湿润亚热带典型白云岩流域不同土地利用下的试片溶蚀速率及岩溶碳汇

Dissolution Rate and Karst Carbon Sink of Different Land Use in Typical Dolomite Watershed with Humid Subtropical Weather

土地利用对石灰岩溶蚀速率的影响已有较多研究报道,但白云岩溶蚀速率对于土地利用的响应研究却罕见相关报道。因此,探究不同土地利用对白云岩溶蚀速率的影响具有一定的意义,并可为评估白云岩地区的岩溶碳汇效应积累基础数据。本文以湿润亚热带典型白云岩小流域——贵州施秉黄洲河白云岩小流域为研究区,利用白云岩溶蚀试片对流域内不同土地利用下的白云岩溶蚀速率及其影响因素进行了研究。结果表明:不同土地利用条件下白云岩试片溶蚀速率的大小为旱地(4.25 mg/(cm^(2)·a))>林地(1.01 mg/(cm^(2)·a))>水田(0.14 mg/(cm^(2)·a));白云岩试片溶蚀速率随土壤有机质含量增加、土壤pH值减少而增大;但其与土壤CO_(2)浓度呈相反的变化趋势;土壤含水量、容重对溶蚀速率的影响不大。由白云岩试片的溶蚀速率估算该白云岩流域的岩溶碳汇总量为351.70 t CO_(2)/a,岩溶碳汇通量为7.31 t CO_(2)/(km^(2)·a),与前人利用水化学径流法计算相比明显较小。与以往在石灰岩区使用溶蚀试片法和水化学径流法计算的岩溶碳汇强度差异大致相同。

There have been many research reports on the influence of land use on limestone dissolution rate,but the research on the response of dolomite dissolution rate to land use is rarely reported.Therefore,exploring the influence of different land uses on the dissolution rate of dolomite is of great significance and can provide a basis for evaluating the effect of karst carbon sinks in the dolomite area.In this paper,a typical small dolomite watershed in the humid subtropical zone—the dolomite watershed of the Huangzhou River in Shibing county,Guizhou province,is used as the research area.The dissolution rate of different land uses in the watershed and its influencing factors are studied using the dolomite dissolution test piece method.The results show that the corrosion rate of the test piece under different land use conditions is in the order of dry land(4.25 mg/(cm^(2)·a))>forest land(1.01 mg/(cm^(2)·a))>paddy field(0.14 mg/(cm^(2)·a)),the dissolution rate of the test piece increases with the increase of soil organic matter and the decrease of soil pH,but it has the opposite trend to the soil CO_(2) concentration,the soil water content and bulk density have little effect on the dissolution rate.According to the dissolution rate of dolomite samples,the total amount of karst carbon sink in the dolomite basin is estimated to be 351.70 t CO_(2)/a,with a karst carbon sink intensity of 7.31 t CO_(2)/(km^(2)·a),which is significantly smaller than the previous calculation using the hydrochemical runoff method.The difference of these two methods obtained in this study is similar to that observed in limestone areas.