有机粪肥施加对不同类型农田土壤重金属污染的影响

Effects of Organic Fertilizer on Heavy Metal Pollution in Different Types of Farmland

摘要: 为认识施加有机粪肥条件下，不同类型农田土壤重金属富集现状和污染危害，探索其防控途径，为有机粪肥的施用、重金属污染防治提供科学依据，确保作物质量安全，选择河北省某大棚生菜土和草莓土为研究对象，种植作物前在土壤中施加园区自制有机粪肥为底肥，作物生长过程中追加有机粪肥，采集施肥前和作物成熟期表层土壤，测定土壤中重金属铜(Cu)、锌(Zn)、镍(Ni)、铅(Pb)、铬(Cr)、镉(Cd)、和砷(As)的含量，与风险筛选值进行比较，并采用单因子污染指数法、内梅罗综合污染指数法、地累积指数法和潜在生态危害指数法对土壤重金属污染程度进行综合评价。结果表明：受到施加有机粪肥的影响，作物成熟期生菜土中Zn、As、Cd、Pb和Cr含量相对于施肥前都有所增加，作物成熟期草莓土中除了Ni以外的六种重金属含量也都有一定程度的升高。施肥前和作物成熟期生菜土和草莓土中七种重金属的含量均低于风险筛选值。从单因子污染指数和内梅罗综合污染指数来看，施肥前和作物成熟期生菜土和草莓土中的重金属污染都未超标。地累积指数的评价结果表明，有机粪肥的施加对生菜土中Zn的地累积指数影响较大，使作物成熟期生菜土中的Zn处于轻度污染。施加有机粪肥对草莓土中Zn、Cd和Pb的地累积指数影响较大，使作物成熟期草莓土中的重金属Cd接近中度污染，Zn和Pb也存在一定的轻度污染。潜在生态危害指数评价结果分析表明，施加有机粪肥后，作物成熟期生菜土中的Cd达到了中度生态危害，总的潜在生态指数也有所增加；草莓土中Cd由施肥前的中度生态危害达到生物成熟期的强生态危害，同时极大地提高了总的潜在生态指数。因此，施加有机粪肥对生菜土中的Zn和Cd以及草莓土中Zn、Pb和Cd的污染作用较大，在进一步生产和施用有机粪肥时应重点把控。

Abstract: In order to recognize the status of heavy metal enrichment and pollution in different types of farmland soil with the application of organic fertilizer, explore its prevention and control methods, ensure the quality and safety of plants, the lettuce soil and strawberry soil in one of the green-houses in Hebei province were studied. Before cultivating the lettuce and strawberry, the organic fertilizer home-made by the park was applied into the soil, and organic fertilizer was added during the growth of plants. The surface soil before fertilization and during the ripening period of the plants was then collected. The heavy metals, including copper (Cu), zinc (Zn), nickel (Ni), plumbum (Pb), chromium (Cr), cadmium (Cd), and arsenic (As) were measured and compared with the risk screening values. The pollution degrees of heavy metals in soil were evaluated comprehensively by single factor pollution index method, Nemerow comprehensive pollution index method, geoaccumulation index method and potential ecological hazard index method, respectively. The results showed that the contents of Zn, As, Cd, Pb and Cr in lettuce soils at ripening stage increased compared with those before fertilization, and the contents of six heavy metals except Ni in strawberry soils at ripening period also increased to a certain extent. The contents of seven heavy metals in lettuce and strawberry soils before fertilization and during the ripening period of the plants were lower than the risk screening values. According to the single factor pollution index and Nemerow comprehensive pollution index, the heavy metal pollution in lettuce soil and strawberry soil before fertilization and during the ripening period of the plants did not exceed the standard. The evaluation results of the geoaccumulation index showed that the application of organic fertilizer had a great influence on the geoaccumulation index of Zn in lettuce soil, which made Zn in lettuce soil slightly polluted during the ripening period of the plants. Application of organic fertilizer had a prominent effect on the geoaccumulation index of Zn, Cd and Pb in strawberry soil, making Cd in strawberry soil during the ripening period of the plants close to moderate pollution, while Zn and Pb were also slightly polluted. Results of potential ecological hazard index evaluation showed that Cd in lettuce soil during the ripening period of the plants reached moderate ecological hazard and the total potential ecological index enhanced after applying organic fertilizer. After the application of organic fertilizer, the moderate ecological harm of Cd in strawberry soil before fertilization reached the strong ecological hazard during the ripening period of the plants, and at the same time, the total potential ecological index was greatly improved. Therefore, the application of organic fertilizer had a significant impact on the pollution of Zn and Cd in lettuce soil and Zn, Pb and Cd in strawberry soil, in that the further production and application of organic fertilizer should be mainly controlled.