Custer Thomas W, Dummer Paul M, Custer Christine M, Li Azusa U, Warburton David, Melancon Mark J, Hoffman David J, Matson Cole W, Bickham John W
US Geological Survey, Upper Midwest Environmental Sciences Center, 2630 Fanta Reed Road, La Crosse, WI 54603, USA.
Environ Monit Assess. 2007 Oct;133(1-3):335-45. doi: 10.1007/s10661-006-9588-8. Epub 2007 Feb 8.
The U.S. Army Corps of Engineers conducted a water drawdown on Navigation Pool 8 of the Upper Mississippi River during the summers of 2001 and 2002 to increase aquatic vegetation production and thereby improve fish and wildlife habitat. Flooding of previously dried wetlands, however, may increase the rate of mercury methylation and make mercury more available to terrestrial vertebrates that feed in aquatic environments. Our objective was to determine if mercury, other elements, and organochlorine contaminants were more available to vertebrates following the 2001 drawdown. Tree swallow (Tachycineta bicolor) eggs and nestlings were collected at two sites on Pool 8 and a nearby Reference site in 2000 (pre-2001 drawdown), 2001 (pre-2001 drawdown) and 2002 (post-2001 drawdown) and tissues were analyzed for mercury, other elements, and organochlorine contaminants. Bioindicator measurements of genetic damage, oxidative stress, ethoxyresorufin-O-dealkylase activity, and the ratio of liver to nestling mass were also measured in nestlings at all sites and all years. Based on a multivariate analysis, the 2001 drawdown of Pool 8 did not influence element concentrations, organochlorine concentrations, or bioindicator response. Concentrations of inorganic and organochlorine contaminants in tree swallow eggs and nestlings were not at toxic levels. Hatching success did not differ among years and was comparable to the nationwide average.
2001年和2002年夏季，美国陆军工程兵团在上密西西比河8号航段进行了水位下降操作，以增加水生植物产量，从而改善鱼类和野生动物栖息地。然而，此前干涸湿地的洪水泛滥可能会提高汞甲基化速率，并使汞更容易被在水生环境中觅食的陆生脊椎动物获取。我们的目标是确定2001年水位下降后，汞、其他元素和有机氯污染物是否更容易被脊椎动物获取。2000年（2001年水位下降前）、2001年（2001年水位下降前）和2002年（2001年水位下降后），在8号航段的两个地点和附近一个参考地点收集了树燕（Tachycineta bicolor）的卵和雏鸟，并对其组织进行了汞、其他元素和有机氯污染物分析。还测量了所有地点和年份雏鸟的遗传损伤、氧化应激、乙氧基异吩唑酮 - O - 脱烷基酶活性以及肝脏与雏鸟体重比的生物指示测量值。基于多变量分析，2001年8号航段的水位下降并未影响元素浓度、有机氯浓度或生物指示响应。树燕卵和雏鸟中无机和有机氯污染物的浓度未达到有毒水平。孵化成功率在各年份之间没有差异，与全国平均水平相当。
