摘 要
本文分析南海及呂宋海峽，海水氧同位素組成在時間與空間之分佈特徵。海水氧同位素組成以CO2-H2O同位素平衡法分析，分析數值精確度可達+0.1?。分析結果指出：呂宋海峽水為南海水及黑潮水之混合水。南海於1998年4月(ORI517)之總降雨量(1.5公釐)，小於1999年4月(ORI546)之總降雨量(169.5公釐)。因此，1998年4月南海表層水之溫鹽度比1999年4月南海表層水之溫鹽度高。南海與呂宋海峽，海水氧同位素與鹽度在垂直剖面變化具有相似的趨勢。就地理位置而言，南海表層水氧同位素值由北(0.09 ?)向南(-0.18 ?)逐漸變輕，呂宋海峽則由東經121.5度(0.42 ?)，逐漸向西遞減(0.02 ?)，顯示黑潮的影響至東北向西南遞減。黑潮水(ORI615)鹽度極大值34.92，d18OSMOW值0.42 ?；南海水(ORI517、546)鹽度為33.34，d18OSMOW值為-0.25 ?。以二者為混合端點，黑潮入侵呂宋海峽所佔百分比，於東經121.5度可達80 %。ORI517、546航次d18OSMOW對鹽度作圖，所得斜率不同為年際間混合層深度與降雨量不同之影響。西菲律賓海表層水平均d18OSMOW值為0.29 ?，次表層水0.25 ?；中層水-0.06 ?；底層水-0.10 ?。呂宋海峽表層水平均d18OSMOW值為0.15 ?，次表層水為0.17 ?；中層水-0.02 ?；底層水-0.08 ?。南海表層水平均d18OSMOW值為-0.03 ?，次表層水為0.18 ?；中層水-0.05 ?；底層水為-0.08 ?。表層水之平均d18OSMOW值由西菲律賓海、呂宋海峽至南海逐漸向西遞減。

Abstract
In this study, we have analyzed systematically the oxygen isotopic compositions of South China Sea (SCS) and Luzon Strait (LS) seawater so that a comprehensive interpretation of their temporary and spatial variability can be delineated. The oxygen isotopic compositions of the samples collected in the two areas were determined using the Epstein-Mayeda technique, and the overall precision of the d18OSMOW measurements is +0.1 ?. Our data suggest that LS seawater is a mixture of SCS and Kuroshio waters. The precipitation (1.5 mm) on SCS in April 1998 (during ORI517 cruise) is much less than that (169.5 mm) in April 1999 (during ORI546 cruise). As LS and SCS waters are concerned, the profiles of d18OSMOW generally share the same trend as those of salinity. The d18OSMOW values of the SCS surface water decrease toward the south, while those of the LS surface water decrease toward the west. These suggest that the effect of the Kuroshio water decreases are it moves from northeast toward southwest after its intrusion through LS. The salinity of Kuroshio water reaches the maximum at 34.92 with the corresponding d18OSMOW value of 0.42 ?, whereas the salinity of the representative SCS surface water is 33.34 and the corresponding d18OSMOW is -0.25 ?. As these two data were selected as end members, the estimated proportion of the intruding Kuroshio water in the composition of LS water could be high up to 80 % at 121.5o E. The plot of d18OSMOW versus salinity for cruises OR517 and 546 shows a difference between the slopes of the two regression lines, indicating the effect of variability in precipitation and the depth of the mixed layer. The average d18OSMOW value for surface water decreases toward the west as the water moves from Western Philippine Sea (WPS) to LS and SCS. The average d18OSMOW values for the surface, subsurface, intermediate, and deep waters are listed in the corresponding order in parentheses preceded by the studied area as follows: WPS (0.29 ?, 0.25 ?, -0.06 ?, -0.10 ?); LS (0.15 ?, 0.17 ?, -0.02 ?, -0.08 ?); SCS (-0.03 ?, 0.18 ?, -0.05 ?, -0.08 ?).

目錄
致謝-------------------------------------------------------------------------------------I
中文摘要-----------------------------------------------------------------------------III
英文摘要-----------------------------------------------------------------------------IV
目錄-----------------------------------------------------------------------------------VI
圖目錄------------------------------------------------------------------------------VIII
表目錄--------------------------------------------------------------------------------XI
附錄目錄-----------------------------------------------------------------------------XII
一、 前言-------------------------------------------------------------------------------1
二、 研究材料及方法---------------------------------------------------------------10
2-1. 研究區域-----------------------------------------------------------------10
2-2. 研究方法-----------------------------------------------------------------10
2-2.1海水樣品之採集-------------------------------------------------10
2-2.2海水氧同位素之測定-------------------------------------------13
三、 實驗分析結果------------------------------------------------------------------17
3-1. 水文資料----------------------------------------------------------------- 17
3-2. 海水氧同位素資料----------------------------------------------------- 23
四、 討論------------------------------------------------------------------------------26
4-1. 水文資料之比較-------------------------------------------------------- 26
4-2. 海水氧同位素值之變化-----------------------------------------------30
4-2.1海水氧同位素值之水平面分佈-------------------------------30
4-2.2海水氧同位素值之垂直面分佈-------------------------------33
4-3. 與前人研究之比較------------------------------------------------------36
4-4. T-S圖與d18OSMOW-S圖之關係-----------------------------------------41
4-4.1南海水T-S圖與d18OSMOW-S圖之關係-----------------------45
4-4.2呂宋海峽水T-S圖與d18OSMOW-S圖之關係-----------------47
4-4.3黑潮於呂宋海峽之混合百分比--------------------------------49
4-4.4南海、呂宋海峽及西菲律賓海各水層
之平均d18OSMOW值----------------------------------------------50
五、 結論------------------------------------------------------------------------------57
六、 參考文獻------------------------------------------------------------------------59
6-1. 中文參考文獻------------------------------------------------------------59
6-2. 英文參考文獻------------------------------------------------------------59

六、參考文獻
6-1. 中文參考文獻
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李孟陽，1995，南海北部上次冰盛期以來之古海洋，國立台灣大學地質學研究所碩士論文，共70頁。
馬名軍，1996，黑潮流經巴士海峽之時空變化，國立台灣大學海洋研究所碩士論文，共70頁。
王麗雯，1997，南海東北部溶解態無機碳碳同位素的變化，國立中山大學碩士論文，共124頁。
王樹倫，1997，西北太平洋邊緣海二氧化碳之研究，國立中山大學博士論文，共226頁。
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林士超，1999，東海海水氧同位素之研究，國立中山大學碩士論文，共145頁。

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