Pollution assessment, source identification, and health risks of heavy metals: a case study in a typical wheat–maize rotation area of eastern China

Winter-wheat–summer-maize rotations are important cropping patterns in China, and the quality of the food produced from these systems can affect human health. However, the effects of heavy metal pollution on both crops remain unclear. We analyzed soil-wheat and soil-maize samples from eastern China for their Cd, Cu, Zn, Cr, Ni, and Pb contents. The concentrations of these metals in the soils analyzed were found to be lower than those recommended by the national guidelines, but the Cd, Cr, Cu, and Ni concentrations were higher than the natural soil background values in China. Quality indices showed that subpollution was predominant in wheat/maize (95.00%/81.25%) samples. Positive matrix factorization model data revealed that the contributions from natural sources, agricultural activities, and traffic to the heavy metal pollution levels were 30.40–43.07%, 34.67–26.63%, and 34.92–30.27%, respectively, in the wheat–maize rotations. Although the health hazard quotient values for wheat were higher than those for maize, there were no health risks for children or adults.