Monsoon and dust signals recorded in Dasuopu glacier, Tibetan Plateau

Abstract

During summer 1997, a 15 m firn core was recovered from Dasuopu glacier (28³23 H N, 85³44 H E; 7000 m a.s.l.) on the northwest margin of Xixabangma Feng in the central Himalaya. Oxygen isotope values and concentrations of Ca 2+ , Mg 2+ , NH 4 + , SO 4 2^a nd NO 3^w ere measured over the 10 years of snow accumulation captured in the firn core. The seasonal variations of 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 18 O values are controlled by the amount effect, with more negative (i.e. lighter) 18 O values representing summer monsoon precipitation characteristic of tropical regions. Higher concentrations of Ca 2+ , Mg 2+ and SO 42^r eflect 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^a ppear to reflect changes in regional biogenic-source strength.

A Complete Isotope (δ15N, δ18O, Δ17O) Investigation of Atmospherically Deposited Nitrate in Glacial‐Hydrologic Systems Across the Third Pole Region

“…− concentration, and their interpretations possess uncertainties due to multiple sources and complex chemical transformation mechanisms for NO 3 − (Kang et al, 2000(Kang et al, , 2004Wake et al, 1994;Zhang et al, 2016). Recent nitrate studies have benefitted from the developments of nitrate isotopic analytical techniques, and isotopic investigations on the fate of atmospherically deposited nitrate over the TP have been reported (Hu et al, 2019;Li et al, 2020;Xia et al, 2019).…”

Enhanced surface warming and accelerated snow melt in the Himalayas and Tibetan Plateau induced by absorbing aerosols

“…Many factors besides greenhouse warming could have led to accelerated warming over the Himalayas and TP. These include increased land-use and land change, increased sunlight duration from reduction in cloudiness, increased water vapor feedback, and reduction of snow albedo by deposition of soot and dust on the snow surface (Kang et al 2000, Prasad and Singh 2007, Flanner et al 2007, Yasunari et al 2009. Recently Ramanathan et al (2007) estimated that atmospheric heating by Asian brown clouds (ABCs) doubles the greenhouse warming over South Asia, and may contribute substantially to the loss of glacier mass in the Himalayas.…”

Statistical extraction of volcanic sulphate from nonpolar ice cores

“…[3] Major ionic impurities in ice cores may be categorized by their typical sources [e.g., Legrand and Mayewski, 1997;Moore et al, 2006;Moore et al, 2005;Kekonen et al, 2005a;Eichler et al, 2011;Kaspari et al, 2007;Kang et al, 2000;Matoba et al, 2002]. Marine ions originating from oceanic sea spray are dominated by soluble salt derived ions, typically Na + and Cl À with significant amounts of SO 4 2À and Mg 2+ .…”

“…Hence volcanic eruptions are typically simply assumed to be the cause of peaks in sulfate. While this assumption may be true in central Antarctica [Legrand and Mayewski, 1997], in Svalbard and mountain glacier areas this is a very poor assumption since volcanic acids account for only 5-10% of sulfate in Svalbard [Moore et al, 2006], and even less when terrestrial input is large, such as in Tibet [Kang et al, 2000;Cong et al, 2009]. In considering the sources of ions, sulfate from volcanic sources has two features that point to a less ambiguous way identifying volcanic markers: (1) the sulfate is not associated with any other ions, and (2) the signal appears as a sharp spike in concentrations.…”