腾格里沙漠沙坡头区流动沙丘CO_2浓度与变化规律

Variation of CO_2 concentration of the moving dune in Shapotou area of Tengger desert

为了查明沙漠区流动沙丘CO2浓度昼夜变化规律，利用红外CO2监测仪在2010年5月对腾格里沙漠东南缘的沙坡头区流动沙丘不同深度的CO2浓度变化进行了昼夜连续观测。测定结果表明：在一昼夜内，从早8点到次日早8点，1m、2m、4m深度处CO2浓度与大气温度变化趋势基本一致．均呈现由低到高再到低的变化规律：1m深度处CO2浓度高低时段的变化与大气温度基本同步．而2m、4m深度处CO2浓度的高低时段比大气温度滞后约1～2h；流动沙丘不同深度CO2浓度与温度之间存在显著的正相关关系．空气温度是影响4m以上沙层CO2浓度大小的主要因素：流动沙丘不同深度CO2浓度累积值呈昼高夜低的变化特点，表明沙漠区微生物活动强度白天大于夜间：4m以上沙层CO2浓度均高于距地面1m高处CO2浓度，表明该区可能是CO2的排放源区．

In order to find out the variation of CO2 concentration of the moving dune in the desert area, we have measured the continuous change of CO2 concentration of the moving dune at different depths by using the infrared monitoring instrument in Shapotou area which is at the southeast edge of Tengger Desert, The results show that the change of 1 m,2 m, 4 m of CO2 concentration and air temperature is consistent that is from low to high then to low in a circadian day from 8 am. to 8 am. the next day. High and low periods of the 1 m of CO2 concentration is basically synchronized with the air temperature. High and low periods of the 2 m and 4 m of CO2 concentration are about 1 - 2 h later than the air temperature. There is a significant positive correlation between CO2 concentration of the moving dune at different depths and air temperature. Air temperature is the main factor which influences the CO2 concentration above 4 m depth in the sand layer. The cumulative value of the CO2 concentration is higher in daytime and low in nighttime which indicates the microbial actives more intensively at the day than at night in the desert. The CO2 concentration above 4 m is higher than lm high from the ground, which indicates this may be the emission area of CO2.