不同条件下土壤CO2浓度及地下水化学特征研究

Study on soil CO2 concentration and groundwater chemical composition under different conditions

为研究土壤CO2浓度变化规律及对地下水化学成分的影响,在进行野外试验观测的基础上,进一步开展了室内土柱降水模拟试验。野外观测发现,自然条件下地表处CO2浓度小于包气带土壤CO2浓度;不同深度的土壤CO2浓度不同,随着深度增加CO2浓度逐渐增加;坡度对土壤CO2浓度变化存在显著影响,坡度越小,对应的土壤CO2浓度越高。不同植被类型下土壤CO2浓度不同。室内试验发现,降水前相同深度下土壤CO2浓度由高到低依次为植被组、空白组、杀菌组,降水后由高到低依次为杀菌组、植被组、空白组;降水后,土壤内CO2浓度明显增加,pH和COD降低,TDS增加;杀菌组中Na+, Mg2+,Ca2+和Cl-含量明显高于其他两组。坡度、植被、微生物均对土壤CO2浓度变化存在显著影响。

In order to study the variation of soil CO2 concentration and its influence on groundwater chemical composition, an indoor soil column precipitation simulation experiment was carried out on the basis of field experiment observation. The field experiment observation results showed that the CO2 concentration at the surface was lower than that in the aerated zone under natural conditions, and the CO2 concentration increased gradually with the increase of depth. Slope has a significant effect on the change of soil CO2 concentration. The slope is smaller, the soil CO2 concentration is higher. Soil CO2 concentration was different under different vegetation types. In the laboratory experiment, the soil CO2 concentration measured at the same depth before precipitation from high to low was vegetation group,blank group,bactericidal group;after precipitation, it was bactericidal group,vegetation group,blank group. After precipitation, the soil CO2 concentration increased significantly, pH and COD decreased, TDS increased, and Na+, Mg2+, Ca2+ and Cl- contents in bactericidal group were significantly higher than those in other two groups. The results showed that slope, vegetation and microorganism all had significant effects on soil CO2 concentration.