Department of Civil & Environmental Engineering, IIHR-Hydroscience and Engineering, The University of Iowa, Iowa City, IA, USA.
Department of Civil & Environmental Engineering, IIHR-Hydroscience and Engineering, The University of Iowa, Iowa City, IA, USA.
Environ Pollut. 2019 Jan;244:469-476. doi: 10.1016/j.envpol.2018.10.048. Epub 2018 Oct 12.
We have developed a method for measuring fluxes of PCBs from natural waters using air and water passive samplers deployed simultaneously in the Indiana Harbor and Ship Canal (IHSC). Net volatilization of ƩPCBs was determined for 2017, and ranged from 1.4 to 2.8 μg m d, with a median of 2.0 μg m d. We confirm earlier findings that the IHSC experiences constant release of gas-phase PCBs. Gas-phase and freely-dissolved water ƩPCB samples median were 4.0 ng m and 14 ng L, both exhibiting increasing concentrations over the year of study, and with a strong positive correlation between them (R = 0.93 for ƩPCBs). The relative concentrations of individual PCB congeners were very similar between air and water samples, and resemble Aroclor 1248, a mixture previously reported to contaminate the IHSC sediments. Monthly variability of the volatilization fluxes was primarily driven by the freely-dissolved water concentration changes (R = 0.87). Although different sampling methods were performed to estimate air-water fluxes between the month of August of 2006 and 2017, ƩPCB net fluxes have decreased by more than 60%, suggesting that either dredging at IHSC from 2012 to 2017 or reduction of upstream sources have decreased the freely-dissolved water concentrations of PCBs, thus reducing the air-water net volatilization in IHSC. Finally, we have shown that this passive sampling approach represents a simple and cost-effective method to assess the air-water exchange of PCBs, increase analytical sensitivity, enable measurements over time, and reduce uncertainties related to unexpected episodic events.
我们开发了一种使用同时部署在印第安纳港和船闸（IHSC）的空气和水被动采样器测量天然水中多氯联苯通量的方法。2017 年确定了ΣPCBs 的净挥发速率，范围为 1.4 至 2.8μg·m-2·d-1，中位数为 2.0μg·m-2·d-1。我们证实了之前的发现，即 IHSC 经历气相 PCBs 的持续释放。气相和自由溶解水ΣPCB 的样本中位数分别为 4.0ng·m-3和 14ng·L-1，均在研究年内呈上升趋势，且两者之间呈强正相关（ΣPCBs 为 0.93）。单个 PCB 同系物在空气和水样中的相对浓度非常相似，与之前报道的污染 IHSC 沉积物的 Aroclor 1248 混合物相似。挥发通量的月度变化主要由自由溶解水浓度变化驱动（R=0.87）。尽管 2006 年 8 月和 2017 年之间使用不同的采样方法来估计气-水通量，但ΣPCB 净通量减少了 60%以上，这表明 IHSC 从 2012 年到 2017 年的疏浚或上游源的减少降低了 PCBs 的自由溶解水浓度，从而减少了 IHSC 中的气-水净挥发。最后，我们表明，这种被动采样方法代表了一种简单且具有成本效益的方法，可以评估 PCBs 的气-水交换，提高分析灵敏度，实现随时间的测量，并减少与意外突发事件相关的不确定性。
