Water-rock Interaction And Temporal And Spatial Evolution In Discharge Squifers Under Mining-induced Disturbance In Coal-mining District

Coal mining is bound to destroy the natural hydrochemical environment and cause the complicated hydrodynamic conditions and frequent water inrush accidents. However, in North China type coal field, the hydrogeochemical characteristics of discharge aquifers under mining-induced disturbance has not been researched from the view of space and time, and the true feature of hydrochemical environment and its possible evolution trend can not be well revealed. For this reason, taking Linhuan coal-mining district as the study area, the conventional ions and the trace elements are studied by the principal component analysis (PCA) to reveal the mechanism of water-rock interaction and discuss the hydrogochemical evolution rules under mining-induced disturbance. Meanwhile taking Linhuan, Suxian and Suixiao coal-mining district as the study area, Analysis basic hydrogeochemical characteristics and discuss the hydrogochemical evolution rules of rare earth elements under mining-induced disturbance to distinguish relations among different discharge aquifers.The results show that the main water-rock interaction is the lixiviation and dissolution for the first principal components and the cation exchange absorption for the second principal components, respectively. In general, the main water-rock interaction in the unconsolidated pore aquifer is the lixiviation and dissolution, which are gradually weakened with the strengthened cation exchange absorption under mining-induced disturbance. The main water-rock interaction in the coal and sandstone cranny aquifer is the cation exchange absorption, which is gradually weakened during the coal mining, following the weaken lixiviation and dissolution. The main water-rock interaction in the karst aquifer is the lixiviation and dissolution with the supplement of cation exchange absorption, and the two kinds of water-rock interactions are strengthened with the coal mining.The results research show for rare earth elements that the unconsolidated pore aquifer of Linhuan and Suxian coal-mining district are in the same groundwater flow system, however Suixiao coal-mining district is in independent groundwater flow system. The coal and sandstone cranny aquifer and the karst aquifer of three coal-mining districts are in the same groundwater flow system or have closely hydraulic connection. The groundwater system is gradually open and the dissolution of rare earth elements gradually tends to balance in the unconsolidated pore aquifer of Linhuan coal-mining district under mining-induced disturbance; The water-rock interaction is gradually strengthened in the coal and sandstone cranny aquifer, which leads to the increase of ΣREE and Eu anomaly is more obvious; The groundwater system is gradually open and groundwater circulation is gradually strengthened in the karst aquifer. The research provides the theoretical foundation for warning water inrush, protecting and utilizing water resources in North China type coal field.