添加有机物料对岩溶系统中碳转移及灰岩溶蚀的影响研究

STUDY ON THE EFFECT OF LIMESTONE DISSOLUTION AND CARBON TRANSFER IN KARST SYSTEM AFFECTED BY ORGANIC AMENDMENT

以贵州茂兰一种灌丛土壤和一种农业用地土壤为研究对象 ,设置了添加和不添加有机物料处理 ,进行了岩溶作用与土壤碳转移的模拟试验。结果表明 ,土壤 CO2 呼吸排放、土壤淋滤液 HCO- 3排泄及灰岩溶蚀均响应于有机物料的添加。对于无机离子 Ca2 +、Mg2 +来说 ,在不添加有机物料情况下 ,其淋出过程表现为一个较高的活跃可迁移库的释放过程及随后较低风化淋滤的稳定释放过程。在添加有机物料条件下 ,分解释放的 Ca及 CO2 产生的 HCO- 3的排释滞后于土壤呼吸 15天以上。添加有机物料下 ,灰岩溶蚀量均有一定幅度的提高 ,但 Ca(Mg)及 HCO- 3的排释大大增强 ,这一方面表明生物可利用性的碳源的加入促进了系统中岩溶作用 ,并强烈驱动土壤中可交换 Ca、Mg的排释 ;另一方面 ,由于土壤中因呼吸增强而形成的高 CO2 在湿润条件下溶解成为 HCO- 3- C排泄 ,而大大促进土壤碳转移的汇效应。本文的研究结果说明 ,自然土壤因植被的破坏或林地转变为农地 ,可能使岩溶系统的汇效应减弱。

WT5BZ]Soils under bush vegetation and under corn field are the objects being studied in this paper. The soils being studied are treated by adding organic matter or not in the study. Simulating experiment for karstification and carbon transfer is done in the study. It is proved that soil respiration emission of CO 2, HCO^- 3 discharge and limestone dissolution acts a prompt response to added organic amendments. The leaching dynamics of Ca~ 2+, Mg~ 2+ is characterized by a release stage of easily mobile cations from soil followed by a slow releasing stage of Ca of non easily exchangeable from limestone dissolution under no addition of organic amendments. However, under addition of organic amendments, the release of Ca or HCO^- 3 discharge, which was enhanced by the decomposition of added organic matters, lag behind the enhanced production for 15 days or longer. While the limestone dissolution is raised prominently, the Ca release or HCO^- 3 discharge showed a great increase under addition of organic amendments. This shows, in one hand, the addition of bioactive carbon have driven the limestone dissolution and drastic release of soil pools of exchangeable Ca, on another hand, the added organic matter stimulates soil CO 2 production, which in turn forced the dissolution of CO 2 for enhancing discharge of HCO^- 3 in the leach process. the leach process conducts a strong sink effect for air CO 2. This study may explain the deforestation or shift of forest to arable land reduces the soil carbon transfer through CO 2- HCO^- 3 pathway, thus diminishing the sink effect of karst system for air CO 2.