Speciation, bioavailability and toxicity of trace metals in the aquatic environment

自20世纪初以来，工业活动大大增加了金属在我们环境中的循环速度。“有毒金属”对空气、水和土壤的污染被认为是社会面临的主要环境问题之一。然而，由合格的分析化学家检测到的环境中仅仅存在污染物并不一定意味着污染物对环境质量有害——对于金属来说尤其如此，因为金属自然存在于环境中，而且同一种金属可能以各种不同的形式或“物种”存在（“物种”=金属在这些形式中的分布）。有些金属种类是相对无害的，而同样的金属的其他种类可能是剧毒的。在过去的20多年里，人们在实验室和合成介质中对金属的“物种形成”与其对各种水生生物的毒性之间的联系进行了广泛的研究，并得出了一些有用的一般性结论。然而，在开始接近自然水的复杂性的系统上所做的工作很少。因此，目前还不清楚迄今为止获得的实验室结果能在多大程度上转化到自然系统中——目前的研究计划旨在帮助弥合这一差距。整体的实验方法是跨学科的，因为它涉及分析化学，地球化学和水生毒理学的各个方面。目前关注的金属包括必需微量营养素（如铜、锌）和没有已知生物功能的有毒金属（如银）。生物“目标”包括淡水藻类和水生无脊椎动物。金属摄取（吸附、积累、亚细胞分配）和生物体反应（生理、生长、死亡）作为接触介质（地球）化学的功能进行监测。预期从这个方案得到的实验结果将有助于环境管理人员不断努力改进目前的金属水质标准，并发展适用于金属排放的“环境影响监测”的可行技术。

Since the beginning of the 20th century, industrial activities have greatly increased the rates at which metals circulate through our environment. The resulting contamination of our air, water and soil by "toxic metals" is recognized as one the major environmental problems faced by society. However, the mere presence of a contaminant in the environment, as detected by a competent analytical chemist, does not necessarily mean that the contaminant is detrimental to environmental quality - this is especially true for metals, since metals are naturally present in the environment, and since the same metal may be present in various different forms or «species» («speciation» = metal distribution among these forms). Some metal species are relatively innocuous, whereas other species of the same metal may be highly toxic. The link between the «speciation» of a metal and its toxicity to various aquatic organisms has been studied extensively over the last 20+ years in the laboratory, in synthetic media, and some useful generalities have emerged. However, very little work has been done on systems that begin to approach the complexity of natural waters. As a result, it is unclear to what extent the laboratory results obtained to date can be transposed to natural systems - the present research programme is designed to help bridge this gap. The overall experimental approach is interdisciplinary, as it involves aspects of analytical chemistry, geochemistry and aquatic toxicology. Metals of current interest include both essential micronutrients (e.g., Cu, Zn) and toxic metals with no known biological function (e.g., Ag). The biological "targets" include freshwater algae and aquatic invertebrates. Metal uptake (adsorption, accumulation, subcellular partitioning) and organism response (physiology, growth, mortality) are monitored as functions of the (geo)chemistry of the exposure media. It is anticipated that the experimental results derived from this programme will be of use to environmental managers in their ongoing efforts to refine current water quality criteria for metals, and to develop viable techniques for "environmental effects monitoring" (EEM) as applied to metal emissions.