Contamination characteristics, source analysis, and spatial prediction of soil heavy metal concentrations on the Qinghai-Tibet Plateau

Purpose Soil heavy metal distribution is a key issue in environmental and health research. In recent years, an increasing number of anthropogenic disturbances have been identified on the Qinghai-Tibetan Plateau, leading to increased heavy metal contamination of soils. Therefore, this study investigated the distribution, sources, ecological risk, and prediction of heavy metals in soils on the Qinghai-Tibetan Plateau. Material and methods Here, for each of the seven heavy metals (i.e., Cr, Ni, Cu, Zn, As, Cd, and Pb) investigated in the soil of the Qinghai-Tibet Plateau, we collected soil concentration values from the literature and carried out field sampling to generate new data. We then assessed the pollution characteristics and sources of soil heavy metals on the Qinghai-Tibet Plateau using geostatistics, positive matrix factorization model (PMF), disjunctive kriging, and mapped the pollution risk probability distribution of each heavy metal element. Results and discussion Spatial autocorrelation was found for all seven heavy metals in the soils. Under different land-use types, the average concentrations of Cr, As, and Cd were highest in the water areas; Ni levels were highest in woodland; and Cu, Zn, and Pb concentrations were highest in residential, industrial, and mining lands. Using analysis by the PMF model and correlation analysis, four heavy metal sources were identified, including industrial sources and atmospheric deposition (Cd), traffic emissions (Cr, Zn, and Zn), natural sources (Ni and As), and mining activities (Cr and Pb). The pollution risk probabilities of Cr, Ni, Cu, Zn, As, and Pb were low in most areas of the Qinghai-Tibet Plateau, whereas the pollution risk probability of Cd was high over 29% of the area of the Qinghai-Tibet Plateau. Conclusion The results highlighted no potential contamination for Cr, local potential contamination for Ni, Cu, Zn, As and Pb, while Cd exhibits more extensive contamination in the soils of the Qinghai-Tibet Plateau. Cd reduction should therefore be considered an important component of the strategy, policy, and action plan for soil pollution management on the Qinghai-Tibet Plateau.