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WATER RESOURCES RESEARCH, VOL. 39, NO. 9, 1247, doi:10.1029/2002WR001571, 2003

Diel cycles in dissolved metal concentrations in streams: Occurrence and possible causes

David A. Nimick

U.S. Geological Survey, Helena, Montana, USA


Christopher H. Gammons

Department of Geological Engineering, Montana Tech of the University of Montana, Butte, Montana, USA


Thomas E. Cleasby

U.S. Geological Survey, Helena, Montana, USA


James P. Madison

Montana Bureau of Mines and Geology, Butte, Montana, USA


Don Skaar

Montana Fish, Wildlife and Parks, Helena, Montana, USA


Christine M. Brick

Department of Geology, University of Montana, Missoula, Montana, USA


Abstract

Substantial diel (24-hour) cycles in dissolved (0.1-μm filtration) metal concentrations were observed during low flow for 18 sampling episodes at 14 sites on 12 neutral and alkaline streams draining historical mining areas in Montana and Idaho. At some sites, concentrations of Cd, Mn, Ni, and Zn increased as much as 119, 306, 167, and 500%, respectively, from afternoon minimum values to maximum values shortly after sunrise. Arsenic concentrations exhibited the inverse temporal pattern with increases of up to 54%. Variations in Cu concentrations were small and inconsistent. Diel metal cycles are widespread and persistent, occur over a wide range of metal concentrations, and likely are caused primarily by instream geochemical processes. Adsorption is the only process that can explain the inverse temporal patterns of As and the divalent metals. Diel metal cycles have important implications for many types of water-quality studies and for understanding trace-metal mobility.

Received 10 July 2002; accepted 18 June 2003; published 17 September 2003.

Index Terms: 1065 Geochemistry: Trace elements (3670); 1045 Geochemistry: Low-temperature geochemistry; 1871 Hydrology: Surface water quality.

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Citation: Nimick, D. A., C. H. Gammons, T. E. Cleasby, J. P. Madison, D. Skaar, and C. M. Brick (2003), Diel cycles in dissolved metal concentrations in streams: Occurrence and possible causes, Water Resour. Res., 39(9), 1247, doi:10.1029/2002WR001571.