渤海中部海域水体中Hg、As的时空分布特征

本研究分析了2013年5月(春季)、7月(夏季)、11月(秋季)、12月(冬季)渤海中部海域表、中、底层海水中汞(Hg)、砷(As)两种元素的时空分布特征。结果显示，Hg 的含量范围为0.0029–0.3926μg/L，平均含量为0.0676μg/L。从垂直分布来看，水体中Hg的含量呈现底层>中层>表层的变化特点；从四季的变化特点看，水体中Hg的含量呈现春季>冬季>秋季>夏季的变化规律，其中，仅有夏季表层水体达到国家海水水质标准(GB3097–1997)，其余水体中 Hg 的含量均有超标现象发生。As的含量范围为0.65–10.83μg/L，平均含量为1.50μg/L，除夏季表层水体中的As含量较高外，水体中的As均呈现均匀的分布模式。从垂直分布来看，As在四季的平均含量均表现为表层>中层>底层，且均未超出国家海水水质标准。研究表明，渤海中部海域水体中，As 的含量均达到Ⅰ类水质标准(20μg/L)，而Hg含量却频频超出Ⅰ类水质标准(0.05μg/L)或Ⅱ类水质标准(0.20μg/L)。渤海中部海域水质已经受到了重金属的污染，推测该现象主要源于人类活动的影响。

The Temporal and Spatial Distribution of Mercury and Arsenic in the Central Bohai Sea

To study the temporal and spatial distribution of Mercury (Hg) and Arsenic (As) in the central Bohai Sea, we collected water samples of the surface, middle, and bottom layers in four survey cruises in May (spring), July (summer), November (autumn) and December (winter) in 2013. The results showed that the content of Hg was in the range of 0.0029–0.3926μg/L with an average of 0.0676μg/L. The vertical distribution of Hg concentration followed the order: bottom layer > middle layer > surface layer; the seasonal distribution showed the pattern: spring > winter > autumn > summer.Except for the surface layer in summer, Hg concentration in all water samples failed to meet the national water quality standard (GB3097–1997). The concentration of As ranged from 0.65 to 10.83μg/L with the mean value of 1.50μg/L, which met the requirement for the national water quality standard (GB3097–1997). The vertical distribution of As followed the order: surface layer > middle layer > bottom layer, and the seasonal distribution displayed an even pattern. The limit of As concentration is 20μg/L according to the national water quality standards, thus the As level met the first water quality standard. However, the Hg level was readily higher than the first (0.05μg/L) or second water quality national water quality standard (0.20μg/L). These data suggested that the overall water quality of the central Bohai Sea was unsatisfying, and there was obvious pollution probably caused by human activities. Therefore the environmental risks in the Bohai Sea should be carefully evaluated in the future economic activities.