Polychlorinated biphenyls (PCBs) in San Francisco Bay
Polychlorinated biphenyls (PCBs) in San Francisco Bay
复制标题
DOI：
10.1016/j.envres.2007.01.013
复制
发表时间：
2007-09-01
影响因子：
8.3
通讯作者：
Mckee, L. J.
中科院分区：
文献类型：
--
作者：
Davis, J. A.;Hetzel, F.;Mckee, L. J.
旧金山弗朗西斯科湾正面临着多氯联苯的遗留问题，这些多氯联苯广泛分布在流域的陆地表面，深入海湾的沉积物中，污染了海湾的食物网，对人类和野生动物构成健康风险。针对这一持续存在的问题，水质管理人员正在制定多氯联苯总最大日负荷（TMDL）和实施计划，以加速海湾从数十年的多氯联苯污染中恢复过来。本文回顾了过去15年来在管理多氯联苯和了解其来源，途径，命运和海湾的影响方面取得的进展，并强调了未来10年应解决的剩余信息需求。1970年代逐步淘汰多氯联苯以及1979年联邦禁止销售和生产，导致从1970年代至今多氯联苯的数量逐渐下降。然而，在禁令实施25年后，今天一些海湾运动鱼中的多氯联苯浓度仍然比人类健康关注的阈值高出十倍以上。如果不采取进一步的管理行动，看来海湾从多氯联苯污染中全面恢复还需要几十年的时间。多氯联苯在游鱼中的浓度，沿着汞，是海湾消费咨询的主要原因，并因此将海湾归类为受损水体。一些信息来源表明，海湾中的多氯联苯浓度也可能高到足以对野生动物，包括稀有和濒危物种产生不利影响。实现保护人类健康的目标所需的食物网污染减少90%以上，也可能普遍消除对野生动物的风险。海湾的多氯联苯污染主要与沿着的工业区和当地流域有关。强的空间梯度PCB浓度持续几十年后，这些化学品释放到湾区水道。通过TMDL过程，注意力更加集中在PCB的来源，是可控的，并有助于最多的PCB损伤的海湾。来自当地流域的城市径流是多氯联苯进入海湾的一个特别重要的途径。大量负载也通过三角洲流出（河流输入）进入海湾。最近的研究表明，在海湾的大部分地区，埋藏沉积物的侵蚀正在发生，这对海湾从多氯联苯污染中恢复造成了严重的问题，因为被侵蚀和重新流动的沉积物来自相对污染的埋藏沉积物。海湾内受污染的场地也可能是海湾食物网中多氯联苯的主要来源。疏浚物处理、废水排放和大气沉积是多氯联苯进入海湾的相对次要的途径。目前的优先信息需求涉及了解城市径流的来源、负荷量和管理办法的有效性、海湾内受污染场地的区域影响;多氯联苯从埋藏的沉积物中的重新流动;历史和目前的趋势;多氯联苯的原地降解率;不同管理设想方案下的可靠恢复预测;多氯联苯在土壤和沉积物中的空间分布;以及多氯联苯与其他压力源相互作用的生物学效应。污染物从流域的缓慢释放和海湾对输入变化的缓慢反应联合收割机相结合，使这个生态系统从流域污染中恢复非常缓慢。海湾PCB污染的历史强调了防止持久性颗粒相关污染物进入这个敏感生态系统的重要性。(c)2007爱思唯尔公司All rights reserved.
San Francisco Bay is facing a legacy of polychlorinated biphenyls (PCBs) spread widely across the land surface of the watershed, mixed deep into the sediment of the Bay, and contaminating the Bay food web to a degree that poses health risks to humans and wildlife. In response to this persistent problem, water quality managers are establishing a PCB total maximum daily load (TMDL) and implementation plan to accelerate the recovery of the Bay from decades of PCB contamination. This article provides a review of progress made over the past 15 years in managing PCBs and understanding their sources, pathways, fate, and effects in the Bay, and highlights remaining information needs that should be addressed in the next 10 years. The phaseout of PCBs during the 1970s and the 1979 federal ban on sale and production led to gradual declines from the 1970s to the present. However, 25 years after the ban, PCB concentrations in some Bay sport fish today are still more than ten times higher than the threshold of concern for human health. Without further management action it appears that the general recovery of the Bay from PCB contamination will take many more decades. PCB concentrations in sport fish were, along with mercury, a primary cause of a consumption advisory for the Bay and the consequent classification of the Bay as an impaired water body. Several sources of information indicate that PCB concentrations in the Bay may also be high enough to adversely affect wildlife, including rare and endangered species. The greater than 90% reduction in food web contamination needed to meet the targets for protection of human health would likely also generally eliminate risks to wildlife. PCB contamination in the Bay is primarily associated with industrial areas along the shoreline and in local watersheds. Strong spatial gradients in PCB concentrations persist decades after the release of these chemicals to Bay Area waterways. Through the TMDL process, attention is being more sharply focused on the PCB sources that are controllable and contributing most to PCB impairment in the Bay. Urban runoff from local watersheds is a particularly significant pathway for PCB entry into the Bay. Significant loads also enter the Bay through Delta outflow (riverine input). Recent studies have shown that erosion of buried sediment is occurring in large regions of the Bay, posing a significant problem with respect to recovery of the Bay from PCB contamination because the sediments being eroded and remobilized are from relatively contaminated buried sediment deposits. In-Bay contaminated sites are likely also a major contributor of PCBs to the Bay food web. Dredged material disposal, wastewater effluent, and atmospheric deposition are relatively minor pathways for PCB loading to the Bay. Priority information needs at present relate to understanding the sources, magnitude of loads, and effectiveness of management options for urban runoff, the regional influence of in-Bay contaminated sites; remobilization of PCBs from buried sediment; historic and present trends; in situ degradation rates of PCBs; reliable recovery forecasts under different management scenarios; the spatial distribution of PCBs in soils and sediments; and the biological effects of PCBs in interaction with other stressors. The slow release of pollutants from the watershed and the slow response of the Bay to changes in inputs combine to make this ecosystem very slow to recover from pollution of the watershed.The history of PCB contamination in the Bay underscores the importance of preventing persistent, partile-associated pollutants from entering this sensitive ecosystem. (c) 2007 Elsevier Inc. All rights reserved.