Hammerschmidt Chad R, Fitzgerald William F
Department of Marine Sciences, University of Connecticut, Groton, Connecticut 06340, USA.
Environ Sci Technol. 2005 May 1;39(9):3034-9. doi: 10.1021/es0485107.
A connection between loadings of inorganic Hg, especially from the atmosphere, and accumulation of methylmercury (MeHg) in aquatic biota has not been firmly established. Mosquitoes (Diptera: Culicidae) may be a useful indictor of Hg contamination or MeHg accumulation in aquatic ecosystems because they have aquatic life stages, and their ubiquitous distribution permits sampling across wide ranges of climate, biological productivity, and atmospheric Hg deposition. We examined MeHg in adult mosquitoes from subtropical (Florida), maritime (California), continental (Michigan), and arctic (Alaska) regions of North America that span a range in wet atmospheric Hg deposition (1.5-15 microg m(-2) y(-1)). More than 90% of the Hg in mosquitoes was MeHg, and concentrations varied among locations. Levels of MeHg differed among mosquito species at six sites in northwest Florida (Ochlerotatus atlanticus < Culex nigripalpus < Anopheles crucians); this may be related to differences in biogeochemical characteristics of the aquatic habitat that affect dietary accumulation of MeHg during the larval stage. Mosquito MeHg was related positively to wet atmospheric Hg deposition among locations where atmospheric deposition is the principal source of Hg, and it was greatly enhanced in Hg-polluted environs near the Sulphur Bank Mine in Lake County, California. These results suggest that MeHg in mosquitoes may be a useful and sensitive indicator of Hg loadings to aquatic systems, including that derived from atmospheric deposition.
无机汞（尤其是来自大气中的无机汞）的负荷与水生生物群中甲基汞（MeHg）的积累之间的联系尚未得到确凿证实。蚊子（双翅目：蚊科）可能是水生生态系统中汞污染或甲基汞积累的有用指示生物，因为它们具有水生生活阶段，且分布广泛，能够在各种气候、生物生产力和大气汞沉降范围内进行采样。我们检测了来自北美亚热带（佛罗里达州）、沿海（加利福尼亚州）、大陆性（密歇根州）和北极（阿拉斯加州）地区成年蚊子体内的甲基汞，这些地区的大气湿汞沉降范围为1.5 - 15微克/平方米·年。蚊子体内90%以上的汞是甲基汞，且浓度因地点而异。在佛罗里达州西北部的六个地点，不同蚊子种类的甲基汞含量不同（大西洋伊蚊 < 黑须库蚊 < 十字疟蚊）；这可能与水生栖息地的生物地球化学特征差异有关，这些差异会影响幼虫阶段甲基汞通过饮食的积累。在大气沉降是汞主要来源的地点，蚊子体内的甲基汞与大气湿汞沉降呈正相关，并且在加利福尼亚州莱克县硫磺银行矿附近的汞污染环境中，甲基汞含量大幅增加。这些结果表明，蚊子体内的甲基汞可能是水生系统汞负荷（包括来自大气沉降的汞负荷）的有用且敏感的指标。
