发酵床熟化垫料重金属含量、形态及农用潜在风险分析

Content,morphology and potential risk of farm-oriented uses of heavy metals in spent fermented litters of bio-beds

通过测定4种使用4年的不同原料组成(稻壳-木屑、酒糟-木屑、菌糠-木屑、棉花秸秆-稻壳-木屑)的发酵床熟化垫料的不同重金属(铬、铜、锌、砷、镉、铅)含量及形态组成等指标,评价发酵床生态养殖熟化垫料的资源化利用价值及潜力。结果表明,4种发酵床熟化垫料的铬、镉、铅含量均低于有机肥料农业行业标准(NY/T3442-2019《畜禽粪便堆肥技术规范》)中相应重金属的含量限值,仅菌糠-木屑熟化垫料中的砷含量略高于标准中砷含量的限值要求。重金属形态分析结果表明,发酵床熟化垫料中可交换态铬、可交换态铜、可交换态锌、可交换态砷、可交换态镉及可交换态铅的比例均较低,铬、镉、铅以残渣态与有机结合态为主,锌、砷以残渣态与铁锰氧化物结合态为主,铜以有机结合态与铁锰氧化物结合态为主。由研究结果可以看出,在施用发酵床熟化垫料的土壤中,锌的年输入总量相对较高,其次是铜、铬、铅。

The resource utilization value and potential of spent fermented litter in bio-beds were evaluated by detecting indices such as contents of different heavy metals(Cr,Cu,Zn,As,Cd,Pb)and morphology composition of four spent fermented litters in bio-beds used for four years with different raw materials(rice hull-wood flour,vinasse-wood flour,mushroom substrate-wood flour,cotton straw-rice hull-wood flour).The results showed that the contents of Cr,Cd and Pb in four spent fermented litters of bio-beds were all lower than the limiting contents of corresponding heavy metals according to the agricultural industry standard for organic fertilizers,only the content of As in the spent mushroom substrate-wood flour litter was slightly higher than the requirements of the standard.The results of heavy metal speciation analysis showed that the proportions of exchangeable Cr,exchangeable Cu,exchangeable Zn,exchangeable As,exchangeable Cd,exchangeable Pb were relatively low,Cr,Cd and Pb were mainly in the forms of residues and organic bounds,Zn and As were mainly composed of residues and iron-manganese oxides forms,Cu was mostly composed of organic bounds and iron-manganese oxides forms.It can be seen from the results that the annual input of Zn in the soils applying spent fermented litter is relatively high,followed by Cu,Cr,Pb.