长期施肥对土壤及玉米籽粒中Pb、As含量的影响

Effect of Long-Term Fertilization on Pb, As Contents of Soil and Maize Grain

【目的】探究褐土区长期施肥农田土壤重金属Pb、As含量的动态变化规律。【方法】基于22年的氮磷化肥与有机肥配施长期定位试验,通过对0—20及20—40 cm土层及2013年玉米籽粒Pb、As含量的测定,分析褐土农田Pb、As的累积状况、年际变化特征、剖面分布特征及对玉米籽粒Pb、As含量的影响。【结果】不施肥处理土壤Pb、As含量均有所减少,其他施肥处理均有所累积;土壤Pb含量整体呈升高趋势,较基础土样升高了1.77—8.41 mg·kg-1,升高幅度为4.42%—20.95%;土壤As含量则呈下降趋势,较基础土样降低了17.10%—41.54%;Pb具有表聚性,As在20—40 cm土层的含量要高于耕层;2013年不同施肥处理土壤重金属Pb、As含量均未超过土壤环境质量二级标准;其中磷肥和有机肥对褐土中Pb、As含量的处理间差异影响不显著;2013年玉米籽粒中Pb、As含量低于国家食品安全限量标准。【结论】施肥处理均表现出重金属Pb累积现象,因此应注意控制肥料的施用量。

【Objective】 The objective of this study is to explore the dynamic changes on contents of heavy metal Pb, As in cinnamon soil of long-term fertilization.【Method】Based on the experiment on 22-year application of nitrogen, phosphorus and organic fertilizers and the analysis of Pb and As contents in 0-20 and 20-40 cm soil layers and maize grains in 2013, the effects of accumulation state, interannual variation characteristics and profile distribution on changes of Pb and As contents in cinnamon soil and maize grains after long-term fertilization were studied.【Result】The soil Pb and As contents of no fertilizer treatment decreased, others increased. The soil Pb content increased 1.77-8.41 mg·kg-1 and variation of Pb was between 4.42% and 20.95%, respectively, as compared to the baseline levels. The soil As content decreased 17.10%-41.54%, respectively, as compared to the baseline levels. The content of Pb has obvious properties of surface-accumulation. The content of As in 20-40 cm soil layer was more than that in the plough layer. The contents of two heavy metals in soil tested in 2013 did not exceed the upper limits of the grade II criteria of the Environment Quality Standard for Soil. Pb and As contents in cinnamon soil were not significantly affected by the use of phosphate and organic fertilizers among treatments. Pb and As contents in maize grains analyzed in 2013 were below their respective thresholds of the national food safety standard.【Conclusion】The accumulation of heavy metal Pb in fertilization treatments was demonstrated. So, more attention should be paid to control the amount of fertilizer application.