Soil assessment and risk evaluation of agricultural sewage irrigation area in south Baotou's urban vicinity

Taking south Baotou's urban vicinity, Inner Mongolia as research area, 945 surface soil samples were collected to measure total concentrations of cadmium（Cd）and lead（Pb）．According to "Determination of Land Quality Geochemical Evaluation"（DZ/T 0295-2016）, investigation areas were divided into polluted areas and non-polluted areas, and 137 combined samples were selected to analyze existence state of soil Cd and Pb forms．Results indicated that Cd had an average concentration of 0.38 mg/kg, while Pb was 151.56 mg/kg on average in research soil．Compared with other combinations, binding states of Pb with humic acid and iron manganese oxides were notably stronger．Analysis based on potential ecological risk index indicated that Cd posed a substantial risk while Pb represented a minor risk．Through the RAC method, it was determined that Cd carried an exceptionally high risk in 65.69%, with a significant risk in 34.31%．Proportion of low risk in Pb elements reached 64.96%, and proportion of high risk or above was 35.04%．To sum up, potential ecological risk of Cd in investigation area was the highest, so it was necessary to reduce Cd content in the soil．Potential ecological risk of Pb was relatively high, and enough attention should be paid to it．