關渡地區土壤中含砷與鉛的礦物─砷鉛鐵礬之研究

The Study of Containing Arsenic and Lead Mineral (beudantite) in Guandu Area Soil

江凱楹(Kai-Ying Chiang) ； 王明光(Ming-Kuang Wang)

《土壤與環境》 14卷1&2期 (2011/12) Pp. 1-13

https://doi.org/10.30058/SE.201112.0001

摘要

本研究在關渡地區選擇一個砷與鉛汙染剖面（pedon 1）以及一個未汙染剖面（pedon 2），來分析土壤物理化學性質。關渡地區土壤為弱酸性、高鹽基之灰色黏壤土，土壤之高鹽基受到海風與地下水位之影響甚大，為典型或暗色的漂白潮濕淋溶土。以X-ray diffraction（XRD）礦物鑑定、掃瞄式電子顯微鏡（Scanning electron microscopy, SEM）、X光能譜散佈分析儀（Energy dispersive spectrometer , EDS）與同步輻射分析技術（X光吸收光譜技術， X-ray absorption spectroscopy, XAS）等方式，分析關渡地區砷與鉛污染土壤。礦物組成以蛭石、伊萊石與高嶺石為主。經粉末XRD礦物分析鑑定，發現汙染土壤剖面各層次皆有砷鉛鐵礬（beudantite）的存在；以SEM分析， 發現似砷鉛鐵礬之八面體構造，輔以EDS，發現該八面體構造中同時含有砷與鉛元素之存在。X光近緣結構（X-ray absorption near edge structure, XANES）圖譜顯示砷原子在污染土壤樣本中主要為+5價，而鉛原子高於+4價鉛離子（PbO2），所有證據說明土壤中有砷鉛鐵礬之存在。

關鍵字

砷 ； 鉛 ； 砷鉛鐵礬 ； 關渡地區

並列摘要

This study collected two pedons of arsenic (As) and lead (Pb) contaminated soils (i.e. Pedon 1) and uncontaminated soils (pedon 2) from Guandu area for soil physical and chemical characterizations. The contaminated soil is weak acid and high base; it can be classified as clay loam, mixed, thermic, Typic or Umbric Albaqualfs. Soil minerals were determined to be vermiculite, illite and kaolinite. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray absorption spectroscopy (XAS) were used to analyze soil samples. The powder XRD of soils from Pedon 1 showed the existence of beudantite at different soil horizons. The corresponding SEM and EDS revealed the association of arsenic and lead in beudantite with an octahedral shape. As shown in the XAS of the soils, the valences of arsenic and lead were +5 and +4, respectively. Accordingly, the existence of beudantite in the soils was confirmed.

並列關鍵字

Arsenic ； Lead ； Beudantite ； Guandu area