Current Status and Evolutionary Patterns of Heavy Metal Environmental Capacity in the Baerdawu Region of the Tibetan Plateau: Based on High-Density Data

Abstract

The Tibetan Plateau, which is called the “Third Pole” and the “Roof of the World,” exhibits a simplistic and clear human footprint due to its unique environmental conditions, primarily influenced by a singular human activity, grazing. Consequently, conducting environmental carrying capacity assessments in this area yield more accurate results. This study focused on the Baerdawu region of the Tibetan Plateau, where the background values of regional soil were calculated based on 7373 surface soil samples. Utilizing material balance linear modeling and the environmental comprehensive index method,a comprehensive soil environmental capacity (SEC) for heavy metals and health risks in the soil was determined. The SEC of the static ranking within the study area was as follows: Zn, Pb, As, U, Hg, La, and Zr. The high-value zones of these elements largely range from the northwest and northeast of the analyzed area, whereas the low-value zones are primarily located in the central and southwest areas. Significance analysis of different geological settings, land-use types, and soil types revealed that the geological background had the greatest influence on SEC, indicating that most elements are controlled by geological sources. Additionally, the residual capacity of most elements was significantly affected by soil type, with the impact being most pronounced in alpine desertified grassland soils, indicating severe disturbances from grazing in the research area. The Baerdawu region’s composite SEC index was 1.17, indicating a high environmental capacity and no health risks. By exploring the characteristics of SEC in the Baerdawu area, this study offers a scientific foundation for formulating policies for soil management. The results of this study can be applied to soil environmental protection in the Qinghai-Tibet Plateau and similar regions.