Solute Transport Simulation of Heavy Metal Contaminants in Sidi River Basin in Guangxi
In order to evaluate heavy metal contamination in Sidi River Basin mining area of Yangshuo County,Guangxi,the watershed hydrological model by ArcSWAT and the solute transport model by MT3DMS in groundwater modeling system(GMS)were combined to quantitatively analyze the migration of zinc and cadmium.The results suggest that utilizing ArcSWAT and GMS can more accurately determine the vertical infiltration amount and accurately groundwater numerical simulation.Without prevention and control measures,mine wastewater poses a significant pollution threat to groundwater environment.It is found that the content of zinc and cadmium in water sample of tailing cave outlet is 18.62 mg/L and 0.096 mg/L respectively,which is the source of heavy metal contamination in entire basin.Within simulated period of 20 years,the contaminated halo of zinc and cadmium reaches the river after about 16 d and 44 d respectively,and the farthest front end of halo is 2 303.75 m and 1 887.04 m away from the center.The longest part at both ends is 3 159.57 m and 2 478.57 m,and the widest part is 1 533.54 m and 1 128.36 m.The mass of zinc and cadmium entered basin is 3 512.44 g and 18.15 g,and flowed out is 1 640.49 g and 8.47 g,remaining proportion are 53.28％and 53.33％separately in basin.There are existing research results show that Solanum nigrum L.is hyperaccumulator for cadmium that the highest accumulation in plant is 1 084.4 mg/kg and strong tolerance to zinc with enrichment exceeding 1 000 mg/kg.Therefore,a simulated circumstance is set up to evaluate the ecological restoration of tailings reservoir.The content of zinc is 0.284 mg/L and cadmium is 0.002 mg/L in tailings pond which is taken as alternative contaminated source.The migration speed of zinc along river valley reduces from 94.38 m/a to 80.78 m/a,and cadmium reduced from 86.09 m/a to 69.13 m/a during simulated period.The maximum halo of zinc reduced from 3.80 × 1 06 m2 to 2.50 × 106 m2 and of cadmium from 1.67 × 106 m2 to 1.29 × 106 m2.It indicated that the ecological restoration has achieved better effects and proposed continue investing in construction.According to simulation results,it is recommended to construct anti-seepage curtains and other prevention measures at the mine tunnel outlet.And prevention areas are classified to strengthen groundwater quality monitoring.Simultaneously,emergency plans for groundwater accidents can be formulated to avoid further deterioration of contamination.
the Sidi River Basinheavy metal contaminationArcSWATMT3DMSsolute transport simulation
万方数据
维普
