Investigating metal bioavailability to aquatic organisms: Biogeochemical perspectives

过去世纪的采矿活动对水生生态系统造成了重大的环境风险，特别是在加拿大，它拥有大量的矿产和水生资源（占世界地表淡水的20%，拥有世界上最长的海岸线）。现在人们普遍认识到，金属对水生生物的生物利用度（即生物累积性和毒性）取决于水的物理化学特性（如pH值、温度、盐度、溶解有机物）。然而，一些关键的环境因素对金属生物利用度的影响仍然很差，削弱了我们准确评估金属生态风险的能力。尽管有相当多的证据表明，盐度影响金属的生物利用度暴露于自然沃茨的全盐度梯度（即0 - 35 ppt）的河口物种，这种调制的机制仍然很差的特点。这种知识差距部分是由于难以破译水化学和生物生理学的相互交织的作用，这两者都随盐度而变化。同样，虽然在温带地区，自然沃茨的温度通常在4至25摄氏度之间，但金属的环境风险主要取决于在实验室环境温度（即15至20摄氏度）下进行的毒理学研究。然而，温度可以影响金属的水地球化学和生物生理，这两个可以有很大的影响金属的生物有效性。然而，很少有研究调查这些温度对水生生物毒理学结果的影响，特别是在冬季与夏季的情况下。利用分析地球化学，生物化学，生理学和生态毒理学的元素，我的实验室将探索金属生物利用度与（1）盐度和（2）温度的调制机制。值得注意的是，我们将开发一种新的离子交换技术来表征盐度对金属水地球化学的影响，然后研究盐度如何影响金属的生物利用度使用广盐性浮游植物。此外，在淡水中，我们将描述温度对金属水地球化学的影响（特别是对金属-DOM结合），然后描述冬季驯化与夏季驯化鱼类的金属生物利用度。目前的研究计划满足了世界范围内需要更好地了解控制金属与水生生物相互作用的过程。值得注意的是，我们将解决有关机制和盐度和温度控制对水生生物的金属生物利用度的相关性的基本知识差距。最终，这项研究将提供急需的信息，以准确地预测金属的空间和季节性风险。最后，该计划构成了一个独特的HQP培训机会，学生将使用跨学科科学来解决公共和私营部门感兴趣的重大社会问题。

Mining activities over the past century have created a significant environmental risk for aquatic ecosystems, particularly in Canada, which holds both large mineral and aquatic resources (20% of the world's surface fresh water and the world's longest coastline). It is now well-recognized that metal bioavailability (i.e. bioaccumulation and toxicity) to aquatic organisms depends on the water's physico-chemical characteristics (e.g. pH, temperature, salinity, dissolved organic matter (DOM)). Yet, the effects of some critical environmental factors on metal bioavailability remain poorly evaluated, impairing our ability to accurately assess metal's ecological risk. Despite considerable evidence that salinity affects metal bioavailability to estuarine species exposed to the full salinity gradient of natural waters (i.e. 0 35 ppt), the mechanisms of this modulation remain poorly characterized. This knowledge gap is partially due to the difficulties in deciphering the intertwined roles of water chemistry and organism physiology, which both vary with salinity. Similarly, while temperatures of natural waters typically range from 4 to 25C in temperate regions, the environmental risk of metals mostly relies on toxicological studies performed at lab ambient temperatures, i.e. around 15 20C. Yet, temperature can affect metal aqueous geochemistry and organism physiology, which can both have strong impacts on metal bioavailability. However, there have been few studies that have investigated these temperature effects on toxicological outcomes in aquatic organisms, especially in winter vs. summer scenarios.******Using elements of analytical geochemistry, biochemistry, physiology and ecotoxicology, my lab will explore the mechanisms underlying the modulation of metal bioavailability to aquatic organisms with (1) salinity and (2) temperature. Notably, we will develop a new ion-exchange technique to characterize the effects of salinity on metal aqueous geochemistry, then investigate how salinity affects metal bioavailability using euryhaline phytoplankton. Furthermore, in fresh water, we will characterize the effects of temperature on metal aqueous geochemistry (notably on metal-DOM binding), then characterize metal bioavailability to winter-acclimatized vs. summer-acclimatized fish.******The present research program meets a worldwide need for an improved understanding of the processes controlling the interactions of metals with aquatic organisms. Notably, we will address fundamental knowledge gaps about the mechanisms and relevance of salinity and temperature controls on metal bioavailability to aquatic organisms. Ultimately, this research will provide critically needed information to accurately predict the environmnental risk of metals, spatially and seasonally. Finally, this program constitutes a unique HQP training opportunity, where students will use interdisciplinary science to address major societal issues of interest to both the public and the private sector.