Dissolved organic matter in the subterranean estuary of a volcanic island, Jeju: Importance of dissolved organic nitrogen fluxes to the ocean

Kim, Tae-Hoon; Kwon, Euna; Kim, Intae; Lee, Shin-Ah; Kim, Guebuem

doi:10.1016/j.seares.2012.12.009

Cited by 55 publications

(35 citation statements)

References 51 publications

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“…Previous studies have suggested that DON concentration may be higher in groundwater relative to surface waters (Kim et al, 2013;Santos et al, 2013Santos et al, , 2014. Here, groundwater nitrogen was dominated by DON, accounting for 66 and 85% of TDN in groundwater in the wet and dry season, respectively.…”

Section: Nutrient Dynamics In Surface and Groundwatermentioning

confidence: 69%

Fresh meteoric versus recirculated saline groundwater nutrient inputs into a subtropical estuary

Sadat‐Noori

Santos

Tait

et al. 2016

Science of The Total Environment

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Section: Nutrient Dynamics In Surface and Groundwatermentioning

confidence: 69%

Fresh meteoric versus recirculated saline groundwater nutrient inputs into a subtropical estuary

Sadat‐Noori

Santos

Tait

et al. 2016

Science of The Total Environment

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“…Measurements of DON flux to the coastal ocean are scarce. Kim et al (2013) reported conservative mixing of DON, with export fluxes of 1.31 × 10 5 mol d −1 in Hwasun Bay (Jeju Island, Korea) and in the Gulf of Mexico; Santos et al (2009) estimated that land-derived DON makes up ∼ 52 % of the total N exported to the coastal ocean.…”

Section: Nitrogen Fluxesmentioning

confidence: 99%

Nitrogen transformations along a shallow subterranean estuary

et al. 2017

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Abstract. The transformations of chemical constituents in subterranean estuaries (STEs) control the delivery of nutrient loads from coastal aquifers to the ocean. It is important to determine the processes and sources that alter nutrient concentrations at a local scale in order to estimate accurate regional and global nutrient fluxes via submarine groundwater discharge (SGD), particularly in boreal environments, where data are still very scarce. Here, the biogeochemical transformations of nitrogen (N) species were examined within the STE of a boreal microtidal sandy beach located in the Magdalen Islands (Quebec, Canada). This study revealed the vertical and horizontal distribution of nitrate (NO, dissolved organic nitrogen (DON) and total dissolved nitrogen (TDN) measured in beach groundwater during four spring seasons (June 2011(June , 2012(June , 2013(June and 2015 when aquifer recharge was maximal after snowmelt. Inland groundwater supplied high concentrations of NO x and DON to the STE, whereas inputs from seawater infiltration were very limited. Non-conservative behaviour was observed along the groundwater flow path, leading to low NO x and high NH + 4 concentrations in the discharge zone. The long transit time of groundwater within the beach (∼ 166 days), coupled with oxygen-depleted conditions and high carbon concentrations, created a favourable environment for N transformations such as heterotrophic and autotrophic denitrification and ammonium production. Biogeochemical pathways led to a shift in nitrogen species along the flow path from NO x -rich to NO x -poor groundwater. An estimate of SGD fluxes of N was determined to account for biogeochemical transformations within the STE based on a N-species inventory and Darcy's flow. Fresh inland groundwater delivered 37 mol NO x yr −1 per metre of shoreline and 63 mol DON m −1 yr −1 to the STE, and NH and DON. Our study shows the importance of tidal sands in the biogeochemical transformation of the terrestrial N pool. This local export of bioavailable N probably supports benthic production and higher trophic levels leading to its rapid transformation in surface sediments and coastal waters.

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“…Fresh submarine groundwater discharge (SGD) is significant here (approximately 2.1 × 10 8 m 3 yr −1 ) (Kim et al ). The sandy aquifer and mixing zone at this beach is very simple because of homogeneity of sediment minerals (Kim et al ), fresh groundwater (Kim et al ), and coastal seawater. Several sampling campaigns have clearly shown conservative mixing trends for dissolved inorganic nitrogen, dissolved inorganic silicate, and dissolved organic carbon in this subterranean estuary (Kim et al ).…”

Section: Methodsmentioning

confidence: 99%

Dependence of pH in coastal waters on the adsorption of protons onto sediment minerals

Lee

Kim

2015

Limnology & Oceanography

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We measured pH, total alkalinity (TAlk), dissolved inorganic carbon (DIC), and d 13 C-DIC in groundwater of a subterranean estuary in Hwasun Bay in the volcanic island of Jeju, Korea. In the sandy aquifer, the pH values (7.4 6 0.2) of fresh groundwater increased sharply to 10 and then behaved conservatively in the mixing zone between alkalified fresh groundwater and seawater. The distributions of d 13 C-DIC, Ca 21 , and Mg 21 in coastal groundwater, along with the results from lab experiments on sediment columns, suggest that the increase of pH in this subterranean estuary is associated with the adsorption of protons (protonation) onto sandy sediments, rather than other geochemical processes. Our lab experiments showed that the protonation (1) occurs commonly for various sediments of Jeju Island, (2) increases pH effectively for low-salinity (salinity < 10) groundwater, and (3) depends on the relative amount of transition metal (i.e., Fe, Ti, and Mn) oxides. The chamber experiments at the interface of seawater and groundwater indicate the direct seepage of high pH water into the ocean. This increase in pH leads to corresponding uptake of CO 2 from the atmosphere. Thus, our result suggests that the reaction between groundwater and coastal sediments should be considered as an important driver of pH change that regulates the magnitude of chemical species in coastal groundwater seeping into the ocean at the volcanic island, Jeju, Korea.

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Dissolved organic matter in the subterranean estuary of a volcanic island, Jeju: Importance of dissolved organic nitrogen fluxes to the ocean

Cited by 55 publications

References 51 publications

Fresh meteoric versus recirculated saline groundwater nutrient inputs into a subtropical estuary

Fresh meteoric versus recirculated saline groundwater nutrient inputs into a subtropical estuary

Nitrogen transformations along a shallow subterranean estuary

Dependence of pH in coastal waters on the adsorption of protons onto sediment minerals

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