Graduate School of Oceanography , University of Rhode Island , Narragansett , Rhode Island 02882-1197 , United States.
Environment and Climate Change Canada , Aquatic Contaminants Research Division , 867 Lakeshore Road , Burlington , Ontario L7S 1A1 , Canada.
Environ Sci Technol. 2018 Dec 18;52(24):14061-14069. doi: 10.1021/acs.est.8b04036. Epub 2018 Nov 29.
The largest fresh water body in North America, Lake Superior, has the potential to both accumulate and serve as a secondary source of persistent bioaccumulative toxins, such as polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs). Polyethylene passive samplers (PEs) were thus simultaneously deployed at 19 sites in surface water and near surface atmosphere across Lake Superior to determine air and water concentrations and air-water gradients of 18 PCBs and 24 OCPs. PCBs in the air and water were characterized by penta- and hexachlorobiphenyls with distribution along the coast correlated with proximity to developed areas. Surface water and atmospheric concentrations were dominated by α-HCH (average 250 pg L and 4.2 pg m, respectively), followed by HCB (average 17 pg L and 89 pg m, respectively). Decreases in open lake concentrations of PCBs in water and air from spring to summer were consistent with ongoing volatilization from the surface layer as the main cause. Conversely, α-endosulfan was consistently deposited into the surface water of Lake Superior. Results indicated that PCBs were depleted in the surface mixed layer, implying a physical limit on evasive fluxes. This was corroborated with measurements from a vertical profile, displaying greater PCB concentrations at depth.
苏必利尔湖是北美洲最大的淡水湖，它具有积累和充当持久性生物蓄积性毒素（如多氯联苯 (PCBs) 和有机氯农药 (OCPs) 的次要来源的潜力。因此，在苏必利尔湖的 19 个地表水和近地表大气地点同时部署了聚乙烯被动采样器 (PEs)，以确定 18 种 PCBs 和 24 种 OCPs 的空气和水中浓度以及空气-水梯度。空气中和水中的 PCBs 以五氯和六氯联苯为特征，其分布与靠近发达地区有关。地表水和大气中的浓度主要由α-六氯环己烷（平均分别为 250 pg/L 和 4.2 pg/m）和六氯苯（平均分别为 17 pg/L 和 89 pg/m）主导。从春季到夏季，开放湖水中 PCBs 的浓度下降与表层不断蒸发一致，这是主要原因。相反，α-硫丹始终被沉积到苏必利尔湖的表层水中。结果表明，PCBs 在表层混合层中被消耗，这意味着逸散通量存在物理限制。这与垂直剖面的测量结果相吻合，显示出更深层的 PCB 浓度更高。
