Groupe de recherche interuniversitaire en limnologie et environnement aquatique (GRIL), Département de sciences biologiques, Université de Montréal , Pavillon Marie-Victorin CP6128, Succ. Centre-Ville, Montréal, Québec H3C 3J7, Canada.
Environ Sci Technol. 2014;48(5):2626-34. doi: 10.1021/es404839t. Epub 2014 Feb 21.
Environmental disturbances like deforestation or climate change may influence lake thermal and oxic stratification, thereby modifying cycles of contaminants such as mercury (Hg). In a lake naturally separated into three basins, the thermocline and oxycline of an experimental basin were deepened by 4 and 3 m, respectively, to study the effect on the methylmercury (MeHg) accumulation. This treatment decreased hypolimnetic MeHg concentration by approximately 90%, zooplankton concentrations by 30 to 50%, and in some fish by 45%. A multiple linear regression indicated that oxycline depth significantly influenced hypolimnetic MeHg concentrations, with no significant effect of thermocline depth, anoxic water volume, interface area of oxic-anoxic water, and sediment area in contact with anoxic water. Fish MeHg decline varied, with a greater response by low oxygen-tolerant bullhead. Increased pelagic primary and secondary production likely caused zooplankton and fish MeHg decreases via algal and growth dilution. Environmental changes leading to oxycline deepening are therefore predicted to cause a decrease in MeHg bioaccumulation in similar Canadian Shield lakes. If associated ecosystem impacts related to the deepening treatment are deemed acceptable, then this experiment provides a potential remediation method for small lakes confronted with MeHg accumulation.
环境干扰，如森林砍伐或气候变化，可能会影响湖泊的热分层和含氧分层，从而改变汞（Hg）等污染物的循环。在一个自然分为三个盆地的湖泊中，实验盆地的温跃层和氧跃层分别加深了 4 米和 3 米，以研究其对甲基汞（MeHg）积累的影响。这种处理使底层湖水中的 MeHg 浓度降低了约 90%，浮游动物浓度降低了 30%至 50%，一些鱼类的浓度降低了 45%。多元线性回归表明，氧跃层深度对底层湖水中的 MeHg 浓度有显著影响，而温跃层深度、缺氧水体积、含氧-缺氧水的界面面积和与缺氧水接触的沉积物面积没有显著影响。鱼类的 MeHg 下降幅度不同，低氧耐受的牛尾巴鱼的反应更大。浮游生物初级和次级生产力的增加可能通过藻类和生长稀释导致浮游动物和鱼类 MeHg 减少。因此，预计导致氧跃层加深的环境变化将导致类似的加拿大盾状湖泊中 MeHg 的生物积累减少。如果与加深处理相关的生态系统影响被认为是可以接受的，那么这种实验为面临 MeHg 积累的小湖泊提供了一种潜在的修复方法。
