Content characteristics and risk assessment of heavy metal elements in Shangluo tea garden soil

Abstract

Abstract The study focused on analyzing the content characteristics of heavy metal elements in the soil of the Shangluo tea garden and conducting a risk assessment. The goal is to offer insights for the prevention and control of soil heavy metal pollution, as well as the protection of the tea garden soil. A comprehensive investigation involved the collection of 165 soil samples from the primary tea production regions in Shangluo. The analysis included the examination of pH values and the concentrations of five heavy metal elements (Cd, Hg, As, Pb, Cr). Pollution levels were evaluated through the utilization of the Nemerow Pollution Index and Geo-accumulation Index. The mean concentrations of Pb, Cd, Cr, As, and Hg in the soil within the research area were 18.99 mg/kg, 0.07 mg/kg, 67.03 mg/kg, 8.67 mg/kg, and 0.03 mg/kg, respectively. These values were all found to be lower than the background levels established for Shangluo soil. According to the single-factor pollution index and geo-accumulation index, the overall status of tea plantation soils in the study area was non-polluted. However, the evaluation based on the Nemerow Pollution Index indicated a mild pollution level due to the light pollution status of Cd, Cr, and Hg, with 87% of the soil samples classified as non-polluted and 12% as mildly polluted. When compared with the risk screening values for agricultural soil, the average concentrations of heavy metals in the examined tea plantation soils were found to be below the prescribed screening thresholds. Pearson correlation analysis and cluster analysis indicated that the heavy metal pollution in Shangluo tea plantation soils is predominantly influenced by natural sources. However, it is important not to disregard the escalating impact of anthropogenic sources. Overall, the tea plantation soils in Shangluo are in a clean state, but there is a risk of pollution with Cd, Cr, and Hg elements.