用Ca^(2+)离子浓度估算岩溶地区岩石溶蚀速率:以贵州普定为例

Estimate of erosion rates in a karst region using calcium concentrations:A case study of Puding,Guizhou,southern China

在探讨岩石溶蚀速率计算方法的基础上,根据研究区特殊的岩溶地质特征,提出了采用Ca2+浓度估算岩溶流域岩石溶蚀速率的新方法.首先,将Ca2+浓度换算成CaCO3浓度,结合实测流量,计算出实际流失的CaCO3,并换算成流域平均岩石溶蚀量,然后根据岩石的平均容重,计算出流域岩石溶蚀厚度,经过换算得到流域岩石溶蚀速率,该方法适用于可溶岩中碳酸钙的比例较大的闭合区域.贵州普定后寨河流域母猪洞子流域为可溶岩中碳酸钙的比例约98%的封闭的洼地,因此可以使用该方法进行计算.通过该方法对研究区岩石溶蚀速率的计算可知,该研究区的平均溶蚀速率为41.5 mm/ka,该研究区枯水期的岩溶溶蚀速率基本都小于丰水期的岩溶溶蚀速率,与前人对该地区的研究结果非常相近,说明该方法是可行的,为以灰岩为主的岩溶地区地质溶蚀研究提供了一种新的思路.

This paper puts forward a new method for estimate of the erosion rates of a karst region using calcium concentrations.First,the calcium concentrations are converted into the calcium carbonate concentrations;then,the CaCO3 loss rates are calculated based on the calcium carbonate concentrations and the discharges;finally,the corrosion rates of the rocks are calculated.The erosion rates are concluded from the average bulk densities and the corrosion rates of the rocks.This method can be applied to an area that is closed and has a high calcium carbonate ratio of rocks.The Muzhudong sub-catchment（Guizhou province,southern China） is a very closed region and the calcium carbonate ratios of the rocks are up to 98%,so this method can be applied to this region.Our results show that the average erosion rate of the Muzhudong sub-catchment is about 41.5 mm/ka,which is very close to the previous estimates obtained based on other methods.Therefore,we believe this method is valuable in that it provides a new tool for studying erosion of the karst regions.