| dc.description.abstract | The dissolved ions in land water are affected by their regional geological and geographic conditions as well as chemo-physical characteristics of ions. The influence factors can be classified into direct and indirect ones: the direct factors include rock, soil, and organisms, whereas the indirect factors are climate and characteristics of water bodies. From June 2009 to May 2010, 23 water samples were collected each month in the study area, in which surface water samples were taken from gullies and rivers, groundwater samples were taken from wells and hot springs. Geochemical indices include δ18O、δD、Cl-、SO42-、HCO3-、Na+、K+、Ca2+、Mg2+、Fe2+、Cu2+、pH and EC were then analyzed. Coping with previous data from the study area, this research aims to understand the characteristics of land water in the study area, as well as the temporal and spatial variation of geochemical indices, the major geochemical indices and their inter-reactions. Furthermore, δ18O is used to identify the recharge source of the research well field in the study area. The results from factor analysis indicate that the major chemical indices are HCO3-、EC、Na+、SO42-、Ca2+、Mg2+, and the major geochemical reaction is weathering, dissolution and cation exchange. In addition, high concentration of SO42- at Mei Ren Tamg hot spring was found to be related to land slide. Stable isotope composition of rainwater is heavier than that of well field groundwater, whereas the isotope of gully or river water is lighter than that of well field groundwater. Accordingly, rainwater must be the major recharge source of groundwater; gully water and river water also additional recharge. Using mass balance principle allows us to calculate the recharge ratios of gully, river and rainwater to groundwater, respectively. The calculation indicates that all the rainwater, gully water and river water contribute to groundwater during the wet season; as for the dry season, river and rain water are the major recharge sources. Groundwater in the well field is concluded flowing from north to south.
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