Keyel Edward R, Etterson Matthew A, Niemi Gerald J, Evers David C, DeSorbo Christopher R, Hoffman Joel C, Nichols John W, Li Yang, Nicoletti Frank
Department of Biology, University of Minnesota Duluth, Duluth, Minnesota, USA.
Natural Resources Research Institute, University of Minnesota, Duluth, Minnesota, USA.
Condor. 2020 Feb 20;122(2):1-17. doi: 10.1093/condor/duz069.
Mercury (Hg) is a toxic heavy metal that, when methylated to form methylmercury (MeHg), bioaccumulates in exposed animals and biomagnifies through food webs. The purpose of this study was to assess Hg concentrations in raptors migrating through the upper midwestern USA. From 2009 to 2012, 966 raptors of 11 species were captured at Hawk Ridge, Duluth, Minnesota, USA. Breast feathers were sampled to determine the concentration of total Hg. Mean Hg concentrations ranged from 0.11 to 3.46 μg g fresh weight across species and were generally higher in raptors that feed on birds in comparison with those that feed on mammals. To evaluate the effect of dietary sources on Hg biomagnification, carbon and nitrogen stable isotope ratios were measured in feathers of the 2 species with the highest Hg concentrations, Merlin () and Sharp-shinned Hawk (). Measured δ C values were similar in both species and indicated a primarily terrestrial-derived diet, whereas δ N values suggested that individual Merlin and Sharp-shinned Hawk feeding at higher trophic levels accumulated higher concentrations of Hg. The risk to birds associated with measured levels of feather Hg was evaluated by calculating blood-equivalent values using an established algorithm. Predicted blood values were then compared to heuristic risk categories synthesized across avian orders. This analysis suggested that while some Merlin and Sharp-shinned Hawk were at moderate risk to adverse effects of MeHg, most of the sampled birds were at negligible or low risk.
汞（Hg）是一种有毒重金属，甲基化形成甲基汞（MeHg）后，会在受暴露动物体内生物累积，并通过食物网进行生物放大。本研究的目的是评估在美国中西部上游迁徙的猛禽体内的汞浓度。2009年至2012年期间，在美国明尼苏达州德卢斯的霍克岭捕获了11个物种的966只猛禽。采集胸部羽毛以测定总汞浓度。各物种的汞平均浓度范围为0.11至3.46微克/克鲜重，以鸟类为食的猛禽体内汞浓度通常高于以哺乳动物为食的猛禽。为了评估食物来源对汞生物放大的影响，对汞浓度最高的两个物种——矛隼（Falco columbarius）和条纹鹰（Accipiter striatus）的羽毛进行了碳和氮稳定同位素比率测量。两个物种的δC测量值相似，表明主要以陆地来源的食物为食，而δN值表明，处于较高营养级的个体矛隼和条纹鹰积累了更高浓度的汞。通过使用既定算法计算血液等效值，评估了与测量的羽毛汞水平相关的鸟类风险。然后将预测的血液值与跨鸟类目综合的启发式风险类别进行比较。该分析表明，虽然一些矛隼和条纹鹰面临甲基汞产生不利影响的中度风险，但大多数采样鸟类面临可忽略或低风险。
