Effect of coal gangue-based porous matrix on soil solute transport
The proposal was to address the issues of nutrient deficiency,drought,water scarcity,and lack of topsoil in min-ing areas by utilizing coal gangue to prepare a porous matrix.This matrix was then chosen as a substitute material for topsoil in ecological restoration.Furthermore,its feasibility was evaluated from the perspective of solute transport.The impact of coal gangue-based porous matrix on the migration characteristics of Cl-and Na+in soil was investigated through vertical col-umn miscible displacement experiments,revealing the influence patterns of porous matrix on soil pore distribution and sol-ute transport in saturated soil.The results indicated that the penetration time of Cl-and Na+was reduced when the content of the porous matrix ranged from 10%to 30%.It was due to the fact that the porous matrix with a small amount of doping filled the soil particles with one another,resulting in an increase in the number of small pores and the formation of a more com-plex migration path.Moreover,the porous matrix had a strong adsorption capacity for Na+,and thus the penetration time of Cl-and Na+was prolonged.As the addition of porous matrix continued to increase(＞30%),the lower bulk density of the po-rous matrix led to an increase in saturated hydraulic conductivity,which in turn shortened the breakthrough time for Cl-and Na+gradually.The application of 30%porous matrix resulted in a decrement of Cl-and Na+concentrations in the effluent by 1.65%～46.30%and 10.12%～32.88%,respectively.The transport of Cl-and Na+was primarily governed by convection.The distribution of soil pores and the adsorptive properties of the soil were the major factors affecting solute transport.The com-pound mode of mixing coal gangue-based porous matrix with loess at a volume ratio of 3∶7 could effectively reduce solute transport.
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