摘 要
此論文利用六個剖面及十五個表水水樣測量，來討論鐳-226在東海及臺灣東北海域的分佈，水樣分別由1997及1998年七月份的493及523航次中所取得。鐳-226的測量是藉由曾廣泛使用於海水樣品的再生氡法。東海表水鐳-226的濃度介於8.7至15.9 dpm/100kg 之間，且隨著測線往北靠近長江口而有增加的趨勢，此結果符合Nozaki等人(1976)研究東海的表水鐳-226分佈狀況，也是愈往北鐳-226濃度有增加的情況，而此情形應是大陸沿岸流提供高鐳所致。至於臺灣東北海域表水鐳-226的濃度則介於9.1至10.8 dpm/100kg 之間，此結果普遍高於1992年7月KEEP-MASS航次所測得同區域表水鐳-226的濃度值（6.6至9.3 dpm/100kg之間）。此外，所採得六個深水剖面，包括1)代表黑潮區的493航次第13、15測站，前者鐳-226濃度由表水9.7dpm/100kg逐漸增加至500米深度的14.3dpm/100kg；後者鐳-226濃度由表水5米之9.8dpm/100kg，隨著深度增加到800米深度的17.7 dpm/100kg。2)代表陸棚水與黑潮水混合之523航次第5、7、13、15測站，其中，位於棉花峽谷出口處的第7測站，其鐳-226濃度剖面在水深600米至750米處有鐳-226濃度的急遽變化，然後到深度900米時鐳-226的濃度不但未增加且有減少的現象，顯示應有側向或水平方向的鐳-226來源。
此外，六個剖面中，每一個剖面之表水鐳-226濃度均低於10 dpm/100kg，且愈靠近底層其鐳-226濃度愈高，顯示底部沉積物是鐳-226的來源。
至於在鉛-210/鐳-226的比值剖面中，523航次第13站在整個鉛-210/鐳-226的比值幾乎都呈現鉛-210超量(excess)的現象，只有在深度400米處才有鉛-210稍微不足量，而在800公尺深度出現有鉛-210濃度的高值。

Abstract

This thesis discusses 226Ra distribution in the seawater of the East China Sea and the sea off northeastern Taiwan. Six profiles and fifteen surface water samples were measured. Water samples were collected during cruises 493 and 523 in July, 1997 and July, 1998, respectively. 226Ra measurements were performed by the regenerated 222Rn method that had been widely used for seawater samples. The surface water 226Ra activities vary between 8.7 and 15.9 dpm/100kg in the East China Sea. There is an increase in surface water 226Ra northward toward the estuary of the Changjiang. This variation is somewhat similar to that observed in the East China Sea by Nozaki et al. (1976). The surface water 226Ra activities vary between 9.1 and 10.8 dpm/100kg in the area off northeastern Taiwan. There values are higher than KEEP-MASS cruise of July, 1992. The Kuroshio Current not easy to enter shelf, so the dilution effect of Kuroshio is smaller. Otherwise, There are 226Ra in profiles were measured from six stations on Cruise 493 (13 and 15) in Kuroshio area and Cruise 523 (5, 7, 13 and 15) in shelf. The deep water profile on Cruise 493 (st.13) displays a phenomenon 226Ra increase from about 9.7 dpm/100kg at 5m to about 14.3 dpm/100kg at 500m, station 15 from Cruise 493 displays a phenomenon 226Ra increase from about 9.8 dpm/100kg at 5m to about 17.7 dpm/100kg at 800m. 226Ra profile at station 7 showed that the gradient from 600m to 750m is large, and 226Ra concentration does not increase below this depth. 226Ra maybe associated with nepheloid layer due to lateral or horizontal transport of the water mass.
Each 226Ra profile shows a downward increase from less than 10 dpm/100kg at the surface, and shows the underlying sediments as the main source.
Based on the radioactive disequilibrium observed between 210Pb and 226Ra, all the ratios of Pb-210/Ra-226 in Station 13 are greater than 1, except at 400m. The 210Pb concentration is high and the ratio of Pb-210/Ra-226 is greater than 1 at 800m.

目 錄
誌 謝………………………………………………………………Ⅰ
摘 要………………………………………………………………Ⅱ
Abstract………………………………………………………………Ⅳ
目 錄………………………………………………………………Ⅵ
圖 目 錄………………………………………………………………Ⅷ
表 目 錄………………………………………………………………Ⅸ

一、緒論……………………………………………………………….1
1.1 前言…………………………………………………………1
1.2 研究區域之地形與水文狀況………………………………3
1.3 研究目的……………………………………………………8
二、實驗方法………………………………………………………….9
2.1 採樣…………………………………………………………9
2.2 材料及方法…………………………………………………9
2.3 α閃爍計數器與Lucas 閃爍腔之效率校正…………….11
2.3.1 α閃爍計數器…………………………………………….11
2.3.2 Lucas閃爍腔………………………………..……………12
2.3.3阿爾伐因子（α-Factor）………….……………14
2.3.4 誤差值之計算…………………………………………….15
2.3.5閃爍腔校正結果…………………………………16
三、結果與討論……………………………………………………...17
3.1 研究區域水文特性…………………………………………17
3.2 鐳-226之表水分佈…………………………………………19
3.3 鐳-226之垂直剖面分佈及探討……………………………23
3.4 鐳-226與鉛-210的不平衡現象……………………………30
3-5 Box model計算之評估…………………………………….33
3.5.1 鉛-210之滯留時間………………………………………..37
3.5.2 釙-210的滯留時間……………………………….43
四、結論………………………………………………………………45
參考文獻……………………………………………………………46

圖 目 錄
圖1.1 採樣位置圖…………………………………………………..3
圖1.2 表水溫度等值圖……………………………………………..6
圖1.3 表水鹽度等值圖……………………………………………..6
圖3.1 493航次第13、15測站溫鹽圖……………………………18
圖3.2 523航次第5、7、13及15測站溫鹽圖…………………..18
圖3.3 表水鐳-226濃度分佈圖…………………………………….22
圖3.4 表水鐳-226濃度等值圖…………………………………….23
圖3.5 493航次鐳-226剖面圖……………………………………..27
圖3.6 523航次鐳-226剖面圖……………………………………..28
圖3.7 523航次第5、7、13及15站懸浮顆粒濃度與鐳-226濃度關係圖…………………………………………………………29
圖3.8 523航次第5站鉛-210/鐳-226值剖面圖………………….30
圖3.9 523航次第7站鉛-210/鐳-226值剖面圖………………….30
圖3.10 523航次第13站鉛-210/鐳-226值剖面圖……………….30
圖3.11 523航次第15站鉛-210/鐳-226值剖面圖……………… 30
圖3.12 第7站清除模式圖………………………………………….39
圖3.13 第13站清除模式圖………………………………………...40
圖3.14 第5站清除模式圖………………………………………….41
圖3.15第15站清除模式圖……………………………………………42

表 目 錄
表2.1 閃爍腔的編號及其偵測效率……………………………17
表3.1 站位水文資料及鐳-226活度表(表水與底水部份)……20-21
表3.2 站位水文資料及鐳-226活度表(剖面部份)…………….25
續表3.2 站位水文資料及鐳-226活度表(剖面部份)…………….26
表3.4

參考文獻
中文部分
尹宏洲，(1993)，臺灣東部及東北部黑潮海域鐳-226分佈之研究，國立中山大學海洋地質研究所碩士論文。
周謀武，(1988)，地下水中氡濃度精密度量方法之設計、設置與校正及其應用，國立中山大學海洋地質研究所碩士論文。
吳佑民，(1995)，台灣東北海域鐳-226 鉛-210 及釙-210之活性不平衡狀態，國立中山大學海洋地質研究所碩士論文。
吳炫賦，(2000)，南沖繩海槽深部水體顆粒體清除與傳輸作用：210Po/210Pb不平衡應用，國立台灣大學海洋研究所碩士論文。

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