Cd、Pb和Zn在土壤-紫茎泽兰-泽兰实蝇系统中的生物富集效应研究

Bioconcentration effects of Cd, Pb and Zn in soil-Eupatorium adenophorum Spreng-Procecidochares utilis Stone system

泽兰实蝇（Procecidochares utilis Stone）是目前入侵杂草紫茎泽兰（Eupatorium adenophorum Spreng）的一种重要天敌,但在重金属污染的矿区泽兰实蝇对紫茎泽兰的植株寄生率明显降低。故利用同心圆采样法在云南兰坪金顶铅锌矿区5 km范围内采集土壤、紫茎泽兰及泽兰实蝇并测定重金属含量,以研究重金属在土壤紫茎泽兰茎泽兰实蝇系统中的生物富集效应,探讨重金属胁迫影响泽兰实蝇控制效果的机制。结果表明：土壤紫茎泽兰茎泽兰实蝇系统中Pb、Zn和Cd含量随着距矿中心距离的增加而极显著下降,Cd、Pb和Zn在土壤紫茎泽兰茎系统中的富集系数分别为0.205~0.614、0.058~0.079和0.222~0.398,平均值分别为0.453、0.067和0.315,在紫茎泽兰茎泽兰实蝇系统中的富集系数分别为1.06~7.69、9.68~20.13和1.13~1.56,平均值分别为2.47、12.83和1.42。Cd和Zn属于强聚集,Pb属于很强聚集的元素。本研究结果证明,Pb、Zn和Cd可以在土壤紫茎泽兰茎泽兰实蝇系统逐级传递富集,并初步阐明了重金属Cd、Pb和Zn在土壤紫茎泽兰泽兰实蝇系统中的传递规律。这丰富了重金属污染的生态毒理学效应,为进一步研究重金属胁迫影响泽兰实蝇控制效果的机制奠定了基础。

Procecidochares utilis Stone is an obligatory parasitic natural enemy widely used to control the highly invasive Eupatorium adenophorum Spreng plant.However,parasitic rate of P.utilis in E.adenophorum has significantly decreased in mining areas polluted with heavy metals.To study bioconcentration effects of Cd,Pb and Zn in soil-E.adenophorum-P.utilis system,soil,E.adenophorum and P.utilis samples were collected at the Lanping Lead-Zinc Mine in Yunnan Province using the concentric circles method.The samples were then analyzed for Cd,Pb and Zn contents.The results showed that Cd,Pb and Zn contents in soil-E.adenophorum-P.utilis system significantly declined from the center outwards.The ranges of bioconcentration factors of Cd,Pb and Zn in the soil-E.adenophorum system were 0.205~0.614,0.058~0.079 and 0.222~0.398 with corresponding averages of 0.453,0.067 and 0.315,respectively.The bioconcentration factors of Cd,Pb and Zn in the E.adenophorum-P.utilis were 1.06~7.69,9.68~20.13 and 1.13~1.56 with corresponding averages of 2.47,12.83 and 1.42,respectively.Pb was more easily absorbed than Cd and Zn.The results confirmed that Cd,Pb and Zn could be transferred and bioaccumulated in soil-E.adenophorum-P.utilis system.This mainly expanded the mode and trend of heavy metal transfer from soil to E.adenophorum to P.utili.This finding was also helpful in enriching the eco-toxicological effects of heavy metal pollution.It further strengthened the basis for future studies of the mechanism of heavy metal stress control effects on P.utilis.