滇池疏浚底泥中重金属对蔬菜种植生态安全的影响

Ecological safety impact of the heavy metal contents in the dredged sediment of Dianchi Lake on the growth of vegetables

滇池疏浚底泥富含蔬菜需求的营养成分,农用可提高土壤保水肥能力,改良土壤的适耕性,有利于植物的生长发育,有一定的增产效果,但可能存在重金属污染问题。通过底泥试验及加入石灰钝化试验,对生菜、白菜、棒菜和萝卜4种蔬菜施用疏浚底泥作为有机肥进行种植,分析底泥农用后其重金属对蔬菜的影响,并进行风险评价。结果表明,盆栽试验中,底泥施用量控制在5%(0.05 kg/kg)内且加入石灰改良后,蔬菜中Cu和Cd含量显著降低,但对Pb、Zn效果不明显。叶菜类蔬菜(生菜、白菜、棒菜)重金属富集能力(BCF)从大到小均表现为Cd、Pb、Zn、Cu,而块茎类萝卜BCF表现为Cd、Zn、Pb、Cu。研究表明,化学致癌物Cd与非化学致癌物Pb、Zn、Cu引起的健康风险均在终身可接受风险水平。

In this study,the author intends to present the investigation results on the influential effects of the heavy metal contents in the dredged sediments of Dianchi Lake,Yunnan,on the vegetable growth.For the said research purpose,the paper has made an analysis of four kinds of vegetables including lettuce（Lactuca sativa）,Chinese cabbage（Brassica rapa var.glabra）,mustard（Brassica juncea） and radish（Raphanus sativus） in the dredged sediments and dredged sediments mixed with calcium oxides,respectively.The fertility of the soil and the yield of the vegetables can he increased if the contamination of the heavy metals in the soil can be somewhat improved.To reduce the risk of the said heavy metal contamination of the soil,we have conducted the pollution risk assessment.The results of our analysis indicate that the dosage of the sediments should be lowered to less than 5%（0.05 kg/kg）,which can help to decrease the concentration of Cu and Cd in the vegetables significandy with calcium oxides being added to the sediments.However,little has been found with the effect by decreasing the concentration of Pb and Zn.We have also found that the bio-concentration factors（BCFs） on different heavy metals of leaf vegetables can be stated in a descending order as is shown below：Cd〉Pb〉Zn〉Cu,whereas the BCFs on different heavy metals of tuber radish can be shown in the order as Cd〉Zn〉Pb〉Cu.Our investigation results also indicate that the health risk caused by the chemical carcinogens Cd tends to be lower than the recommended maximum lifetime acceptable risk level set by the international radiation protection（ICRP） committee.Among the non-chemical carcinogenic heavy metals,Zn proves to bring about the most serious health risks than Pb,while Cu turns to be the lowest.We have also found that the health risks that can be brought about by the non-carcinogenic heavy metals turn to be much lower than that provided by the British Royal Society,the Swedish Environmental Protection Agency and the Dutch Ministry of Construction and Environment.