As a major alkaline gas in the atmosphere, ammonia (NH3) plays an important role in atmospheric chemistry. However, there is little knowledge about NH3 variations in the Central Asia. Here we ana- lyzed the ammonium (...As a major alkaline gas in the atmosphere, ammonia (NH3) plays an important role in atmospheric chemistry. However, there is little knowledge about NH3 variations in the Central Asia. Here we ana- lyzed the ammonium (NH+4) history recorded in an ice core from the East Pamir in Central Asia, which was drilled on the Mt. Muztagata at the elevation of 7010 m a.s.l. in 2003. The core was carefully dated and NH4+ concentration history during 1907―2002 was reconstructed. The result shows that NH4+ con- centration remained approximately constant until the 1930s after a sudden decrease at the very begin- ning of the 20th century, followed by a minimum in 1940 before increasing steadily to the peak at the end of 1990s. It is found that the annual mean NH4+ concentration was strongly associated with the Northern Hemisphere temperature, suggesting the impact of temperature on NH3 emissions in the Central Asia. Moreover, an increase of NH+4 concentration after 1940 also reflects the enhancement of NH3 emissions from anthropogenic sources such as fertilizer applications and livestock wastes in the 20th century.展开更多
Fixed ammonium contents and fixation capacities of some representative cultivated soils collectedfrom 16 provinces of China were studied. Results showed that the contents of fixed ammonium in soilsranged from 35 to 5...Fixed ammonium contents and fixation capacities of some representative cultivated soils collectedfrom 16 provinces of China were studied. Results showed that the contents of fixed ammonium in soilsranged from 35 to 573 mg N kg￣(-1), with an average of 198 mg N kg￣(-1). The content of fixed ammoniumcorrelated very significantly with mica content for tropical and subtropical soils, whereas this was not thecase for soils in the temperate zone. At the end of K-exhansting experiment the fixed ammonium contentincreased in most soils studied. However, it decreased in some temperate soils. Generally, fixation of addedNH could not be found either before or after K-exhausting experiment for highly weathered soils, includingtropical soils and soils derived from granite-gneiss or Quaternary red clays in the subtropic zonet while formost soils in the Yangtze River dalta the NH fixation capacity was rather high and increased siguificantlyin the K-exhausted soils.展开更多
基金the National Basic Research Program of China (Grant No. 2005CB422004) the National Natural Science Foundation of China (Grant Nos. 40121101, 40571039 and 40471022)
文摘As a major alkaline gas in the atmosphere, ammonia (NH3) plays an important role in atmospheric chemistry. However, there is little knowledge about NH3 variations in the Central Asia. Here we ana- lyzed the ammonium (NH+4) history recorded in an ice core from the East Pamir in Central Asia, which was drilled on the Mt. Muztagata at the elevation of 7010 m a.s.l. in 2003. The core was carefully dated and NH4+ concentration history during 1907―2002 was reconstructed. The result shows that NH4+ con- centration remained approximately constant until the 1930s after a sudden decrease at the very begin- ning of the 20th century, followed by a minimum in 1940 before increasing steadily to the peak at the end of 1990s. It is found that the annual mean NH4+ concentration was strongly associated with the Northern Hemisphere temperature, suggesting the impact of temperature on NH3 emissions in the Central Asia. Moreover, an increase of NH+4 concentration after 1940 also reflects the enhancement of NH3 emissions from anthropogenic sources such as fertilizer applications and livestock wastes in the 20th century.
文摘Fixed ammonium contents and fixation capacities of some representative cultivated soils collectedfrom 16 provinces of China were studied. Results showed that the contents of fixed ammonium in soilsranged from 35 to 573 mg N kg￣(-1), with an average of 198 mg N kg￣(-1). The content of fixed ammoniumcorrelated very significantly with mica content for tropical and subtropical soils, whereas this was not thecase for soils in the temperate zone. At the end of K-exhansting experiment the fixed ammonium contentincreased in most soils studied. However, it decreased in some temperate soils. Generally, fixation of addedNH could not be found either before or after K-exhausting experiment for highly weathered soils, includingtropical soils and soils derived from granite-gneiss or Quaternary red clays in the subtropic zonet while formost soils in the Yangtze River dalta the NH fixation capacity was rather high and increased siguificantlyin the K-exhausted soils.
