Preliminary Geochemical Study of Groundwater Near the Chelungpu and the Changhua Faults, Central Taiwan

• Main Authors: Chu Hui-Yao, 朱輝耀
• Other Authors: You Chen-Feng
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/24807934600325556137

碩士 === 國立成功大學 === 地球科學系 === 89 === ABSTRACT More than 40 groundwater, including artisan-well waters, river waters and surface run-off, along the Chelungpu fault and the Changhua fault in Central Taiwan were collected and were analyzed for major anion and cation concentrations. Additional twenty-eight wet precipitation samples collected at NCKU were analyzed for a better understanding of possible rain input in groundwater. These results were evaluated applying the multivariate principle component method and factor analysis to gain further insights regarding factors that may affect chemical source or contamination in groundwater. The Na/Cl and Mg/Cl in rains are similar to that of seawater ratio, indicating the possible inputs of Cl-, Na+ and Mg2+ from seasalt-spray. However, the detected Ca2+ and SO42- concentrations in rains are principally of non-seasalt origin (i.e., 97.6% and 90.6%, respectively). Three main components in rains are seasalt (i.e., Cl-, Na+ and Mg2+), anthropogenic pollution (i.e., NO3-, nsSO42-, NH4+) and dust (i.e., nsCa2+, HCO3-). The seasalt component explain about 32.9％ of the chemical variations. Other important factors are carbonate dust dissolution and industrial aerosol pollution (i.e., (NH4)2SO4, NH4HSO4, and NH4NO3). In groundwater, the main components are chemical weathering (i.e., nsCa2+, nsSO42-, nsMg2+, Alkalinity), seasalt (i.e., Cl-, Na+), pollution (i.e., NO3-) and ambient soil (i.e., K+). The weathering component explain about 37.7％ of the chemical variations in groundwater. The charge balance calculation of major cation (nsCa2+ + nsMg2+) and anion (nsSO42 -+ Alkalinity) agree with the weathering argument. The degree of influence caused by chemical weathering and seasalt in groundwater show regional distribution.