Abstract
Strontium (Sr) and neodymium (Nd) are commonly contained in natural substances and their stable isotopic ratios can be used as tracers of the elements in biological and geochemical processes. We analyzed these isotopic ratios mineral dust and organic matter (cryoconite) collected on four glaciers from different locations in Asia (Altay, Tien Shan, Qillian Shan, and Himalaya). The cryoconite was chemically separated into fractions (minerals and organic matter) and the isotopic ratios of each fraction were measured. The isotopic ratios of silicate minerals showed highest values in all fractions and significantly varied according to geographical location of the glaciers: Sr and Nd ratios were higher and lower, respectively on the glacier located north. The isotopic ratios were close to those of desert sand, loess, and river sediment around each glacier. This indicates that the provenance of the silicate minerals (eolian dusts) differed among the glaciers and was the area around the respective glacier. The isotopic ratios in saline, carbonate, and phosphate mineral fractions are also likely to reflect those of their original source. The Sr isotopic ratios in the organic matter may reflect those of the mineral sources used as nutrients by living microbes on the glacier.
