Canadian Wildlife Service, Environment Canada, Toronto, ON, Canada.
Ecotoxicology. 2011 Oct;20(7):1644-58. doi: 10.1007/s10646-011-0755-5. Epub 2011 Aug 11.
Current concentrations and spatial and temporal trends of total mercury (Hg) were assessed in eggs of the Herring Gull (Larus argentatus) over the period 1974-2009 at 15 sites in the Great Lakes: 2-3 sites per lake and one site in each of 3 connecting channels. Current (2009) concentrations ranged from 0.064 μg/g (wet weight) at Chantry Island (Lake Huron) to 0.246 μg/g at Middle Island (Lake Erie). There were significant inter-colony differences in mean Hg concentrations (2005-2009). Mercury concentrations at 14 of 15 sites declined from 23 to 86% between when it was first measured (usually 1974) and 2009. Declining temporal trends over the entire period (1974-2009) were significant at 10 of the 15 sites. On the other hand, there were no significant trends in mercury over the last 15 years. In the early years, declines of Hg in Herring Gull eggs tracked those in Rainbow Smelt (Osmerus mordax) in most Great Lakes. More recently, declines in gull eggs were more evident than in smelt and may be partially explained by temporal changes in the gull diet. When gull Hg data were adjusted for temporal changes in the gull diet, as inferred from stable nitrogen isotope values in eggs, significant declines in egg mercury levels were found only at 4 of 15 sites. Overall, Hg concentrations have declined in Great Lakes Herring Gull eggs over the period 1974-2009 but changes in the gull diet may be contributing, in part, to those declines. Examination of contaminant temporal trends in multiple indicator species will ensure accurate inferences regarding contaminant availability in the environment.
在 1974 年至 2009 年期间，在大湖区的 15 个地点（每个湖泊有 2-3 个地点，3 个连接通道中的每个通道有 1 个地点）评估了鲱鸥（Larus argentatus）卵中的总汞（Hg）的当前浓度和时空趋势。当前（2009 年）浓度范围从休伦湖的钱特里岛的 0.064μg/g（湿重）到伊利湖的米德尔岛的 0.246μg/g。在 15 个地点中的 14 个地点，在 2005-2009 年期间，平均 Hg 浓度存在显着的种间差异。在 15 个地点中的 10 个地点，从 1974 年首次测量（通常在 1974 年）到 2009 年，汞浓度下降了 23%至 86%。在整个时期（1974-2009 年），15 个地点中有 10 个地点的时间趋势呈显着下降趋势。另一方面，在过去 15 年中，汞的趋势没有显着变化。在早期，鲱鸥卵中 Hg 的下降与大湖区大多数彩虹鲱（Osmerus mordax）的下降相吻合。最近，在鸥卵中的下降比在鲱鱼中更为明显，这可能部分解释了鸥鸟饮食的时间变化。当根据卵中稳定氮同位素值推断出鸥鸟饮食的时间变化来调整鸥鸟 Hg 数据时，仅在 15 个地点中的 4 个地点发现卵中汞水平显着下降。总体而言，在 1974 年至 2009 年期间，大湖区鲱鸥卵中的 Hg 浓度有所下降，但鸥鸟饮食的变化可能部分导致了这些下降。检查多种指示物种的污染物时间趋势将确保对环境中污染物可用性的准确推断。
