Zn Isotope Tracing Unveils Primary Anthropogenic Zn Sources in Glacial Cryoconite of the High Asian Mountains

Abstract

Zinc (Zn) exerts a significant influence on the global environment, terrestrial ecosystems, and human health. The application of Zn isotopes (δ⁶⁶Zn) has been suggested as a potent tool for tracing environmental contamination. However, studies focusing on Zn isotope tracing within the cryosphere areas are notably limited. Here we present the first data set on Zn isotopes in glacial cryoconite, based on observations over a large regional scale in High Asian Mountains (including Tibetan Plateau (TP) and its surroundings of western China). The results showed that glacial cryoconite had a general heavy Zn isotopic signature in various TP locations, with δ⁶⁶Zn values ranging from −0.22‰ to +0.87‰. Employing the MixSIAR model, the overall Zn contribution source to the cryoconite was mineral dust (36%) > coal burning (33%) > non-exhaust traffic emissions (22%) > industrial smelting (10%). We ascertained that anthropogenic sources account for the primary contribution (about 60%–73%) of Zn inputs in all glacial locations, with coal burning emerging as the foremost anthropogenic contributor (mean 33%). Anthropogenic Zn in various TP locations was primarily derived from Zn emissions resulting from coal combustion, though it is also predominantly influenced by industrial smelting source in cryoconite of the Tianshan Mountains. Our results aligned with coal combustion data from the energy inventory of western China, suggesting that regional coal burning likely represents the foremost source of atmospheric Zn pollutant emission and deposition in the High Asia mountain glaciers.