Open AccessTwentieth century increase of atmospheric ammonia recorded in Mount Everest ice core
Author(s) -
Kang Shichang,
Mayewski Paul A.,
Qin Dahe,
Yan Yuping,
Zhang Dongqi,
Hou Shugui,
Ren Jiawen
Publication year - 2002
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2001jd001413
Subject(s) - ice core , glacier , ammonia , empirical orthogonal functions , atmospheric sciences , environmental science , environmental chemistry , physical geography , chemistry , geology , climatology , geography , organic chemistry
An NH 4 + record covering the period A.D. 1845‐1997 was reconstructed using an 80.4 m ice core from East Rongbuk Glacier at an elevation of 6450 m on the northern slope of Mount Everest. Variations in NH 4 + are characterized by a dramatic increase since the 1950s. The highest NH 4 + concentrations occur in the 1980s. They are about twofold more than those in the first half of twentieth century. Empirical orthogonal function (EOF) analysis on the eight major ion (Na + , K + , Mg 2+ , NH 4 + , Ca 2+ , NO 3 − , SO 4 2− and Cl − ) series from this core indicates that NH 4 + is loaded mainly on EOF3 (60% of NH 4 + variance), suggesting that NH 4 + has a unique signature. Instrumental sea level pressure (SLP) and regional temperatures are used to explore the relationship between NH 4 + variations and both atmospheric circulation and natural source strength over Asia. Higher NH 4 + concentrations are associated with an enhanced winter Mongolian High and a deepened summer Mongolian Low. A positive relationship also exists between NH 4 + concentrations and regional temperature changes of the GIS Box 36 (Indian subcontinent), indicating that an increase in temperature may contribute to the strengthening of natural ammonia emissions (e.g., from plants and soils). A close positive correlation between NH 4 + and acidic species (SO 4 2− plus NO 3 − ) concentrations suggests that a portion of the increase in NH 4 + concentrations could be contributed by enhanced atmospheric acidification. Anthropogenic ammonia emissions from enhanced agricultural activities and energy consumption over Asia in concert with population increase since the 1950s appear also to be a significant factor in the dramatic increase of NH 4 + concentrations during the last few decades.