University of New Brunswick/Canadian Rivers Institute, 100 Tucker Park Rd, Saint John, NB E2L 4A6, Canada.
University of New Brunswick/Canadian Rivers Institute, 100 Tucker Park Rd, Saint John, NB E2L 4A6, Canada.
Sci Total Environ. 2015 Mar 15;509-510:195-205. doi: 10.1016/j.scitotenv.2014.04.133. Epub 2014 Jun 6.
In temperate regions of Canada, mercury (Hg) concentrations in biota and the magnitude of Hg biomagnification through food webs vary between neighboring lakes and are related to water chemistry variables and physical lake features. However, few studies have examined factors affecting the variable Hg concentrations in landlocked Arctic char (Salvelinus alpinus) or the biomagnification of Hg through their food webs. We estimated the food web structure of six high Arctic lakes near Resolute Bay, Nunavut, Canada, using stable carbon (δ(13)C) and nitrogen (δ(15)N) isotopes and measured Hg (total Hg (THg) in char, the only fish species, and methylmercury (MeHg) in chironomids and zooplankton) concentrations in biota collected in 2010 and 2011. Across lakes, δ(13)C showed that benthic carbon (chironomids) was the dominant food source for char. Regression models of log Hg versus δ(15)N (of char and benthic invertebrates) showed positive and significant slopes, indicting Hg biomagnification in all lakes, and higher slopes in some lakes than others. However, no principal components (PC) generated using all water chemistry data and physical characteristics of the lakes predicted the different slopes. The PC dominated by aqueous ions was a negative predictor of MeHg concentrations in chironomids, suggesting that water chemistry affects Hg bioavailability and MeHg concentrations in these lower-trophic-level organisms. Furthermore, regression intercepts were predicted by the PCs dominated by catchment area, aqueous ions, and MeHg. Weaker relationships were also found between THg in small char or MeHg in pelagic invertebrates and the PCs dominated by catchment area, and aqueous nitrate and MeHg. Results from these high Arctic lakes suggest that Hg biomagnification differs between systems and that their physical and chemical characteristics affect Hg concentrations in lower-trophic-level biota.
在加拿大的温带地区，生物体内的汞 (Hg) 浓度以及通过食物网进行汞生物放大的程度在相邻湖泊之间存在差异，这与水化学变量和湖泊物理特征有关。然而，很少有研究考察影响内陆北极红点鲑 (Salvelinus alpinus) 体内汞浓度变化或通过其食物网进行汞生物放大的因素。我们使用稳定的碳 (δ(13)C) 和氮 (δ(15)N) 同位素来估计加拿大努纳武特地区雷索卢特湾附近的六个高北极湖泊的食物网结构，并测量了 2010 年和 2011 年采集的生物体内的汞浓度（只有一种鱼类——北极红点鲑体内的总汞 (THg) 和摇蚊和浮游动物体内的甲基汞 (MeHg)）。在湖泊之间，δ(13)C 表明底栖碳（摇蚊）是北极红点鲑的主要食物来源。log Hg 与 δ(15)N（北极红点鲑和底栖无脊椎动物）的回归模型显示出正相关且显著的斜率，表明所有湖泊都存在汞生物放大作用，且在某些湖泊中这种放大作用更为明显。然而，没有一个使用所有水化学数据和湖泊物理特征生成的主成分 (PC) 可以预测不同的斜率。以水合离子为主的 PC 是摇蚊中 MeHg 浓度的负预测因子，这表明水化学会影响这些低营养级生物的汞生物可利用性和 MeHg 浓度。此外，PC 还可以预测由流域面积、水合离子和 MeHg 主导的回归截距。THg 在小型北极红点鲑或浮游无脊椎动物中的 MeHg 与由流域面积、水合硝酸盐和 MeHg 主导的 PC 之间也存在较弱的关系。这些高北极湖泊的结果表明，汞生物放大作用在不同系统之间存在差异，其物理和化学特征会影响低营养级生物体内的汞浓度。
