Assessing Anthropogenic and Natural Contributions to Groundwater Salinization in the Coastal Area of Central Taiwan Using Transition Metal Signatures

抄録

Taiwan's steep terrain and uneven precipitation patterns result in a strong dependence on groundwater resources, which play a critical role across various sectors of water use. In the coastal region of central Taiwan, particularly in the southern portion of the Jhuoshuei River alluvial fan, shallow aquifers are experiencing significant salinization. Sampling locations for this study were selected based on statistical analyses of historical groundwater quality data collected between 2015 and 2019. Multiple sets of groundwater samples were collected and analyzed to investigate their hydrochemical characteristics and seasonal variations. The results reveal a general trend of decreasing salinity with increasing depth. However, the elevated salinity in certain samples imposes limitations on conventional water quality analyses. Furthermore, basic hydrochemical parameters are insufficient to trace the origins of salinity, as they primarily reflect the presence rather than the source of saline intrusion. To address this limitation, further treatment of the samples was undertaken to differentiate between natural (e.g., lateral seawater intrusion) and anthropogenic (e.g., fish farming) sourc