圖書典藏及影音數位平台

為持續掌握各地下水分區地下水質變化趨勢，本年度擬循往年以兩年為一循環期程，完成全臺七百餘口地下水觀測井水質檢測分析工作之作業模式辦理。檢測項目包括採樣現場檢測溶氧、水溫、氧化還原電位、導電度、pH及甲烷氣等6項，實驗室水質檢驗項目包括碳酸氫根、碳酸根、鈣、鎂、鉀、鈉、氯鹽、硫酸鹽、硝酸鹽氮、氨氮、銅、鎘、鉛、鋅、鎳、鉻、砷、鐵、錳、總有機碳、硫化物、大腸桿菌群、鈉吸著率與殘餘碳酸鈉等24 項，並提供各觀測井滯留水溶氧、水溫、氧化還原電位、導電度、pH及甲烷氣等6項現場基本水質分析。另針對濁水溪沖積扇扇頂區觀測井，每半年辦理1次硝酸鹽氮濃度加強監測。除藉由2年一次循環辦理此等水質分析項目外，本計畫將可完整提供台灣地區各地下水分區地下水水質狀況，掌握沿海地區地下水鹽化範圍，並探討鹽化之趨勢與研擬因應之道，以及濁水溪?積扇扇頂地下水補助區硝酸鹽氮污染情況分佈趨勢分析，以了解其豐枯水期濃度變化與分布情形。

To comprehend the groundwater quality of Taiwan and provide valuable information for development, protection, and research of groundwater resources, the groundwater samples of 380 monitoring wells in Taiwan are collected and analyzed. The major achiecements of this project including: 1. Over-pumping of groundwater in coastal area of southwestern Taiwan may cause the seawater intrusion, accompanying with high EC values in most wells. 2. The characteristics of groundwater in mountain area were O2-riched and oxidation, whereas those in downstream area were anaerobic and reductive conditions. 3. Major characteristics of groundwater in Taiwan includes degradation of organic C/formation of inorganic C, nitrate/nitrite redox cycling, reductive dissolution of As, Fe, and Mn, and generation of sulfides. 4. The dissolution of metals from deposits and borehole materials may result the groundwater contamination of Cu, Pb, Zn, Cr, Ni,Cd in some wells. 5. Extensive use fertilization of agriculture may lead to critical nitrate pollution of groundwater, especially in the uppermost aquifer. The nitrate concentrations in wet season are higher than those in dry season, which is caused by the hydrogeological characteristics and groundwater flow direction. 6. Critical salinalization of groundwater was found in Chianan plains, causing by modern seawater intrusion and sulfate reduction. The saline groundwater are also found in part of groundwater of Choushui river alluvial fan and Pindong plain. 7. The reductive condition has caused the elevated nitrite, Fe, and Mn concentrations in most groundwater samples. The adsorbed As may be liberated during the reductive dissolution of Fe/Mn minerals, especially in coastal areas of Yunlin, Pindong and Lanyan plains, and Chianan plain. 8. The urgent wells for drought period or wartime of Taipei basin, Taichung area, Chianan plain, Pindong plain are located in mountain area, whereas those of Choushui river alluvial fan and Lanyan plains are located in shallow groundwater aquifer. The further investigations of the havey metals pollution, seawater intrusion, nitrate pollution are needed to achieve the goal of the sustainable operation of monitoring wells.