Masaryk University, Faculty of Science, Research Centre for Toxic Compounds in the Environment (RECETOX), Kamenice 753/5, 625 00 Brno, Czech Republic.
Masaryk University, Faculty of Science, Research Centre for Toxic Compounds in the Environment (RECETOX), Kamenice 753/5, 625 00 Brno, Czech Republic.
Sci Total Environ. 2019 May 10;664:424-435. doi: 10.1016/j.scitotenv.2019.01.242. Epub 2019 Jan 24.
We investigated a combination of approaches to extend the attainment of partition equilibria between silicone passive samplers (samplers) and surface or treated waste water towards more hydrophobic organic compounds (HOC). The aim was to identify the HOC hydrophobicity range for which silicone sampler equilibration in water is feasible within a reasonable sampler deployment period. Equilibrium partitioning of HOC between sampler and water is desirable for a simpler application as a "chemometer", aiming to compare chemical activity gradients across environmental media (e.g. water, sediment, biota). The tested approaches included a) long sampler exposure periods and high water flow to maximize mass transfer from water to sampler; b) the use of samplers with reduced sheet thicknesses; and c) pre-equilibration of samplers with local bottom sediment, followed by their exposure in surface water at the same sampling site. These approaches were tested at three sites including a fish pond with a low level of pollution, a river impacted by an urban agglomeration and an effluent of municipal wastewater treatment plant. Tested compounds included polychlorinated biphenyls (PCB), polycyclic aromatic hydrocarbons (PAH), DDT, its metabolites and their isomers, hexachlorobenzene (HCB) and polybrominated diphenyl ethers (PBDE). The study shows that samplers with a surface area of 400-800 cm consisting of thin (100-500 μm) silicone sheets exposed at sampling rates of 10-40 L d for a time period of up to four months reach partition equilibrium with water for compounds with log K ≤ 5.5. Nevertheless, for compounds beyond this limit it is challenging, within a reasonable time period, to reach equilibrium between sampler and water in an open system where water boundary layer resistance controls the mass transfer. For more hydrophobic HOC (log K > 6), the kinetic method using performance reference compounds is recommended instead.
我们研究了多种方法的组合，以扩展硅酮被动采样器（采样器）与表面或处理废水之间分配平衡的范围，使其适用于更疏水性的有机化合物（HOC）。目标是确定在合理的采样器部署时间内，硅酮采样器在水中达到平衡的 HOC 疏水性范围。HOC 在采样器和水中之间的平衡分配对于更简单的应用是理想的，例如作为“化学计”，旨在比较环境介质（如水、沉积物、生物群）之间的化学活性梯度。测试的方法包括：a）延长采样器暴露时间和提高水流速度，以最大限度地从水中向采样器转移质量；b）使用厚度减小的采样器；c）用当地底部沉积物预平衡采样器，然后在同一采样点暴露在地表水。这些方法在三个地点进行了测试，包括一个污染水平较低的鱼塘、一个受到城市集聚影响的河流和一个城市污水处理厂的废水出口。测试的化合物包括多氯联苯（PCB）、多环芳烃（PAH）、滴滴涕及其代谢物及其异构体、六氯苯（HCB）和多溴联苯醚（PBDE）。研究表明，表面积为 400-800 cm 的采样器，由薄（100-500 µm）硅酮片组成，以 10-40 L/d 的采样速度暴露长达四个月，对于 log K ≤ 5.5 的化合物可以达到与水的分配平衡。然而，对于超过这个限制的化合物，在一个开放系统中，水边界层阻力控制质量传递，在合理的时间内达到采样器和水之间的平衡是具有挑战性的。对于更疏水性的 HOC（log K > 6），建议使用性能参考化合物的动力学方法。
