湿润亚热带典型白云岩流域的化学剥蚀速率——以贵州施秉黄洲河流域为例

Chemical Denudation Rate in Typical Humid Subtropical Dolomite Catchments: A Case Study in the Huangzhou River Basin,Shibing,Guizhou

针对白云岩岩溶作用过程研究较为缺乏、白云岩地区的化学剥蚀速率报道较少等问题,本文以中国南方喀斯特施秉世界自然遗产地内黄洲河典型白云岩流域为研究区,采用流域水化学径流法,通过获得的2015年3月～2016年3月水文年内钙、镁离子的月平均浓度和高时间分辨率的流量数据,结合白云岩流域的水化学稳态行为,计算出该白云岩流域的化学剥蚀速率为46.91 mm/ka,与其他相似气候条件下白云岩流域的化学剥蚀速率相当,但比以石灰岩为主的碳酸盐岩流域的化学剥蚀速率高38%。这主要是因为在自然条件下,亚热带典型白云岩在地域尺度上有足够的时间达到溶解平衡态,进而使白云石较高的溶解度成为影响其化学剥蚀速率的主要因素。

The insufficient researches on the karst process of dolomite and the chemical denudation rate throttled the comprehensive understanding of the ecological environment evolution of dolomite areas. This study chose the Huangzhou River Basin,a typical dolomite basin in the World Natural Heritage of South China Karst,Shibing,as the study area,collected and reported the monthly mean concentrations and high time-resolution discharge data of calcium and magnesium in rivers from March,2015 to March,2016. The chemical denudation rate of the basin was estimated as 46. 91 mm/ka on assuming chemostatic behaviors in this dolomite catchment. The denudation value is roughly equivalent to those of other dolomite basins under similar climate,but higher than those of limestone basins. It can be concluded that the water-dolomite interaction reaches equilibrium in the scale of typical subtropical catchment,consequently,the high solubility of dolomite plays a key role in controlling the dolomite chemical denudation rate.