Department of Biology, Laurentian University, Cooperative Freshwater Ecology Unit, Sudbury, Ontario, Canada.
Sci Total Environ. 2013 Feb 1;444:409-16. doi: 10.1016/j.scitotenv.2012.11.109. Epub 2012 Dec 29.
Much of the mercury (Hg) in freshwater fish of the boreal shield ecoregion is believed to originate from atmospheric deposition. As such, declines in fish Hg concentrations would be expected in response to recent declines in atmospheric Hg deposition in this ecoregion. We compared recent (2005-2010) and historic (1974-1981) muscle total mercury concentrations ([THg], standardized to a fish body mass of 1 kg) in seven fish species (five piscivores, two benthivores) from 73 lakes in northern Ontario (Canada) using a paired-comparisons approach. The rate of bioaccumulation (i.e., slopes of log(e)[THg] vs log(e) total length relationship) increased for walleye (Sander vitreus) but did not change significantly for any other species. There was no significant decline in mean [THg] between recent and historic time periods for any species. In fact, recent mean [THg] were slightly higher (<0.08 ppm) than historic mean [THg] for all species, and this difference was significant for northern pike (Esox lucius). The magnitude of the temporal change in northern pike declined significantly from south to north over the study area but there were no discernible geographic patterns in the temporal change in [THg] for any other species. This study shows that [THg] of most large-bodied fish species in boreal shield lakes are not declining in response to the decline in atmospheric Hg deposition.
在北方盾牌生态区的淡水鱼中，大部分汞（Hg）被认为来自大气沉降。因此，随着该生态区大气 Hg 沉降的减少，鱼类 Hg 浓度预计会下降。我们使用配对比较的方法，比较了加拿大安大略省北部 73 个湖泊中 7 种鱼类（5 种肉食性鱼类，2 种底栖鱼类）最近（2005-2010 年）和历史（1974-1981 年）的肌肉总汞浓度([THg]，标准化为鱼体质量 1 公斤)。拟饵鲈的生物积累率（即对数(e)[THg]与对数(e)体长关系的斜率）增加，但其他任何物种的变化都不显著。任何物种最近和历史时期的平均[THg]都没有明显下降。事实上，最近的平均[THg]略高于（<0.08ppm）所有物种的历史平均[THg]，并且这种差异在北方狗鱼（Esox lucius）中非常显著。在研究区域内，北方狗鱼的时间变化幅度从南到北显著下降，但其他任何物种的[THg]时间变化都没有明显的地理模式。这项研究表明，北方盾牌湖泊中大多数大型鱼类的[THg]并没有因大气 Hg 沉降减少而下降。
