圖書典藏及影音數位平台

在全球總水量中，人類可取用的淡水資源不到1%，而淡水資源中又以地下水的貯存總量居冠。由於地表可用的水源有限，且為了滿足日益增加的農業、工業及民生用水的需求量，除了利用水庫調節之外，地下水就成為用水的重要來源之一。因此地下水水質優劣將會影響其使用用途，並可能影響人體健康。執行地下水水質持續監測，可提供水資源利用調配與環境衛生安全參考，並追蹤地下水污染源。依據水利署資料庫統計至民國99年之井口數資料顯示，全台灣現存共計727口自記式地下水觀測井，其中包括& #63775;陽平原有41口、台& #63843;盆地有30口、桃園中壢台地有29口、新苗地區有48口、台中地區有34口、濁水溪沖積扇有210口、嘉南平原有163口、屏東平原有142口、花東縱谷有23口及澎湖地區有7口。藉由這些觀測井所提供之長期水位監測資料，可提供相關單位對於地下水資源永續利用之規劃參考。由過去地下水水質採樣分析結果顯示，台灣地區地下水水質有幾項共通問題，一為沿海地區水質鹽化，如彰雲地區、嘉南平原、屏東平原沿海地區；二為地下水補注區硝酸鹽氮污染，如彰雲投地區、屏東平原扇頂補注區等；三為雲林、嘉南平原、蘭陽平原地下水中砷含量偏高，過去也在這些區域發生烏腳病及引發癌症；四為地下水鐵、錳、氨氮、總有機碳偏高，如台灣西南平原地區(雲林至屏東)。綜合以上分析，本計畫99年度將持續針對全台9大地下水分區之自記式觀測井，扣除98年度已篩選之觀測井進行其餘約380口地下水觀測井之水質檢測分析與評估，以持續監測並提出因應對策與建議。檢測項目包括現場檢測之溶氧、水溫、氧化還原電位、導電& #64001;、pH 及甲烷氣等6項，實驗室水質檢驗鹼& #64001;(碳酸氫根與碳酸根)、鈣、鎂、鉀、鈉、氯鹽、& #63950;酸鹽、硝酸鹽氮、氨氮、銅、鎘、鉛、鋅、鎳、鉻、砷、鐵、錳、總有機碳(TOC)、& #63950;化物、大腸桿菌群、鈉吸著率與殘餘碳酸鈉等24 項，並進行各觀測井滯& #63949;水基本水質分析；辦理濁水溪沖積扇扇頂新光、六合、溫厝等18站20口觀測井，每半年辦理1次補注區硝酸鹽氮濃度檢測與監測，本年(99)度預計執行採樣2次，共計40口。本計畫期望藉由各項水質項目之分析與評估，提供了解沿海地區地下水鹽化影響程度及分布情形、地下水補注區硝酸鹽氮污染因應對策與建議及雲彰濁水溪扇頂地下水補注區硝酸鹽氮污染情形分布趨勢分析與加強監測。此外， 本團隊也將進行滯留水質監測，並利用相關指標Langelier Saturation Index (LSI)、Ryznar Stability Index (RSI)以及Aggressive Index (AI)之變化情形，評估滯留水質之腐蝕趨勢及對井體結構之影響，並提供具體建議，以作為未來井體維護保養之參考。

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 Chianan and Pindong plains 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. Extensive use fertilization of agriculture may lead to critical nitrate pollution of groundwater, especially in the uppermost aquifer. 4. 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. 5. The development of industry and the dissolution of metals from deposit materials may result the groundwater contamination of Cu, Pb, Zn, Cr, Ni,Cd in some wells. 6. Critical salinalization of groundwater was found in Chianan and Pindong plains, causing by modern seawater intrusion and/or residual paleo-seawater. The reductive condition further induced the sulfate reduction and sulfide accumulation. 7. 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. 8. About 60% of monitoring wells in Taiwan can be used as urgent wells for drought period or wartime. The further investigations of the havey metals pollution and seawater intrusion are needed to achieve the goal of the sustainable operation of monitoring wells.