土壤重金属含量对3种常见菊科叶菜重金属累积的影响

为了解蔬菜产地土壤重金属含量对蔬菜重金属累积的影响,以我国南方常见的3种菊科叶菜(苦荬菜Sonchus oleraceus、生菜Lactuca sativa var.crispa、油麦菜Lactuca sativa)为研究对象,选择5种重金属为研究指标,对蔬菜及其产地土壤重金属含量的相关性等进行了分析。3种蔬菜的重金属富集系数表明,3种蔬菜吸收、累积不同重金属元素的能力存在明显差异(p0.05),5种重金属被蔬菜吸收的容易程度从大到小依次为镉、铬(汞)、铅(砷)。各蔬菜品种的重金属超标率和土壤重金属超标率存在不一致现象。其中,蔬菜中镉、铬、砷、汞的超标率均低于土壤的超标率,而蔬菜中铅的超标率则高于其对应土壤的超标率。对3种蔬菜产地土壤与蔬菜重金属质量比的相关性分析表明,其中除生菜中铅和砷与土壤中相应重金属元素相关性不显著外,其他情况下都呈显著相关性(p0.05)。建立了3种蔬菜及其土壤重金属含量的回归分析模型,并据此推算出种植3种蔬菜的土壤重金属安全阈值,其中,除生菜产地土壤中铅阈值在现行标准范围内之外,其他土壤重金属阈值均远高于现行标准。该阈值结合了大田土壤环境的实际情况,对当地农产品安全生产具有更强的针对性和可靠性。

Effect of heavy metal contents in the soil on their pollution accumulation of the 3 kinds of Composite leafy vegetables

The given paper is aimed to explore the correlation of heavy metal content pollution and the absorptive regularity between the specific vegetable species and the soils of their cuhivation plots so as to provide a reasonable evaluation of the soil's environmental quality and its relation to the vegetable production safety.The reason for our choice is that the 3 kinds of common composite leafy vegetables are typically common in China South (Sonchus oleraceus,Lactuca sativa var.crispa and L.sativa),which are under strong influence by the following five heavy metal contaminants (Cd,Cr,Pb,As and Hg).The relation between the heavy metal contents in the vegetables and the soil in which they grow has been investigated and analyzed via the bio-contented factors of the five heavy metals,the results of which prove to be noticeably different in the accumulation ability (p ＜ 0.05).The degree of the five heavy metals absorbed by the said three vegetables has been found in a descending order as follows:Cd ＞Cr,Hg ＞ Pb,As.On the other hand,we have also noticed the sheer inconsistencies of the over-standard rates found between the vegetables and the soils wherein they grow for each heavy metal element.For example,the over-standard rates of Cd,Cr,As and Hg in the above mentioned vegetables has been found lower than those in the soils,whereas the reverse has been found for the over-standard rates of Pb.Based on the regression analysis,we have established a relational model of the heavy metal content rates in the vegetables and the soils.And,next,we have worked out the soil threshold value of each heavy metal element for the safety production of each kind of the aforementioned vegetable.Among them,except for the soil Pb threshold of L.sativa var.crispa in the scope of the current standards,the other heavy metal threshold values of the three vegetables in the soil have been found much higher than those given in the current standards,particularly,the soil's Hg threshold values prove to be 13-23 times higher than in the general standards.For the soil threshold values under study combined with the actual situation of the local field environment,it can be said that they are more suitable and reliable for the safety production of the local agriculture.