Monsoon and dust signals recorded in Dasuopu glacier, Tibetan Plateau

Abstract

Abstract During summer 1997, a 15 m firn core was recovered from Dasuopu glacier (28°23′ N, 85°44′ E; 7000 m a.s.l.) on the northwest margin of Xixabarngma Feng in the central Himalaya. Oxygen isotope values and concentrations of Ca 2+ , Mg 2+ , NH 4 + , SO 4 2− and NO 3 − were measured over the 10 years of snow accumulation captured in the firn core. The seasonal variations of δ 18 O values and major-ion concentrations in the Dasuopu core indicate that summer monsoon and dust signals are clearly recorded in Dasuopu glacier. Annual variations in δ 18 O values are controlled by the amount effect, with more negative (i.e. lighter) δ 18 O values representing summer monsoon precipitation characteristic of tropical regions. Higher concentrations of Ca 2+ , Mg 2+ and SO 4 2− reflect the influx of mineral aerosols from the vast arid and semi-arid desert regions to the north and west during the spring dust-storm period. High spring concentrations of NH 4 + and NO 3 − appear to reflect changes in regional biogenic-source strength.