兰州市排污沟表层淤泥中重金属元素分布及其环境危害特征

通过对兰州市排污沟淤泥的元素分析,研究重金属元素的来源、空间分布、迁移富集行为以及对环境的影响特征.相关分析表明:排污沟中淤泥的w(有机质)和粒度对重金属元素的迁移、富集有重要影响,高的w(有机质)和较细的沉积物有利于重金属元素的迁移、富集.污染源分析表明排污沟周边生活和工业生产活动的多污染源对淤泥中重金属蓄积有直接影响.通过潜在生态危害指数法评价生态风险,结果显示:单一重金属生态风险系数均小于40,各排污沟的潜在生态风险指数均小于150,排污沟表层淤泥均处于轻微的生态风险等级,各种重金属元素的生态风险由强到弱顺序为As>Pb>Cu>Cr>Zn.综合分析显示兰州市各排污沟渠淤泥已蓄积了一定量重金属污染元素,直接排入黄河后对黄河兰州段以及下游造成了潜在的风险危害.

Distribution and ecological risk assessment of heavy metals in the surface mud in Lanzhou open-ditch drainages

The contents and enrichments of heavy metals in surface sediments of Lanzhou open-ditch drainages were analyzed,so as to reveal their sources,distribution,removal and enrichment in surface sediments and their influence on the environment.The results show that TOC and particle size play an important role on the removal and enrichment of heavy metals.Human activities and production activities have direct influence on the enrichment of heavy metals in mud.The ecological risk factor for a single heavy metal and the potential ecological risk index are below 40 and 150 respectively,indicating that the risk of heavy metals is minor and the ecological risk of five heavy metals is in the sequence of As>Pb>Cu>Cr>Zn.The results indicated that the sullage in open-ditch drainages at Lanzhou has been rich in quantities of heavy metal pollution,which is harmful to the Yellow River if those pollutants are let out into the river directly.