 |
| Titel |
Using Radon and Radium isotopes to trace submarine groundwater discharge in Yilan Plain, Taiwan |
| VerfasserIn |
Chun-Kai Huang, Chih-Chieh Su |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250103806
|
| Publikation (Nr.) |
 EGU/EGU2015-3221.pdf |
|
|
|
|
|
| Zusammenfassung |
| The Yilan Plain which located in the northeast Taiwan was selected for submarine
groundwater discharge (SGD) study. The geomorphic and climatic conditions induce lush
rain drenched mountains and create abundant groundwater resource in the Yilan Plain. The
annual precipitation in 2014 is 2025 mm with most of the precipitation concentrated on
autumn (from September to November).
In this study, radon and radium isotopes are used as tracers for SGD survey.
The 224Ra (t1/2 =3.6 days) was measured by a delayed coincidence counter (RaDeCC).
The 222Rn (t1/2 =3.8 days) was measured by RAD-7 equipped with RAD H2O and RAD
AQUA system.
The river-water samples were collected from the main stream of Lanyang River and its
tributaries from upstream to river mouth. The spring-water samples were collected at 8 sites
in April, July and October 2014. Ten surface seawater samples along the coastline of the
Yilan Plain were collected in August 2014.
Our results show the activities of 222Rn and 224Ra in springs ranging from 3400 to
30850 Bq/m3 and 0.02 to 0.29 Bq/m3, and there are no significant differences between wet
and dry seasons. Unexpectedly, the springs are characterized with high 222Rn and low 224Ra
activities. For river samples, the activities of 224Ra in downstream and river mouth (0.18 to
1.48 Bq/m3) are higher than upstream (0 to 0.3 Bq/m3). The average activity of
224Ra in downstream samples which collected in April (0.98 Bq/m3) has the highest
value than other seasons (0.41-0.51 Bq/m3). In coastal seawater, the activities of
222Rn and 224Ra ranged from 0 to 366 Bq/m3 and 0.10 to 1.14 Bq/m3 in August
2014.
In summary, this study points out in some coastal regions of the Yilan Plain, where
without riverine input, have high 222Rn and 224Ra activities in seawater. We suggest the
SGD plays an important role on land-sea exchange along the coastline of the Yilan Plain.
Compare with the spring water samples, the 224Ra activities in coastal seawater are 3-4 times
higher than springs. It reveals that the SGD of the Yilan Plain may derive from deep aquifers. |
|
|
|
|
|
|