Mercury in Lake Michigan
Mercury in Lake Michigan
复制标题
DOI：
10.1021/es960656l
复制
发表时间：
1997-03-01
影响因子：
11.4
通讯作者：
Sullivan, KA
中科院分区：
文献类型：
--
作者：
Mason, RP;Sullivan, KA
水生系统的汞污染是一个重要的全球性健康问题（1，2）。最近的研究表明，北美、欧洲和亚洲的许多淡水湖泊中的鱼类汞（Hg）浓度升高，即浓度超过州、联邦或国际健康指南（3-12）。在美国，过去十年中，越来越多的州发布了淡水鱼消费的健康指南，主要是基于食鱼鱼类中汞浓度的升高（11）。与此同时，美国环境保护署（EPA）根据其综合风险信息系统降低了鱼类中汞的参考剂量，美国许多州（例如明尼苏达州（12））也降低了鱼类中汞的可接受标准。这些管制行动已被证明是有争议的（11），并导致重新评估美国沃茨的汞来源和控制鱼类中汞积累的因素，因为我们对水生系统的汞来源以及大气沉积和人为排放在为水生系统提供“生物可利用”汞方面的作用的认识存在重大差距（11-15）。许多研究主要集中在较小的湖泊，试图将鱼类中汞浓度升高与环境参数相关联（例如，参考文献7-10和15-17），并证明了人为输入大气对附近和偏远流域汞污染的重要性（13，18）。然而，关于密歇根湖和其他五大湖中汞含量的公开数据很少。之前对五大湖汞和其他微量金属的研究（19）报告了平均总汞浓度范围，从上级湖的10 pM（2 ng/L）到密歇根湖的225 pM（1980-1983年收集的数据）。我们的数据是在1994年和1995年由EPA赞助的密歇根湖质量平衡研究（LMMB; 20）期间从近海沃茨（图1）收集的，平均总汞为1.6 pM，比密歇根湖类似地点的早期数据低2个数量级。其浓度与公海的浓度更接近（例如，参考文献21）。样品的历史污染可能是我们的值和以前的数据之间的差异的原因，正如在密歇根湖发现的一些其他微量金属，最明显的是铅（22）。最近在分析公海沃茨中的痕量金属时也发生过这种情况（23）。最近在密歇根湖进行的其他测量（24）发现，在距离芝加哥6公里以内的一个监测站，汞的含量范围为5至50 pM。与我们的测量结果相比，这些浓度有所升高，但该地点可能收到来自芝加哥的河流和大气的增强输入。然而，我们的一个站点，离岸约20公里，与远离城市影响的站点相比，浓度没有任何增加（20）。Gill和Bruland（25）发现，从安大略湖和伊利湖岸边采集的样本的浓度值分别为4.5和18 pM，相对于开阔的湖泊，这两个值略高
Mercury contamination of aquatic systems is an important worldwide health concern (1, 2). Recent research has demonstrated that many freshwater lakes in North America, Europe, and Asia contain fish with elevated mercury (Hg) concentrations, ie, concentrations that exceed state, federal, or international health guidelines (3-12). IntheUnitedStates in the last decade, an ever-increasing number of states have issued health advisories for freshwater fish consumption, based primarily on the elevated Hg concentrations in piscivorous fish (11). In conjunction, the US Environmental Protection Agency (EPA) has lowered the reference dose for Hg in fish, based on EPA’s Integrated Risk Information System, and many states in the United Statessfor example, Minnesota (12) shave also lowered the acceptable criteria for Hg in fish. These regulatory actions have proven to be contentious (11) and have led to a re-evaluation of the sources of Hg to US waters and the factors controlling Hg accumulation in fish, as there are significant gaps in our knowledge of the sources of Hg to aquatic systems and the role of atmospheric deposition and anthropogenic emissions in providing “bioavailable” Hg to aquatic systems (11-15). A number of studies, focused primarily on smaller lakes, have sought to correlate elevated concentrations of mercury in fish with environmental parameters (eg, refs 7-10 and 15-17) and have demonstrated the importance of anthropogenic inputs to the atmosphere in contributing to mercury contamination of both nearby and remote watersheds (13, 18). There is, however, little published data for Hg in Lake Michigan and the other Great Lakes. A previous study of mercury and other trace metals in the Great Lakes (19) reported average total mercury concentrations ranging from 10 pM (2 ng/L) for Lake Superior to 225 pM for Lake Michigan (data collected in 1980-1983). Our data, collected in 1994 and 1995 from offshore waters (Figure 1) during the EPA-sponsored Lake Michigan Mass Balance Study (LMMB; 20), averaged 1.6 pM total Hg and are 2 orders of magnitude lower than these earlier data for similar sites in Lake Michigan. The concentration is more comparable to that of the open ocean (eg, ref 21). Historical contamination of samples likely accounts for the differences between our values and previous data, as has been found in Lake Michigan for some of the other trace metals, most obviously for lead (22). It has occurred even recently during the analysis of open ocean waters for trace metals (23).Other recent measurements in Lake Michigan (24) found values for mercury ranging from 5 to 50 pM at a station within 6 km of Chicago. These concentrations are elevated as compared to our measurements, but this site likely receives enhanced inputs, both fluvial and from the atmosphere, from Chicago. One of our sites, approximately 20 km offshore, did not however show any enhancement in concentration as compared to sites more remote from urban influence (20). Gill and Bruland (25) found values of 4.5 and 18 pM for samples collected from the shores of Lake Ontario and Lake Erie, respectively, somewhat elevated relative to the open Lake