本研究主要目的為了解並比較南海北部與呂宋海峽東西側水體中210Po與210Pb在顆粒態及溶解態中的分佈及其不平衡狀態，以探討此研究區域之生地化作用及其機制與速率，並比較226Ra與210Pb剖面之間的活度不平衡關係。研究水樣來自海研一號於2003年7月（ORI-688航次）、2004年2月（ORI-707）及2004年10月（ORI-734航次）在I、J、F及S5站之剖面採樣。除S5站在海峽東側外，各站均在南海北部。
表水的溶解態210Pb，活度約介於14-28 dpm/100kg之間，明顯比深水層高，反映大氣輸入之訊息。剖面分佈以F站為例，最大值出現在200 m處約為26 dpm/100kg，1500 m以下活度變化小，約維持在10 dpm/100kg左右。表層水溶解態210Pb以S5站最高，可能是因該站位於黑潮傳輸途徑中，而黑潮又由北太平洋赤道流開始持續收集大氣沈降之210Pb，故210Pb持續增加。
各測站的210Po在混合層50 m內相對於顆粒清除作用之滯留時間約為0.62年，而210Pb滯留時間介於0.34-1.13年之間。各測站剖面的210Po相對於210Pb大致呈現活度不足的情形，表示210Po比210Pb更容易被清除。
210Pb在深層水的平均滯留時間在F站為87年，J站為60年，比太平洋深層水以及同是邊緣海的東海深層水滯留時間稍長。亦即南海深層水的顆粒清除速率較大洋以及東海慢些。南海的湧升速率遠比太平洋區高，相對降低了顆粒的沈降速率，因此210Pb在水體中的滯留時間較長。

The purposes of this study are to understand and compare: the distributions of the particulate and dissolved 210Po and 210Pb in the northern South China Sea and in the east and west sides of the Luzon Strait; the associated biogeochemical processes, including their mechanisms and rates involved in the area; and the disequilibrium between 226Ra and the 210Pb as observed in profiles. Seawater samples were collected from three stations in the northern South China Sea (station I, J, and F) and one station to the east of the Luzon Strait (station S5) using a Rosette sampling system during three Ocean Researcher I cruises (ORI-688 in July, 2003, ORI-707 in February, 2004, and ORI-734 in October, 2004).
The dissolved 210Pb in surface water generally displays higher activities (around 14-28 dpm/100kg) relative to deep water, reflecting atmospheric input. The dissolved 210Pb profile as seen at station F displays a maximum of 26 dpm/100kg at 200 m and lower values at about 10 dpm/100kg below 1500 m. Highest value at 28 dpm/100kg was observed at S5 surface water. It is probably due to being on the path of the Kuroshio which has accumulated atmospheric 210Pb continually from the northern Equatorial Current on its way.
The mean residence time with respect to particle scavenging is about 0.62 years for total 210Po within a 50 m mixed layer, and ranges between 0.34 to 1.13 years for total 210Pb in the mixed layer. 210Po is deficient relative to 210Pb in most profiles, suggesting that 210Po is more readily scavenged.
The mean scavenging residence time is about 87 years for total 210Pb in the deep water at station F, and 60 years at station J. This residence time is longer than that in both the Pacific and East China Sea deep waters, i.e. a lower scavenging rate in the South China Sea. As the upwelling rate is much higher in the South China Sea than in the Pacific, it may effectively reduce the sinking rate of the sinking particulates, resulting in higher 210Pb residence time in the water columns of the South China Sea.

目 錄
頁碼
中文摘要………………………………………………………………I
英文摘要………………………………………………………………III
目錄……………………………………………………………………V
圖目錄………………………………………………………………VII
表目錄………………………………………………………………VIII

第一章 緒論…………………………………………………………1
第二章 研究方法…………………………………………………4
2.1 採樣地點及方法………………………………………4
2.2 210Po核種分析…………………………………………7
2.3 210Pb核種分析…………………………………………8
2.4 210Po活度計算方法…………………………………11
2.5 β偵測效率之校正…………………………………12
2.6 210Pb活度的計算方法………………………………14
2.7 誤差值之計算………………………………………17

第三章 結果與討論………………………………………………16
3.1 水文資料描述………………………………………16
3.2 懸浮顆粒（SPM）分佈……………………………22
3.3 210Po和210Pb分佈……………………………………25
3.4 210Po/210Pb不平衡狀態………………………………41
3.5 210Pb與226Ra活性不平衡現象及210Pb滯留時間……46
3.6 210Po的滯留時間……………………………………50
第四章 結論………………………………………………………54

參考文獻………………………………………………………………56

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