酸鹼值控制下沉積物中萃取重金屬的初步探究

Preliminary Study of Extraction of Heavy Metals in Sediments under pH-controlled Conditions

高嫚聰(Man-Tsung Kao)

指導教授 ： 呂學諭

國立中正大學/理學院/地球與環境科學系應用地球物理與環境科學研究所/碩士(2014年)

摘要

台灣地區不論是飲用水、灌溉用水或養殖用水，其來源有相當大的比例來自於地下水；因此，地下水水質對人體健康有很大影響，但長久以來地下水中重金屬離子含量，在飲用水水源水質的標準下時有超過管制標準的趨勢，尤其是地下水砷污染的範圍廣泛，一直是台灣水質污染的重要議題，更值得重視並投入心力研究污染發生的機制。使用飽和碳酸鈣萃取液的分析結果，經多變量分析後，可擷取到兩個因素，因素一包含附了砷以外的大多數元素，且相互之間為正相關，可解釋為吸脫附反應的控制；而因素二含As、Sr、Zn等三個元素，其可能為沉積物中有機物的影響。再者，飽和碳酸鈣萃取液在時間序列上的萃取實驗結果顯示，As在初期濃度增加的趨勢，之後即呈快速下降，至14天時達最低濃度，此結果顯示As及重金屬的吸脫附可能主要受控於酸醶值。另利用不同鹽度的氯化鈉溶液進行萃取實驗，結果顯示在氯化鈉濃度低於1000 ppm時，可溶出的As並無太大的差異，直到氯化鈉溶液濃度達5000 ppm時，As濃度有大幅增加的現象，顯示水中氯離子可能有與砷酸鹽競爭吸附位的情況發生。

關鍵字

沉積物 ； 砷污染 ； 嘉南平原

並列摘要

Groundwater is one of the major source for supplying daily and agricultural usages in Taiwan; therefore, the groundwater quality is crucial to have considerable effect on public health. Arsenic pollution increases increases the risk of developing diseases and gradually becomes a serious issue in the management of groundwater resources in Taiwan. According to the principal component analysis on the results of BCR extraction procedure, two principal components can be extracted. Factor 1 includes most of the heavy metals except As. It can be explained with the sorption behavior between extraction solution and sediments. Factor 2 is composed of As, Sr and Zn. It could be controlled by the proportion of organic matter in sediments. In addition, an increase trend of arsenic can be observed in the early stage of extraction experiments. However, the extracted arsenic gradually decreased after 5 day extraction and achieved a minimum concentrations on the final (14 day extraction). This could result from the increase of pH during the extraction experiments. The extraction experiments with various concentrations of NaCl were also performed in this study. The results demonstrate that the amount of extracted arsenic is stable when the extraction solution has a lower concentration of NaCl. However, the extracted arsenic dramatically increases if the concentration of NaCl was greater than 5000 ppm.

並列關鍵字

Arsenic Pollution ； Chianan Plain ； Sediment

參考文獻

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