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Trends in metals in urban and reference lake sediments across the United States, 1970 to 2001

Environmental Toxicology and Chemistry

By:
, , and
DOI: 10.1897/05-459R.1

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Abstract

Trends in metals concentrations in sediment cores from 35 reservoirs and lakes in urban and reference settings were analyzed to determine the effects of three decades of legislation, regulation, and changing demographics and industrial practices in the United States on concentrations of metals in the environment. Decreasing trends outnumber increasing trends for all seven metals analyzed (Cd, Cr, Cu, Pb, Hg, Ni, and Zn). The most consistent trends are for Pb and Cr: For Pb, 83% of the lakes have decreasing trends and 6% have increasing trends; for Cr, 54% of the lakes have decreasing trends and none have increasing trends. Mass accumulation rates of metals in cores, adjusted for background concentrations, decrease from the 1970s to the 1990s, with median changes ranging from -46% (Pb) to -3% (Hg and Zn). The largest decreases are from lakes in dense urban watersheds where the overall metals contamination in recently deposited sediments has decreased to one-half its 1970s median value. However, anthropogenic mass accumulation rates in dense urban lakes remain elevated over those in lakes in undeveloped watersheds, in some cases by as much as two orders of magnitude (Cr, Cu, and Zn), indicating that urban fluvial source signals can overwhelm those from regional atmospheric sources. ?? 2006 SETAC.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Trends in metals in urban and reference lake sediments across the United States, 1970 to 2001
Series title:
Environmental Toxicology and Chemistry
DOI:
10.1897/05-459R.1
Volume
25
Issue:
7
Year Published:
2006
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Environmental Toxicology and Chemistry
First page:
1698
Last page:
1709
Number of Pages:
12