淡水河流域中鐵之地球化學研究

Geochemical Behavior of Dissolved Iron in the Danshuei River Watershed

馮英哲(Ying-Che Fong)

指導教授 ： 溫良碩

國立臺灣大學/理學院/海洋研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.01497

摘要

本研究透過物理分離（孔徑大小為0.1 μm、0.45 μm之正壓過濾法及分子量1000之交流過濾法）與化學分離（陰陽離子交換法），探討淡水河全流域河水及河口水中，溶解相鐵及其物種之大小分布與化學親和性。研究顯示，三條主支流中，基隆河之溶解相鐵（≦0.45 μm）濃度最高（579±85 nM），新店溪（116±27 nM）與淡水河（95±28 nM）次之，大漢溪最低（75±28 nM）。以分子量大小判斷，鐵及其化合物主要以膠體相（≧1 kDa）存在（~94%），其中部分為0.1~0.45 μm之微顆粒態或高分子化合物，真溶解相（≦1 kDa）於淡水河流域僅佔極小比例(~6%)。由化學親和性分析，基隆河之鐵化合物以FeCation-exchanged（~52%）最多，新店溪、大漢溪與淡水河則以FeInert（鐵錯合物）為主要物種（55~73%）；此外，FeZwitterionic於全流域皆存在，但比例較低（~9%）。研究結果顯示，淡水河流域中鐵之相變化頻繁、反應劇烈、濃度分布差異大，且大部分為非守恆型移除型態。膠體鐵本身具有不同之化學特性，可能為各種化學型態相異之鐵物種所組成，且各物種間存在著比例關係。

關鍵字

鐵 ； 物種變化 ； 淡水河 ； Chelex-100樹脂 ； AG MP-1樹脂

並列摘要

Using physical (0.1 and 0.45 μm cut-off filters) and ion exchange (Chelex-100 and AG MP-1 resins) separation techniques, detailed distribution patterns and chemical affinities of Fe were investigated under different redox conditions in the watershed of the Danshuei River, a macro-tidal, temporally anoxic estuary, passing though the metropolitan area of Taipei. Concentrations of dissolved Fe in the Danshuei River tributary/estuary ranged from 9 to 1543 nM, with the majority residing in the 1 kDa~0.1 μm fraction (~50%), in which the largest fraction occurred as cation-exchanged species (~47%). Concentrations of truly dissolved Fe (≦1kDa) showed almost at constant fraction (~6%) in the whole watershed, except in the estuary where it was lower (~15%). Furthermore, the results indicated that ~9% dissolved Fe showed zwitterionic behavior. Concentrations of dissolved iron in the upstream Keelung River were significantly higher than in the other rivers. Results obtained in this study clearly demonstrate that under different flow and redox conditions in estuarine waters, iron remaining in the water column during the removal process had a distinct pattern of size distribution and chemical affinity. Geochemical factors, including salinity, pH, dissolved oxygen and suspended particulate matter concentrations, control concentrations and distributions of the different fractions for the physical and chemical speciation scheme.

並列關鍵字

iron ； speciation ； Danshuei River ； ion exchange ； Chelex-100 ； AG MP-1

參考文獻

林盈君, 2007. 硫酸錳催化靛藍法測氨之研究. 國立台灣大學海洋研究所碩士論文

行政院環境保護署網站 ( http://www.epa.gov.tw/ )

Boyle E.A., Edmond J.M., Sholkovitz E.R., 1977. The mechanism of iron removal in estuaries. Geochimica et Cosmochimica Acta 41, 1313-1324.

Coale, K., Bruland, K., 1988. Copper complexation in the Northeast Pacific. Limnology and Oceanograpy 33, 1084–1101.

Coale, K., Bruland, K.W., 1990. Spatial and temporal variability in copper complexation in the North Pacific. Deep-Sea Research 37, 317–336.