温州温瑞塘上游调水河段底泥重金属分布及污染评价

Spatial Distribution and Pollution Assessment of Heavy Metals of Sediments in Upper Reach of the Wenruitang River

为了揭示温州温瑞塘河调水上游仙门河主要过境河段表层底泥的重金属分布特征和污染程度,在仙门河郭溪段设置7个样点采集沉积物样品,对其Pb、Zn、Cu、Cr以及Hg含量的垂向和沿程分布特征开展了研究,并进行污染评价。结果表明,除Cu和Zn(含量分别为212.38±119.76 mg/kg和274.35±91.88 mg/kg)外,其他重金属的含量均符合《土壤环境质量标准》(GB15618-1995)二级标准。表层底泥重金属含量的垂向分布呈现"三段式"结构,而沿程分布表现为从上游到下游,先增后减。风险评价结果表明,Cu的富集程度最高,Cr富集程度最低。Hg的潜在危害指数大于其他金属,Hg和Cu是郭溪底泥中重金属潜在生态风险增加的主要原因。底泥重金属的潜在生态风险空间差异依次为太阴宫>河头大渡桥B>仙庄A>鹇湖桥B>河头大渡桥A>仙庄B>鹇湖桥A,小工业区的近源污染对底泥重金属污染影响较大。

To obtain the distribution characteristics of heavy metals in the upper reach of the Wenruitang River, some sediment cores at seven sites were collected in Guoxi of the Xianmen River. The heavy metal contents of Pb, Zn, Cu, Cr and Hg were analyzed for pollution assessment. The results showed that the contents of all these heavy metals were in compliance with the second grade of national soil environmental quality standard（GB15618-1995）, except for Cu and Zn（212.38 ± 119.76 mg/kg and 274.35 ± 91.88 mg/kg, respectively）. The vertical distribution of heavy metals was in a＂three-segments＂ structure. The distribution of heavy metals from upstream to downstream gradually increased at the upriver and reached the maximum at the middle of the river, then decreased at the downriver. Cu had the highest concentration in the sediments and Cr had the lowest concentration. The potential hazard index of Hg was much greater than the other metals. Hg and Cu were intensifying the potential ecological risks in the sediments of the upper Wenruitang River. The potential ecological risk in different sediments was ranked as Taiyingong Daduqiao Station B Xianzhuang Station A Xianhuqiao Station B Daduqiao Station A Xianzhuang Station B Xianhuqiao Station A.The heavy metal contents of sediment were deeply affected by the source of pollution near the small industrial zone.