Using freshwater animals to understand trace element exposure in nature

作为铜和镍等金属的开采和精炼的世界领导者，加拿大有责任在理解和减轻这些污染物的环境影响方面也成为世界领导者。为了解释和预测水生动物的金属积累，需要考虑金属在水、沉积物和食物中的各种形式以及所涉生物的行为（摄食、挖洞等）。通过测量金属在动物细胞中的分布方式，人们还可以预测这些污染物引起毒性效应并转移到更高营养水平的可能性。为了理解和模拟这些过程，我和我的学生考虑：i）微量元素存在于水和沉积物中的地球化学形式（物种），ii）动物的穴居和进食行为; iii）微量元素在动物细胞中的分布。我们研究的微量元素，如镉，镍和硒，可能存在于高浓度的采矿和化石燃料开采影响的加拿大生态系统。以前，我们证明了在高酸性金属影响的湖泊中，镉和镍的浓度在湖水中可能非常高，但在昆虫中可能很低，而我们最近的测量结果表明，硒的情况正好相反。我们计划确定为什么会出现这种情况。我们还将通过测量哨兵生物中金属浓度的时空变化以及生活在污染梯度沿着的水生群落结构，来测量废弃矿区流出的酸性、金属污染水的影响。在这方面，我们将解释为什么共享相同栖息地的密切相关的动物在金属浓度上会有如此大的差异，并解释哨兵物种如何在高污染场所生存。总的来说，这些研究活动将使我们能够完善环境风险评估员所需的工具，以更好地了解，预测和减轻微量元素的影响，并允许培训学生，他们将非常有资格成为下一代环境研究人员的一部分。

As a world leader in the mining and refining of metals such as copper and nickel, the onus is on Canada to also be a world leader in understanding and mitigating the environmental impacts of these contaminants. To explain and predict metal accumulation by aquatic animals one needs to consider the various forms in which metals occur in water, sediment and food as well as the behaviour of the organisms involved (feeding, burrowing, etc.). By measuring the way in which metals are distributed in animal cells, one can also predict the likelihood that these contaminants will cause toxic effects and be transferred to higher trophic levels. To understand and model such processes, my students and I consider: i) the geochemical forms (species) in which trace elements exist in water and sediment, ii) the burrowing and feeding behaviours of animals; iii) the distribution of trace elements in animal cells. We study trace elements such as cadmium, nickel and selenium that are likely to be present at high concentrations in Canadian ecosystems influenced by mining and fossil-fuel extraction. Previously, we demonstrated that in highly-acidic metal-impacted lakes, cadmium and nickel concentrations can be very high in lakewater but low in insects, whereas our recent measurements suggest that the opposite is the case for selenium. We plan to determine why this is the case. We will also measure the impacts of acidic, metal-contaminated, water flowing from abandoned mine sites by measuring spatial and temporal changes in metal concentrations in sentinel organisms, as well as the structure of aquatic communities living along the contamination gradient. In this regard, we will explain why closely related animals sharing the same habitat can differ so widely in their metal concentrations, as well as explaining how sentinel species survive at highly-contaminated sites. Overall, these research activities will allow us to refine the tools needed by environmental risk assessors to better understand, predict and mitigate the effects of trace elements, as well as permit the training of students who will be eminently qualified to take their places as a part of the next generation of environmental researchers.