Analysis of the Spatial Distribution of Heavy Metals in Soil of Sewage-Irrigated Agricultural Fields in Arid Regions and Comprehensive Evaluation Methods

This study aimed to propose a comprehensive evaluation index for assessing agricultural soil quality, integrating soil fertility, heavy metal contamination, and health risk assessments.

A thorough investigation was conducted, involving the sampling and analysis of 159 soil samples and 159 crops. Various indices, including soil fertility, pollution load, and health risk, were utilized to assess soil quality. The spatial distribution features were interpolated to develop a comprehensive soil quality index using a semi-empirical approach.

The study revealed a significant cadmium contamination issue in the study area, with an excess rate of 71.1%. The average soil fertility level was 0.35, indicating a medium level. Notably, the consumption of corn and vegetables posed higher risks for children compared to adults, with rates of 29.2% for corn and 48.4% for vegetables.

The spatial distribution of soil heavy metals, soil fertility, and health risks from sewage-irrigated agricultural fields were observed, leading to the proposal of a Soil Comprehensive Quality Index for large-scale soil quality assessments. Additionally, the study identified a noticeable decrease in soil heavy metal concentrations along the irrigation flow, with the most significant reduction observed in cadmium levels.