| 摘要: | 台灣雖然降雨量豐富，但由於山坡陡峭、雨勢集中再加上河川短促，所以大部分的雨水無法有效被截流，都迅速地流入海洋能使用的淡水反而不足。因此與世界各國相比台灣反而屬於缺水的國家，為了取得更多的淡水水源，許多地區紛紛開採地下水，尤其雲林沿海一帶地下水資源被使用的更為頻繁。過多的地下水抽取會導致地層下陷、海水入侵、地下水鹽化等問題，因此本研究選定雲林沿海地陷較嚴重的台西、口湖、水林三個區域作為研究對象。實驗主要方法參考文獻中效率較高的固相萃取技術-微波消化萃取法，分析浸沒在地下水含水層的沉積物岩芯，以海水入侵、養殖漁業、農業污染三方面切入探討，透過導電度、氯離子、溴離子(氯溴比)、硫酸鹽、硝酸鹽5項地下水鹽化指標進行量化的濃度比較、離子相關性分析，從中找出可能造成地下水鹽化之原因。
研究結果發現，雲林台西、口湖、水林三個區域都可能有地下水鹽化情形，然而各區域鹽化程度、原因不盡相同，台西區域地下水鹽化原因較類似養殖漁業廢水入滲和農業施肥導致；口湖地區地下水可能同時受到海水入侵、養殖漁業、農業污染三種以上之污染源影響；水林地區則可能為海水入侵和農業污染造成。各區域皆同時有發現兩個或兩個以上的污染源，而比對各離子相關係數發現，在鹽化程度較高的採樣點其氯離子與溴離子具有高度相關性，且氯溴比(Cl/Br)與標準海水濃度(SMOW)差異在10%內，和海水組成較為類似，符合海水入侵之推測。
本研究結果可幫助研究地下水鹽化之相關人員了解雲林沿海地區地下水鹽化情形，包含鹽化範圍、鹽化原因、深度變化等。
;Although Taiwan has abundant rainfall, however, due to the narrow and densely populated land, steep hillsides, concentrated rainfall, and short rivers, most of the rainwater flows into the ocean quickly, and the fresh water that can be used is insufficient. Compared with the world, Taiwan is a country short of water, in order to obtain more fresh water sources, groundwater has been exploited in many areas, especially in the coastal areas of Yunlin where it is used more frequently. Excessive groundwater extraction leads to problems such as stratum subsidence, seawater intrusion, and groundwater salinization. Therefore, this study selected six drilling wells in the three areas of Taixi, Kouhu and Shuilin, where subsidence is more serious in the Yunlin coastal area of the Zhuoshuixi River Basin. The groundwater aquifer core was taken as the research object, and the groundwater conductivity analysis was simulated by the test results of the core extract to discuss the salinization of the groundwater layer at different sampling points in the Yunlin coastal area.
In the reference literature of this research method, the solid item extraction technology with high efficiency - microwave digestion and extraction method, is used with ion analyzer to detect the salinization index, and the conductivity, chloride ion, bromide ion (chlorine-bromine ratio), sulfate, and nitrite are selected. Nitrate and 6 items of nitrate are used as indicators to measure the degree of salinization of groundwater, and the detection data are simulated through the correction of soil moisture content to simulate the concentration of groundwater. This study focuses on the key ions of seawater intrusion, fish farming, and agricultural pollution, and finds out the causes of soil and groundwater salinization.
The results of the study found that there may be groundwater salinization in Yunlin, Taixi, Kouhu, and Shuilin, and the causes of salinization in each region are different. Taixi is more similar to aquaculture fishery wastewater infiltration and agricultural fertilization. There may be more than three pollution sources causing salinization in the lake area, but it is not obvious from the perspective of the area. The water forest area may be caused by seawater intrusion and agricultural pollution. Two or more pollution sources are found in each area at the same time. It causes salinization, and comparing the correlation coefficients of various ions, it is found that conductivity and chloride ions are highly correlated, which is a key indicator of groundwater salinization. The results of this study are similar to the results of many literatures on groundwater salinization, and the experimental results can be used as a reference for tracking the causes of groundwater salinization and methods for preventing and controlling groundwater pollution. |
