Air pollution caused by human activities has left its mark in the glaciers of the Tianshan Mountains in Xinjiang, at least 105 km away from the hustle and bustle of Xinjiang's regional capital, Urumqi.

Chinese scientists say they have found evidence of air pollution in the Tianshan Mountains in a 14-meter-long ice core formed between 1955 and 1998.

The peak of the Tianshan Mountains is 5,445 meters above sea level and a geological label of the Xinjiang Uygur Autonomous Region, which covers one sixth of Chinese territories. The Tianshan Mountains are also famous among tourists and climbers.

The ice core is located on the Heyuan-1 Glacier east of Urumqi in an area surrounded by deserts and previously believed to be free from human influence.

"We have analyzed its organic acid content, which we think is a result of air pollution and acid rain," said Li Xinqing, a geochemist based in Guiyang, southwest China's Guizhou Province.

The analysis of the acid content suggests that the air over Tianshan Mountain has been contaminated by pollutants from forest fires, vehicle emissions and industrial waste in Urumqi and its surrounding regions.

"The organic acid content can reflect the direct impact of human activity on the environment, even in uninhabited areas," said Li, a senior researcher with the State Key Laboratory of Environmental Geochemistry in Guiyang.

Glaciers or icecaps are thought to be the best recorders of organic substances in the atmosphere as well as changes in their chemical composition.

The researchers also found abrupt changes in the organic acid content in the "ice chip" in the 43 years between 1955 and 1998. "The average content change is basically consistent with the industrial development and environmental protection efforts over the years," said Li.

Based on the research finding, he has co-authored a thesis with Qin Dahe, head of China Meteorological Bureau, and Ding Wenci, a scientist with the Chinese Academy of Sciences.

The thesis is published in the latest supplement edition of the Bulletin of Mineralogy, Petrology and Geochemistry, a quarterly science magazine published in China.

Air quality is a pressing issue worldwide now that more scientific evidences have linked fine aerosol with human illnesses.

(Xinhua News Agency August 19, 2006)