Decadal trends of silver and lead contamination in San Francisco Bay surface waters.
Decadal trends of silver and lead contamination in San Francisco Bay surface waters.
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DOI：
10.1021/es015746r
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发表时间：
2002-05
影响因子：
11.4
通讯作者：
S. Squire;G. Scelfo;J. Revenaugh;A. Flegal
中科院分区：
文献类型：
--
作者：
S. Squire;G. Scelfo;J. Revenaugh;A. Flegal
在过去十年中，尽管在此期间努力减少海湾的污染物负荷，但旧金山湾地表水仍然富含溶解（<0.45微米）银和铅浓度(年代际平均值为5.7 ng kg(-1) Ag[过滤]和31 ng kg(-1) Pb[过滤])，而东北太平洋邻近海域的地表水(0.26 ng kg（-1) Ag[过滤]和2.7 ng kg(-1) Pb[过滤]）。虽然时间序列模型显示，1989年至1999年期间河口系统南段的总铅浓度下降了40%，但过滤后的铅分数在此期间没有显著变化。这种持久性归因于：(1)以前的大气沉积和工业铅不断进入其流域，它们正缓慢地平流到河口；(2)海湾内表层沉积物和水柱之间铅的内部循环。相比之下，在过去十年中，南部地区的过滤银浓度和总银浓度分别下降了70%和40%。这些时间上的下降是由于在过去十年中，公共拥有的处理厂的银负荷减少了2倍，该地区地表沉积物的银浓度也相应下降。在1989年至1999年期间，北部河段的银和铅浓度基本保持不变，反映了这十年来这些元素对这一水域的人为输入不变。
Over the past decade, San Francisco Bay surface waters have remained enriched with dissolved (<0.45 microm) silver and lead concentrations (decadal means of 5.7 ng kg(-1) Ag[filtered] and 31 ng kg(-1) Pb[filtered]) compared with those (0.26 ng kg(-1) Ag[filtered] and 2.7 ng kg(-1) Pb[filtered]) of adjacent oceanic surface waters of the northeast Pacific, despite efforts to reduce pollutant loadings to the Bay during that period. While time series models show that there has been a 40% decline in total lead concentrations in the southern reach of the estuarine system between 1989 and 1999, the filtered lead fraction has not changed significantly during that time. That persistence is attributed to (i) the ongoing input from previous atmospheric depositions and industrial lead to its drainage basin, which are slowly being advected into the estuary and (ii) the internal recycling of lead between the surface sediments and the water column within the Bay. In contrast, both filtered and total silver concentrations in the southern reach have declined by 70% and 40%, respectively, within the past decade. These temporal declines are attributed to a 2-fold decrease in silver loadings from publicly owned treatment works and a comparable decline in the silver concentration of surficial sediments within that region during the past decade. In the northern reach, silver and lead concentrations have remained essentially constant between 1989 and 1999, reflecting invariable anthropogenic input of these elements to this embayment over that decade.