我国不同肥料品种中砷、铬、铅、镉、汞和铊的含量与评价

The status quo of arsenic,chromium,lead,cadmium,mercury and thallium content in main chemical fertilizer categories in China

【目的】研究我国不同肥料品种中砷(As)、铬(Cr)、铅(Pb)、镉(Cd)、汞(Hg)和铊(Tl)的含量及污染程度,为了解我国肥料安全现状,减轻重金属环境风险,保障粮食安全提供支撑。【方法】本研究中采集氮肥、磷肥、钾肥、复合肥料、掺混肥料和其他肥料共6类17种代表性肥料样品400个。采用GB/T 23349—2020《肥料中砷、镉、铬、铅、汞含量的测定》规定的方法检测了肥料中As、Cd、Pb、Cr、Hg和Tl 6种重金属的含量,同时采用单因子污染指数法和内梅罗综合污染指数法评价了重金属的污染程度。【结果】所检测的400个样本中共有11个样本出现重金属超标情况,超标率为2.75%。6类肥料中有3类出现超标样品,超标率由高到低分别为磷肥、其他肥料和复合肥料;6类重金属中仅Cr未出现超标情况。综合单因子污染指数和内梅罗综合污染指数计算结果显示,6类肥料大类中磷肥达到轻度污染等级,磷肥的6种重金属的单因子污染指数处于较高水平,其中Hg的单因子污染指数达到1.5,达到轻度污染等级。【结论】依据我国现行的强制性国家标准GB 38400—2019《肥料中有毒有害物质的限量要求》,除磷肥外,我国其他肥料总体质量较好,重金属超标率较低,农田施用安全。磷肥、复合肥料和其他肥料中Hg、As和Tl主要来源于生产原料,肥料生产过程中应尽量避免原料中重金属的引入。

【Objectives】Investigation of the contents of As,Cr,Pb,Cd,Hg and thallium(Tl)in different kinds of chemical fertilizers will provide reference for the safe application of chemical fertilizers,and insurance of the food safety.【Methods】Total 400 samples were taken from 17 kinds of representative fertilizers in 6 categories including nitrogenous fertilizer,phosphate fertilizer,potassium fertilizer,compound fertilizer,bulk blending fertilizer and other fertilizer,and the contents of As,Cd,Pb,Cr,Hg and Tl were determined.The safety status of the fertilizers was evaluated via GB/T 23349−2020 Determination of arsenic,cadmium,chromium,lead and mercury contents for fertilizers.The contamination level of heavy metals was calculated using the method of single factor index and Nemerow pollution index.【Results】In 11 fertilizer samples,the heavy metal contents exceed the standard limit,accounting for 2.75%of total samples.Three in the 6 types of fertilizers were tested standard-exceeded samples,and phosphate fertilizer,other fertilizers and compound fertilizer ranked the top three in over-standard rate from high to low.Among the six heavy metals,Cr did not exceed the standard limit in all kinds of fertilizers.Based on the comprehensive calculation results of single factor pollution index and Nemerow pollution index,phosphorus fertilizer reached light pollution level,due to the relatively high level of six heavy metals,and Hg had the highest single factor pollution index(1.5),indicating that the level of Hg in phosphorus fertilizer reached the light pollution level.【Conclusions】Evaluated with the existing domestic standard GB 38400−2019,all the chemical fertilizer categories,excluding phosphate fertilizer,are low in heavy metal contents and safe for field application.Inspection is recommended based on the levels of Hg,As and Tl in phosphate fertilizer,compound fertilizer and new-type fertilizers,due to the heavy metal sources in the raw materials.