†Institute for Risk Assessment Sciences, Utrecht University, P.O. Box 80177, 3508 TD Utrecht, The Netherlands.
‡Rijkswaterstaat, Water, Transport and Environment, P.O. Box 17, 8200 AA, Lelystad, The Netherlands.
Environ Sci Technol. 2015 Jun 2;49(11):6791-9. doi: 10.1021/acs.est.5b00286. Epub 2015 May 15.
Nowadays, passive sampling is a widely applied technique to determine freely dissolved aqueous concentrations of hydrophobic organic chemicals (HOCs), such as polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Crucial to the measurements are sampler-water partition coefficients, which are generally determined in the laboratory under "standard conditions" (in freshwater at 20 °C). Theoretically, however, the coefficients are dependent on environmental conditions, such as temperature and salinity. Yet, there are insufficient experimental data in the scientific literature to prove this for different polymers. Several polymers are already being applied during field monitoring, however, and neglecting any effects may lead to imprecise results. In the present study, we therefore quantified the effects of temperature and salinity on the sampler-water partition coefficients of PAHs and PCBs for silicone rubber, a material used in Dutch passive sampling monitoring campaigns. The results demonstrated a chemical-specific and hydrophobicity-dependent temperature effect, being independent of salinity, and a chemical- and temperature-independent salinity effect. Based on the obtained data, location-specific silicone rubber-water partition coefficients (Ksr-w; adjusted for temperature and salinity) can be calculated. The impact of applying such location-specific values was demonstrated using the Dutch passive sampling field monitoring database, covering ten years of PAH and PCB data for several locations. Adjusting the Ksr-w values resulted in aqueous concentrations that were lowered by a factor of 1.6 on average. The reduction was rather constant because of the manner of sampling (under nonequilibrium conditions and using performance reference compounds) and calculating. When sampling under equilibrium conditions in seawater at temperatures at about freezing, and/or applying different calculation approaches, the adjustment effect can potentially increase up to a factor of about 5-6 for the more hydrophobic PAHs and PCBs. Although this study exclusively focused on silicone rubber, qualitatively the results will also apply to other passive sampling materials.
如今，被动采样是一种广泛应用于测定疏水性有机化学品（HOCs）如多环芳烃（PAHs）和多氯联苯（PCBs）在水中自由溶解浓度的技术。对于测量来说，关键是采样器-水分配系数，这些系数通常是在“标准条件”（在 20°C 的淡水中）下在实验室中确定的。然而，从理论上讲，这些系数取决于环境条件，如温度和盐度。然而，科学文献中缺乏关于不同聚合物的实验数据来证明这一点。尽管如此，已有几种聚合物在现场监测中得到了应用，而忽略任何影响都可能导致结果不准确。在本研究中，我们因此量化了温度和盐度对用于荷兰被动采样监测计划的硅橡胶中 PAHs 和 PCBs 的采样器-水分配系数的影响。结果表明，温度对 PAHs 和 PCBs 的影响具有化学特异性和疏水性依赖性，而与盐度无关，并且盐度对化学物质和温度具有独立性。基于获得的数据，可以计算出特定位置的硅橡胶-水分配系数（Ksr-w；根据温度和盐度进行调整）。通过使用荷兰被动采样现场监测数据库来证明了应用这种特定位置值的影响，该数据库涵盖了十年内多个地点的 PAH 和 PCB 数据。调整 Ksr-w 值可使水相浓度平均降低 1.6 倍。由于采样方式（在非平衡条件下和使用性能参考化合物）和计算方式，降低幅度相对稳定。当在接近冰点的海水中在平衡条件下采样，和/或应用不同的计算方法时，对于更疏水性的 PAHs 和 PCBs，调整效果可能会增加高达 5-6 倍。虽然本研究仅专注于硅橡胶，但从质量上讲，结果也将适用于其他被动采样材料。
