Stability of organic selenium species in waters receiving industrial discharges

加拿大的几种不同类型的采矿作业无意中从他们正在加工的自然资源中转移了硒(Se)。在某些情况下，硒可能会对水生生物造成不利影响，受硒问题影响的水产养殖作业在排放之前会从其工艺水中去除大部分可活化的硒。然而，由于过去的排放和/或当前的低水平排放，一些正在接受污染的环境中的沉积物中的硒浓度升高。众所周知，沉积物中的微生物可以将沉积的一些硒转化为生物可利用的有机形式(“物种”)，但尚不清楚这些有机硒物种是否会从沉积物中释放回上覆水域，在那里它们可能会被水柱中的生物利用。我们最近开发了一种分析方法，可以在ng/L浓度水平上测量水中的离散有机硒形态，现在可以研究环境水中的此类化合物。如果这种有机硒形态出现在受采矿影响的水系中，一个主要的公开研究问题是它们在这些水域中的稳定性。在实验室实验中，以前已经表明，这些有机污染物很容易被氧化，例如被氧气或紫外线辐射，但到目前为止，还没有现场数据来量化这些降解过程在实际接收水中的速率。在这个项目中，我们将从受Se影响的生态系统中的几个地点收集水样，并在受控的实验室条件下跟踪这些水域中有机硒(原生或添加)的降解情况。该项目的目标是确定环境水域中离散的有机硒物种的降解率，以评估它们可能可用于生物积累的时间。作为一个有用的侧面，这项研究还将确定所研究的有机硒在这些水域中的短期稳定性，以检查从采样点到分析实验室的运输过程中是否发生了显著的降解。

Several different types of mining operations in Canada inadvertently mobilize selenium (Se) from the naturalresources they're processing. In some cases, selenium may cause adverse effects on aquatic organisms, somining operations affected by Se issues remove most of the mobilized Se from their process waters prior todischarge. However, as a result of historic emissions and/or current low level emissions, some receivingenvironments have elevated Se concentrations in their sediments. It is known that microbes in sediments mayconvert some of the deposited Se into more bioavailable organic forms ("species"), but it is unknown whetherthese organic Se species are released from the sediments back into the overlying waters, where they might thenbe available to organisms in the water column. We have recently developed analytical methods to measurediscrete organic Se species in waters at the ng/L concentration level, and are now able to study suchcompounds in environmental waters.If such organic Se species occur in mining-impacted aquatic systems, one primary open research question istheir stability in these waters. In laboratory experiments, it has been shown previously that these organic Sespecies are susceptible to oxidation, e.g. by oxygen or UV-radiation, but there are to date no field data thatquantify the rates of these degradation processes in actual receiving waters. In this project, we will collectwater samples from several sites within a Se-impacted ecosystem, and follow the degradation of organic Sespecies (native or spiked) in these waters under controlled laboratory conditions over time. The goal of thisproject is to determine the degradation rates of discrete organic Se species in environmental waters, in order toassess for how long they might be available for bioaccumulation. As a useful side aspect, this study will alsodetermine the short term stability of the studied organic Se species in these waters, to check if significantdegradation occurs during transport from sampling site to analytical laboratory.