Distribution Characteristics of Heavy Metal Pollution in Soil and Crops in the Pijiang River Basin

Through field surveys and laboratory tests, the characteristics of the spatiotemporal changes of heavy metal pollution in farmland soils and crops along the Pijiang River Basin in Yunlong County were analyzed from 2016 to 2018 to explore the sources of heavy metal pollution. The results showed that the heavy metal pollution in the soil of Pijiang River was heavy, of which cadmium was the most concentrated, followed by lead and zinc, and the arsenic content was low. From 2016 to 2018, the degree of heavy metal pollution in the soil has eased. During the survey, from the upper reaches of the county to the lower reaches of Lancang River, the heavy metal content in the farmland soil increased first and then decreased. The analysis of pollution characteristics along the way is related to geological background values and mining activities. Excessive levels of heavy metals in crops exist in the survey area, and lead and cadmium contents are the most common. The concentration of heavy metals is expressed as vegetables more than cereals, and more than potatoes. There was no obvious enrichment of arsenic and zinc in crops. Correlation analysis showed that the sources of zinc, lead, and cadmium in the soil are similar, and the content of zinc, lead, and cadmium in crops is also affected by similar factors, but soil heavy metal pollution is only one of the factors affecting the heavy metal enrichment of crops.