The rouge river watershed pollution by trace elements: atmospheric depositions and emission sources

Abstract

Atmospheric inputs of trace elements to the Rouge River watershed by particle dry deposition and aerosol scavenging by precipitation were presented along with the annual emission of trace elements to the atmosphere by emission source category. A dynamic physical-based model was used to evaluate the dry and wet deposition flux of particle-segregated trace elements and its temporal and spatial variation in the Rouge River watershed from 1982 to 1992. Annual emissions of trace elements to the atmosphere were estimated assuming a controlled status for all the emission sources which include coal and oil combustion utilities, iron-steel manufacturing plants, metal production from primary and secondary pyrometallurgical processes, cement manufacturing, solid waste and sewage sludge incinerators. In general, there is a good agreement between the trend in the atmospheric input (dry + wet deposition fluxes) to the Rouge River watershed and that in the annual emission of trace elements to the atmosphere with r2 in the range of 0.84 to 0.98. Atmospheric inputs and emissions are following downward trends for Pb, whereas for Cd, Cr, Ni and Hg show a steady increase since 1987/1988. The modeled long-term average of the total (dry + wet) deposition flux of trace elements to the Rouge River watershed is 3167 ± 2548 g km−2 yr−1 for Pb, 397 ± 132 g km−2 yr−1 for Ni, 350 ± 160 g km−2 yr−1 for Cr, 130 ± 39 g km−2 yr−1 for Cd, and 8.6 ± 3.7 g km−2 yr−1 for Hg.