试验模拟包气带CO2变化及对水化学的影响

包气带作为参与碳循环的重要场所,CO2起到重要作用。利用土柱模拟不同条件下包气带CO2含量变化及水化学成分变化。研究发现:不同条件下土柱内CO2存在明显差异,均随着深度增加CO2含量增加;CO2含量植被组大于无植被组。随着降水不断入渗包气带,CO2含量不断增加。植被存在时,增加幅度略大于无植被组,且降水后期杀菌组包气带CO2增加幅度达一百倍。降水后pH值降低,Ca^2+、Mg^2+离子浓度增大,NO3^-、Cl^-、SO42-离子含量也出现一定程度的增加。植被、微生物和降水均可影响包气带中CO2含量,且包气带CO2在降水与地下水转化过程中起到重要作用。

Experimental Simulation of CO2 Change in Vadose Zone and Its Effect on Chemical Composition of Water

As an important place to participate in carbon cycle, CO2 plays a key role. In this paper, indoor soil column was used to simulate the change of CO2 content in the vadose zone under different conditions and the change of water chemical composition. This study found that there are significant difference of CO2 under the different conditions. The CO2 content increases with the increase of depth. The CO2 content of vegetation is greater than bare soil. With infiltration of the precipitation, CO2 content increases. In vegetation, the increase is slightly greater than that in non-vegetation. In addition, the CO2 increases by 100 times in the sterilization group. After precipitation, the pH decreases, Ca2+, Mg2+ increases, and the contents of NO3-, Cl-, SO42- ions also increase to a certain extent. Vegetation, microorganism and precipitation can all affect the CO2 content in the vadose zone. It is concluded that the aeration zone CO2 plays an important role in the process of precipitation and groundwater transformation.