharge Waters on Soils and Vegetation Diversity

* Stearns, M (maria_stearns@yahoo.com) , U.S. Geological Survey, MS 413, Box 25046, DFC, Denver, CO 80225 United States
Tindall, J A (jtindall@usgs.gov) , U.S. Geological Survey, MS 413, Box 25046, DFC, Denver, CO 80225 United States
Friedel, M J (mfriedel@usgs.gov) , U.S. Geological Survey, MS 413, Box 25046, DFC, Denver, CO 80225 United States
Cronin, G (gcronin@carbon.cudenver.edu) , Univ. Colorado, Denver, Dept. of Biology, Campus Box 171, Denver, CO 80217 United States
Berquist, E (eberquist@csu.edu) , Dept. of Agric. and Resource Economics, Colorado State University, Ft. Collins, CO 80523 United States

Coal bed methane co-produced discharge waters in the Powder River Basin of Wyoming, resulting from extraction of methane from coal seams, have become a priority for chemical, hydrological and biological research during the last few years. Soil and vegetation samples were taken from impacted and reference sites (upland elevations and wetted gully) to investigate impacts of CBM discharge waters on soil physical and chemical properties and on native and introduced vegetation richness and diversity. Results indicate a significant increase of salinity and sodicity within local soil ecosystems at sites directly exposed to CBM discharge waters. Elevated concentrations of sodium in the soil appear to be due to consistent exposure to CBM waters. Clay-loam soils in the study area, which have a much larger specific surface area than the sandy soils, readily allow sodium ions to adsorb quickly to exchange sites. There was no significant relation between increasing water SAR values and increasing sediment SAR values downstream; however, soils exposed to the CBM water ranged from the moderate to severe SAR hazard index. Native vegetation species richness was highest at the reference (upland and gully) and impacted upland sites. The impacted gully had the greatest percent composition of introduced vegetation species. Salt-tolerant species had the greatest richness at the impacted gully, implicating a potential threat of invasion and competition to established native vegetation. CBM waters could have detrimental impacts to the local ecosystem, causing dispersion of soils and making it difficult for native vegetation to exist. These waters could also have a devastating effect on agricultural production operations and long-term water quality.

H53A-1209 1340h

Measurement Errors in Microbial Water Quality Assessement: the Case of Bacterial Aggregates

* Plancherel, Y (yves@soest.hawaii.edu) , University of Hawaii at Manoa, 1000 Pope Rd. Department of Oceanography Marine Science Building, Honolulu, HI 96822 United States
Cowen, J P (jcowen@soest.hawaii.edu) , University of Hawaii at Manoa, 1000 Pope Rd. Department of Oceanography Marine Science Building, Honolulu, HI 96822 United States

The quantification of the risk of illness for swimmers, bathers, or consumers exposed to a polluted water body involves the measurement of microbial indicator organism densities. Depending on the organism targeted, there exist two widely used (traditional) techniques for their enumeration: most probable number (MPN) and membrane filtration (MF). Estimation of indicator organism density by these traditional methods is subject to large measurement error, which translates into poorly constrained relationships between indicator organism density and illness rate. Neither the MPN nor the MF method can discriminate multiple cells that form an aggregate. Mathematical formulations and computer simulations are used to investigate the effects that bacterial clumps have on the measurement error of the concentrations. The first case considered is that of the formation of clusters induced during the membrane filtration process assuming a randomly distributed population of cells growing into colonies. The computer simulations indicate that this process induces a typical measurement error $<$15% with the MF method. Replication of the MF measurements does not reduce this type of error. The second case describes a mathematical framework for the modeling of particle-associated bacteria. When aggregates harboring bacteria are present in a sample, an additional measurement error of 5-35% is expected. Empirical results from laboratory and field experiments enumerating aggregated bacteria using the MF method agree well with these model values. Furthermore, the data reveal that this type of error depends on the microbial indicators used (Enterococcus, {\it C. perfringens}, Heterotrophic Plate Count bacteria) and highlights the importance of small bacterial clusters ($<$5 $\mu$m).

http://www2.hawaii.edu/~plancher/

H53A-1210 1340h

Regional Assessment of Pathogen Pollution Using Kriging Approach

* Teegavarapu, R S (ramesh@engr.uky.edu) , Department of Civil Engineering, 161 Oliver Raymond Hall University of Kentucky, Lexington, KY 40506 United States
Ormsbee, L (lormsbee@engr.uky.edu) , Department of Civil Engineering, 161 Oliver Raymond Hall University of Kentucky, Lexington, KY 40506 United States

A stochastic surface interpolation technique, Kriging, is used to assess regional pathogen pollution levels. Assessment is carried out using several models fitted to semivariograms established from the available data. Data collected from the sampling efforts conducted as a part of PRIDE (Personal Responsibility in Desirable Environment) project in Southeastern Kentucky are used for this study. The main pollution causing sources in the study area are straight pipes and failing septic systems. Validation of interpolated data is achieved by using sampled data that are not included in the Kriging interpolation process. Causal validity of the interpolated results is also assessed using the pollution causing sources using a geographical information system framework. Preliminary results suggest that Kriging can be used for identifying heavily impaired watersheds due to pollution after sufficient confidence is established in the interpolation results.

http://pride.uky.edu

H53A-1211 1340h

Statistical characterization of contaminated groundwater in the agricultural area by multivariative analysis and kriging

* Kaown, D (dugin1@snu.ac.kr) , School of Earth and Environmental Science, Seoul Nation University, Seoul, 151-747 Korea, Republic of
Hyun, Y (yjhyun@snu.ac.kr) , School of Earth and Environmental Science, Seoul Nation University, Seoul, 151-747 Korea, Republic of
Lee, K (kklee@snu.ac.kr) , School of Earth and Environmental Science, Seoul Nation University, Seoul, 151-747 Korea, Republic of

The characterization of groundwater contamination at a hydrologically complex agricultural site in Youpori, Chooncheon (Korea) was undertaken by analyzing hydro-chemical data of groundwater within a statistical framework. The data show that high and correlated concentrations of Ca, Mg, and NO3 reflected the polluted nature of groundwater at the site. More than 39% of samples showed nitrate concentrations above the human affected value (3mg/L as NO3-N ), while about 25% samples exceeded the maximum acceptable level (10mg/L as NO3-N ) according to the EPA regulation. Multivariate analyses (factor and cluster analyses) were used to identify contaminant pathway, source and geochemical process. The geostatistical method was applied in order to delineate the spatial extent and variation of nitrate contamination. Factor and cluster analyses indicate that hydrochemical data can clearly characterize the non-point contamination over the area by agrochemical fertilizer as well as point-source pollution like manure spreading near barn or pigpen on groundwater. Nitrate-N, the critical species in the study area, was used to delineate the spatial spread of the contaminants using kriging in the study area.

H53A-1212 1340h

Risk-Cost-Benefit Analysis Of Atrazine In Drinking Water From Agricultural Activities

* Aklilu, T A (akliluanges@cc.usu.edu) , Civil and Environmental Engineering, UWRL, Utah State University, Logan, UT 84321
Jagath, K J (jkalu@cc.usu.edu) , Civil and Environmental Engineering, UWRL, Utah State University, Logan, UT 84321
Arthur, C J (acaplan@cc.usu.edu) , Department of Economics, Utah State University, Logan, UT 84322-3530

This study provides a new methodology for investigating the trade-offs between the health risks and economic benefits of using atrazine in the agricultural sector and a more holistic insight to pesticide management issues. Regression models are developed to predict the stream atrazine concentrations and finished water atrazine concentration at high-risk community water supplies in the US using surface water. The predicted finished water atrazine concentrations are then used in health risk assessment. The computed health risks are compared with the total surplus in the US corn market for different atrazine application rates using the demand and supply functions developed in this work. Analysis of different scenarios with consumer price premiums (preferences) for chemical-free to reduced chemical corn provided interesting results on the potential for future pesticide and land use management. This is an interdisciplinary work that has attempted to integrate and consider the interaction between weed sciences, economics, water quality, human health risk and human reaction to changes in different pesticide use scenarios. The results showed that this methodology provides a scientific framework for future decision-making and policy evaluation in pesticide management, especially when better regional and national data are available.

H53A-1213 1340h

Changes in Storm Flow as a Result of Direct Seed Farming Practices on the Columbia Plateau Semiarid Croplands

* Williams, J D (johnd.williams@oregonstate.edu) , USDA-Agricultural Research Service, Columbia Plateau Conservation Research Center, 48037 Tubbs Ranch Road, Adams, OR 97810 United States

Mass cultivation of the prairie and shrubland-steppe on the Columbia Plateau began in the 1880's. This region is characterized by very fertile, highly erodible silt-loam soils, developed on steep slopes over Miocene basalts. Early farming practices led to excessive soil loss; lower cropland productivity, fouled in-stream habitat for andronomous and non-andronomous salmonids and eels, and deposition of sediment in first, second, and third order channels that continues to migrate down stream during storm runoff events. Sixty years of soil and water conservation efforts have slowed soil loss from fields. Presently much of the sediment moved during stormflow originates from stream bank erosion, although the annual development of rills in many fields is still observed. To quantify the continuing contribution of sediment to streams, and to evaluate the effectiveness of direct seed farming practices to soil and water conservation, four first order drainages, and one hillslope were instrumented with flumes, weirs, and storm sediment samplers. The area of instrumented drainages and hillslope were, respectfully, 25.0, 18.1, 10.0, and 6.1 ha, and a 25 percent hillslope of 1.6 ha. The 6.1 ha drainage was managed using fallow and inversion tillage practices. In October 2002, the crop stubble was fall burned and the soil was inverted using a moldboard plow; the following spring and summer the drainage was field cultivated and rod-weeded three times to control weeds and prepare the seed bed for winter wheat in October 2003. All other drainages, and the hillslope site, were farmed using direct seed technology consisting of one pass using a direct seed drill to seed and fertilize the crop, one pass to harvest the crop, one pass to break-up crop stubble, and multiple passes to spray herbicides for weed control. Total crop year precipitation for 2002-03 and 2003-04 was 10 percent lower and 15 percent higher, respectively, than the long-term average, representing typical winter-time precipitation patterns for the Columbia Plateau. Four runoff events were recorded from October 2002 through September 2003; the stage recorder failed in the conventionally tilled drainage during two of the events. During the events in which the runoff was recorded, the conventionally tilled drainage yielded 19.39 m3 and 20.83 m3; for those same events the 10.0 ha direct seed drainage yielded 0 m3 and 7.24 m3. Total recorded runoff for the year from the conventionally tilled drainage was 40.21 m3, and 40.96 m3 from the 10.0 ha direct seeded drainage. Total annual erosion from the conventionally tilled drainage was 127.05 kg/ha and 8.18 kg/ha from the direct seeded drainage. No runoff or erosion were recorded from the direct seeded 25.0, 18.1 drainages, or the 1.6 ha hillslope. From October 2003 through September 2004, one runoff event was missed and eight events were recorded from the conventionally tilled drainage, yielding 149.89-m3 runoff, and 286.71-kg/ha soil loss. The direct seeded drainages and hillslope produced no runoff or erosion. Under the climatic conditions during these two winters, the direct seed practices used in this study effectively controlled, runoff and erosion compared to a conventionally farmed drainage, at scales both larger than and smaller than the conventionally drained area. These results demonstrate the immediate soil and water conservation effectiveness of the direct seed technology. They also portend changes in the downstream processes as channels adjust to reduced stormflow volume and energy, and a reduced sediment supply.

H53A-1214 1340h

Edge of Field Nitrate Loss and Oxygen-18 Dynamics in a Dryland Agriculture Setting

* Wannamaker, C N (caroline_wannama@wsu.edu) , Dept. of Geology, Washington State University, P.O. Box 642812, Pullman, Wa 99164-2812 United States
Goodwin, A J (angiegoodwin@gmail.com) , Dept. of Geology, Washington State University, P.O. Box 642812, Pullman, Wa 99164-2812 United States
Keller, C (ckkeller@wsu.edu) , Dept. of Geology, Washington State University, P.O. Box 642812, Pullman, Wa 99164-2812 United States
Allen-King, R (richelle@geology.buffalo.edu) , Dept. of Geology, University at Buffalo, SUNY, 876 Natural Sciences Complex, Buffalo, NY 14260 United States
Smith, J L (jlsmith@mail.wsu.edu) , USDA-ARS, 225 Johnson Hall, P.O. Box 646420, Pullman, Wa 99164-6420 United States

Four complete water years of nitrate concentrations and oxygen isotope ($\delta$O$^{18}$) ratios have been monitored in a tile drain and adjacent soil-water sampling lysimeters beneath a dryland, agricultural field in the Palouse Region of Washington State, USA. The Palouse is semi-arid and is characterized by undulating loess hills and swales drained by ephemeral to perennial streams. Soil type is dominated by silt-loam Mollisols. Our field is subject to typical farming practices and crop rotations, receiving ammonia fertilizer during fall and spring planting at a rate of $\sim$70kg of nitrogen per acre. Tile drains play an essential role in environmental nitrogen dynamics in this region as they are widely utilized to drain water from lower fields. Nitrate concentrations in tile drainage fluctuate on a seasonal basis ranging from low concentrations of $\sim$1mg/ NO$_{3}$-N/L in late October/November to higher concentrations of 20-30mg NO$_{3}$-N/L in late January/February. Rise in concentration occurs rapidly with the onset of high flow conditions differing from a typical dilution effect. Lysimeter waters show similar nitrate patterns ranging in concentration from ~10mg NO$_{3}$-N/L to as high as 120mg NO$_{3}$-N/L. In the lysimeters, nitrate concentrations are apparently positively correlated with $\delta$O$^{18}$ values. Precipitation collected at the field site shows a 12 per mil seasonal variation in $\delta$O$^{18}$. A seasonal pattern is also observed in soil water with a smaller range of about 6 per mil. These seasonal fluctuations are not observed in tile drainage, where values vary only 2 per mil with a mean of -15 per ml. We hypothesize that residence-time and scaling effects can explain the $\delta$O$^{18}$ fluctuation differences between soil water and tile drainage. The very large nitrate fluctuations throughout the system may be due in part to the seasonality of soil nitrogen cycling.

H53A-1215 1340h

Long-term Effects of Clearcutting on N Availability and Soil Solution Chemistry in the Fraser Experimental Forest, CO

* Starr, B (bstarr@fs.fed.us) , USDA Forest Service Rocky Mountain Research Station, 240 West Prospect, Fort Collins, CO 80526 United States
Stottlemyer, R (robert_stottlemyer@usgs.gov) , U.S. Department of the Interior U.S. Geological Survey, 2150 Centre Avenue, Bldg C , Fort Collins, CO 80526 United States
Elder, K (kelder@fs.fed.us) , USDA Forest Service Rocky Mountain Research Station, 240 West Prospect, Fort Collins, CO 80526 United States
Rhoades, C (crhoades@fs.fed.us) , USDA Forest Service Rocky Mountain Research Station, 240 West Prospect, Fort Collins, CO 80526 United States

The effects of timber harvest on soil water ion chemistry and flux have been studied for more than two decades at the Fraser Experimental Forest in central Colorado. We examined the long-term effects of a clearcutting experiment, 18 years after harvesting of a high-elevation mixed conifer forest (2900 m). Early effects of harvesting included elevated concentrations and flux of NO3-N in soil water, and these increases continued through 18 years. In 2003, total N loss from the harvested plot (2.0 kg ha-1 yr-1) was four times greater than the control (0.5 kg ha-1 yr-1). The most pronounced differences in subsurface chemistry and flux were found for nitrate (NO3-N). The proportion of total N in subsurface discharge as NO3-N increased from < 1% in the control to greater than 50% in the clearcut. The annual loss of NO3-N equaled 1.2 kg ha-1 in the clearcut, about one-sixth the loss rate for the first 8 years after harvest. Total post harvest leaching losses of inorganic N were about 67 kg/ha. Nitrate losses from the control forest were negligible (< 0.001 kg ha-1 yr-1) for all periods. On an annual basis net N mineralization showed no effect of harvest after 18 years, but resin bags collected more N in the clearcut site than in the control. High current losses of nitrogen from the clearcut may result from the biological factors of lower plant uptake and increased microbial nitrification, and the physical factors of greater snow accumulation and snowmelt discharge.

H53A-1216 1340h

Nitrate Storm Flux from Coastal Catchments in Southern California

* Leydecker, A (al.leydecker@cox.net) , Marine Science Institute, University of California, Santa Barbara, CA 93106 United States
Robinson, T H (trobinson@bren.ucsb.edu) , Bren School of Environmental Science and Management, University of California, Santa Barbara, CA 93106 United States
Melack, J M (melack@lifesci.ucsb.edu) , Bren School of Environmental Science and Management, University of California, Santa Barbara, CA 93106 United States

We have been sampling nutrient concentrations in 19 coastal streams in the vicinity of Santa Barbara, CA., as part of the Santa Barbara Coastal LTER since Oct. 2000. These streams, with land cover varying from coastal sage and chaparral to agricultural and urban development, are representative of the 790 square km of coastal watershed extending 120 km from Point Conception to the Ventura River. The topography of these small coastal catchments (average area of about 10 square km) consists of mountainous headwaters and mild sloping coastal plains separated by transitional foothills. Annual rainfall varied from 27 to 74 cm during the 2001, 2002 and 2003 water years, and year-around sampling, with hourly collections during rainfall, and continuous measurements of stage were used to determine the magnitude and variation of nutrient concentrations and fluxes. Annual volume-weighted mean concentrations of nitrate generally ranged from 5 to 25 $\mu$mol per L in undeveloped areas, increased to about 100 $\mu$mol per L for urban and most agricultural catchments, and were in excess of 1000 in catchments with greenhouse-based agriculture. Different land uses produced different, but relatively characteristic, nitrate fluxes during stormflow. The fluxes, highly correlated with storm discharge, were similar for urban and agricultural catchments, over an order-of-magnitude higher for industrial greenhouse agriculture and, generally, an order-of magnitude lower in undeveloped catchments. A striking feature of the nitrate flux during storms producing large amounts of runoff were high concentrations during the falling hydrograph from upslope undeveloped areas, and the maintenance of these concentrations for several days. An interesting and potentially significant inference based on this pulse of upper catchment nitrate is that the influence of the developed portion of the catchment can become less than that of the undeveloped portion. If nitrate flux per ha is plotted against runoff, it appears that for storm runoff exceeding 2 to 5 cm per unit area the flux from the upper, undeveloped catchment exceeds the flux from lower urbanized or agricultural areas. Interactions among atmospheric deposition, biological nitrogen fixation and mineralization of organic nitrogen, and seasonal runoff from these areas appear to control the supply and export of nitrate.

H53A-1217 1340h

Draw-Down of Metals During a Spring Phytoplankton Bloom in South San Francisco Bay

* Luengen, A C (allisonl@ucsc.edu) , ETOX Department, UCSC, ETOX Department, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States
Flegal, A R (flegal@etox.ucsc.edu) , ETOX Department, UCSC, ETOX Department, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States

This research measured concentrations of Co, Cu, Ni, Pb, and Zn during a South San Francisco Bay (South Bay) spring bloom to evaluate the role of phytoplankton in metal uptake and cycling. Water samples (dissolved and total) were collected using trace-metal clean techniques during 10 cruises at 3 sites in the South Bay channel. Vertical profiles of the water column were conducted by Jim Cloern's group from the United States Geological Survey. The spring 2003 bloom was a roughly 40 day period of high hytoplankton biomass when chlorophyll-a concentrations peaked at $>$150 $\mu$g/L at station 36 in the extreme South Bay. Principal Component Analysis was used to reduce the variables to 3 diagnostic factors that were then used to characterize processes governing the biogeochemical cycles of trace elements in the bay. These statistical analyses demonstrated that concentrations of some elements (e.g. Ni and Pb) were depleted during the spring bloom whereas others (e.g. Cu) were not. These results are consistent with other studies on the speciation and bioavailability of different trace elements in San Francisco Bay.

H53A-1218 1340h

Sustainable Exploitation of the Coastal Aquifer in Israel: Search for Water Quality Stratification in the Saturated Zone

* Raanan, H (raanan@bgumail.bgu.ac.il) , Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, P.O.B. 653, Be'er Sheva, 84105 Israel
Vengosh, A (avnerv@bgumail.bgu.ac.il) , Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, P.O.B. 653, Be'er Sheva, 84105 Israel
Seiler, K P (Seiler@gsf.de) , GSF-National Research Center, Ingolstadter Landstrasse 1, Neuherberg, D-85758 Germany
Maloszewski, P (maloszewski@gsf.de) , GSF-National Research Center, Ingolstadter Landstrasse 1, Neuherberg, D-85758 Germany

Stratification of water layers in the upper part of the saturated zone in unconfined aquifer has been reconstructed by environmental isotope tracers in combination with traditional hydrogeology, hydrochemistry, and numerical modeling. In particular the relationship between modern recharged and old recharged waters was evaluated. Numerical modelling and field studies conducted in Germany and Venezuela have demonstrate that more than 85 % of the groundwater recharge is turned over in aquifers close to the water table (i.e., active recharge zone) and less than 15 % reaches greater depths (passive recharge zone or deep groundwater). Here we investigate the water quality stratification in the saturated zone of the coastal aquifer of Israel. We use pumping wells with different screen depths to provide access for multiple depth analysis of the aquifer along several cross-sections perpendicular to the coast line. Tritium data of deep wells (top end screen deeper than 80m below sea level) show low values ($<$0.9TU). In contrast, shallow wells (upper than 30m) reveal higher tritium levels ($>$3.0TU). A transition zone was identified at a depth range of 30-80m, showing a wider tritium range (0-4.2TU). Our data reveal water layering of different ages in the upper part of the saturated zone in spite of lack of physical separation by low-conductivity layers.

H53A-1219 1340h

Monitoring of Water Quality Dynamics in Fresno River and Hensley Lake, California*

* Wang, Z ( (zwang@csufresno.edu) , Department of Earth and Environmental Sciences Department, MS MH24, California State University, Fresno, Fresno, CA 93740 United States
Blumenshine, S (sblumens@csufresno.edu) , Biology Department, MS SB73, California State University, Fresno , Fresno, CA 93740 United States
Wright, A (awright@csufresno.edu) , Biology Department, MS SB73, California State University, Fresno , Fresno, CA 93740 United States
McClanahan, M (mmcclana@csufresno.edu) , California Water Institute, California State University, Fresno 6014 N. Cedar Ave, Fresno, CA 93710 United States
Holcomb, R E (daleron@csufresno.edu) , Department of Earth and Environmental Sciences Department, MS MH24, California State University, Fresno, Fresno, CA 93740 United States
Sartono, O (oriindo@csufresno.edu) , Department of Earth and Environmental Sciences Department, MS MH24, California State University, Fresno, Fresno, CA 93740 United States

The Fresno River is located near the geographical center of California and is the first major tributary east of the San Joaquin River. Hensley Lake was created by the construction of Hidden Dam on the Fresno River for flood control, irrigation, resource management, and recreation. The reservoir has a storage capacity of 90,000 acre feet (110 million m3) and a water surface area of about 1,500 acres (6 km2). In recent years, algae blooms appeared in the lake, causing public concerns over continued beneficial uses of Fresno River and Hensley Lake. This monitoring and simulation project was conducted to identify the major nutrient sources and nutrient and algae dynamics in the watershed and reservoir. A GIS-aided BASINS model was set up for basin scale water quality simulation in the future. Historical data analysis and field sampling of physical, chemical and biological parameters of the River and Lake waters indicated that: (1) The annual contribution of river water to the lake has significantly decreased after the year 2000 (reasons to be investigated). This caused a decrease in water storage in the reservoir likely lead to eutrophic and even hypereutrophic conditions in the lake; (2) The dissolved oxygen in the river is at a critical (near minimum) level for potential beneficial uses. Oxygen levels quickly declined with depth in the lake during summer, far below the minimum concentrations for warm water systems as determined by California Water Quality Standards (5.0mg/L). Oxygen deficit is caused not only by not having enough light through surface water but also oxygen consumption by surface algae and their decomposers in the deep water through respiration; (3) Nutrient concentrations in the watershed were always lower than the lake site closest to the river inflow, strongly suggesting that the river water is diluting the lake; and (4) High bacteria (total Coliform and E. Coli) numbers prevailed in the middle and downstream reaches of the river, indicating that disease-causing bacteria may be present in the watershed. * This project was funded in part by a grant from the U.S. Environmental Protection Agency, administered through the California State Water Resources Control Board.

H53A-1220 1340h

Hydrology and Water Quality of Restored Riparian Buffers in the Blue Ridge and Piedmont Physiographic Regions, N.C., USA.

* Allan, C J (cjallan@uncc.edu) , Dept. of Geography and Earth Sciences, UNC Charlotte, 9201 University City Blvd., Charlotte, NC 28223 United States
Thomasson, M J (mjthomas@email.uncc.edu) , Dept. of Geography and Earth Sciences, UNC Charlotte, 9201 University City Blvd., Charlotte, NC 28223 United States
Wu, J (jwu@uncc.edu) , Dept. of Civil Engineering, 9201 University City Blvd., Charlotte, NC 28223 United States

Non Point Source (NPS) pollution is a major contributor to water quality degradation in most of the major river basins in North Carolina and elsewhere. The use of riparian, vegetated buffers has been identified as a Best Management Practice (BMP) to reduce NPS sediment and nutrient inputs to surface waters. However, water quality improvements are strongly related to riparian hydrologic characteristics such as water table depth and flow path configuration. Hydrologic conditions are in turn influenced by the geologic characteristics of the aquifer system. In this study we examined the effectiveness of restored vegetated riparian buffers in controlling nutrient and sediment export from livestock farming operations in the Piedmont and Blue Ridge regions of the state. Both aquifer systems were unconfined but exhibit different water table fluctuations and flow path configurations. Piezometer nests with groundwater wells were installed at various locations and depths along two transects at each site. Water table position was measured continuously and hydraulic gradients and water quality samples were collected every 14-36 days since installation. Water samples were analyzed for NH4-N, NO3-N, Cl, TP and TKN. Here we present a detailed spatial and temporal analysis of solute transport through both aquifer systems.

H53A-1221 1340h

Modern Limnological and Contamination Records from a Drinking Water Lake in Central New York

* Bookman, R (rbookman@syr.edu) , Syracuse University, Department of Earth Sciences, 204 Heroy Geology Lab, Syracuse, NY 13244 United States
Seltzer, G (goseltze@syr.edu) , Syracuse University, Department of Earth Sciences, 204 Heroy Geology Lab, Syracuse, NY 13244 United States
Driscoll, C (ctdrisco@mailbox.syr.edu) , Syracuse University, Civil and Environmental Engineering, 220 Hinds Hall, Syracuse, NY 13244 United States
Montesdeoca, M (mmontesd@ecs.syr.edu) , Syracuse University, Civil and Environmental Engineering, 220 Hinds Hall, Syracuse, NY 13244 United States
Philippon, J (jphilipp@syr.edu) , Syracuse University, Department of Earth Sciences, 204 Heroy Geology Lab, Syracuse, NY 13244 United States

Otisco Lake is the easternmost of the Finger Lakes in central New York. It is a mesotrophic lake with a maximum depth of 20 m and a drainage area of 94 km$^{2}$. Since the beginning of the 20$^{th}$ century the lake waters have been used for drinking water supply. Using a gravity corer we collected four sediment cores with a maximum length of 45 cm from the bottom of the lake. The cores represent the last $\sim$150 years. The changes with depth in nitrogen, carbon, and the trace metal mercury were recorded by analyzing 1 to 2 cm long segments from each core. The chronology was obtained on one of the cores using the Lead-210 dating method and by identifying the rise in copper concentration as a marker horizon of the year 1942, when copper sulfate was first added to the lake to control algal blooms. Lead-210 was measured by $\alpha$-spectrometry and dates were calculated according to the CRS model. The sediment accumulation rates calculated from the unsupported lead activity show an increase from 0.06 g cm$^{-2}$yr$^{-1}$ at the bottom of the core to 0.15 g cm$^{-2}$yr$^{-1}$ at depth of 13 cm. In the upper part of the core the sediment accumulation fluctuates between 0.10 and 0.13 g cm$^{-2}$yr$^{-1}$, with the lowest value at the uppermost cm in the core. Background copper concentrations average 25 ug g$^{-1}$ in the lower 20 cm of the core, but from depth of 22 cm to 13 cm the concentrations rapidly increase up to 142 ug g$^{-1}$. Concentrations along the rest of the upper core fluctuate around 112 ug g$^{-1}$. The beginning of increased concentration correlates well with the Lead-210 chronology marking the 1942-year horizon. Mercury contamination in lakes is largely attributed to atmospheric deposition of pollutant emissions. Total mercury at Otisco Lake was measured in the four cores showed almost identical profiles. Mercury flux increased from around 50 ug m$^{-2}$yr$^{-1}$ in the 1870's to a maximum value of 132 ug m$^{-2}$yr$^{-1}$ during the mid 1970's, with a steep increase beginning at the 1940's. At the beginning of the 1980's the mercury flux decreased to ~90 ug m$^{-2}$yr$^{-1}$, but rose again in the 1990's. The top 2 cm dated to the last decade show a significant decrease in concentration to values around 80 ug m$^{-2}$yr$^{-1}$. Carbon and nitrogen fluxes mimic the trends of mercury, although their concentrations peak a decade later. Fluxes start to rise in the 1940's from an average of 2.3 and 0.25 mg cm$^{-2}$yr$^{-1}$, respectively, and reach their peak values (8 and 0.66 mg cm$^{-2}$yr$^{-1}$, respectively) during the 1980's. As with mercury, the nutrient flux in the top 2 cm of the record shows decreasing values. The mercury fluxes in the sediments represent increased atmospheric pollution from industrial activities that reached their maximum values before pollution problems were addressed seriously with the 1970 Clean Air Act. The passage of the 1990 Clean Air Act amendments that strengthen enforcement provisions may be the cause for the decreasing trends in the last decade. The lake waters are likely contaminated mainly by atmospheric pollution. However, since there is a good correlation between the sediment accumulation rate, mercury flux, and nutrients fluxes, we believe that land-use changes have a major influence on the lake and sediment chemistry. This study may assist in policy making and management of Otisco Lake and its watershed, as well as similar water bodies that are used as drinking water supplies.

H53A-1222 1340h

Black Shale: A Source of Dissolved Organic Matter in Natural Waters

* Schillawski, S (sschilla@geo.umass.edu) , Dept. of Geosciences, University of Massachusetts-Amherst, 611 N. Pleasant St., Amherst, MA 01003 United States
Petsch, S (spetsch@geo.umass.edu) , Dept. of Geosciences, University of Massachusetts-Amherst, 611 N. Pleasant St., Amherst, MA 01003 United States

Black shales are fine-grained laminated sedimentary rocks that are rich in organic matter (OM). Exposure of shales to earth surface environments results in oxidative weathering of the shale. While prior studies have demonstrated a loss of organic carbon during weathering of shales, other efforts have shown that rivers draining watersheds underlain with black shale transport significantly aged ($^{14}$C-depleted) dissolved and particulate OM when compared to rivers draining other lithologies. Consequently, it is uncertain if complete oxidation of ancient sedimentary OM occurs within an outcrop during weathering, or whether black shales can be a source to rivers of OM that is distinct in composition and isotopic character from other pools such as soils, decaying vegetation, and authochthonous production. To address this, column experiments were initiated in which sterile, air-saturated water was passed through shale substrates packed in glass flow-through cells. A Late Devonian black shale from the Appalachian Basin, USA, (7.60% TOC) was used. The Type-II kerogen contained in this shale is representative of kerogen compositions found in most marine sedimentary rocks. Three parallel column experiments including crushed shale, solvent-extracted crushed shale, and a baked-sand blank have been continually monitored for several months. Effluent from the columns has been collected and analyzed daily for dissolved organic carbon concentrations (DOC). Solution pH, conductivity, major cations/anions, and $^{13}$C NMR spectra of effluent collected on solid-phase-extraction disks have also been monitored. Within several days after initiation of experiments, DOC concentrations exiting both columns stabilized at 0.5 mg/L, which equates to 3.2 x 10$^{-3}$ mg$_{carbon}$/g$_{toc}$/hr or 2.2 x 10$^{-4} mg$_{carbon}$/m$^{2}$/hr. At this rate, organic carbon in the 82g shale column will fully dissolve in 36 years. However, release of kerogen into solution is not likely to be simple dissolution, but instead dominated by absorption/desorption exchange with the kerogen and mineral matrix. Streams draining black shales exhibit DOC concentrations that are similar to what is observed in these column experiments, which suggests that during weathering, sedimentary rock rich in organic carbon may be a source of OM to river ecosystems. If this OM is not remineralized during transport, these waters may be one source of $^{14}$C-depleted organic matter to seawater that is distinct in composition from other terrestrial sources.

H53A-1223 1340h

Modeling Nitrogen Loading on the Groundwater in Response to Land-Use Change

* Tripathy, D (dtripath@purdue.edu) , Purdue University, Dept. of Earth & Atm Sc. 550 Stadium Mall Drive, West Lafayette, IN 47906

Effect of nutrient loading on the groundwater, specifically nitrogen loading, due to land-yuse change is a complex but understudied phenomena. Nitrate contamination of the yworld's groundwater supply poses a serious human health threat. This research is aimed yat better understanding how land-use affects nitrogen loading on the groundwater at a ylocal scale, and to examine the possibility of using orchard grass as a medium to reduce ynitrogen (i.e. nitrate) contamination of groundwater. y A 100 acre land having different land-use categories in the Centre County, PA, is used as ya study area. The Non Point Source (NPS) nitrogen loading on the surface runoff is yestimated using the Long-Term Hydrologic Impact Assessment (L-THIA) model. The ynitrogen laden runoff is then diverted over a strip of orchard grass, and the amount of ynitrogen leaching on groundwater beyond the root zone is estimated using the Grazing ySimulation Model (GRASIM). y A strong positive correlation is found between rainfall, nitrogen loading on the runoff, and ynitrate leaching to groundwater. The results show that routing storm runoff over a strip of yorchard grass detention base can reduce the amount of nitrogen leaching to the ygroundwater by 62 %. Thus, due to its ability to substantially reduce nitrogen yleaching, orchard grass strips (or, meadows) can be used as effective, low cost, and yenvironment friendly option for preventing groundwater contamination due to nitrate yleaching. The results underscore increasing use of grass and forested buffers for reducing ynutrient contamination of both surface water (streams, lakes), and the groundwater. y

H53A-1224 1340h

Changes in concentration of contaminants in Scott Creek, Western North Carolina

* Allmendinger, N E (allmendinge@email.wcu.edu) , Western Carolina University, Department of Geosciences and Natural Resource Management, 349D Stillwell Building, Cullowhee, NC 28723 United States
Clapp, R B (RBC99@aol.com) , Watershed Association of the Tuckasegee River, 835 Main Street, Bryson City, NC 28713 United States

Scott Creek is a 4th-order gravel-bedded stream in the Little Tennessee watershed in a mountainous region of Western North Carolina. The region is highly dependent on this river for water contact sports and input for a paper mill. Recently, water sample have shown high levels of fecal coliform in spite of efforts to fix a broken sewer pipeline and eliminate straight-piping. Our objective is to assess the current quality of the water, and to devise methods for future monitoring and prediction of contaminant concentration in the river. During a 5-day period in July 2004, we monitored the stage and velocity of the river as well as the concentration of nitrates, reactive phosphorous and fecal coliform in the water. Our results suggest that the nutrients and the bacteria counts vary in phase with the river discharge. Our analysis of the data leads us to conclude that both discharge and E. coli concentration are related to precipitation. The relationship between river stage and precipitation is complex, requiring a "multiple" regression equation which plots Q as a function of the previous 3 days of rainfall. The relationship between E. coli concentration and precipitation is much simpler, showing that the abundance of bacteria varies directly with daily rainfall. We infer from our data that it is unlikely that E. coli in Scott's Creek has a "point" source, suggesting that the bacterial contamination is related to undetected straight pipes and not to a steady sewer failure.

H53A-1225 1340h

Is wetland mitigation successful in Southern California?

* Cummings, D L (deanna.l.cummings@usace.army.mil) , U.S. Army Corps of Engineers, 915 Wilshire Blvd, Los Angeles, CA 90017 United States
Rademacher, L K (lradema@calstatela.edu) , Department of Geological Sciences California State University, Los Angeles, 5151 State University Drive, Los Angeles, CA 90032 United States

Wetlands perform many vital functions within their landscape position; they provide unique habitats for a variety of flora and fauna and they act as treatment systems for upstream natural and anthropogenic waste. California has lost an estimated 91% of its wetlands. Despite the 1989 "No Net Loss" policy and mitigation requirements by the regulatory agencies, the implemented mitigation may not be offsetting wetlands losses. The "No Net Loss" policy is likely failing for numerous reasons related to processes in the wetlands themselves and the policies governing their recovery. Of particular interest is whether these mitigation sites are performing essential wetlands functions. Specific questions include: 1) Are hydric soil conditions forming in mitigation sites; and, 2) are the water quality-related chemical transformations that occur in natural wetlands observed in mitigation sites. This study focuses on success (or lack of success) in wetlands mitigation sites in Southern California. Soil and water quality investigations were conducted in wetland mitigation sites deemed to be successful by vegetation standards. Observations of the Standard National Resource Conservation Service field indicators of reducing conditions were made to determine whether hydric soil conditions have developed in the five or more years since the implementation of mitigation plans. In addition, water quality measurements were performed at the inlet and outlet of these mitigation sites to determine whether these sites perform similar water quality transformations to natural wetlands within the same ecosystem. Water quality measurements included nutrient, trace metal, and carbon species measurements. A wetland location with minimal anthropogenic changes and similar hydrologic and vegetative features was used as a control site. All sites selected for study are within a similar ecosystem, in the interior San Diego and western Riverside Counties, in Southern California.

H53A-1226 1340h

Comparative adsorption of arsenic, boron, chromium, molybdenum and selenium on fresh and weathered fly ash.

* Bhattacharyya, S (bhatt001@bama.ua.edu) , Dept. of Geological Sciences, University of Alabama, Tuscaloosa, Al 35487-0338, 202 Bevill Building, Tuscaloosa, Al 35487 United States
Donahoe, R J (rdonahoe@wgs.geo.ua.edu) , Dept. of Geological Sciences, University of Alabama, Tuscaloosa, Al 35487-0338, 202 Bevill Building, Tuscaloosa, Al 35487 United States
Graham, E Y (bgraham@wgs.geo.ua.edu) , Dept. of Geological Sciences, University of Alabama, Tuscaloosa, Al 35487-0338, 202 Bevill Building, Tuscaloosa, Al 35487 United States
Patel, D V (dvpatel@southernco.com) , Southern Company Services Inc., Southern Company Services Inc. Inverness Center Parkway, Birmingham, Al 35242 United States

Coal-fired electric power plants in the US generated over 130 million tons of fly ash and other combustion waste materials last year. While approximately 35% of the produced coal combustion by-products (CCBs) are recycled for beneficial use, the majority of the waste is impounded in lagoons and landfills located throughout the country. The EPA is currently re-evaluating these disposal facilities for regulation under Subtitle D. The objective of this study is to determine and compare the adsorption capacities of fresh and weathered fly ash for the toxic metals arsenic, boron, chromium, molybdenum, and selenium in order to evaluate the long-term mobility of these metals in the ash disposal environment. Two power plant sites were selected for study, one producing acidic ash and the other alkaline ash. Weathered ash samples were collected at each site from cores drilled from the surface through the bottom of ponds that have been closed for more than 35 years. Fresh fly ash was obtained directly from the power plants. Batch experiments were performed to study the competitive adsorption of As, B, Cr, Mo and Se on fresh and weathered ash materials. Experiments performed at pH values of 3, 4, 6, 8 and 10, using initial metal concentrations of 5 mg/L, show similar adsorption behavior for both ash compositions. The metal selectivity sequence for fresh fly ash is As >> Mo > Cr ~ Se ~ B. Maximum arsenic adsorption on fresh fly ash occurs at pH = 6 with almost 100% removal, while maximum arsenic adsorption on weathered ash takes place at pH = 3. Maximum adsorption of B, Cr, Mo and Se occurs at pH = 3 for both fresh and weathered ash. The experiments indicate that the adsorption capacity of fly ash for the metals of interest is reduced by weathering. Experiments are currently underway to compare the adsorption capacity of fresh and weathered fly ash for varying initial metal concentrations, ionic strength and solid/liquid ratio.

H53A-1227 1340h

Effects of Modern Timber Harvest Practices on Suspended Sediment Concentrations in Mica Creek, Idaho

* Karwan, D L (diana.karwan@yale.edu) , Yale University School of Forestry and Environmental Studies, 210 Prospect Street, New Haven, CT 06511
Gravelle, J (jag@pineorchard.com) , University of Idaho, 1205 Pro-Mall Blvd #112, Pullman, WA 99163

The concern regarding sedimentation effects from modern timber harvest practices emphasizes the necessity for a greater understanding of how both road construction and timber harvest relate to stream sediment levels. In order to investigate this, a network of seven automated stream monitoring stations was installed in the Mica Creek Experimental Study Area in north Idaho. Water samples analyzed for total suspended solids (TSS) were collected regularly since 1991 under both flow-based and stream-stage storm rise conditions from 1991 to 2003. This period of time encompasses a pre-treatment time interval from 1991 to 1997, and two treatment time intervals: post-road from 1998 to 2001 and post-road/post-harvest from 2001 to 2003. Using a paired watershed approach, treated and control catchments were statistically compared for each time interval. At this time the impacts corresponding to road construction and timber harvest using modern practices remain difficult to discern from the larger variation in the entire suspended sediment record. Continued monitoring at these sites is planned to evaluate trends over subsequent years. This analysis is part of a long-term integrated study that measures both physical change in the watershed as well as biological response to road construction and timber harvest conducted under current best management practices (BMPs). Mica Creek is believed to be one of the first comprehensive study basins which examines the effects of using modern practices on privately managed timberland.

H53A-1228 1340h

RESULTS OF INDOOR 222 RADON AND IN DRINKING WATER IN ALBANIA

* Dogjani, S (sdogjani@yahoo.com) , Albanian Geological Survey, Qendra Gjeofizike, blloku Vasil Shanto, Tirana, Alb 0000 Albania
Mema, S (sh_mema@yahoo.com) , Environmental Ministry, Rruga Durresit, Tirana, Alb 0000 Albania

The measurements of Radon indoor concentration of constructions gave the following results: - From 128 tests carried out, 92 percent are clean environments, 5 percent have some higher values and 3 percent have the anomalous values over 400 Bq/m3. The clean environments are with of avRn under 150 Bq/m3. The avRn activity in these residences is from 17 to 142 Bq/m3 while in the maximal values avRn up to 364 Bq/m3. The environments with grown avRn, 151 - 400 Bq/m3 are 6 distributed residences or 5 percent of all cases. The normal value of avRn in these environments is 160 - 280 Bq/m3, with maximal value up to 478 Bq/m3. The environments with high avRn, over the permitted norm, 411 - 1837 Bq/m3 take 3 percent of the constructions. The maximal values of avRn reach up to 10000 Bq/m3. The probability value of 3 percent or 4 abnormal cases in 148 estimated ones, is high. The necessary recommendations are given for isolation and ventilation, to protect the health of the inhabitants. More detailed estimations should be carried out in the future in such areas. All drinking water depots have low radon values

H53A-1229 1340h

Effect of Well Bore Mixing on Formation Decontamination by Pumping

* Chen, J (jschen@app.geo.ncu.edu.tw) , Institute of Applied Geology, National Central University, No. 300, Jungda Rd., Jhongli city, Taoyuan, 320 Taiwan
Liang, C (sc048@mail.fy.edu.tw) , Department of Environmental Engineering and Science, Foo-Yin University, No.151 Chin-Hsueh Rd., Ta-Liao Hsiang, Kaohsiung, 831 Taiwan
Liu, C (lcw@gwater.agec.ntu.edu.tw) , Department of Bioenvironmental Systems Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei, 106 Taiwan

Various techniques have been developed to remediate contaminated groundwater. The conventional means of cleaning up contaminated formation is the "pump-and-treat" approach, which uses a series of extraction wells to withdraw contaminated groundwater for above-ground treatment. Given the strong interest in remediation of contaminated formation, models to describe contaminant transport induced by pumping at extraction wells have been formulated and applied to evaluate the efficiency of the pump-and-treat system. As the contaminants enter a large-diameter pumping well,the well bore water will tend to mix and dilute the contaminated groundwater. However,few studies have examined how well mixing volume affects contaminant transport for formation decontamination by pumping. This work presents a novel mathematical model to evaluate the effect of pumped well bore mixing volume on formation decontamination. The model equation is solved by the Laplace transform finite difference method. A sensitivity analysis of the developed model is performed to assess the effect of well bore mixing volume. The well bore volume effect is pronounced for initial plumes with a small maximum contaminated radius, and in media such as bedrock formation where aquifer porosity and longitudinal dispersivity are small. In such systems, the pumped well bore mixing effect reduces the early contaminant concentrations, shifts the peak breakthrough curves to the right and spreading the breakthrough curve, and thus increasing the decontamination time. If such a system does not account for pumped well mixing effect, estimates of decontamination time required to the regulatory level will be inaccurate.

H53A-1230 1340h

Evaluation of the Optimal Remediation Design in Heterogeneous Domain

* Ko, N (fuu@netian.com) , Seoul National University, School of Earth and Environmental Sciences, Seoul, 151-747 Korea, Republic of
Lee, K (kklee@snu.ac.kr) , Seoul National University, School of Earth and Environmental Sciences, Seoul, 151-747 Korea, Republic of

In the problems of optimal remediation design in groundwater hydrology, hydraulic conductivity or transmissivity has significant influence on optimal design and its level of success. So, its heterogeneity may be important factor for optimal remediation design as well. In this study, probabilistic approaches are applied to the problem of groundwater remediation design to consider the risk of design and heterogeneity of real aquifers. To examine the effect of heterogeneity of hydraulic conductivity, optimal remediation design computed in simple base condition is evaluated for both homogeneous and heterogeneous domains. For homogeneous hydraulic conductivity field, Latin hypercube method is used. For heterogeneous field, random fields having same mean and variance with a certain spatial correlation are constructed. For both hydraulic conductivity fields, the optimal remediation design is evaluated in terms of remediation cost. To compare the results, cumulative distribution functions (CDFs) of relative costs are calculated. Results show that CDF has very wide range of cost and the influences of different penalty values are relatively significant for homogeneous case. For heterogeneous case, CDF shows narrow range and the influence of penalty values is hardly observed. This indicates that CDF can reflect on the risk of optimal solution in a simple example condition and be effective in estimating the cost of groundwater remediation including the penalty cost.

H53A-1231 1340h

Optimal Remediation Design considering Effects of Degradation Processes: Pumping Strategy with Enhanced Natural Attenuation

* Park, D K (ecolede1@snu.ac.kr) , Seoul National University, School of Earth and Environmental Sciences, Seoul, 151-747 Korea, Republic of
Lee, K (kklee@snu.ac.kr) , Seoul National University, School of Earth and Environmental Sciences, Seoul, 151-747 Korea, Republic of

The optimal remediation design using the pump and treat (P&T) method is accomplished in consideration of degradation processes such as sorption and biodegradation. In order to investigate the effect of sorption and biodegradation on the pump and treat strategy, optimal remediation designs are numerically evaluated for various degradation process conditions. Remediation designs are optimized against the pumping rates as well as the location and number of wells. When sorption effect increases, the pumping rate and the number of pumping wells increase. The location of operated wells is on the centerline of contaminant plume. In addition, wells near hot spot make significant influences on the optimal design when sorption effect increases. In this study, biodegradation is considered as a first-order decay reaction. The higher first-order decay rate, the less pumping volume is required. As a result, degradation processes can be one of the essential factors for the optimal remediation design. For effective remediation, this study presents a new remediation strategy, so-called enhanced natural attenuation (ENA), which induces aerobic biodegradation by maintaining oxygen concentration. To investigate the performance of ENA with respect to both cost and contaminant removal, four scenarios under a specific sorption condition are considered; (1) only P&T (2.5yrs) (2) P&T (1.5yrs) and ENA (1yrs) (3) P&T (1.5yrs), ENA (0.5yrs) and NA (0.5yrs) (4) P&T (1.5yrs), two different ENA schemes (each 0.5yrs). The optimal design for each scenario is computed. Results show that the most cost-effective remediation design is the third scenario although first scenario removes the most amount of contaminant in the aquifer. Consequently, we conclude that application of ENA may be helpful to design cost-effective remediation.

H53A-1232 1340h

Field Investigation of Natural Attenuation of a Petroleum Hydrocarbon Contaminated Aquifer, Gyeonggi Province, Korea

* YANG, J (yjh2003@snu.ac.kr) , Seoul National University, School of Earth and Environmental Sciences, Seoul, 151-747 Korea, Republic of
LEE, K (kklee@snu.ac.kr) , Seoul National University, School of Earth and Environmental Sciences, Seoul, 151-747 Korea, Republic of
BAE, G (gokbae@snu.ac.kr) , Seoul National University, School of Earth and Environmental Sciences, Seoul, 151-747 Korea, Republic of

In remediation of a petroleum hydrocarbon contaminated aquifer, natural attenuation may be significant as a remedial alternative. Therefore, natural attenuation should be investigated in the field in order to effectively design and evaluate the remediation strategy at the contaminated site. This study focused on evaluating the natural attenuation for benzene, toluene, ethylbenzene, and xylene (BTEX) at a contaminated site in South Korea. At the study site, the aquifer is composed of a high permeable gravel layer and relatively low permeable sandy-silt layers. Groundwater level vertically fluctuated between 1m and 2m throughout the year (April, 2003~June, 2004) and showed direct response to rainfall events. Chemical analyses of sampled groundwater were performed to investigate the concentrations of various chemical species which are associated with the natural attenuation processes. To evaluate the degree of the biodegradation, the expressed biodegradation capacity (EBC) analysis was done using aerobic respiration, nitrate reduction, manganese reduction, ferric iron reduction, and sulfate reduction as an indicator. High EBC value of sulfate indicate that anaerobic biodegradation by sulfate reduction was a dominant process of mineralization of BTEX at this site. The EBC values decrease sensitively when heavy rainfall occurs due to the dilution and inflow of electron acceptors through a gravel layer. The first-order biodegradation rates of BTEX were estimated by means of the Buscheck and Alcantar method (1995). Results show that the natural attenuation rate of benzene was the highest among the BTEX.

H53A-1233 1340h

3-D Source Identification of Borden Emplacement Site

* Jin, X (xjin@ncsu.edu) , North Carolina State Uiversity, Dept. of Civil Engineering, North Carolina State University, Raleigh, NC 27695-7908 United States
Mahinthakumar, K (gmkumar@ncsu.edu) , North Carolina State Uiversity, Dept. of Civil Engineering, North Carolina State University, Raleigh, NC 27695-7908 United States

Finding the location and concentration of contaminant sources is an important step in groundwater remediation and management. This typically requires the solution of an inverse problem. In this study, an optimization-based approach is used for solving a three-dimensional field scale source identification inverse problem. Inverse modeling using optimization techniques requires many solutions of the corresponding forward problem and is computationally intensive. Fortunately, with the wide-spread use of parallel computing technology, solving inverse problems such as these are increasingly becoming feasible. We have developed a parallel hybrid optimization framework that can solve various compute-intensive groundwater inverse problems. In this study, the identification of the emplaced source at Borden site, Ontario, Canada, as described by Rivett, Feenstra and Cherry 2001 (RFC 2001), is carried out using this optimization framework by employing the supercomputing environment at North Carolina State University. The forward simulation model was first calibrated by selecting an appropriate heterogeneous hydraulic conductivity field that leads to a modeled contaminant plume that closely matches published field measurements reported by RFC2001. The randomly heterogeneous hydraulic conductivity field was generated by a turning bands algorithm using previously published statistical parameters for the Borden site (Sudicky 1985). The emplaced source location and concentration is then determined by using the hybrid optimization framework. The hybrid optimizer uses genetic algorithms (GAs) coupled with various local search approaches. In this study, real encoded GA (RGA), and two local search approaches, (i) Nelder-Mead simplex method, (ii) Fletcher and Reeves conjugate gradient method were used. The MPI (Message Passing Interface) communication library is used to implement parallelism in the optimizer and the simulators. Simulation results indicate that the combination of parallel computing and efficient optimization algorithms has enabled the solution of a field-scale three-dimensional source identification problem at the Borden site with over 90% accuracy in a timely manner.

H53A-1234 1340h

Modeling Bacteria Transport Using Fractional Derivatives

* Kurita, S (skurita@unr.edu) , University of Nevada, Reno, Department of Mathematics and Statistics, Reno, NV 89557 United States
Meerschaert, M (mcubed@unr.edu) , University of Nevada, Reno, Department of Physics, Reno, NV 89557 United States
Baeumer, B (bbaeumer@maths.otago.ac.nz) , University of Otago, Department of Mathematics and Statistics P.O.Box 56, Dunedin, 9999 New Zealand

Usually contaminant transport through porous media is modeled through the advection-dispersion equation (ADE), while the heterogeneities in the system are modeled stochastically. Unfortunately, stochastic models are computationally intensive. An alternative is to use fractional ADEs, which are capable of capturing the greater variation in particle locations that are seen in various breakthrough curve data. We model bacteria transport through porous media using fractional ADEs, and solve the resulting fractional initial value problem with forcing functions numerically.

H53A-1235 1340h

Modeling Multi-process Transport of Pathogens in Porous Media

* Cheng, L (chengli@arizona.edu) , Department of Hydrology and water Resources, University of Arizona 429 Shantz Building, Tucson, AZ 85721 United States
Brusseau, M L (brusseau@Ag.arizona.edu) , Department of Hydrology and water Resources, University of Arizona 429 Shantz Building, Tucson, AZ 85721 United States
Brusseau, M L (brusseau@Ag.arizona.edu) , Department of Soil, Water and Environmental Science, University of Arizona 429 Shantz Building, Tucson, AZ 85721 United States

The transport behavior of microorganisms in porous media is of interest with regard to the fate of pathogens associated with wastewater recharge, riverbank filtration, and land application of biosolids. This interest has fomented research on the transport of pathogens in the subsurface environment. The factors influencing pathogen transport within the subsurface environment include advection, dispersion, filtration, and inactivation. The filtration process, which mediates the magnitude and rate of pathogen retention, comprises several mechanisms such as attachment to porous-medium surfaces, straining, and sedimentation. We present a mathematical model wherein individual filtration mechanisms are explicitly incorporated along with advection, dispersion, and inactivation. The performance of the model is evaluated by applying it to several data sets obtained from miscible-displacement experiments conducted using various pathogens. Input parameters are obtained to the extent possible from independent means.

H53A-1236 1340h

Modeling Hematite Bioreduction under Growth Conditions

* Yu, J (ji324333@pegasus.cc.ucf.edu) , University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816 United States
Chen, C (ch674162@pegasus.cc.ucf.edu) , University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816 United States
Yeh, G (gyeh@mail.ucf.edu) , University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816 United States
Burgos, W D (wdb3@psu.edu) , The Pennsylvania State University, 212 Sackett Bldg, University Park, PA 16802 United States
Mynyard, M L (mminyards@psu.edu) , The Pennsylvania State University, 212 Sackett Bldg, University Park, PA 16802 United States

The focus of this work is on simulating and analyzing bioreduction kinetics of natural hematite-coated sand by dissimilatory metal-reducing bacterium (DMRB), Shewanella putrefaciens CN32, under growth conditions with lactate as the electron donor. A reaction-based biogeochemical model was used. A series of batch experiments with different initial conditions were performed to determine the rate formulations/parameters for hematite bioreduction and related reactions. Three different kinetic reaction rate formations were used to model hematite bioreduction. The consistency of mass conservation equations was assessed. Assumptions regarding equilibrium reactions were also assessed. Column experiments focused on transient reactive transport were conducted under otherwise identical conditions, except that the flow rate was systematically varied. The determined rate formulations/parameters were systematically tested with these column experiments using a reactive biogeochemical transport model that coupled hydrologic transport and reactive biogeochemistry. The model simulated the hematite bioreduction of hematite-coated sand in column experiments reasonably well using rate formulation/parameters determined from batch experiments. This study supports the hypothesis that mechanistic-based reaction rates of batch experiments can be scaled up and ported to column experiments.