Past 43 year oxalate record: Ürümqi glacier No. 1, Tien Shan, China, and its link with Far East Rongbuk Glacier, Qomolangma (Mount Everest)

Abstract

A 43 year oxalate record has been recovered in a 14.08 m ice core from Ürümqi glacier No. 1 (43°06′N, 86°49′E), a mid-latitude glacier at Ürümqi river head, Tien Shan, western China. Averaging 3.6 ± 9.2 ng g-1 (x̄ ± 1 σ, N = 534), the oxalate has a background level <2 ng g-1 with sporadic concentration enhancements. Most of the spikes reach beyond 10 ng g-1 and have durations < 1 year. The oxalate variation correlates with that in Far East Rongbuk Glacier (27°59′N, 86°55′ E), Qomolangma (Mount Everest), which is located 1600 km away across the Qinghai-Tibetan Plateau and Taklimakan desert. Although the concentration enhancement in the latter is much higher, and lasts longer, oxalate reaches its highest concentration in both cores at the same time, during winter. The correlation of oxalate records suggests that the two areas may have had the same kind of local sources, but with a much larger (COO)22- flux in the Qomolangma area, or that they may have had a common source in the Indian subcontinent through the longitudinal atmospheric circulation. The concentration variation in the past 40 years coincides with industrial/economic development in southern Asia, and is mainly due to anthropogenic pollution.