Silver interactions with dissolved organic matter: Importance of reduced sulfur and implications for aquatic toxicity mitigation

银可能从个人护理产品（肥皂、洗发水、除臭剂等）进入环境。例如由Unilever和Unilever Canada制造和全球分销的那些。 重要的是能够理解和预测排放到环境中的银的影响。 仅仅知道总银是不够的，因为不同形式的金属具有不同的潜在毒性。 生物利用度方法有助于为水生环境中的金属制定适当的保护标准。这些方法使用计算来预测总金属的哪一部分可用于与生物体结合并可能有毒。 为了正确完成银的生物利用度建模，首先需要填补数据缺口。 该数据缺口是对还原硫化物在银结合和最终毒性缓解中的作用的详细理解。众所周知，银与还原的硫化物配体强烈结合，但在为风险评估目的表征样品时，测量硫化物不是常规分析的一部分。 即使有硫化物数据，目前还没有经过验证的计算机模型来估计测量的水化学数据的生物利用度。 因此，监管机构和排放者，如加拿大联合利华，还没有足够的信息或工具来对环境中的银做出适当的管理决策。这项研究将提供必要的数据开发预测工具的银在水生系统。 为了实现这一点，真实的世界样品将向其中添加银，并且游离形式的添加的银的部分将通过离子选择性电极来消除。 使用这种实验方法，将为各种不同硫化物含量的样品生成所谓的结合等温线。 这些等温线将在数学上适合于银与表面以及废水沃茨中出现的化合物结合的模型。 所得到的形态模型可以与现有的生物利用度实验相结合，并用于根据特定接收水的特性来预测水中银的安全水平。

Silver is potentially input to the environment from personal care products (soap, shampoo, deodorant, ...) such as those manufactured and distributed globally by Unilever and Unilever Canada. It is important to be able to understand and predict impacts of silver discharged into the environment. Just knowing total silver is not enough as different forms of a metal have different potential toxicity. Bioavailability approaches have been useful in setting appropriate and protective criteria for metals in aquatic environments. These approaches use calculations to predict what fraction of the total metal is available to bind to organisms and potentially be toxic. To properly accomplish bioavailability modelling for silver, there is a data gap that needs to be filled first. This data gap is a detailed understanding of the role of reduced sulfide in silver binding and ultimately toxicity mitigation. It is well understood that silver binds strongly to reduced sulfide ligands but measuring sulfide is not part of routine analysis when characterizing samples for risk assessment purposes. Even with sulfide data, there do not currently exist validated computer models to estimate bioavailabilty from measured water chemistry data. Thus regulators and dischargers, such as Unilever Canada, do not yet have sufficient information or tools to make appropriate management decisions for silver in the environment. This research will provide data necessary to develop predictive tools for silver in aquatic systems. To accomplish this real world samples will have silver added to them and the fraction of added silver in the free form will be deterimined by ion selective electrode. Using this experimental approach so-called binding isotherms will be generated for a variety of samples of variable sufide content. These isotherms will be mathematically fit to models for silver binding to compounds occuring in surface as well as waste waters. The resultant speciation model can be coupled with existing bioavailability experiments and used to predict safe levels for silver in water depending on characteristics of the specific receiving water.