穿透曲线反演管壁溶质通量的实验研究

Laboratory Inversion for Wall Solute Fluxes from Breakthrough Curves

泉口穿透曲线提供了一个便捷有效的方法来研究岩溶含水层中污染物的运移。在旱季,滞留在石灰岩中的污染物通过岩壁释放入管道,与管道水相混合并运输到下游泉口,因此,泉口穿透曲线能够反演出污染物释放时的管壁溶质通量。笔者利用一个基于运移稀释模型的解析解,由40条实验室测量的穿透曲线来反演出相应的管壁溶质通量。结果表明,其基本形状与穿透曲线相似,管壁透水的非均匀性在穿透曲线上明显表现出来,而在管壁溶质通量上表现为强振荡。因此,管壁溶质通量比泉口穿透曲线对管壁透水的非均匀性有更高的分辨率。该通量是一个连接泉口穿透曲线和污染物在岩石中早期分布的中间量,本文提供了一种研究管壁污染物释放过程的新方法。

Spring breakthrough curves provide a convenient and effective way to investigate migration and fate of contaminants in karst aquifers. During a dry season,contaminants sequestered inside limestone are released through the wall into conduits,mix with conduit water,and are then transported to the downstream springs. Thus breakthrough curves acquired at the springs may be inverted to obtain the fluxes of solutes across the conduit wall as sequestered contaminants are released. Using the analytical solution based upon an advection-dilution model,we invert for the wall solute fluxes from 40 breakthrough curves measured in the laboratory. The basic shape of the fluxes is similar to that of the breakthrough curves. The inhomogeneity of water flux across the wall is evident on the breakthrough curves,and appears as very strong oscillations on the wall solute fluxes. Therefore,it is concluded that wall solute flux has higher resolution to the inhomogeneity of water flux across the wall than spring breakthrough curve does. The wall solute fluxes are an intermediate quantity connecting spring breakthrough curves with earlier distribution of contaminants in limestone. This study provides a new approach to investigate the release of contaminants across the conduit wall.