Submarine groundwater discharge around Taiwan
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Submarine groundwater discharge around Taiwan CHEN Chen-Tung Arthur1, 2*, ZHANG Jing3, PENG Tsung-Ren4, KANDASAMY Selvaraj5, WANG Deli5, LIN Yi-Jie1 1 Department of Oceanography, National Sun Yat-sen University, Kaohsiung 804, Taiwan, China 2 State Key Laboratory of Satellite Ocean Environmental Dynamics, Second Institute of Oceanography, State Oceanic
Administration, Hangzhou 310012, China 3 Environmental Biology and Chemistry, Graduate School of Science and Engineering, University of Toyama, 930-
8555 Toyama, Japan 4 Department of Soil and Environmental Sciences, National Chung Hsing University, Taichung 402, Taiwan, China 5 State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, China
Received 6 October 2017; accepted 20 March 2018 © Chinese Society for Oceanography and Springer-Verlag GmbH Germany, part of Springer Nature 2018
Abstract
A preliminary study shows that the submarine groundwater discharge (SGD) exists around Taiwan even though groundwater overdrawing on the island is serious. Fifteen of the 20 sites studied for major anions and cations recorded a clear SGD signal with freshwater outflow. A total of 278 salinity and major ion measurements were made. Sixteen nearly freshwater SGD (salinity≤1.0) samples were obtained, providing strong and direct evidence for the existence of fresh meteoric groundwater entering the ocean from Taiwan. The total SGD flux is estimated to be 1.07×1010 t/a which is about 14% of the annual river output. The freshwater component of the SGD is 3.85×109 t which is about 5.2% of the annual river discharge in Taiwan. The collected SGD has a composition similar to seawater with an addition of Ca, CO3 and HCO3 due to dissolution of calcareous rocks. Some samples with high Cl/(Na+K) may indicate pollution. Key words: submarine groundwater discharge, Taiwan, flux, major components, seawater intrusion Citation: Chen Chen-Tung Arthur, Zhang Jing, Peng Tsung-Ren, Kandasamy Selvaraj, Wang Deli, Lin Yi-Jie. 2018. Submarine groundwater discharge around Taiwan. Acta Oceanologica Sinica, 37(6): 18–22, doi: 10.1007/s13131-018-1216-2
1 Introduction The coastal zone is marked by rich biodiversity and is of great importance for fisheries, agriculture and human settlements. For islands, the groundwater is a particularly important freshwater resource (Aris et al., 2013). Yet, the groundwater in coastal zones faces many threats; of which, seawater intrusion is a notable example. In order to deal with potential threats to this critical resource it is therefore important to understand the freshwaterseawater interface. The seawater intrusion mentioned above involves the penetration of seawater landward. On the other hand, the submarine groundwater discharge (SGD) involves the flow of groundwater and associated dissolved material seaward (the conceptual model is depicted in Fig. 1 of Moore (2010)). SGD, in a way, is a waste of the freshwater resource, and is the subject of this study. The subtropical island of Taiwan has an area of 35 873 km2 which is mostly mountai
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