Fresh and Recirculated Submarine Groundwater Discharge Evaluated by Geochemical Tracers and a Seepage Meter at Two Sites in the Seto Inland Sea, Japan
Submarine groundwater discharge (SGD) consists of fresh submarine groundwater discharge (FSGD) and recirculated submarine groundwater discharge (RSGD). In this study, we conducted simultaneous 25-hour time-series measurements of short-lived <sup>222</sup>Rn and <sup>224</sup>...
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| Format: | Article |
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MDPI AG
2018-11-01
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| Series: | Hydrology |
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| Online Access: | https://www.mdpi.com/2306-5338/5/4/61 |
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| author | Toshimi Nakajima Ryo Sugimoto Osamu Tominaga Masaru Takeuchi Hisami Honda Jun Shoji Makoto Taniguchi |
| author_facet | Toshimi Nakajima Ryo Sugimoto Osamu Tominaga Masaru Takeuchi Hisami Honda Jun Shoji Makoto Taniguchi |
| author_sort | Toshimi Nakajima |
| collection | DOAJ |
| description | Submarine groundwater discharge (SGD) consists of fresh submarine groundwater discharge (FSGD) and recirculated submarine groundwater discharge (RSGD). In this study, we conducted simultaneous 25-hour time-series measurements of short-lived <sup>222</sup>Rn and <sup>224</sup>Ra activities at two sites with differing SGD rates in the central Seto Inland Sea of Japan to evaluate SGD rates and their constituents. At both sites, we also quantified the total SGD, FSGD, and RSGD using a seepage meter to verify the water fluxes estimated with <sup>222</sup>Rn and <sup>224</sup>Ra. SGD rates estimated using <sup>222</sup>Rn and <sup>224</sup>Ra at the site with significant SGD approximated the total SGD and RSGD measured by the seepage meter. However, SGD rates derived using <sup>222</sup>Rn at the site with minor SGD were overestimated, since <sup>222</sup>Rn activity at the nearshore mooring site was lower than that in the offshore area. These results suggest that the coupling of short-lived <sup>222</sup>Rn and <sup>224</sup>Ra is a powerful tool for quantification of FSGD and RSGD, although it is important to confirm that tracer activities in coastal areas are higher than those in offshore. |
| first_indexed | 2024-12-11T09:20:36Z |
| format | Article |
| id | doaj.art-a9a81b446e1443eeb5a133038a097df5 |
| institution | Directory Open Access Journal |
| issn | 2306-5338 |
| language | English |
| last_indexed | 2024-12-11T09:20:36Z |
| publishDate | 2018-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Hydrology |
| spelling | doaj.art-a9a81b446e1443eeb5a133038a097df52022-12-22T01:13:16ZengMDPI AGHydrology2306-53382018-11-01546110.3390/hydrology5040061hydrology5040061Fresh and Recirculated Submarine Groundwater Discharge Evaluated by Geochemical Tracers and a Seepage Meter at Two Sites in the Seto Inland Sea, JapanToshimi Nakajima0Ryo Sugimoto1Osamu Tominaga2Masaru Takeuchi3Hisami Honda4Jun Shoji5Makoto Taniguchi6Faculty of Marine Biosciences, Fukui Prefectural University, Obama, Fukui 917-0003, JapanFaculty of Marine Biosciences, Fukui Prefectural University, Obama, Fukui 917-0003, JapanFaculty of Marine Biosciences, Fukui Prefectural University, Obama, Fukui 917-0003, JapanFaculty of Marine Biosciences, Fukui Prefectural University, Obama, Fukui 917-0003, JapanResearch Institute for Humanity and Nature, Kyoto 603-8047, JapanGraduate School of Biosphere Science, Hiroshima University, Hiroshima 739-8528, JapanResearch Institute for Humanity and Nature, Kyoto 603-8047, JapanSubmarine groundwater discharge (SGD) consists of fresh submarine groundwater discharge (FSGD) and recirculated submarine groundwater discharge (RSGD). In this study, we conducted simultaneous 25-hour time-series measurements of short-lived <sup>222</sup>Rn and <sup>224</sup>Ra activities at two sites with differing SGD rates in the central Seto Inland Sea of Japan to evaluate SGD rates and their constituents. At both sites, we also quantified the total SGD, FSGD, and RSGD using a seepage meter to verify the water fluxes estimated with <sup>222</sup>Rn and <sup>224</sup>Ra. SGD rates estimated using <sup>222</sup>Rn and <sup>224</sup>Ra at the site with significant SGD approximated the total SGD and RSGD measured by the seepage meter. However, SGD rates derived using <sup>222</sup>Rn at the site with minor SGD were overestimated, since <sup>222</sup>Rn activity at the nearshore mooring site was lower than that in the offshore area. These results suggest that the coupling of short-lived <sup>222</sup>Rn and <sup>224</sup>Ra is a powerful tool for quantification of FSGD and RSGD, although it is important to confirm that tracer activities in coastal areas are higher than those in offshore.https://www.mdpi.com/2306-5338/5/4/61submarine groundwater dischargeradiumradonseepage metercoastal seas |
| spellingShingle | Toshimi Nakajima Ryo Sugimoto Osamu Tominaga Masaru Takeuchi Hisami Honda Jun Shoji Makoto Taniguchi Fresh and Recirculated Submarine Groundwater Discharge Evaluated by Geochemical Tracers and a Seepage Meter at Two Sites in the Seto Inland Sea, Japan Hydrology submarine groundwater discharge radium radon seepage meter coastal seas |
| title | Fresh and Recirculated Submarine Groundwater Discharge Evaluated by Geochemical Tracers and a Seepage Meter at Two Sites in the Seto Inland Sea, Japan |
| title_full | Fresh and Recirculated Submarine Groundwater Discharge Evaluated by Geochemical Tracers and a Seepage Meter at Two Sites in the Seto Inland Sea, Japan |
| title_fullStr | Fresh and Recirculated Submarine Groundwater Discharge Evaluated by Geochemical Tracers and a Seepage Meter at Two Sites in the Seto Inland Sea, Japan |
| title_full_unstemmed | Fresh and Recirculated Submarine Groundwater Discharge Evaluated by Geochemical Tracers and a Seepage Meter at Two Sites in the Seto Inland Sea, Japan |
| title_short | Fresh and Recirculated Submarine Groundwater Discharge Evaluated by Geochemical Tracers and a Seepage Meter at Two Sites in the Seto Inland Sea, Japan |
| title_sort | fresh and recirculated submarine groundwater discharge evaluated by geochemical tracers and a seepage meter at two sites in the seto inland sea japan |
| topic | submarine groundwater discharge radium radon seepage meter coastal seas |
| url | https://www.mdpi.com/2306-5338/5/4/61 |
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