As the globally largest area covered by high altitudinal permafrost, the Qinghai-Xizang (Tibet) Plateau may have great potential in the sources and sinks of atmospheric CH₄ and CO₂. When global warming, the plateau permafrost will contribute substantially to global atmospheric CH₄ and CO₂ budget. Preliminary observations on CH₄ and CO₂ emission with static chamber technique in Qingshuihe region from November 5 to 14, 1995 and Wudaoliang from and October 7 to 17, 1994 show that alpine grassland and river surface may be a source for atmospheric CH₄ and a sink or source for CO₂. The 15-day-observation in Qingshuihe shows that the emission rates of CH₄ from moist grassland surface vary from -0.016 to 0.024 mg m^-2 h^-1 with an average of 0.002 mg m^-2 h^-1, the emission rates of CO₂ vary from -169.882 to 313.178 mg m^-2 h^-1 with an average of -5.925 mg m^-2 h^-1; whereas the observation in Wudaoliang indicates that emission rates of CH₄ from dry grassland vary from -0.032 to 0.048 mg m^-2 h^-1 with an average of 0.001 mg m^-2 h^-1, that of CO₂--from -56.503 to 61.425 mg m^-2 h^-1 with an average of 0.095 mg m^-2 h^-1. Emission rates of CH₄ from water surface of Qingshuihe River are from -0.021 to 0.037 mg m^-2 h^-1 with an average of 0.002 mg m^-2 h^-1; meanwhile, that of CO₂ from the water surface are from -81.699 to 32.164 mg m^-2 h^-1, with an average of -2.871 mg m^-2 h^-1. The emission rates of CH₄ and CO₂ in active layer and shallow permafrost at the depth from 30 to 200 cm are in the range from -0.069 to 0.037 mg m^-2 h^-1 and from -300.273 to 313.178 mg m^-2 h^-1, respectively. The mean emission rates of CH₄ and CO₂ in the active layer and permafrost indicate that frozen active layer and permafrost tend to absorb and sequester CO₂ in winter; the lower part of active layer tends to release CH₄, and no flux is found in the upper part. The largest mean absorption rates and largest rate variation are located in the vicinity of permafrost table where the water/ice content is largest in the region. The ground temperature at the sampling depth are weakly correlated with the emission rates of CH₄ and CO₂.

Jin Huijun
State Key Laboratory of Frozen Soil Engineering
Lanzhou Institute of Glaciology and Geocryology
Academy Sinica
174 W. Donggang Rd.
Lanzhou 730000 CHINA
Fax: 86-931-8885241
E-mail: hjjin@ns.lzb.ac.cn