重金属与农药交互作用对青菜生长的影响

调节重金属Cu、Pb、Zn、Cd复合污染红壤(投加浓度分别为:50,150,125和0.15 mg/kg)的pH在5.6左右,培养数月后盆栽青菜。在收获的前10 d喷施马拉硫磷和灭多威,研究重金属与农药交互作用对青菜生长的影响。结果表明,收获的青菜样品中,2种农药均无残留。青菜中可食部分的重金属含量主要取决于土壤中重金属含量,重金属Cu、Zn和Cd含量均在标准限量之内,但Pb含量超过标准限量值,主要是由于多种重金属的协同作用,活化了土壤中铅的生物有效性。在重金属与农药交互作用条件下,青菜生物量显著降低。主要是由于这两种农药在水解条件下产生了酸性物质,降低了土壤的pH值,提高了重金属的生物有效性,增强了重金属对青菜生长的抑制作用。

The Effect of Interaction between Heavy Metals and Pesticides on the Growth of Greens

This paper mainly studies the impact of the interaction between heavy metals and pesticide on the growth of greens based on pot experiment.The vegetables,were planted on red soil polluted by heavy metal,and the concentrations of Cu,Pb,Zn and Cd were 50,150,125 and 0.15 mg/kg respectively.The pH of the soil was about 5.6 after adjusted by calcareousness.10 days before harvest,malathion and methomyl were sprayed in the greens.The results indicated that there was no pesticide residue in the vegetables,and the concentration of the heavy metals did not exceed the standard except Pb.The interrelation of the four heavy metals caused the improvement of lead biovailability.The biomass was reduced significantly under the interaction,compared with the controlled treatment.The main reason was that the two pesticides could hydrolyze into organic acids,which would decrease the pH of the soil and then enhance the activity of the heavy metals,so the biomass was notably depressed.