Study On Geochemical Features Of Groundwater Source In North Anhui Province

Based on the investigation and assessment of the basic condition of groundwater nationwide by four ministries, this paper integrated theories and methods of hydrology geochemistry, hydrological geology, isotope water chemistry, studied the characteristics of groundwater at the water source of northern Anhui, evaluated the groundwater quality, defined the evolution rule of chemical composition of groundwater, revealed the interaction mechanism between groundwater and the environment, verified the source of groundwater recharge, and provided scientific basis for rational development, utilization and protection of groundwater resources. The main research conclusions are as follows:1. Using the mathematical statistics method to contrast and analyze to centralized water source and decentralized water source respectively. The bigger space variation coefficient of chemical composition at distributed water source water shows that the hydrological chemical properties on the spatial variability are large and the influence of external factors is bigger.2. The TDS content of groundwater increases gradually from northwest to southeast of the centralized water source; the water there is basically fresh water suitable for human development and utilization. TDS content of decentralized water source is significantly different, related to human activities. The chemical type of water at centralized water source is unitary, while that of decentralized water source is complex. The fluorine content in groundwater sources is related to geological factors, and the nitrogen mainly comes from human activities.3. Respective evaluations were made on the water quality and health risk, and pollution status of water sources in northern of Anhui Province. Results show that the major indices influencing the quality of groundwater water are SO42-, Cl-,Mn, F-, TDS, total hardness, SO42-, NO3-and NO2- and NH4+. Exceeding the limit is mainly due to the geological reasons and human activities. The comprehensive assessment indicated the water quality at centralized water source is better than that of decentralized water source which is seriously polluted. That is mainly caused by human activities. Health risk evaluation of heavy metals revealed that the total health risks are mainly carcinogenic; part of the water source were marked "medium and high level".4. Using Gibbs figure, correlation analysis, ion ratio method and isotope techniques to disclose the formation mechanism of chemical composition of ground water at the water source of northern Anhui. The atmospheric precipitation constituted major source of water supplement, the formation mechanism of chemical composition of ground water featured rock weathering and evaporation, and the chemical composition of water mainly came from halitum infiltration and human activities. Decentralized water source was strongly swayed by evaporation and greatly affected by human activities.5. Factors influencing and deciding the formation and evolution rules of water composition in research regions mainly included:water rock interaction, human activity and content of soil soluble salt. Human activities such as the irrational groundwater exploitation, random discharge of pollutants and so on, will cause the higher concentration of pollutants and TDS in groundwater.