室内模拟不同因子对岩溶作用与碳循环的影响

为分析岩溶作用及岩溶碳循环的影响因素,设计了6个不同的处理以进行模拟实验.结果表明H2SO4含量、水动力条件以及土壤厚度对岩溶作用及岩溶碳循环具有重要影响.具有相同土壤厚度的3个处理,其Ca2++Mg2+浓度与SO2-4浓度均表现为:B20-2B20-1B20-3,B50-2B50-1B50-3,说明H2SO4的输入导致了岩溶作用增强,并且下渗水水量增加对水化学性质产生了明显的稀释作用.在煤铁残渣输入量及水动力条件相同而土壤厚度不同的条件下,Ca2++Mg2+浓度与SO2-4浓度表现为:B50-1B20-1、B50-2B20-2、B50-3B20-3.这说明较厚的土壤更有利于岩溶作用的进行.另外,由于实验中H2CO3对碳酸盐岩的溶解量贡献较小,岩溶作用对CO2的净消耗量主要取决于H2SO4含量.但B50-2的SO2-4浓度最大,CO2的净消耗量却最高.这可能是由于煤铁残渣向土壤中输入了有机质或其它养分促进了土壤深部CO2的形成,并且B50-2上部较厚的土壤也导致了H2CO3对碳酸盐岩溶解量的贡献增加,因此B50-2的CO2净消耗量也比较高.

Modeling the Influencing Factors of Karstification and Karst Carbon Cycle in Laboratory

To analyze the influencing factors of karstification and karst carbon cycle, a simulation experiment was carried out and 6 soil columns were designed. The results showed that the content of H₂SO₄, hydrodynamic condition and thickness of the soil had important influence on karstification and karst carbon cycle. For the soil columns which were covered by the same thickness of soil, the concentrations of Ca²⁺ + Mg²⁺and SO₄^2- followed the order of B20-2>B20-1>B20-3, B50-2>B50-1>B50-3. This meant that input of H₂SO₄ enhanced the karstification and increasing infiltration water had significant dilution effect on the chemical properties. For the soil columns with different thickness of soil but with the same slag pile and hydrodynamic conditions, the concentrations of Ca²⁺ + Mg²⁺and SO₄^2- followed the order of B50-1>B20-1,B50-2>B20-2,B50-3>B20-3. It was demonstrated that more carbonate rock was dissolved under the thick soil columns. In addition, the net consumption of CO₂ mainly depended on the content of H₂SO₄ in this experiment due to slight contribution of H₂CO₃ to carbonate rock dissolution. More content of H₂SO₄ brought about less net consumption of CO₂, but B50-2 was an exception. Organic matter and other nutrients might be input into deep soil with the slag pile, and they promoted the production of soil CO₂. Therefore, more CO₂ was consumed due to the increased contribution of H₂CO₃ to karstification.