Mercury Cycling in Stream Ecosystems. 3. Trophic Dynamics and Methylmercury Bioaccumulation

被引:185
作者
Chasar, Lia C. [1 ]
Scudder, Barbara C. [2 ]
Stewart, A. Robin [3 ]
Bell, Amanda H. [2 ]
Aiken, George R. [4 ]
机构
[1] US Geol Survey, Florida Integrated Sci Ctr, Tallahassee, FL 32303 USA
[2] US Geol Survey, Wisconsin Water Sci Ctr, Middleton, WI 53562 USA
[3] US Geol Survey, Natl Res Program, Menlo Pk, CA 94025 USA
[4] US Geol Survey, Natl Res Program, Boulder, CO 80303 USA
关键词
MARINE FOOD-WEB; METAL BIOACCUMULATION; ISOTOPE RATIOS; METHYL MERCURY; NITROGEN; CARBON; FISH; DELTA-N-15; POSITION;
D O I
10.1021/es8027567
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
Trophic dynamics (community composition and feeding relationships) have been identified as important drivers of methylmercury (MeHg) bioaccumulation in lakes, reservoirs, and marine ecosystems. The relative importance of trophic dynamics and geochemical controls on MeHg bioaccumulation in streams, however, remains poorly characterized. MeHg bioaccumulation was evaluated in eight stream ecosystems across the United States (Oregon, Wisconsin, and Florida) spanning large ranges in climate, landscape characteristics, atmospheric Hg deposition, and stream chemistry. Across all geographic regions and all streams, concentrations of total Hg (THg) in top predator fish and forage fish, and MeHg in invertebrates, were strongly positively correlated to concentrations of filtered THg (FTHg), filtered MeHg (FMeHg), and dissolved organic carbon (DOC); to DOC complexity (as measured by specific ultraviolet absorbance); and to percent wetland in the stream basins. Correlations were strongest for nonurban streams. Although regressions of log[Hg] versus delta N-15 indicate that Hg in biota increased significantly with increasing trophic position within seven of eight individual streams, Hg concentrations in top predator fish (including cutthroat, rainbow, and brown trout; green sunfish; and largemouth bass) were not strongly influenced by differences in relative trophic position. Slopes of log[Hg] versus delta N-15, an indicator of the efficiency of trophic enrichment, ranged from 0.14 to 0.27 for all streams. These data suggest that, across the large ranges in FTHg (0.14-14.2 ng L-1), FMeHg (0.023-1.03 ng L-1), and DOC (0.50-61.0 mg L-1) found in this study, Hg contamination in top predator fish in streams likely is dominated by the amount of MeHg available for uptake at the base of the food web rather than by differences in the trophic position of top predator fish.
引用
收藏
页码:2733 / 2739
页数:7
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