Precipitation chemistry in the westerly domain of the Tibetan Plateau

Abstract

Based on the interaction of water with natural and anthropogenic airborne particles, precipitation chemistry reflects the degree of pollution in the area. Characterizing the local hydrochemical features and regional geochemical cycle requires an understanding of the chemical characteristics of precipitation and its sources. As a result, major ion concentrations were quantified and their chemical properties were identified in event-based precipitation samples. Ca2+, Mg2+, and K+ were crucial in neutralizing the acidity of precipitation. The order of the ions' concentrations was Na+ > SO42− > HCO3− > Ca2+ > Cl− > Mg2+ > K+ > NO3−. Ionic sources in the region included biomass burning, anthropogenic emissions, crustal dust, and salt. The HYSPLIT trajectory further supports biomass burning and aerosol movement from multiple sites. The National Center for Environmental Prediction Final dataset, clusters of air mass backward trajectory analysis, and source identification suggest that the higher concentration of anthropogenic ions (SO42−) in the study site may have been transported from Xinjiang and nearby locations in Central Asia and the Middle East. These datasets provided an overview for evaluating the regional atmospheric chemistry over the westerly domain of the Tibetan Plateau during the monsoon season based on the ionic characteristics.