FastFind »   Lastname: doi:10.1029/ Year: Advanced Search  

AGU: Geophysical Research Letters

 

Keywords

  • global multicompartmental modeling
  • persistent organic pollutants

Index Terms

  • Oceanography: General: Marine pollution
  • Global Change: Earth system modeling
  • Oceanography: Biological and Chemical: Biogeochemical cycles, processes, and modeling

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L24602, 5 PP., 2009
doi:10.1029/2009GL041340

Cycling of DDT in the global environment 1950–2002: World ocean returns the pollutant

Irene Stemmler

Max Planck Institute for Meteorology, Hamburg, Germany

Gerhard Lammel

Max Planck Institute for Chemistry, Mainz, Germany

Research Centre for Environmental Chemistry and Ecotoxicology, Masaryk University, Brno, Czech Republic

The global distribution and fate of the insecticide DDT was modeled for the first time using a spatially resolved global multicompartment chemistry-transport model comprising a 3D coupled atmosphere and ocean GCM, coupled to 2D vegetation surfaces and top soils. DDT enters the model environment as a pesticide in agriculture only. Final sinks of DDT in the total environment are degradation in air (hydroxyl radical reaction), on vegetation surfaces, in ocean sediments and soils. The process resolution of the ocean compartment, i.e., either a fixed or variable size and sinking velocity of suspended particles, has almost no effect on the large-scale cycling and fate of DDT. The residence times in various ocean basins were declining but varied regionally. The global ocean absorbed until 1977 and since then has been losing DDT, while large sea areas are still accumulating the pollutant. The main sink is volatilization to the atmosphere. In 1990, the year when emissions ceased, 292 kt of DDT were deposited to the global ocean, 301 kt were volatilized, and 41 kt were exported from the surface layer to the deeper levels. The sea region that has been representing the most significant (secondary) DDT source is the western N Atlantic (Gulf stream and N Atlantic Drift regions). It has been a source since approximately 1970. Also large parts of the tropical ocean and the southern mid-latitude ocean have turned net volatilizational (i.e., volatilization flux > deposition flux) during the 1980s. Despite the emissions migrating southward as a consequence of substance ban in mid latitudes, the geographic distribution of the contaminant (and, hence, environmental exposure) has been migrating steadily northward since the 1960s.

Received 13 October 2009; accepted 23 November 2009; published 31 December 2009.

Citation: Stemmler, I., and G. Lammel (2009), Cycling of DDT in the global environment 1950–2002: World ocean returns the pollutant, Geophys. Res. Lett., 36, L24602, doi:10.1029/2009GL041340.

Cited By

Please wait one moment ...