半干旱区岩溶碳汇原位监测方法适宜性研究

Applicability of Karst Carbon Sinks Calculation Methods in Semi-Arid Climate Environment

选择正确的方法准确计算北方干旱半干旱岩溶区的岩溶碳汇量,有助于提高我国岩溶碳汇效应估算精度和改进全球碳循环模型。利用水化学径流法和标准溶蚀试片法对山西马跑神泉域的岩溶碳汇量进行了计算,结果表明,标准溶蚀试片法计算出的流域碳汇量和碳汇强度为386.15t/a和1.821t/（km^2·a）,水化学径流法的结果为2 084.08t/a和9.83t/（km^2·a）,试片法计算结果仅为水化学径流法的1/5。试片溶蚀速率和土壤无机碳质量分数呈负相关关系,进一步表明土壤无机碳质量分数高（是有机碳质量分数的2.85~5.06倍）是造成试片法计算结果偏小的主要原因：高含量的无机碳在半干旱气候条件下容易沉积,从而使试片溶蚀速率偏小;流域边界清楚,水化学和流量易于监测,利用水化学径流法计算岩溶碳汇强度结果更为准确。因此,在半干旱地区,计算岩溶碳汇效应宜采用水化学径流法。

By choosing the appropriate method for accurately calculating the amount of karst carbon sink in arid and semiarid regions in Northern China,the estimation accuracy of China＇s karst carbon sink and global carbon cycle models can be improved.The results show that karst carbon sink intensity（1.821t/（km^2·a））with the standard dissolution method is only 1/5of that of the hydrochemistryrunoff method（9.83t/（km^2·a））in the Mapao Spring Catchment,Shanxi Province by using the hydrochemical runoff method and standard dissolution method.The negative correlation between tablets dissolution rate and soil inorganic carbon further indicates that the high levels of soil inorganic carbon（2.85-5.06 times of organic carbon content）is the major cause for the smaller results by standarddissolution method.In semi-arid regions,the high inorganic carbon content was easily deposited,resulting in a low dissolution rate for the tablets.The water chemistry and flow is easy to be monitored for a clear boundary condition basin,so the results of karst carbon sink intensity with the hydrochemistry-runoff method is more accurate.Therefore,for calculating karst carbon sink intensity in the semi-arid regions,the hydrochemical-runoff method should be used.