Geochemistry: Exploration, Environment, Analysis; May 2002; v. 2; no. 2;
p. 131-142; DOI: 10.1144/1467-787302-016
© 2002 Geological Society of London
The effect of mining and related activities on the sediment trace element geochemistry of the Spokane River Basin, Washington, USA
Cecile A. Grosbois1,
Arthur J. Horowitz2,
James J. Smith2 and
Kent A. Elrick2
1 Laboratoire
de Geologie, Universite de Limoges, 123 Av. A. Thomas, Bat. Les
Dryades, 87000 Limoges,
France
2 US Geological
Survey, Peachtree Business Center, Suite 130, 3039 Amwiler Road,
Atlanta, GA 30360, USA(e-mail:
HOROWITZ{at}USGS.GOV)
Surface
sediments in the Spokane River Basin are enriched in Pb, Zn, As, Cd,
Sb, and Hg relative to local background levels. Maximum enrichment
occurs in the Upper Spokane River in close proximity to Lake Coeur
d'Alene. On average, enrichment decreases downstream. Subsurface
sediments also are enriched in Pb, Zn, As, Cd, Sb, and Hg relative to
background levels. Enrichment began between 1900 and 1920 in the middle
of the basin; this is contemporaneous with similar findings in Lake
Coeur d'Alene (the upstream source of the Spokane River), as well
as the completion of Long Lake Dam (1913). In the most downstream part
of the basin, enrichment began between 1930 and 1940. This temporal
shift may reflect the latter's greater distance from the Coeur
d'Alene River Basin, the presumptive source of the enriched trace
elements, but is more likely the result of the completion of Grand
Coulee Dam (19341941) which backed up the Spokane River, and
elevated water levels by about 30 m in the most downstream part
of the
basin.
Copyright © 2009 by Geological Society of London