摘要
对北运河上游沙河水库沉积物中典型重金属元素的污染特征进行了分析,采用Lars H¨okanson潜在生态风险指数评价了重金属的污染程度和环境风险,并利用一维孔隙水扩散模型(Fick定律)估算了微量重金属在沉积物-水界面的扩散通量。结果表明,沙河水库沉积物重金属质量比随深度增加均呈现明显下降趋势,以库心区最明显。沉积物中Cr、Cu、Ni、Pb、Zn的平均质量比分别为49.8 mg/kg、42.8 mg/kg、42.9 mg/kg、18.3 mg/kg、167.9 mg/kg,除Pb外均超过北京市土壤自然重金属质量比近2倍。库心区重金属污染最为严重,表层沉积物中Cr、Cu、Ni、Zn质量比分别超过北京市土壤自然背景值2.8、4.3、2.6、5.9倍。各采样点综合潜在生态风险指数(RI)以库心区最大,为49.9,但所有样点RI及均值都低于150,处于低潜在生态风险状态。随深度增加沉积物孔隙水中Cr质量浓度基本保持恒定;As质量浓度呈明显增加趋势,即存在孔隙水中As向上覆水释放;Zn、Ni和Cu质量浓度随深度增加呈下降趋势,并逐渐趋于稳定。Cr、Zn、As、Ni、Cu在沉积物-水界面的扩散通量分别为13.05μg/(m2·d)、-20.89μg/(m2·d)、108.4μg/(m2·d)、-35.67μg/(m2·d)、-5.11μg/(m2·d)。
The paper intends to make a study of heavy-metal contaminant distribution features and the diffusion flux estimation in the sediment of Shahe Reservoir, Beijing. As is known, the central part of the sediment area of Shahe Reservoir is in the upper reach of the China North Canal, which serves as the focus of our analysis of the sedimentary heavy metal contents, including Cr, Cu, Ni, Pb and Zn at the vertical profile. And, then, we have done the environmental risk assessment of the heavy metal contends above mentioned by using Lars H kanson potential ecological risk index. In proceeding with our research, we have worked out the fluxes of heavy metals via a single-dimensional transport-reaction model （the Fick＇s First Law）, that helps to acquire the concentration gradient of heavy metals （Cr, Zn, As, Ni and Cu） across the sediment-water interface. The results of our risk assessment have shown that the heavy metal content has had a significant decreasing trend with the increase of the depth, especially for the sediment core in the central part of the reservoir. We have also worked out that the average content of Cr, Cu, Ni, Pb and Zn in the sediment cores accounts for 49.8 mg/kg, 42.8 mg/kg, 42.9 mg/kg, 18.3 mg/kg and 167.9 mg/kg, respectively, which proves to be over twice as much as the background value of Beijing ground soil except for Pb. The central part of the reservoir has been suffering the most serious metal pollution, with its surface sediments being 2.8, 4.3, 2.6 and 5.9 times of Cr, Cu, Ni, and Zn as compared to the background values of Beijing soil. What is more, the maximum value of the risk index （RI） appears in the central reservoir, 49.9, but all six RI values of Shahe Reservoir were less than 150, which indicates the sediments of Shahe Reservoir has experienced a low ecological risk. Moreover, with the increase of the depth, the profile of porewater shows a different trend, that is, while Cr content remains constant, As tends to reveal a significantly increasing trend. Whereas the contents of Zn, Ni and Cu, tend to decrease with the increase of depth and gradually come to get stabilized, the fluxes of Cr, Zn, As, Ni and Cu account for 13.05 μg/（m 2 ·d）, -20.89 μg/（m 2 ·d）, 108.4 μg/（m 2 ·d）, -35.67 μg/（m 2 ·d） and -5.11 μg/（m 2 ·d）, respectively.
出处
《安全与环境学报》
CAS
CSCD
北大核心
2014年第2期244-249,共6页
Journal of Safety and Environment
基金
中国科学院院仪器设备功能开发技术创新项目(2011007)
关键词
环境学
沙河水库
沉积物
重金属
扩散通量
environmentalology
Shahe Reservoir
sediment
heavymetal
diffusion fluxes
