A model for the presence of polychlorinated biphenyls (PCBs) in the Willamette River Basin (Oregon)
A model for the presence of polychlorinated biphenyls (PCBs) in the Willamette River Basin (Oregon)
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DOI：
10.1021/es8000213
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发表时间：
2008-08-15
影响因子：
11.4
通讯作者：
Hope, Bruce K.
中科院分区：
文献类型：
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作者：
Hope, Bruce K.
威拉米特河排干了俄勒冈州西北部一个32,000公里的盆地。由于其持久性和毒性，该流域内常驻鱼类中的多氯联苯水平高于消费建议阈值，是一个人类和环境健康问题。这一担忧可能会引发威拉米特河对多氯联苯的总最大日负荷(TMDL)，届时多氯联苯的可能来源和分布在整个流域的机制都将引起相当大的监管兴趣。全球初级(1930-1980年)和次级(1980年后)排放的一部分通过大气中的远程平流输送到达的盆地内的沉积被认为是一种解释。对这一命题进行了探讨，建立了一个季节性反应、动态质量平衡的分水岭尺度模型，该模型估计了90年期间各种环境介质中有毒相关同系物(多氯联苯-077、-118、-169)的浓度，假设流入盆地大气的平流是多氯联苯的唯一同系物来源。模型结果表明，1930年至1975年期间一次排放的增加(1970年的PCB-118峰值流入，约为11 kg y(-1))以及此后一次和二次排放的减少导致的空气浓度上升和相关的平流流入，可能会在1993年至2003年期间在空气、土壤和鱼类中观察到同种物质的浓度。观测到的浓度可能完全可以通过全球遗留来源的投入获得，这就对主要针对局部点源或面源的TMDL的效力提出了疑问。更好地描述潜在来源，收集更多的土壤和空气数据，并结合更复杂的建模，似乎是威拉米特河任何多氯联苯TMDL的必要先兆。
The Willamette River drains a 32,000 km(2) basin (Basin) in northwestern Oregon. Owing to their persistence and toxicity, polychlorinated biphenyls (PCBs) in resident fish within the Basin at levels above consumption advisory thresholds are a human and environmental health concern. This concern may trigger a Willamette River Total Maximum Daily Load (TMDL) for PCBs, at which time both their probable sources and the mechanism by which they came to be distributed throughout the Basin will be of considerable regulatory interest. Deposition within the Basin of some portion of global primary (1930-1980) and secondary (post-1980) emissions arriving via long-range advective transport in the atmosphere was posited as an explanation. This proposition was explored with a seasonally responsive, dynamic mass balance watershed-scale model that estimated concentrations of toxicologically relevant congeners (PCB-077, -118, -169) in various environmental media over a 90-year period, assuming advective inflow to the Basin's atmosphere to be the only PCB congener source. Model results suggest that rising air concentrations, and associated advective inflows, from increasing primary emissions between 1930 and 1975 (PCB-118 peak inflow, 1970, approximate to 11 kg y(-1)) and declining primary and secondary emissions thereafter, could have yielded congener concentrations observed in air, soil, and fish between 1993 and 2003. The possibility that observed concentrations may be obtainable entirely with inputs from global legacy sources raises questions as to the efficacy of a TMDL directed primarily at local point or area sources. Better characterization of potential sources, and collection of additional soil and air data combined with more sophisticated modeling, appear to be necessary precursors to any PCB TMDL for the Willamette River.