Assessment of the variation of heavy metal pollutants in soil and crop plants through field and laboratory tests

Heavy metal contamination in cultivated land is turning out to be a major problem these days. This paper presents the experimental results of the variation of heavy metal concentration in the cultivated land before and after planting different crops and accumulation of heavy metal concentration in the crops. Six crops including corn, potato, broad beans, oats, beans and soybeans were planted in 13 test fields (15,686.75 m2) in Wushan County, Gansu, China in 2020. In total, 26 subsurface soil specimens and 47 crops samples were collected for which the concentration of heavy metals such as arsenic (As), lead (Pb), cadmium (Cd), chromium (Cr) and mercury (Hg) and pH were analyzed. The results showed that the average concentration of As, Cd, Cr, Hg and Pb in 26 subsurface soil samples were 58.9, 0.251, 72.4, 0.0342 and 32.2 mg/kg, respectively. The concentration of As in the study area was even higher than the average concentration of As in Gansu Province. It was also detected from the test results of crops that Hg was mostly accumulated in corn, broad beans, soybeans and oats, while Cd was most likely accumulated in potato. The ecological risk of heavy metal contamination was assessed using index of geoaccumulation (Igeo), pollution index (Pi), potential ecological risk index (RI) and bioconcentration factor (BCF). The reason of high heavy metal concentration in the study area was also explored and suitable crops and planting strategies were recommended. This paper provided a comprehensive approach to investigate the heavy metal contamination in cultivated land soil and crops and offered a reasonable method to mitigate heavy metal contamination.