新乡市郊区大棚菜地土壤重金属Pb、Cd、Cr和Hg污染评价

Pollution and assessment of soil heavy metal Cd, Cr, Pb and Hg in greenhouse vegetable fields of Xinxiang suburb, China

科学评估菜地土壤重金属污染对保障食品安全和公众身体健康具有重要的现实意义。采用原子吸收光谱法和冷原子吸收光谱法，研究了新乡市郊区菜地土壤重金属Pb、Cd、Cr和Hg的质量分数，并参照HJ 333-2006《温室蔬菜产地环境质量评价标准》，对土壤重金属污染进行评价。结果表明：菜地土壤重金属Cd、Pb、Cr、Hg的平均质量分数分别为25.64、156.18、992.38、0.316 mg·kg-1。东黑堆、前河头、后河头和东水东菜地土壤重金属Cd、Pb、Cr均全部超标，其中以Cd污染最为严重，后河头土壤重金属Cd的质量分数达到33.78 mg·kg-1，超过土壤环境质量评价指标限值的111.6倍，东水东采样点次之，也超标66倍。除了前辛庄Hg污染超标127%以外，其他采样点重金属Hg均不超标。表层（0~10 cm）土壤重金属Hg质量分数高于耕层（10~20 cm），其他重金属没有表现出明显的规律性。在不同季节，Cr质量分数随着季节变化逐渐递增，Hg质量分数则呈递减的趋势；Cd和Pb质量分数没有明显规律性。不同采样点综合污染指数以后河头的为最高，达到了82.49，其他依次为前河头、前辛庄、东黑堆、东水东。总体上讲，新乡市近郊菜地土壤重金属综合污染指数远远超过Ⅴ级的限值3.0，前河头、后河头和前辛庄菜地土壤都处于极高风险的重金属污染状态；东黑堆和东水东菜地土壤也处于高风险状态。

To evaluate heavy metal pollution of greenhouse vegetable soil is of great significance to ensure food security and public health in China. Heavy metal Pb, Cd, Cr and Hg content in greenhouse vegetable soils in Xinxiang suburb were studied by using atomic absorption spectrometry and cold atomic absorption spectrometric method. According to the Environmental Quality Evaluation Standard for Farmland of Greenhouse vegetable production （HJ 333-2006）, the pollution situation of heavy metals Cd, Pb, Cr and Hg in greenhouse vegetable soil were also evaluated. The results showed that the contents of Cd, Pb Cr and Hg in greenhouse vegetable soils were 25.64, 156.18, 992.38 and 0.316 mg·kg-1, respectively, which were higher than the official standard, suggesting that greenhouse vegetable soils were seriously contaminated by heavy metal Pb, Cd and Cr. Cd pollution was the most serious in Houhetou sampling sites, which the average content was 33.78 mg·kg-1, 111.6 times exceed the concentration limit of the＆amp;nbsp;official standard for Cd, followed by 66 times in Dongshuidong sampling site. Hg content in Qianxinzhuang sampling sites were exceed the standard 127%, while under the official standard in other sampling sites. In different layers of soils, heavy metals Hg content in 0 to 10 cm in depth was higher than in 10 to 20 cm in depth, while showed no obvious regularity for other heavy metals. In different seasons, Contents were gradually increased for Cr from spring to autumn, and decreased for Hg, with no consistent trend for Pb and Cd. Comprehensive pollution index was the highest in Houhetou （82.49）, following by Qianhetou （66.01）, Qianxinzhuang （63.30）, Dongheidui （52.50）, and Dongshuidong （49.32）. Generally speaking, comprehensive pollution indexes of heavy metals were far more than the V grade limit （≥3.0）, which implied that greenhouse vegetable soils were heavily polluted by heavy metal Pb, Cd, Cr and Hg. It was suggested that the greenhouse vegetable soil is of high ecological risk in Qianhetou, Houhetou and Qianxinzhuang, and moderate risk in Dongshuidong and Dongheidui sampling sites.