Smithsonian Environmental Research Center, Edgewater, Maryland, USA.
Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland, Baltimore, Maryland, USA.
Environ Toxicol Chem. 2022 Sep;41(9):2052-2064. doi: 10.1002/etc.5406. Epub 2022 Jul 26.
We describe the validation of a novel polymeric equilibrium passive sampler comprised of agarose gel with embedded activated carbon particles (ag+AC), to estimate aqueous monomethylmercury (MeHg) concentrations. Sampler behavior was tested using a combination of idealized media and realistic sediment microcosms. Isotherm bottle experiments with ag+AC polymers were conducted to constrain partitioning to these materials by various environmentally relevant species of MeHg bound to dissolved organic matter (MeHgDOM) across a range of sizes and character. Log of partitioning coefficients for passive samplers (K ) ranged from 1.98 ± 0.09 for MeHg bound to Suwannee River humic acid to 3.15 ± 0.05 for MeHg complexed with Upper Mississippi River natural organic matter. Reversible equilibrium exchange of environmentally relevant MeHg species was demonstrated through a series of dual isotope-labeled exchange experiments. Isotopically labeled MeHgDOM species approached equilibrium in the samplers over 14 days, while mass balance was maintained, providing strong evidence that the ag+AC polymer material is capable of equilibrium measurements of environmentally relevant MeHg species within a reasonable deployment time frame. Samplers deployed across the sediment-water interface of sediment microcosms estimated both overlying water and porewater MeHg concentrations within a factor of 2 to 4 of measured values, based on the average measured K values for species of MeHg bound to natural organic matter in the isotherm experiments. Taken together, our results indicate that ag+AC polymers, used as equilibrium samplers, can provide accurate MeHg estimations across many site chemistries, with a simple back-calculation based on a standardized K Environ Toxicol Chem 2022;41:2052-2064. © 2022 SETAC.
我们描述了一种新型聚合平衡被动采样器的验证，该采样器由琼脂糖凝胶和嵌入的活性炭颗粒（ag+AC）组成，用于估计水溶液中的一甲基汞（MeHg）浓度。通过理想化介质和现实沉积物微宇宙的组合测试了采样器的行为。使用 ag+AC 聚合物进行了等温瓶实验，以通过各种与大小和性质相关的与溶解有机质（MeHgDOM）结合的环境相关的 MeHg 物种来约束这些材料的分配。被动采样器的分配系数（K ）的对数范围从与苏万尼河腐殖酸结合的 MeHg 的 1.98 ± 0.09 到与密西西比河上的天然有机物结合的 MeHg 的 3.15 ± 0.05。通过一系列双同位素标记交换实验证明了环境相关的 MeHg 物种的可逆平衡交换。同位素标记的 MeHgDOM 物种在 14 天内接近采样器中的平衡，同时保持质量平衡，这有力地证明了 ag+AC 聚合物材料能够在合理的部署时间内平衡测量环境相关的 MeHg 物种。在沉积物微宇宙的沉积物-水界面上部署的采样器，根据等温实验中与天然有机物结合的 MeHg 物种的平均 K 值，估计了上层水和孔隙水 MeHg 浓度，其测量值的因子在 2 到 4 之间。总的来说，我们的结果表明，作为平衡采样器的 ag+AC 聚合物可以在许多现场化学物质中提供准确的 MeHg 估计值，只需基于标准化的 K 值进行简单的反向计算即可。环境毒理化学 2022；41:2052-2064。© 2022 SETAC。
