INVESTIGATION AND EVALUATION OF HEAVY METALS IN AN INFORMAL LANDFILL SITE

The main objective of the paper was to comprehensively assess pollution level of an informal landfill in Zhejiang. The landfill gas, leachate and humus of this landfill were investigated and analyzed in terms of common parameters including methane, H₂S, COD, etc.. Standard index, Nemero pollution index and index of geoaccumulation were also used to evaluate heavy metal pollution in the humus of the studied landfill. The obtained results showed that the methane content of the landfill gas ranged from 2.59% to 53.62%. Moreover, the concentration of several parameters including H₂S, NH₃, odor and non methane total hydrocarbon was significantly higher than the standard. In terms of the landfill leachate, the content of 11 kinds of common pollutants exceeded the standard of GB 16889-2008, among which the concentration of chroma, suspended matters, COD, BOD₅, total nitrogen and ammonia nitrogen of all samples were found to exceed the standard. The concentration of heavy metals, including Ni and Pb was slightly higher than the risk screening values of the first type of land in the Soil Environment Quality Risk Control Standard for Soil Contamination of Development Land (China National Standard, GB 36600-2018). The results obtained from the index of geoaccumulation evaluation demonstrated that part of humus were slightly polluted by Ni and Pb. Nemero pollution evaluation result further indicated that the pollution level of heavy metals in humus soil was mild. Overall, there was potential safety risk from this informal landfill. More attention should be paid to pollution from landfill in the future studies.