生物炭基肥中重金属、多环芳烃的含量及风险

Content and Risk of Heavy Metals and Polycyclic Aromatic Hydrocarbons in Biochar-based Fertilizer

生物炭基肥虽然能够增加土壤养分、改善土壤结构,但也存在给土壤带来重金属、多环芳烃污染的风险。该研究为探究生物炭基肥的风险性问题,测定了7种不同原料生物炭基肥重金属、多环芳烃(PAHs)的含量并进行风险评价。结果表明:不同原料炭基肥中重金属的浓度差别较大,畜禽粪便类MA-P中重金属浓度最高,达到648 mg/kg。重金属中,Zn的含量最高,As的含量虽然低但由于其高迁移率及高毒性造成高环境风险指数,是炭基肥重金属风险的主要来源。生物炭基肥中的PAHs均以3环为主,低分子量PAHs含量高。总体TEQ值低于先前研究,畜禽粪便类MA-P的TEQ毒性高于其他植物源炭基肥,5环PAHs对于TEQ值贡献最大,只有MA-P中2环PAHs具有贡献量。当生物炭基肥施用量高于7.76 t/hm^(2),人类暴露于生物炭基肥改良的土壤的终生癌症风险增量值超过10^(-6),表明具有低致癌风险。成人污染物致癌风险高于小孩,且ED对于ILCR风险值的影响最大。研究表明,生物炭基肥中的重金属和多环芳烃具有一定的风险,在施用生物炭基肥时应控制施用量,椰壳炭基肥(PL-5)的风险性最低,可优先广泛应用。

Although biochar based fertilizer can increase soil nutrients and improve soil structure,it also has the risk of pollution of heavy metals and polycyclic aromatic hydrocarbons.In order to explore the risk of biochar based fertilizer,the contents of heavy metals and polycyclic aromatic hydrocarbons(PAHs)in 7 different raw materials of biochar based fertilizer were determined and the risk assessment was carried out.The results showed that the concentration of heavy metals in the biocharbased fertilizer varied greatly among different raw materials,and the concentration of heavy metals in animal feces was the highest,reaching 648 mg/kg.Among the heavy metals,the content of Zn is the highest,while the content of As is low,but due to its high mobility and high toxicity,resulting in high environmental risk index,which is the main source of potential risk of heavy metals in biochar-based fertilizer.The PAHs in biochar-based fertilizers were mainly 3-ring PAHs,and the content of low molecular weight PAHs was high.The overall TEQ value was lower than that of previous studies,and the TEQ toxicity of animal feces was higher than that of other plant-derived biochar-based fertilizers.The 5-ring PAHs contributed the most to the TEQ value,and only the 2-ring PAHs in MA-P had a contribution.When the application rate of biochar based fertilizer was higher than 7.76 t/hm^(2),the lifetime cancer risk increment value of human exposure to biochar based fertilizer improved soil was more than 10^(-6),indicating a low cancer risk.The carcinogenic risk of adult pollutants is higher than that of children,and ED has the greatest effect on ILCR risk value.Studies have shown that heavy metals and polycyclic aromatic hydrocarbons in biochar based fertilizer have certain risk problems,and the application amount of biochar based fertilizer should be controlled.Coir biochar based fertilizer has the lowest risk and can be widely used in priority.