福建省部分菜园土壤及蔬菜重金属含量的测量及污染评价

Heavy Metal Contents and Pollution Assessment of Soils and Vegetables Sampled in Fujian Province

采集了福建省10个典型地区50份菜园土壤样品及32份小白菜样品,测定了土壤及蔬菜(小白菜)样品中的重金属含量,并采用单项及综合污染指数法对土壤及蔬菜的重金属污染进行评价分析,通过改进的BCR连续提取法测定了土壤中铅和镉的形态含量和分布,并对蔬菜中铅和镉的污染进行相关性分析。结果表明:菜园土壤和蔬菜大多存在不同程度的重金属污染,主要表现为以重金属Cd和Pb的污染。其中,德化浔中所采集的菜园土壤及蔬菜样品分别受Pb和Cd的污染特别严重;只有厦门同安、龙岩新罗地区的土壤及蔬菜则均未受重金属污染。此外,蔬菜对土壤中的Cd表现出极强的富集能力。土壤中Cd的酸可提取态比例平均为36.6%,而土壤中Pb的酸可提取态比例(除德化浔中达到13%外)则不足2%,但酸可提取态Pb的含量与蔬菜中的Pb含量具有极显著的相关性(r=0.952,P<0.01),而Cd相应的相关系数只有0.66(P<0.01)。

Concentrations of heavy metals in fifty soils and thirty two Chinese white cabbage samples collected in ten typical vegetable-grown regions in Fujian Province were measured, and the contamination of heavy metals in soils and vegetables was assessed with the methods of single-factor pollution index and comprehensive pollution index. The chemical forms of Pb and Cd in soils were studied with a modified approach of BCR sequential extraction procedures. The results showed that most of the vegetables and soils were contaminated with heavy metals to some extend, but mainly contaminated by the elements of Pb and Cd. In particular, the soils and vegetables collected from Dehua Xunzhong were seriously contaminated by Pb and Cd, while both of the soils and vegetables in Xiamen Tongan and Longyan Xinluo were not found contamination with the heavy metals. Vegetables were found to be able to strongly absorb and enrich Cd from soils based on the high enrichment factors. The chemical form analysis of Pb and Cd in soils revealed that the larger amounts （mean value of 36.6%） of Cd in vegetable-grown soils could be extracted in the acid-extractable forms, while the amounts of acid-extractable forms of Pb were less than 2% except for Dehua Xunzhong, with 13% of acid-extractable of Pb in the soils. However, a significant correlation （r=-0.952） of Pb contents between the acid-extractable fractions and the vegetables was found at P〈0.01, while the correlation coefficient was only 0.66 （P〈0.01） for that of Cd.