汕头市典型区域土壤重金属污染特征及评价

对汕头市电子垃圾环境污染典型区域土壤中的铜、铅、锌、镉、铬、镍、砷和汞的分布特征进行了调查和分析,根据重金属含量对土壤环境质量及其污染风险状况进行评价.结果表明,以单因子污染指数评价,在118个表层土壤样品中,有42个样品的重金属含量超标,超标率为35.6％.超标金属依次为：Ni超标26.3％, Cu超标18.6％,Hg超标7.6％,As超标0.85％,其余重金属未超标.5个土壤剖面点共20个分层样品中,有7个样品的重金属含量超标,超标率为35.0％.超标金属依次为：Ni超标20.0％,Hg超标15.0％,Cu超标10.0％.所测土壤重金属污染综合指数在0.32～6.08之间,平均1.26.受污染土壤占39.1％,其中重度污染为7.2％,中度污染为10.9％,轻度污染为21.0％.在汕头市各区域中,以潮阳区土壤重金属污染综合指数平均值最高（1.98）,其余依次为金平区、澄海区、潮南区、龙湖区、濠江区和南澳县.环境污染、工农业活动以及污灌水是造成汕头土壤重金属污染的主要原因.汕头市土壤中,Cu、Pb、Hg的含量均显著高于广东省、国家和世界的土壤背景值.采取控制源头,以综合治理方法促进土壤改良是恢复和改进汕头土壤质量的有效措施.

Distribution of Heavy Metals in Soils from the Typical Regions of Shantou and Their Environmental Pollution Assessment

Distribution of Copper (Cu), Zinc (Zn), Nickel (Ni), Lead (Pb), Chromium (Cr), Cadmium (Cd), Arsenic (As), and Mercury (Hg) in soils from the typical regions of Shantou such as electrical wastes recycling sites were studied, and pollution risk of heavy metals on the environment was evaluated. Among the 118 surface soil samples, 42 (corresponding to 35.6%) were above the national standards when evaluated with single factor index method. Specifically, Ni, Cu, Hg, and As exceeded the standards by 26.3%, 18.6%, 7.6%, and 0.85%, respectively. Among the 20 samples from five section soil sites, 7 (corresponding to 35.0%) were above the national standards with Ni, Hg, and Cu exceeding respectively by 20.0%, 15.0%, and 10.0%. The composite pollution index of all samples ranged from 0.32 to 6.08, with an average of 1.26. Overall, 39.1% of soils were polluted, and which composed of heavily (7.2%), moderately (10.9%), and lightly (21.0%) contaminated soils. The highest composite pollution index (1.98) was found in Chaoyang district, followed with descending order by Jinping, Chenghai, Chaonan, Longhu, Haojiang districts, and Nanao town. Pollution, industrial and agricultural wastes, and contaminated irrigation water were the main sources of heavy metal contamination in soils. Except for Cr and As, concentrations of Cu, Pb, and Hg in soils from Shantou districts were much higher than the corresponding soil background concentrations recorded for Guangdong province, China, and the whole world. Controlling heavy metal output from industrial and agricultural sources and reducing the concentrations of soil heavy metals through integrated treatment techniques are the effective methods to improve the soil quality in Shantou.