岷江下游丘陵区3种农业种植模式对铅(Pb)污染土壤的修复效益

Remediation Efficiency of Three Cropping Systems for Lead(Pb) Contaminated Agricultural Soils in Hilly Region of Minjiang River

为了解间作和轮作组成的农业种植模式对中轻度Pb污染土壤的修复效益,定点调查了岷江下游丘陵区3种农业模式（M1玉米＋红薯-小白菜＋菠菜,M2玉米＋生姜-茎用芥菜,M3水稻）作用下,土壤中Pb含量的变化以及Pb在土壤和作物系统中迁移和分配的特征,采用有时序的灰色关联分析法,比较了3种模式的综合效益。结果发现,土壤Pb含量变化在模式M1、M2中表现为显著下降后持平的＂L＂形特点（降幅10.65、13.91）,M3中为显著下降（降幅14.17）。Pb在作物非食用器官中含量是食用器官的1.10~33.00倍。玉米和稻谷食用器官中Pb的含量安全,生姜受到中度Pb污染,红薯、小白菜、菠菜等食用器官中Pb污染较严重,人体通过模式中作物日摄入Pb总量是WHO/FAO标准的4.23倍,但由于人体对Pb具有的耐性和清除机制、食用前对农产品的加工措施、当地农户将红薯和菠菜等作为猪饲料使用,以及现今社会人类日常饮食种类的丰富性等,有效地降低了农产品中Pb含量超标对人体危害的风险性。分析表明,3种模式的综合效益是显著的,灰色关联分析法的排序结果为M2〉M1〉M3。

Lead（Pb） pollutant has been considered as one of the most serious environmental problems worldwide.Including others,monoculture in agriculture may be successful for metal phytoremediation in short-term（two to three years）,although significant yield reduction in longer term applications.Intercropping and rotation systems might remedy this flaw by reasonably assigned.However,little information has been available on the remediation efficiency of cropping systems by assigning intercropping and rotation systems for Pb contaminated agriculture soil in field.Therefore,to understand the remediation efficiency of cropping systems for agricultural soils contaminated by mild to moderate Pb metal,field experiments were conducted in hilly region of Minjiang River,southwest of China.Three typical cropping systems including M1：maize ＋ sweet potato-chinese cabbage ＋ spinach,M2：maize ＋ ginger-stem mustard,and M3：rice were selected.The variations of Pb metal in soil and the accumulation and transfer characteristics of Pb from soil to the crops were investigated.GRATS（Grey Relational Analysis with Time Series） was used to evaluate comprehensive remediation efficiencies of three systems.The variation of Pb content in soils decreased significantly then flat as＂L＂ shapes in M1 and M2（decreased to 10.65% and 13.91%,respectively）,and decreased significantly in M3（decreased to 14.17%）.Accumulations of Pb metal in inedible parts of crops exceeded 1.10 to 33 times than that of edible parts of crops.Although accumulations of Pb in edible parts were security in maize and rice,which exceeded 2.75 times than related standard limits in ginger.Compared with others,sweet potato,cabbage,spinach,and stem mustard have contaminated seriously by Pb metal.The daily intake amount of Pb per day for an adult through crop productions from three systems exceeded 4.23 times of corresponding permit maximum limit of standards by WHO/FAO.But the risk of Pb content in crop productions for human body has reduced effectively,because of tolerance and cleanup mechanism of human body for Pb,machine processing measures before food,sweet potato,spinach and so on were used as pig feedstuff by farmers,and diversification foods in daily and others.Based on the above-analysis results,significant remediation efficiency of three systems were observed,and showed the order as M2M1M3 by GRATS.