2006-08-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/683532摘要：湄公河是東南亞最長的河川，亦是世界重要河川之一，其流經整個中南半島，最後從越南南部流入南海，對於南海陸源物質的來源扮演著重要的角色。故本研究之目的是藉由分析湄公河外海陸棚及陸坡沉積物中有機碳、碳酸鈣、金屬鋁、銅、鉛、鎘含量及顆粒大小組成，來探討湄公河外海沉積物之空間分佈變化，並進一步探討影響本研究區域有機碳及金屬空間分佈變化的主要控制因子。 研究結果顯示湄公河外海陸棚地區沉積物主要由有機碳及金屬含量較低的粗顆粒沉積物所組成，而僅於東方之南海陸坡海域發現有有機碳含量較高之細顆粒沉積物堆積。這可能是湄公河的泥質懸浮顆粒未直接輸出至南海，而多直接於河口三角洲沉積；或是受到季風及海流等因素影響，細顆粒沉積物未沉積於陸棚地區，而被帶至南海陸坡或往西傳輸至泰國暹羅灣內沉積。影響沉積物有機碳及金屬含量分佈的主要控制因子為沉積物顆粒大小組成。鋁含量與砂含量呈現明顯之反向關係，而銅、鋅、鎘金屬及有機碳含量則與鋁呈現明顯的正向關係，顯示沉積物金屬及有機碳含量受到沉積物細顆粒鋁矽鹽黏土礦物的多寡所控制。而碳酸鈣含量則於西南陸棚區域呈現異常高值，可能是上層水體大量碳酸鈣殼體沉降所致。粗顆粒之石英顆粒可能為降低金屬及有機碳含量之主要稀釋劑，更且亦控制碳酸鈣含量之分佈變化。 <br> Abstract: Understanding terrigenous material burial in the marine environment is important in evaluating fate of terrigenous material transport to the ocean. Mekong River is an important source of terrigenous material entering the South China Sea. Very few data is currently available in evaluating fate of terrigenous from the Mekong River to the South China Sea. The purpose of this study is to investigate burial of organic carbon and inorganic metals associate with aluminosilicates in the shelf and slope region offshore Mekong River. Sediment grain size, metals (aluminum, copper, lead, cadmium) and organic carbon as well as carbonate content were determined. The results showed that most suspended sediment may not reach the shelf. Coarse-grained sediments with lower organic carbon and metal concentrations were found in the shelf area offshore Mekong River while most fine-grained sediments were found in the eastern slope region. Organic carbon and metals associated with aluminum silicate showed good linear relationships with respect to the aluminum concentrations, indicating a grain size effect on sediments organic carbon and metals concentrations. Unusual high content of carbonate, however, was found in the southwestern shelf sediments, indicating high carbonate production and precipitation. Almost no fine-grained sediment deposited in the shelf region offshore Mekong River indicated that most fine-grained suspended particle exported from the Mekong river do not reach offshore and were deposited within the Mekong Delta, or transported further offshore to the slope region.