长江口九段沙湿地土壤石油类污染评价及其源特征分析

Assessment and Source Analysis of Petroleum-contaminated Soils in Jiuduansha Wetland

通过分析九段沙土壤及附近水域石油类物质的时空分布,研究了土壤石油类污染现状及其来源特征。结果表明:九段沙土壤石油类物质以碳原子数小于10的烷烃和芳香烃类为主,有少量烯烃、羧酸及含氧杂环化合物。土壤石油烃类平均含量为23.98mgkg-1,单因子污染指数在0.431～0.525,污染样本超标率为0,目前土壤石油类污染尚处于清洁水平。土壤石油类物质含量沿高程有显著变化,中潮滩最高,光滩最低;其季节性差异显著,表明湿地土壤有外源石油类物质的输入;夏秋两季含量较高,与期间频繁的海上作业及陆源污染相关;经监测,九段沙附近水域石油类污染含量为0.246～0.309mgL-1,其季节差异明显、且涨潮>落潮,表明九段沙土壤石油类污染主要来自外围水域,水体石油类物质在湿地有部分沉积。

In order to study and assess the petroleum contaminants and its source characteristics,the spatial and temporal distribution of the soil petroleum contaminants in Jiuduansha wetland were analyzed.The results showed that the main pollutants were alkane and aromatic hydrocarbons with less than 10 C-atom,and its average concentration was 23.98 mg kg-1.Single factor contaminant index ranged from 0.431 to 0.525,so all samples were in the grade of safety.The content of the petroleum contaminants in the soil changed significantly along with tidal elevation variation,and the highest was in the middle-tidal elevation while the lowest was in the low-tidal elevation.The seasonal variation of petroleum content was notable,which indicated that petroleum contaminants were input into wetland.Because of the frequent marine work activities,the concentration of oil was higher in the summer and autumn.the concentration of the petroleum contaminants of water near Jiuduansha wetland ranged from 0.246 to 0.309 mg L-1 and differed among every seasons,Moreover,the oil concentration of flood tide was higher than that of ebb tide.It could be concluded that the petroleum contaminants in the soil of Jiuduansha wetland mainly came from surrounding water and there were some oil deposits in the wetland soils.