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处理的自然资源中动员硒（Se）。在某些情况下，硒可能会对水生生物造成不利影响，一些受硒问题影响的采矿作业在排放前将大部分活动的硒从其工艺沃茨中去除。然而，由于历史排放和/或目前的低水平排放，一些receivingenvironments有升高的Se浓度在其沉积物中。已知沉积物中的微生物可以将沉积的硒转化为生物可利用的有机形式（“物种”），但这些有机硒物种是否从沉积物中释放回上覆的沃茨中，然后被水体中的生物所利用尚不清楚。近年来，我们发展了一种分析方法，可以在ng/L的水平上测定沃茨中的有机硒，并可以对环境沃茨中的有机硒进行研究。如果这些有机硒存在于受采矿影响的水体中，那么一个主要的研究问题就是它们在这些沃茨中的稳定性。在实验室实验中，以前已经表明，这些有机物种容易被氧化，例如被氧气或紫外线辐射氧化，但迄今为止还没有实地数据来量化这些降解过程在实际接收沃茨中的速率。在这个项目中，我们将从硒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，随着时间的推移，在这些沃茨中的有机物种（天然或加标）的降解。本项目的目标是确定环境沃茨中离散有机硒物种的降解速率，以评估它们可用于生物累积的时间。作为一个有用的侧面，本研究还将确定所研究的有机硒物种在这些沃茨中的短期稳定性，以检查在从采样点到分析实验室的运输过程中是否发生显著降解。

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.