天津郊区土壤-蔬菜系统中Cd的积累特征及污染风险

Cadmium accumulation and pollution risks to human health based on Monte-Carlo model of soil and vegetable-using vegetable field in Tianjin suburbs as example

在对天津郊区蔬菜地大规模采样调查的基础上,对土壤和蔬菜系统中Cd积累特征进行分析,比较了不同种类蔬菜吸收Cd的能力,利用Monte-Carlo模型研究了土壤Cd通过饮食途径对人体健康造成的风险.结果表明,研究区内Cd积累呈log正态分布,其含量范围、算术平均值和中值分别为0.04～3.2,0.31,0.24mg/kg,土壤Cd含量均值远高于天津市土壤Cd背景水平,呈现明显的积累趋势.圆白菜、芥菜、黄瓜、西葫芦、西红柿、茄子、豆角和大葱中Cd积累量均有超过国家食品卫生标准的样本检出,综合超标率为7.6%.根据各类蔬菜对Cd的富集系数,采用CHAID系统聚类方法,将天津郊区蔬菜分为4类,各类蔬菜吸收Cd能力的差异显著.基于Monte-Carlo模型的分析结果表明,达到重污染水平时,土壤Cd会对人体健康产生较大风险.

Based on a large scale survey of cadmium concentration in soil and vegetables in Tianjin five suburbs,the characteristics of cadmium levels in soil and vegetables were analyzed. In addition,absorption capability of soil cadmium with different vegetable species was researched. Risk of vegetable soil cadmium to human health through soil-vegetable-body was assessed by Monte-Carlo technique. The data of soil cadmium complies with the log normal distribution. Cadmium concentrations in soils ranged from 0.04 to 3.2mg/kg,with arithmetic mean,median of 0.31mg/kg and 0.24mg/kg. Compared with the background cadmium concentrations of soil from tianjin,the arithmetic mean of soil cadmium was higher,there appeared to be a significant accumulation of cadmium in soil collected from fields that produce vegetables. In all of the vegetable species,wild cabbage,brassica juncea,cucmuls sativus,cucurbita pepo,lycopersicon esculentum,solanum,bean and allium fistulosum has the samples that the cadmium concentration is higher than the maximum levels of cadmium in food. The synthetically ration of the cadmium contents exceeding criterion is 7.6 percents. CHAID system cluster analysis on the cadmium bioconcentration factor（BCF） in vegetables indicated that the samples could be separated into four groups based on BCF and there were significant difference between the four groups. The assessed results by Monte-Carlo model testify that there was significant risk to human health under heavy metal pollution soil.