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Fluxes and behaviors of groundwater-borne nutrients in the ocean : 해양에서 지하수 기원 영양염의 플럭스와 거동

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dc.contributor.advisor김규범-
dc.contributor.author조형미-
dc.date.accessioned2017-10-27T17:14:18Z-
dc.date.available2017-10-27T17:14:18Z-
dc.date.issued2017-08-
dc.identifier.other000000146609-
dc.identifier.urihttps://hdl.handle.net/10371/137171-
dc.description학위논문 (박사)-- 서울대학교 대학원 자연과학대학 지구환경과학부, 2017. 8. 김규범.-
dc.description.abstractSubmarine groundwater discharge (SGD) into coastal waters is an important pathway for transporting nutrients to the ocean. Although the fluxes of SGD and associated nutrient discharge to the ocean at local and regional scales have been well studied, detailed estimates and models of SGD-related nutrient inputs to coastal waters on a global scale are few in number. Therefore, in this study, the global magnitude of SGD and its associated nutrient fluxes into the global ocean were estimated using a radium isotope (228Ra). The re-estimated magnitude of global SGD flux was approximately 1–1.5 times the river discharge and SGD-derived nutrient fluxes were comparable to the river-driven fluxes to the global ocean. These results imply that SGD is a critical source of nutrients to the ocean and therefore plays a critical role in marine productivity.

Nutrient fluxes through SGD can be calculated by multiplying the endmember concentrations of nutrients in groundwater by the SGD flux. However, groundwater nutrient concentrations are altered through biogeochemical reactions in the subterranean estuary (STE), where mixing between groundwater and aquifer solids occurs, prior to entering the ocean. Furthermore, the adsorption and desorption behaviors of silicon (Si) and phosphorus (P) in the STE have not been investigated although these processes influence Si and P fluxes through SGD. Based on laboratory experiments, rapid desorption of P (5–20 μmol/L) occurred from the sediment columns when Si was 40−90% removed in the initial stage within the first 24 hours. These results suggest that Si adsorption can result in significant P desorption from sediments in the STE into seeping groundwater.

Nutrient inputs via SGD play a significant role in nutrient cycling and primary productivity in the coastal ocean. This study based on seasonal sampling campaigns shows that SGD plays a critical but different role in nutrient budgets and stoichiometry in coastal waters off a volcanic island depending on open-ocean nutrient conditions. When bay seawater was influenced by the N-limited Tsushima Current, SGD was the major source of DIN in N-limited bay waters. SGD was also the absolute source of DIP in P-depleted bay waters that were influenced by P-limited Changjiang River diluted water (CDW). In addition, excessive inputs of nutrients from SGD resulted in an almost complete transfer of SGD-derived nutrients to the open ocean during the season in which a large flux of SGD occurs.
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dc.description.tableofcontents1. Introduction 1
1.1. Submarine groundwater discharge 1
1.2. Behaviors of nutrients in the subterranean estuary 4
1.3. Nutrient fluxes via submarine groundwater discharge and biological effects in the coastal ocean 6
1.4. Aims and the scope of study 10
2. Estimation of global magnitude of submarine groundwater discharge 13
2.1. Introduction 13
2.2. Data compilations 17
2.3. Results and discussion 19
2.3.1. Effects of geographical gridding methods 19
2.3.2. Effects of groundwater salinity 23
2.3.3. Revisiting basin-scale SGD magnitude estimations 27
2.4. Conclusions 33
3. Nutrients fluxes via submarine groundwater discharge to the global ocean 34
3.1. Introduction 34
3.2. Materials and methods 37
3.2.1. Data compilations and the SGD-driven net nutrient fluxes 37
3.2.2. Geographical gridding method and the effects of salinity 40
3.3. Results and discussion 44
3.3.1. Effects of geographical gridding methods 44
3.3.2. Effects of groundwater salinity 46
3.3.3. Global SGD-driven nutrient fluxes 51
3.4. Conclusions 55
4. Behaviors of silicate and phosphate in subterranean estuaries 56
4.1. Introduction 56
4.2. Materials and methods 59
4.2.1. Sampling 59
4.2.2. Sediment column experiments 61
4.2.3. Beaker experiments 65
4.2.4. Bottle experiments 67
4.3. Results 69
4.3.1. Sediment column experiments 69
4.3.2. Beaker and bottle experiments 73
4.4. Discussion 76
4.4.1. Adsorption of Si from groundwater to sediments 76
4.4.2. Desorption of P from sediments to groundwater 78
4.4.3. Effects of pH and salinity on P-Si exchange 80
4.5. Conclusions 82
5. Contributions of groundwater-borne nutrients to coastal waters off a volcanic island 83
5.1. Introduction 83
5.2. Materials and methods 86
5.2.1. Study area 86
5.2.2. Sampling and analyses 89
5.3. Results and discussion 90
5.3.1. Concentrations of nutrients in groundwater, outer-bay seawater, and bay seawater 90
5.3.2. Contributions of SGD on nutrient budgets 95
5.4. Conclusions 102
6. Summary and conclusions 103
Bibliography 105
Abstract (in Korean) 133
Appendix 136
Publications and Presentations 148
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dc.formatapplication/pdf-
dc.format.extent3326307 bytes-
dc.format.mediumapplication/pdf-
dc.language.isoen-
dc.publisher서울대학교 대학원-
dc.subjectsubmarine groundwater discharge (SGD)-
dc.subjectnutrients-
dc.subjectsubterranean estuary-
dc.subjectnutrient fluxes-
dc.subjectcoastal ocean-
dc.subjectglobal ocean-
dc.subject.ddc550-
dc.titleFluxes and behaviors of groundwater-borne nutrients in the ocean-
dc.title.alternative해양에서 지하수 기원 영양염의 플럭스와 거동-
dc.typeThesis-
dc.description.degreeDoctor-
dc.contributor.affiliation자연과학대학 지구환경과학부-
dc.date.awarded2017-08-
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