臺灣博碩士論文加值系統

東海是全世界最重要的邊緣海之一，其廣大的陸棚在物質循環及對深海物質輸出上扮演重要的角色。因此為瞭解東海陸棚、陸坡區沉降顆粒的化學物質組成之時序變化、主要來源、輸送管道及輸出通量，本研究利用pps-3型錨碇式時間序列沈積物收集器(T1∼T10)，在台灣東北海域之陸坡收集沈降顆粒進行組成分析及通量之推估，其中T1∼T3位於棉花峽谷，T4∼T6位於棉花峽谷出口至沖繩海槽，T8位於棉花峽谷西南側，T9在棉花峽谷及北棉花峽谷中間的陸坡上，T10則位於北棉花峽谷附近。主要分析項目包括陸源物質、鋁矽酸鹽礦物、POC、PIC、opal及Fe、Mn、Ca、Mg、K等金屬元素。研究結果顯示台灣東北海域棉花峽谷總顆粒通量明顯高於鄰近之陸坡區，顯示棉花峽谷為陸棚物質重要輸出管道之一，總顆粒通量並且沿著棉花峽谷由近岸之T1至近沖繩海槽之T6銳減(71.51∼4.98g/㎡/d)。T1∼T10沉降顆粒各組成中，以陸源物質含量最高，約佔76.16∼89.31%，POC約佔0.525∼3.268%，opal為0.671∼3.496%，而PIC則為0.760∼1.712%。從T1至T6近底部收集器之鋁矽酸鹽礦物、POC、opal含量均遞增，而PIC含量則遞減。各化學組成通量因受總通量控制，故從T1至T6皆隨總通量變化而遞減，但同一串列收集器化學組成通量均隨深度而遞增。T8至T10三處化學組成通量皆以T8最高，而T9最小，但同樣具有由上層至下層漸增的趨勢。
由T1∼T10各化學組成之分佈情形顯示陸源性及生物性顆粒大部份是經側向傳輸而來。T1-T10之POC/PIC、opal/POC及opal/PIC值以秋季時較高應與矽藻在秋季時增生有關，故opal與POC含量在秋季時亦有顯著相關。在本研究區域內，Al、K、Mn、Mg、Fe等陸源性金屬元素呈現顯著相關，印證陸源物質在決定顆粒通量上的重要性。但T6下層收集器出現Mn/Al的異常高值，反映出可能有海底火山活動，而Ca在本研究區域與生物性顆粒相關良好，顯示其在顆粒中含量受生物活動影響很大。利用底層沉積通量作為定點總輸出通量的依據，則棉花峽谷POC、PIC輸出量分別為１.１８ ×１０8gC/d及７.１７×１０8 gC/d，而棉花峽谷至基隆水道之截面POC、PIC輸出通量分別為２.１１×１０8 gC/d及１.２４×１０9 gC/d，顯示棉花峽谷以南相對於棉花峽谷在碳輸出上也同樣扮演重要的角色。此輸出通量若與模式推估之東海陸棚輸出通量(Chen，1996；Chen and Wang，1997)比較，可得知棉花峽谷或棉花峽谷以南為顆粒態碳重要的輸出孔道，但非唯一管道。

As a part of the KEEP (Kuroshio Edge Exchange Processes) program, ten arrays ( T1~T10) of sediment traps were deployed on the continental slope of the southern East China Sea (ECS) northeast of Taiwan to understand the temporal variabilities, sources, transport conduits and constituent fluxes of sinking particles. The traps were respectively moored in the Mien-Hwa Canyon (T1∼T3), along the outlet of Mien-Hwa Canyon to the Okinawa Trough (T4∼T6), in the southwest of Mien-Hwa Canyon (T8), on the slope between the Mien-Hwa Canyon and the North Mien-Hwa Canyon (T9) and on the slope near the North Mien-Hwa Canyon (T10). A portion of each recovered sample was analyzed for lithogenic matter, aluminosilicate, POC, PIC, opal and metals (Fe, Mn, Ca, Mg, K). Total mass fluxes were much higher in the Mien-Hwa Canyon than in sites north of the canyon, indicating that the Mien-Hwa Canyon is an important conduit in material transport. The fluxes of total mass and chemical constituents decreased seaward from the Mien-Hwa Canyon to the Okinawa Trough. The sinking particles were largely composed of lithogenic materials (76.16∼89.31%). The relatively small contents of POC, PIC and opal were 0.525∼3.268%, 0.760∼1.712% and 0.671∼3.496%, respectively. The contents of aluminosilicate, POC, opal increase and PIC decrease seaward from T1 to T6 sites in the bottom traps. Meanwhile, fluxes of chemical constituents increased with depth. The flux magnitudes of all chemical constituents of T8∼T10 were found to be an order of T8>>T10>T9.
The flux characteristics of chemical constituents suggest that the lithogenic and biogenic materials are largely derived from the shelf area through the lateral transport. The values of POC/PIC, opal/POC and opal/PIC are greater in autumn than in other seasons, which may be associated with the greater productivity of diatoms in autumn. Consequently, the contents of opal are correlated significantly with POC in autumn. In the study area, Al, K, Mn, Mg and Fe correlated very well with each other reflecting the fact that the sinking particles are mainly lithogenic. The anomalously high Mn/Al values in the bottom trap of T6 imply the effect of cold vents on the enrichment of Mn. However, distributions of Ca are primarily determined by biological processes. Based on organic carbon fluxes in bottom traps, the exports of POC and PIC from the ECS shelf to the Okinawa Trough via the Mien-Hwa Canyon are １.１８ ×１０8 g/d and ７.１７ ×１０8 g/d, respectively. Whereas the exports of POC and PIC via the crosssection from the Mien-Hwa Canyon to the Keelung Valley are ２.１１×１０8 g/d and １.２４×１０9 g/d, respectively. These results suggest that either the Mien-Hwa Canyon or the crosssection from the canyon to the Keelung Valley is an important, but not a solely, conduit in transport of particulate carbon from the ECS shelf to the Okinawa Trough, as compared with those modelling exports (Chen, 1996; Chen and Wang, 1997).