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標題: | 西菲律賓海溶解態銅之化學反應性及物種 Chemical Reactivity and Speciation of Dissolved Copper in West Philippine Sea |
作者: | Ya-Huei Huang 黃雅慧 |
指導教授: | 溫良碩(Liang-Saw Wen) |
關鍵字: | 銅物種,腐植質,交流超微過濾,離子交換樹脂,固相萃取法,黃酸錯合銅, Cu,speciation,cross flow ultrafiltration,XAD-4,Chelec-100,AG MP-1,humic substances,fulvic bound Cu, |
出版年 : | 2012 |
學位: | 碩士 |
摘要: | 海水中溶解態銅主要是以有機分子錯合物型態存在。過去研究普遍認為占海洋溶解有機物的主要組成之腐植質(humic substances),對於銅在水體中的物種組成有很大的影響,並且能左右生物對於銅的利用性。本研究利用超微過濾(cross flow ultrafiltration, 1kDa)、離子交換樹脂(Chelex-100, AG MP-1)及固相萃取法(solid phase extraction, XAD-4)等分析技術,探討西菲律賓海域溶解態銅的化學反應性及物種的濃度分布。
總溶解態銅(≤ 0.4um)之垂直濃度分布為 0.5~3 nM,有光層(euphotic zone)中,確實受到生物攝取控制,不受內潮及水團混合之影響。膠體態銅(1 kDa~0.4 um)為本研究海域之主要物種,占總溶解態銅60~80 %以上,且膠體態銅其中有60 %以上為有機銅(organic Cu),其主要可能為浮游生物之排出液(exudates)、細菌的再礦化作用(re-mineralization)產生的膠體物質和生物性黏液(mucilages)等高分子化合物;且膠體態銅確實為陽離子可交換態(cationic exchangeable),為生物可以利用之型態。本研究全球首度發現,有光層中,上層水域之黃酸含銅量確實會受到生物及光化學分解作用之影響;微光層以下之黃酸濃度無明顯變化,但其含銅量卻隨深度漸增,產生金屬富集現象(metal enrichment),這些黃酸錯合銅(fulvic bound Cu)占小分子(<1kDa)惰性銅之 25~60 %,可推測水中其它之惰性銅應主要為硫化銅及少量未知物。 Dissolved Cu in seawater is now recognized to be dominated by complexation with naturally occurring ligands. Marine humic substances (HS) are known to be one of the main components of bio-refractory DOM which plays an important role in copper speciation, affecting its bioavailability. In this study, depth profiles of reactivity and speciation of dissolved copper in West Philippine Sea waters were investigated by cross flow ultrafiltration (1kDa), ion exchange (Chelex-100, AP MG-1), solid phase extraction(XAD-4) and differential elution (hydrochloric acid, sodium hydroxide and methanol) techniques. Results had shown that the concentration of total dissolved Cu(≤ 0.4 um), from surface to near bottom (~3000 m) waters, ranged 0.5~3 nM. The distribution and concentration of dissolved Cationic Cu in euphotic zone were significantly affected by the phytoplankton uptake even under strong internal wave and water mass mixing conditions in West Philippine Sea. The major part of dissolved Cu was in colloidal fraction (1 kDa~0.4 um), and cationic-exchangeable which’s bio-available, mediated by colloidal compounds released from planktons and bacterial re-mineralization, as microbial mucilages. In euphotic zone, both fulvic fluorescence and fulvic bound Cu had similar distribution as chlorophyll-a, indicated that part of the fulvic bound Cu released by photochemical oxidation and then uptake by phytoplankton. In aphotic zone, with almost unchanged fulvic concentration through out the water column, however, Cu concentration in these fulvic acid increased with depth, a metal enrichment process possible caused by re-mineralized free Cu ions re-established bounding with previously photo-altered metal depleted fulvics. In addition, as world first discover, fulvic bound Cu changed accounted only for 8~15 % of truly dissolved Cu (≤1 kDa), and 25~60 % of its refractory fraction. These evidences suggested, that majority of refractory Cu in the ocean water might be metal sulfide compounds. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/64050 |
全文授權: | 有償授權 |
顯示於系所單位: | 海洋研究所 |
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