Low-density polyethylene sheets are used as passive samplers for aquatic environmental monitoring to measure the freely dissolved concentration (Cfree ) of hydrophobic organic contaminants (HOCs). Freely dissolved HOCs in water will partition into the polyethylene until a thermodynamic equilibrium is achieved; that is, the HOC's activity in the passive sampler is the same as its activity in the surrounding environment. One way to evaluate the equilibrium status or estimate the uptake kinetics is by using performance reference compounds (PRCs). A fractional equilibrium (feq ) can be determined for target HOCs, under the assumption that PRC desorption from the passive sampler occurs at the same rate as for the unlabeled target HOCs. However, few investigations have evaluated how effectively and accurately PRCs estimate target contaminant Cfree under in situ conditions. In the present study, polyethylene passive samplers were preloaded with 6 13 C-labeled polychlorinated biphenyls (PCBs) as PRCs; deployed in New Bedford Harbor, Massachusetts, USA; and collected after 30-, 56-, 99-, and 129-d deployments. Using this unique temporal sampling design, PRC results from each deployment were fit to a diffusion model to estimate the Cfree of 27 PCB congeners and compare the results between the different deployment times. Smaller PCBs had variable concentrations over the 4 deployments, whereas mid-molecular weight PCBs had consistent Cfree measurements for all deployments (relative standard deviation <20%). High-molecular weight PCBs had the largest Cfree estimates after 30 d; these estimates and their standard deviations decreased with longer deployment times. These findings suggest that when targeting PCBs with more than 6 chlorines or contaminants with a log octanol-water partition coefficient ≥6.5, a deployment time longer than 30 d may be prudent. Environ Toxicol Chem 2020;39:1165-1173. © 2020 SETAC.

中文翻译：

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对海水柱中 PCB 平衡被动采样器浓度和 Cfree 的基于性能参考化合物的估计进行原位研究。


低密度聚乙烯片材用作水生环境监测的被动采样器，用于测量疏水性有机污染物（HOC）的自由溶解浓度​​（Cfree）。自由溶解在水中的 HOC 将分配到聚乙烯中，直至达到热力学平衡；也就是说，HOC 在被动采样器中的活动与其在周围环境中的活动相同。评估平衡状态或估计吸收动力学的一种方法是使用性能参考化合物 (PRC)。假设被动采样器的 PRC 解吸发生率与未标记的目标 HOC 的速率相同，则可以确定目标 HOC 的分数平衡 (feq )。然而，很少有研究评估 PRC 在原位条件下如何有效和准确地估计目标污染物 Cfree。在本研究中，聚乙烯被动采样器预装了 6 个 13 C 标记的多氯联苯 (PCB) 作为 PRC；部署于美国马萨诸塞州新贝德福德港；并在 30 天、56 天、99 天和 129 天部署后收集。使用这种独特的时间采样设计，将每次部署的 PRC 结果拟合到扩散模型，以估计 27 种 PCB 同系物的 Cfree 并比较不同部署时间之间的结果。较小的 PCB 在 4 次部署中具有不同的浓度，而中等分子量的 PCB 在所有部署中具有一致的 Cfree 测量值（相对标准偏差 <20%）。高分子量 PCB 在 30 天后具有最大的 Cfree 估计值；这些估计值及其标准差随着部署时间的延长而减小。 这些发现表明，当针对氯含量超过 6 种的 PCB 或辛醇-水分配系数对数≥6.5 的污染物时，部署时间长于 30 天可能是谨慎的做法。环境毒物化学 2020；39：1165-1173。 © 2020 SETAC。