The Study On Dynamic Variation And Influencing Factors Of The Karst Groundwater Quality

Karst groundwater resources are the main form of water resources in Karst area which affected by hydrogeology and geological structure and usually exist as the double-layer structure form in hydrogeology. At the same time, it is difficult to form soil and uneven spatial and temporal distribution of groundwater resources exist in Karst area, the fragile environment of Karst area is often influenced by human activities. As the Karst groundwater used as the domestic water in mountain areas and agricultural areas, it is so important to solve problems exist in water resources there.Qingmuguan karst groundwater system lies in an agricultural area where many quarry have and abandoned coal mines. Jiangjia spring is the discharge ports of the whole underground river system which provide domestic water to surrounding residents, the water quality directly affect the health of surrounding residents. This research mainly focus on the chemical characteristics of groundwater and contributing factors and analyze the source of sulfate in the underground river system.So as to further understand the temporal and spatial variation of groundwater and provide the basis for effective governance and rational exploitation of groundwater in the area.The weather stations, monitoring stations are established to monitor the charges of underground rivers, and physical characteristics of the flow control output system and the main physical indicators include water temperature (T), electrical conductivity (EC), pH value variations. And moreover, field observations are coincided to describe the physical changes of the year in Qingmuguan The combination method of field sampling, field observations and laboratory analysis is adopted in Qingmuguan Basin to analyze different water types with continuous sampling, from January 2010 to November 2010 (once per month). Field observations include temperature (T), electrical conductivity (EC). pH value and Ca2+, HCO3-and so on. Laboratory analysis, including major cations such as, K+, Na+, Ca2+, Sr2+,Mg2+; and the main anion, HCO3-,NO3-,SO42-, Cl-. Afterwards, chemical characteristics of water changes are acquired in Qingmuguan throughout the year.As in the agricultural area, due to the frequently agricultural activities, the "fertilization activities" period is being monitored intensively, carried on observation and sampling from May to June,2010 (once per two days). Observing content and indicators do as the same as 2nd mentioned. The analysis revealed a strong disturbance of agricultural activities in the short time scale, to the variation of karst groundwater quality.Analyzed the carbon and strontium isotopic characteristics of Qingmuguan, and combined with water chemistry analysis methods to identify and distinguish natural factors from humans' on the impact of groundwater quality in agricultural areas.Through the study we got conclusion:The quality of the underground river water is batter when it goes into dry season and it may be affect by the dissolve of the limestone.While in the wet season the rainfall increase as well as the discharge, and the karst effect, leaching effect, ion exchange and the role of sulfuric acid is became bigger, the anions and the cation are increased in some level. The ground water was severely polluted when the water level is rise and the agricultural activities became frequent.Through the research ofδ13CDIC, the ground water was affected by the chemical weathering of carbonate rocks by sulfuric acid. By using the 87Sr/86Sr. we give a conclusion that the ground water was severely affected by human activities during agricultural time.Through the hydrochemistry research and using the methods ofδ13CDIC and 87Sr/86Sr we know that the groundwater quality is better in the dry season, and the chemical weathering of carbonate rocks by H2CO3 was the main impact factor. While during the wet season the groundwater quality was affect by fertilization and emission from human and the chemical weathering of carbonate rocks by sulfuric acid. This makes the ground water quality worse.