Scavenging Phenomenon in the Taiwan Strait: 234Th/238U Disequilibria
Date Issued
2007
Date
2007
Author(s)
Hou, Yen-Ruei
DOI
zh-TW
Abstract
This study aims at the investigation of scavenging phenomenon by 234Th/238U disequilibria in the surface water of Taiwan Strait. Spatial sampling of 234Th was carried out by the Joint Hydrographic Survey during May 20~27, 2006. Along with 234Th measurement, basic hydrographic parameters (temperature, salinity, fluorescence and light transmission), total suspended matter concentration and particulate organic carbon concentration were also measured. The scavenging model incorporating the physical transport effect was used to estimate 234Th scavenging and removal rates in the region.
According to the distributions of hydrographic parameters and 234Th, five major domains in the Taiwan Strait can be identified: (Ⅰ) the Southern Taiwan Strait; (Ⅱ) the Taiwan Bank; (Ⅲ) the Cho-shuei River mouth; (Ⅳ) the Middle Taiwan Strait; and (Ⅴ) the Ming River mouth. The 234Th scavenging rates ranged from 57 to 520 dpm/m3/d. The Cho-shuei River mouth showed the highest scavenging rate, and the lowest scavenging rate was found in the Taiwan Bank. The 234Th removal rates ranged from 24 to 381 dpm/m3/d. The highest removal rate appeared in the Cho-shuei River mouth, and the lowest removal rate was found in the Ming River mouth. The residence times of dissolved and particulate 234Th in the Taiwan Strait were short, 0~6 and 1~3 days, respectively. Using 234Th as a proxy of particulate organic carbon, average removal rates of particulate organic carbon in the Cho-shuei River mouth, the Middle Taiwan Strait, and the Ming River mouth were 7.2, 6.6, and 5.0 mmole/m3/d, respectively.
Subjects
清除作用
234Th
滯留時間
顆粒有機碳
Taiwan Strait
scavenging
residence time
particulate organic carbon
Type
thesis
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