Using Radon and Radium isotopes to estimate submarine groundwater flux in Yilan Bay
Date Issued
2015
Date
2015
Author(s)
Huang, Chun-Kai
Abstract
In this study, radon and radium isotopes are used as tracers for SGD survey. The samples were collected from spring-water, coastal seawater, the Lanyang River and its tributaries in dry and wet seasons. Our results show the activities of 224Ra in coastal seawater ranged from 0.43 to 1.14 Bq/m3 in August 2014, 0.48 to 1.98 Bq/m3 in January 2015, and the differences between summer and winter were observed. In spring-water samples, the activities of 222Rn and 224Ra are ranging from 386 to 32220 Bq/m3 and 0.02 to 0.29 Bq/m3, and no significant difference between wet and dry seasons. Unexpectedly, the spring-water samples are characterized with high 222Rn and low 224Ra activities. Compare with the coastal seawater and spring-water samples, the 224Ra activities in coastal seawater are 3-4 times higher than spring-water. A deep groundwater sample which collected from a deep well at 600 meter depth shows high 224Ra activity (20.97 Bq/m3). It reveals that the SGD in the coastal area of the Yilan Plain may derive from deep aquifers. The evaluation results of SGD flux in Yilan Bay indicate the minimum flux is 4.3×105 m3/day in August 2014, accounting for 8% of the Lanyang River output; 8.4×105 m3/day in January 2015, accounting for 16% of the Lanyang River output. Nitrate flux is 7.7×105 mole/day in August 2014, about 6 times higher than the Lanyang River output；1.5×106 mole/day in January 2015, about 12 times higher than the Lanyang River output.
Subjects
SGD
Radium
Radon
Yilan Plain
SDGs
Type
thesis
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