典型北方菜田常用肥料中重金属含量分析及污染风险评价

为了解北方菜田典型肥料中重金属的含量情况,以有机肥、水溶性肥料、微生物肥料、生物有机肥和复混肥料等5种北方菜田常用肥料作为研究对象,采集了268个代表性肥料样品,检测分析了肥料中As、Cd、Pb、Cr、Hg 5种重金属的含量情况,同时采用单因子污染指数法与综合污染指数法评价了重金属污染程度。结果显示,所有肥料中均检测出5种重金属。其中,有机肥中Pb的平均含量最高,为28.16 mg·kg~(-1),其次为CrAsCdHg。对比我国肥料重金属限定标准发现,尽管样品中Cd含量普遍较低,但是依然有0.63%的有机肥样品超标。其余4种肥料中,Cd含量最高的为水溶性肥,As、Pb、Cr和Hg含量最高的为生物有机肥;同时,生物有机肥中As、Pb、Cd的超标率分别为40%、20%和10%,Cr、Hg未发现超标。单因子污染指数和综合污染指数表明,所有肥料中重金属污染均属于清洁水平,但Pb和Cd的综合污染指数已分别达到了0.62和0.53,存在一定的污染风险,其安全性应该特别关注。

Content analysis and pollution risk assessment of heavy metal in common fertilizers in typical north vegetable fields

One of the main sources of heavy metals in farmland is the agricultural inputs, and long-term application of fertilizers with high level of heavy metals may lead to the accumulation of heavy metals in soil. In order to analyze heavy metals of the representative fertilizers of vegetable fields in the north of China, 268 representative fertilizer samples were collected from typical north vegetable fields, which are organic fertilizers, water-soluble fertilizers, microbial fertilizers, bio-organic fertilizers and compound fertilizers. In this study, heavy metals such as arsenic, cadmium, lead, chromium, and mercury in fertilizers were analyzed. Detailed observation indicated that five kinds of heavy metals were detected in almost all fertilizers, and Pb in organic fertilizers was the highest with 28.16 mg·kg^-1, followed by Cr, As, Cd, and Hg respectively. Compared with the national fertilizer limit standards, the excessive percentage of Cd was 0.63% in organic fertilizers. Among the other four fertilizers, the highest Cd occurred in water-soluble fertilizers and the highest As, Pb, Cr and Hg were found in bioorganic fertilizers. The excessive percentage of As, Pb and Cd in bio-organic fertilizers were 40%, 20% and 10% respectively. As and Hg did not exceed the standards. Meanwhile, the level of heavy metal pollution was evaluated by the Nemerow index method. The results indicated that the content of heavy metal in these typical fertilizers was at the clean level, while the comprehensive pollution index of Pb and Cd reached to 0.62 and 0.53 respectively. Based on these results, more attention should be paid to heavy metals contamination in fertilizers.