Mercury Cycling in Stream Ecosystems. 3. Trophic Dynamics and Methylmercury Bioaccumulation
Mercury Cycling in Stream Ecosystems. 3. Trophic Dynamics and Methylmercury Bioaccumulation
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DOI：
10.1021/es8027567
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发表时间：
2009-04-15
影响因子：
11.4
通讯作者：
Aiken, George R.
中科院分区：
文献类型：
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作者：
Chasar, Lia C.;Scudder, Barbara C.;Aiken, George R.
营养动力学（群落组成和摄食关系）已被确定为湖泊、水库和海洋生态系统中甲基汞生物累积的重要驱动因素。营养动力学和地球化学控制的相对重要性，在流中的甲基汞的生物积累，但是，仍然很少的特点。对美国8个河流生态系统（俄勒冈州、威斯康星州和佛罗里达）中的甲基汞生物累积进行了评估，这些生态系统在气候、景观特征、大气汞沉积和河流化学方面涵盖了很大的范围。在所有的地理区域和所有的流，总汞（THG）的浓度在顶级捕食鱼类和饲料鱼类，和无脊椎动物中的甲基汞，强烈的正相关的浓度过滤THG（FTHG），过滤甲基汞（FMeHg），和溶解有机碳（DOC）; DOC的复杂性（通过特定的紫外线吸收测量）;和百分比湿地流域。非城市溪流的相关性最强。虽然对数[汞]与三角洲N-15的回归表明，生物群中的汞显着增加的营养位置内7个8个流，汞浓度在顶级捕食鱼类（包括割喉，彩虹，褐鳟鱼;绿色翻车鱼;和大口黑鲈）的相对营养位置的差异没有强烈的影响。斜率的日志[汞]与三角洲N-15，营养富集的效率的指标，范围从0.14到0.27的所有流。这些数据表明，在FTHg的大范围内，（0.14-14.2 ng L-1），FMeHg（0.023-1.03 ng L-1），DOC（0.50-61.0 mg L-1），河流中顶级捕食者鱼类的汞污染可能主要取决于食物网底层可吸收的甲基汞量，而不是营养位置的差异顶级掠食者的鱼。
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.