近海潮间带水体及沉积物中重金属的含量及分布特征

利用ICP-MS分析技术,系统测定了天津沿海潮间带表层海水、悬浮物、沉积物及沉积物间隙水中13种重金属元素的含量.结果表明,不同介质中重金属总含量和个体含量差别较大,最大相差4～7个数量级(水和悬浮物中).在相同介质中,各采样点重金属总含量差别不大,变异系数小于30%,个体重金属浓度除间隙水中差别较大外,变异系数均小于50%.潮间带海水中溶解态重金属含量均值为41.2μg·L^-1,原水、沉积物间隙水、悬浮物和沉积物中重金属含量均值分别为62.7μg·L^-1、112.7μg·L^-1、345.0mg·kg^-1和262.3 mg·kg^-1.潮间带各介质中重金属构成有显著差别,典型重金属元素Zn、Cu、Pb和Cr在原水和过滤水中约占40%～50%,而在悬浮物、沉积物及其间隙水中约占到50%～80%.潮间带水体、悬浮物、沉积物与滨岸土壤中重金属元素组成和分布模式的相似性表明其污染来源为陆源污染物.对悬浮物和沉积物中重金属含量与有机质含量的相关分析结果显示二者间相关性较弱,但各重金属含量之间有显著的相关关系,说明它们有相似的地球化学行为.

Contents and Distribution Characteristics of Heavy Metals in Water and Sediment of Intertidalite

ICP-MS analytical technology was used to analyze the concentration of 13 heavy metals in surface water, pore water in sediment, suspended particulate matter, and sediment of intertidalite of Tianjin. Results show that both total amount and single concentration of heavy metals vary greatly in different media, the biggest and smallest values differ by 4 or 7 magnitudes. While the variation coefficients of the contents of total metals or single metal in the same medium are less than 0.3 and 0.5 respectively except for the pore water. The average concentration of total dissolved heavy metals is 41.2 microg x L(-1), while total contents of heavy metals in original water, pore water, sediment and suspended particles are 62.7 microg x L(-1), 112.7 microg x L(-1), 262.3 mg x L(-1) and 345.0 mg x L(-1) respectively, they are similar to inland natural river but higher then those of ocean. The composition of heavy metals in different media varied greatly, metals prone to dissolve such as Mo account for more than 20% in water, but metals uneasy to dissolve mainly exist in sediment and suspended particles and absorbed by particles. Typical heavy metals, such as Zn, Cu, Pb and Cr, account for 40% - 50% in water and 50% - 80% in other media. The similarity in distribution mode of heavy metals in intertidalite and terrestrial soil suggest that they are originated from terrestrial soil that is contiguity to the sea. Notable correlativity can be seen between concentrations of all heavy metals except for Mo in sediment, which can explain the similarity of their environmental behavior, but only wake correlation between the content of organic carbon and concentrations of heavy metals in suspended particulates and sediment.