Abstract:
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.
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