BACKGROUND Cu, Pb, Zn and As were widely used as feed additives in the study area. However, the absorption rate of heavy metals by livestock and poultry was low. The concentration of heavy metals in livestock wastewater was high. The livestock wastewater as organic fertilizer may lead to the accumulation of heavy metals in the soil.

OBJECTIVES To evaluate the pollution degree, the potential ecological risk and health risk of heavy metals from the long-term swine manure irrigated vegetable soils in Fuzhou City of Jiangxi Province, China.

METHODS Eleven topsoil samples were obtained from the long-term swine manure irrigated vegetable soils in Fuzhou City of Jiangxi Province, China. The concentrations of As, Cd, Cr, Cu, Pb and Zn were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS). The degree of pollution and the potential ecological risks of the heavy metals were assessed using the pollution load index (PLI) and the potential ecological risk index (RI), respectively. The health risk was evaluated by a health risk assessment model.

RESULTS The average concentrations of Cu, Zn, As and Cr are 75.8, 32.8, 93.7, and 21.3mg/kg, respectively, which were higher than the soil background values of Fuzhou City. The average concentration of Cd (0.09mg/kg) was very close to the background value, and the average concentration of Pb (15.2mg/kg) was lower than the soil background value. The pollution load index indicated that the moderate pollution of As occurred in the researched soils, and there was slight pollution of Cu and Zn, and no pollution of Cd in the majority of the sampling sites. There was no pollution of Pb and slight pollution of Cr in all sampling sites. The average PLI of the six heavy metals from all sampling sites was 1.22, which was categorized as slight pollution. Low potential ecological risk was posed by the six heavy metals. The mean RI was 66.26 which represented a low ecological risk. The annual child and adult non-carcinogenic risk index was 0.06 and 0.12, respectively. The annual child and adult carcinogenic risk index was 1.65×10^-5 and 3.67×10^-5, respectively. Non-carcinogenic and carcinogenic health risks of adults and children in the soil were acceptable.

CONCLUSIONS There was generally slight pollution of heavy metal in the study area but it was moderately polluted by As in most sampling points. However, due to the accumulative effect of heavy metals in the soil, close attention must be paid to changes in the concentration of heavy metals in the irrigated soil in the future, to prevent the risk caused by heavy metals pollution.