Heavy Metal Pollution in the Soil of Kumquat Orchards in Youxi County and Its Risk Assessment

In order to clarify the present situation of heavy metal content in the soil of kumquat orchards in Youxi County and to evaluate its risk, a total of 100 soil samples were collected from 20 orchards in Guanqian town and Baziqiao town of Youxi County, and the contents of heavy metals such as As, Hg, Pb, Cd, Cu and Cr were analyzed. Then, the soil pollution was evaluated by the single factor index, Nemero comprehensive index and Hakanson potential ecological risk index. The results showed that the pH of the soil samples from the kumquat orchards in Youxi County ranged from 4.52 to 6.45, showing the weak acidity. The contents of heavy metals all met the requirements of the national standards for soil pollution risk control of agricultural land. The single factor pollution indexes of six heavy metals in the 20 orchards were all within 0.7 except Hg. The comprehensive pollution index was greater than 0.7 and less than 1, indicating that the pollution of six heavy metals in the soil was at the warning level. The assessment index of potential ecological risk was 126.4, indicating that the soil of the main kumquat orchards in Youxi County was at the level of mild ecological damage. Although the six heavy metals in the soil of 20 kumquat orchards in Youxi County reached the level of mild pollution, it was still within the limits of heavy metal content in the soil of producing areas for the safe production of orchards.