The present study accessed the use of diffusive gradients in thin film (DGT) as a surrogate for estimating the bioavailability and bioaccumulation of copper (Cu) and zinc (Zn) in a freshwater mussel. We coupled DGTs with mussels and deployed them in a constructed wetland. Water quality parameters were measured for a 4‐d period on 3 continuous occasions during 12‐d trials in the summer and winter; metal speciation was modeled for each occasion. Higher cumulative rainfall and water turbidity during the summer trial resulted in higher particulate metal concentrations compared to the winter trial. Mussel accumulated metals did not correlate with DGT‐measured metals but positively correlated with particulate metals in the summer because filtering particulate food mainly contributed to the bioaccumulation. In contrast, the winter trial suggested a positive correlation between metal bioaccumulation and DGT‐measured metals because uptake of dissolved organic matter (DOM) from water mainly contributed to the bioaccumulation, and the labile metal species complexed with DOM generally overlapped with DGT‐targeted metals. Though Cu has a higher affinity for organic ligands than Zn, the interactions between Cu and Zn in the mixture did not impede their uptake and bioaccumulation. The deployment duration when DGTs and mussels are coupled to compare metal bioavailability should be no less than 12 d so that mussels have enough time to accumulate contaminants from the environmental media. In summary, DGT is a convenient surrogate for biomonitoring, but it may not fit the real environment such as the aquatic system with unstable water chemistries. Geochemical modeling is good at calculating metal speciation but inferior to DGT in predicting bioavailability and mimicking bioaccumulation. Environ Toxicol Chem 2020;39:2485–2495. © 2020 SETAC

中文翻译：

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应用DGT预测水化学不稳定的水生系统中金属混合物的生物利用度的局限性。

本研究利用薄膜中的扩散梯度（DGT）作为替代物来估算淡水贻贝中铜（Cu）和锌（Zn）的生物利用度和生物累积。我们将DGT与贻贝结合在一起，并将它们部署在人工湿地中。在夏季和冬季的12天试验中，连续3次在4天时间内测量了水质参数；每种情况都对金属形态进行了建模。与冬季试验相比，夏季试验期间较高的累积降雨和水浑浊导致较高的颗粒金属浓度。夏季，贻贝中积累的金属与DGT测定的金属不相关，而与颗粒金属呈正相关，这是因为过滤颗粒食品主要是生物积累的原因。相反，冬季试验表明，金属生物蓄积量与DGT测定的金属之间存在正相关关系，因为从水中吸收溶解性有机物（DOM）主要是生物蓄积的原因，与DOM结合的不稳定金属通常与DGT靶向金属重叠。尽管Cu对有机配体的亲和力比Zn高，但混合物中Cu和Zn之间的相互作用并不妨碍其吸收和生物积累。将DGT和贻贝耦合以比较金属生物利用度时的部署持续时间应不少于12 d，以便贻贝有足够的时间从环境介质中积累污染物。总而言之，DGT是一种方便的生物监测替代品，但它可能不适合实际环境，例如水化学不稳定的水生系统。2020年《环境毒理学》； 39：2485–2495。©2020 SETAC