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Nakajima T, Kuragano M, Yamada M, Sugimoto R. Comparing nearshore and embayment scale assessments of submarine groundwater discharge: Significance of offshore groundwater discharge as a nutrient pathway. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 908:168068. [PMID: 37914127 DOI: 10.1016/j.scitotenv.2023.168068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/07/2023] [Accepted: 10/21/2023] [Indexed: 11/03/2023]
Abstract
Submarine groundwater discharge (SGD) can influence biogeochemical cycles in coastal seas by delivering nutrients from the seafloor. Comparison between the nearshore and embayment scale assessments of SGD against river water discharge would be crucial for understanding biogeochemical impacts on the coastal seas because the discharge pattern (non-point or point pathway) is different. Here, we quantified SGD contribution to rivers in nutrient budgets at two scales within a coastal embayment (Obama Bay, Japan) by mass balance models of radon and radium isotopes. We then compared the SGD contribution between the two scales by the meta-analysis for regional data sets conducted in nearshore and embayment scales. The estimated SGD rates in the nearshore and embayment scales in the bay were 7.8 cm d-1 and 20.0 cm d-1, indicating that offshore SGD was more significant than nearshore. The ratios of nutrient fluxes derived from SGD to rivers (SGD:River) in the nearshore scale were 1.7 for dissolved inorganic nitrogen (DIN), 3.0 for phosphorus (DIP), and 0.5 for silica (DSi), while those in the embayment scale increased to 10.4 for DIN, 18.5 for DIP, and 3.9 for DSi. This result indicates that SGD-derived nutrients become more important at larger spatial scales. Meta-analysis revealed that the difference in the contribution of SGD to rivers was affected by the seafloor size and there was no significant difference in SGD rates between nearshore and embayment scale studies. However, our regional study shows the site-specific pattern that SGD rates in the embayment scale were higher than those in the nearshore scale. Overall, we clarified that SGD can be a crucial nutrient pathway for coastal embayments regardless of the spatial scales and contribute to coastal nutrient biogeochemistry in more offshore areas.
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Affiliation(s)
- Toshimi Nakajima
- Graduate School of Bioscience and Biotechnology, Fukui Prefectural University, Fukui, Japan.
| | - Mao Kuragano
- Graduate School of Bioscience and Biotechnology, Fukui Prefectural University, Fukui, Japan.
| | - Makoto Yamada
- Faculty of Economics, Ryukoku University, Kyoto, Japan.
| | - Ryo Sugimoto
- Faculty of Marine Biosciences and Technology, Fukui Prefectural University, Fukui, Japan.
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Factors affecting the radon (222Rn) emanation from aquifer rock materials: Implications for radiological and groundwater tracer studies. Appl Radiat Isot 2022; 189:110433. [DOI: 10.1016/j.apradiso.2022.110433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 08/16/2022] [Accepted: 08/21/2022] [Indexed: 11/22/2022]
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Submarine Groundwater Discharge (SGD) to Coastal Waters of Saipan (Commonwealth of the Northern Mariana Islands, USA): Implications for Nitrogen Sources, Transport and Ecological Effects. WATER 2020. [DOI: 10.3390/w12113029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Seagrass meadows and coral reefs along the coast of Saipan, a US commonwealth in the Northern Pacific, have been declining since the 1940s, possibly due to nutrient loading. This study investigated whether submarine groundwater discharge (SGD) contributes to nutrient loading and supports primary production on Saipan’s coast. SGD can be an important source of freshwater, nutrients, and other pollutants to coastal waters, especially in oceanic islands without well-developed stream systems. Ra and Rn isotopes were used as natural tracers of SGD. Nitrate, phosphate, and ammonium concentrations, ancillary water quality parameters, δ15N and δ18O of dissolved nitrate, and δ15N of primary producer tissue were measured. Our results pointed to discharge of low-salinity groundwater containing elevated concentrations of sewage-derived N at specific locations along Saipan’s coast. High SGD areas had lower salinity and pH, higher dissolved inorganic nitrogen concentrations, and elevated primary producer δ15N, indicative of sewage nitrogen inputs. We estimated that SGD could support 730–6400 and 3000–15,000 mol C d−1 of primary production in Tanapag and Garapan Lagoons, respectively, or up to approximately 60% of primary production in Garapan Lagoon. Efforts to improve water quality, reduce nutrient loading, and preserve coastal ecosystems must account for groundwater, since our results demonstrate that it is an important pathway of nitrogen delivery.
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Fresh and Recirculated Submarine Groundwater Discharge Evaluated by Geochemical Tracers and a Seepage Meter at Two Sites in the Seto Inland Sea, Japan. HYDROLOGY 2018. [DOI: 10.3390/hydrology5040061] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
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 222Rn and 224Ra 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 222Rn and 224Ra. SGD rates estimated using 222Rn and 224Ra at the site with significant SGD approximated the total SGD and RSGD measured by the seepage meter. However, SGD rates derived using 222Rn at the site with minor SGD were overestimated, since 222Rn activity at the nearshore mooring site was lower than that in the offshore area. These results suggest that the coupling of short-lived 222Rn and 224Ra 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.
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Rapid 224Ra measurements in water via multiple radon detectors. J Radioanal Nucl Chem 2018. [DOI: 10.1007/s10967-018-5981-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Eleftheriou G, Tsabaris C, Patiris DL, Androulakaki EG, Vlastou R. Estimation of coastal residence time of submarine groundwater discharge using radium progenies. Appl Radiat Isot 2016; 121:44-50. [PMID: 28024218 DOI: 10.1016/j.apradiso.2016.12.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 10/27/2016] [Accepted: 12/16/2016] [Indexed: 11/26/2022]
Abstract
A methodology based on γ-spectrometry measurements of untreated coastal water samples is proposed for the direct estimation of coastal residence time of submarine discharged groundwater. The method was applied to a submarine spring at Stoupa Bay covering all seasons. The estimated residence time exhibited an annual mean of 4.6±1.7 d. An additional measurement using the in situ underwater γ-spectrometry technique was performed, in the same site. The in situ method yielded a value of 2.8±0.2 d that was found consistent with the corresponding value derived using the developed lab-based method (3.4±2.0 d) for the same period.
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Affiliation(s)
- G Eleftheriou
- Hellenic Centre for Marine Research, Institute of Oceanography, P.O. Box 712, GR-19013 Anavyssos, Greece.
| | - C Tsabaris
- Hellenic Centre for Marine Research, Institute of Oceanography, P.O. Box 712, GR-19013 Anavyssos, Greece
| | - D L Patiris
- Hellenic Centre for Marine Research, Institute of Oceanography, P.O. Box 712, GR-19013 Anavyssos, Greece
| | - E G Androulakaki
- Hellenic Centre for Marine Research, Institute of Oceanography, P.O. Box 712, GR-19013 Anavyssos, Greece; National Technical University of Athens, Department of Physics, Zografou Campus, GR-15780 Athens, Greece
| | - R Vlastou
- National Technical University of Athens, Department of Physics, Zografou Campus, GR-15780 Athens, Greece
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Radon transfer velocity at the water-air interface. Appl Radiat Isot 2015; 105:144-149. [PMID: 26296057 DOI: 10.1016/j.apradiso.2015.07.058] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 07/31/2015] [Accepted: 07/31/2015] [Indexed: 11/19/2022]
Abstract
Radon is a radionuclide that is one of the most commonly used natural tracers, for example in groundwater. The transport of radon at the water-air interface is investigated in this work at very low turbulence such as when water samples are taken for radon measurements. This very important process for the accurate measurement of radon in water has, surprisingly, not been investigated very often. By using a mathematical model and an experiment the radon transfer velocity coefficient (k) from the water-air interface was found to be (1.4±0.2)×10(-6)ms(-1). This radon transfer velocity indicates that the escape is a relatively slow process which justifies the use of radon in water measurements.
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Medley P, Martin P, Bollhöfer A, Parry D. 228Ra and 226Ra measurement on a BaSO 4 co-precipitation source. Appl Radiat Isot 2014; 95:200-207. [PMID: 25464199 DOI: 10.1016/j.apradiso.2014.09.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 08/23/2014] [Accepted: 09/28/2014] [Indexed: 11/30/2022]
Abstract
One of the most commonly-used methods for determination of 226Ra, particularly in water samples, utilises co-precipitation of Ra with BaSO4, followed by microfiltration to produce a source for alpha counting. This paper describes two extensions to BaSO4 co-precipitation methods which enable determination of 228Ra using the same source. The adaptations presented here do not introduce any contaminants that will affect the separation of radium or alpha counting for 226Ra, and can be used for re-analysis of already existing sources prepared by BaSO4 co-precipitation. The first adaptation uses detection of 228Ac on the source by gamma spectrometry. The detection efficiency is high, allowing analysis of water samples at sufficiently low activity to be suitable in testing for compliance with drinking water quality standards. As 228Ac grows in quickly, taking less than 2 days to reach equilibrium with the 228Ra parent, this can also be useful in radiological emergency response situations. The second adaptation incorporates a method for the digestion of BaSO4 sources, allowing separation of thorium and subsequent determination of 228Th activity. Although ingrowth periods for 228Th can be lengthy, very low detection limits for 228Ra can be achieved with this technique.
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Affiliation(s)
- Peter Medley
- Environmental Research Institute of the Supervising Scientist (eriss), Darwin, NT 0810, Australia.
| | - Paul Martin
- Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Yallambie, Vic. 3085, Australia
| | - Andreas Bollhöfer
- Environmental Research Institute of the Supervising Scientist (eriss), Darwin, NT 0810, Australia
| | - David Parry
- Charles Darwin University, Darwin, NT, Australia
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El-Shahawi MS, Kadi MW, El-Khouly SH, Abd El-Mohty A, Saad SM, Eweda NEA. Separation of Y from Sr by zirconium vanadate gel ion-exchanger sorbent: kinetics and thermodynamic study. J Radioanal Nucl Chem 2012. [DOI: 10.1007/s10967-012-1892-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hosono T, Ono M, Burnett WC, Tokunaga T, Taniguchi M, Akimichi T. Spatial distribution of submarine groundwater discharge and associated nutrients within a local coastal area. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:5319-5326. [PMID: 22502591 DOI: 10.1021/es2043867] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
To understand the local-scale distribution of submarine groundwater discharge (SGD) and dissolved nutrients, a multiple-detector (222)Rn monitoring survey was undertaken along the Mt. Chokai volcanic coast in northern Japan. The surveys revealed that the highest SGD (calculated to be 6.2 × 10(4) m(3) d(-1), within an area of 2 × 10(4) m(2)) with the greatest nutrient fluxes (sum of NO(3)(-), NO(2)(-), and NH(4)(+) (DIN): 9.2 × 10(2) mol d(-1); PO(4)(3-) (DIP): 56 mol d(-1)) is present at the edge of the youngest volcanic lava flow in the area. Recharged groundwater transports nutrients through porous volcanic flows and discharges as SGD near shore. Our results demonstrate that the spatial distribution of SGD in the study area is closely regulated by the local geology and topography. Furthermore, we show that continuous (222)Rn monitoring with a multidetector system at boat speeds of 1-2 knots provides details at a scale one order of magnitude greater than has been reported previously. In addition, the results of our study suggest that SGD-borne DIP may play an important role in the important local oyster production.
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Affiliation(s)
- Takahiro Hosono
- Priority Organization for Innovation and Excellence, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan.
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Separation of the 90Sr–90Y pair with cerium(IV) iodotungstate cation exchanger. Appl Radiat Isot 2009; 67:530-4. [DOI: 10.1016/j.apradiso.2008.12.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Accepted: 12/11/2008] [Indexed: 11/19/2022]
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