https://scholars.lib.ntu.edu.tw/handle/123456789/86201
標題: | 行政院國家科學委員會補助專題研究計畫成果報告:濁水溪沖積扇南翼地層環境中砷之富集、釋出、分布及地化傳輸(1/3) | 作者: | 劉振宇 | 關鍵字: | 砷;來源;海相序列;沈積盆地;arsenic;occurrence;marine sequence;sedimentary basin | 公開日期: | 2005 | 出版社: | 臺北市:國立臺灣大學生物環境系統工程學系暨研究所 | 摘要: | 砷為一具有毒性且致癌之重金屬,於嘉南平原曾造成大規模之烏腳病疫情,相關研究 報告說明此與當地居民飲用含砷之深層井水有關。而根據歷年研究報告指出鄰近嘉南平原 之濁水溪沖積扇南端之淺層地下水中亦含有高砷含量,唯兩地區地下水中發現高砷含量之 深度有所差異,故本研究為三年期計畫之第一年,挑選濁水溪沖積扇南端之13 口地質鑽探 井,針對655 個岩心樣本之砷含量進行分析,並蒐集地層岩心質地資料與地年分析結果, 探討此區地層岩心之砷含量、土壤質地與沉積年代三者之關係,最後歸納此區地下水中砷 含量可能之主要來源。此區沉積地層中相互交錯之三個海相層與三個陸相層為冰河時期之 海進海退現象所造成,而海相層與陸相層即分別相當於現今之阻水層與含水層,由本研究 結果發現濁水溪沖積扇南端地層中,高砷含量主要發生於多屬黏土質之淺層阻水層,其顆 粒較小,易吸附高砷含量,反之,土壤顆粒較大之含水層岩心,其砷含量則較低,且岩心 定年結果約為3,000 至9,000 年前之全新世沖積土壤,此與嘉南平原深層地層岩心之定年結 果相近,即濁水溪沖積扇南端與嘉南平原兩者之高砷含量地層雖具不同深度,卻屬同一時 期形成,此結果說明地下水中高砷含量之發生與岩心質地及其所屬年代呈現相關。另外, 利用阻水層岩心與含水層岩心之平均砷濃度分別與地下水中之砷濃度進行迴歸分析,發現 阻水層岩心砷含量與地下水砷含量為顯著正相關(R2=0.51),而含水層岩心砷含量與地下水 砷含量之R2 則為0.21 且非顯著,此結果說明地下水中砷含量不僅由地層中傳輸而得,阻水 層岩心更可能為主要來源。本研究同時提出濁水溪沖積扇地下水砷來源之概念模式,然而, 地層中砷含量之富集與釋放機制為未來所必須深入探討,以期建構完整之砷循環模式。 High arsenic, As, concentrations in deep well water have been verified to be associated with blackfoot disease, which was once common on the Chianan plain in Taiwan. This is the first-year report of a three-year project. An investigation of shallow groundwater quality revealed that high arsenic, As, concentrations were found in both aquifers and aquitards in the southern Choshui river alluvial fan of Taiwan. 655 geological core samples from 13 drilling wells were collected and analyzed. High As contents were found primarily in aquitards, to a maximum of 590 mg/kg. The contents were correlated with the locations of the marine sequences. Additionally, strong correlations among the As concentrations of core samples, the clay and the geological age of the Holocene transgression were identified. Most of the As in groundwater originated from the aquitard of the marine sequence. The high As content in marine formations with high clay contents may be attributable to the bioaccumulation of As in the sea organisms, which accumulated and were deposited in the formation. A preliminary environmental model of the origin of the high As concentration in the shallow sedimentary basin of the Choshui river alluvial fan of Taiwan is proposed. The enrichment and release mechanism will be investigated in the second and third years study to establish a model of the ecological cycle of As in Choshui river alluvial fan in Taiwan. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/10790 | 其他識別: | 932313B002071 | Rights: | 國立臺灣大學生物環境系統工程學系暨研究所 |
顯示於: | 生物環境系統工程學系 |
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932313B002071.pdf | 357.42 kB | Adobe PDF | 檢視/開啟 |
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