Heterogeneity of key ecological elements and environmental effects in open-pit coal mines of arid and semi-arid regions

BIAN Zhengfu; LEI Shaogang; HAN Xiaotong; XU Yufan; CAI Zhen; DUAN Yating; JIANG Lixiang

doi:10.13247/j.cnki.jcumt.20250444

Abstract：After undergoing a series of mining activities such as overburden removal,excavation,dumping,and reclamation,the original natural strata,landforms,landscapes,and other key ecologi-cal elements in open-pit coal mines undergo profound structural changes,resulting in a unique large-scale artificial ecosystem.This paper analyzed the spatial heterogeneity of ecological factors such as hydrothermal conditions,topography,and rock-soil strata in open-pit coal mines,as well as their en-vironmental effects,across three scales:regional,mine-scale,and local dump-site scales.At the re-gional scale,an analytical method based on the hydrothermal coordination index was established.It was found that the hydrothermal conditions of open-pit coal mine ecosystems in arid and semi-arid re-gions of China exhibit significant spatial differences.Hydrothermal coordination directly affects the ef-fectiveness of vegetation restoration in mining areas and should be considered as one of the key factors in planning the production capacity layout of open-pit mines.At the mine scale,changes in elevation and slope before and after mining in typical open-pit coal mines were analyzed.Based on Sentinel-2 satellite atmospheric water vapor data and Envi-met numerical simulations,it was revealed that an"inversion effect"forms in open-pit mines at night,which exacerbates the upward migration and accu-mulation of dust from the mine pit towards the temperature inversion layer.During the daytime,an"M-shaped wet island effect"characterized by"high in the removal area-low in the excavation area-high in the dumping area"emerges,while a"dry island effect"occurs at night.These phenomena ex-acerbate the loss of surface soil moisture in the mining area.At the local dump-site scale,a typical particle-size segregation phenomenon was observed on the step slopes of reconstructed dump strata,with the particle-size distribution along the slope direction conforming to the Rosin-Rammler distribu-tion function.The reconstructed dump strata exhibit a typical vertical differentiation feature of"or-dered structure in the lower part and disordered structure in the upper part".Under the influence of particle-size segregation,a vertical permeability gradient is formed in the reconstructed dump strata,and the internal seepage field shows nonlinear migration characteristics dominated by"preferential channel migration-retention at heterogeneous interfaces".Such a disordered structure lacks the condi-tions to impede groundwater infiltration,making it difficult to restore the phreatic water level.There-fore,the systematic implementation of ecological restoration in open-pit mines should also include sci-entific reconstruction of dump strata to control seepage conditions in the restored strata and prevent risks of solute migration pollution.This study holds significant theoretical importance for understand-ing the evolution mechanisms of mining ecosystems,optimizing mining design,and formulating eco-logical protection and restoration measures for mining areas.