土壤-灰岩岩溶系统中水文地球化学动力学过程模拟及其意义

Kinetics of hydrogeochemistry in assimilated soil-limestone karst system and its implications

在实验室模拟了土壤－灰岩岩溶系统，对降水淋滤下元素地球化学动态进行了系统监测。结果表明，岩溶作用使土壤中易移动性组分淋溶，Ｃａ^（２＋）、ＨＣＯ_３~－的淋出动态表现为开始的快速下降和随之的平衡两个淋出阶段，淋出量与土壤中水溶性Ｃａ、可氧化有机质的含量有关。土壤对ＨＣＯ_３~－的淋出与排释有促进作用。这种动力学特征对解释岩溶沉积古记录和岩溶作用的大气ＣＯ_２汇效应具有重要意义。

Element concentration dynamics during leaching is studied under soil treatments in assimilated soil-limestone systems. The leaching and release of Ca^(2+) and HCO_3, the key elements for karstification, is characterized by a first high concentration but fast decreasing phase followed by a phase steady to equilibrium, indicating removal of readily mobile Ca and bicarbonate is involved in epigenic limestone dissolution as evaluated by karst water chemistry. The enhanced dissolution and adsorption of air CO_2 seems to make greater contribution to increased sink effect for air CO_2 of soil-karst system. Therefore, the kinetics of the element. leaching would be important for interpretation of paleo-climatic records of stalagmites and for assessment of karst system for atmospheric CO_2 dynamics.