Estimating submarine groundwater discharge in Jeju volcanic island (Korea) during a typhoon (Kong-rey) using humic-fluorescent dissolved organic matter-Si mass balance

Abstract

We examined the residence time, seepage rate, and submarine groundwater discharge (SGD)-driven dissolved nutrients and organic matter in Hwasun Bay, Jeju Island, Korea during the occurrence of a typhoon, Kong-rey, using a humic fluorescent dissolved organic matter (FDOMH)-Si mass balance model. The study period spanned October 4–10, 2018. One day after the typhoon, the residence time and seepage rate were calculated to be 1 day and 0.51 m day−1, respectively, and the highest SGD-driven fluxes of chemical constituents were estimated (1.7 × 106 mol day−1 for dissolved inorganic nitrogen, 0.1 × 106 mol day−1 for dissolved inorganic phosphorus (DIP), 1.1 × 106 mol day−1 for dissolved silicon, 0.5 × 106 mol day−1 for dissolved organic carbon, 1.6 × 106 mol day−1 for dissolved organic nitrogen, 0.4 × 106 mol day−1 for particulate organic carbon, and 38 × 106 g QS day−1 for FDOMH). SGD-driven fluxes of dissolved nutrient and organic matter were over 90% of the total input fluxes in Hwasun Bay. Our results highlight the potential of using the FDOMH-Si mass balance model to effectively measure SGD within a specific area (i.e., volcanic islands) under specific weather conditions (i.e., typhoon/storm). In oligotrophic oceanic regions, SGD-driven chemical fluxes from highly permeable islands considerably contribute to coastal nutrient budgets and coastal biological production.

Impact of aquaculture on distribution of dissolved organic matter in coastal Jeju Island, Korea, based on absorption and fluorescence spectroscopy

“…However, the average concentrations in the drainage (0.98 ± 0.20 mg/L) were relatively higher than in the coastal groundwater in Jeju Island. Although we could not directly obtain the water intake sample from the groundwater well owing to the lack of access authority, the DOC concentration in the fresh groundwater was consistently and significantly low in the coastal Jeju Island in different seasons (Cho et al 2021 ; Kim and Kim 2017a ; Kim and Kim 2017b ; Kim et al 2013 ; Song et al 2018 ). Additionally, the contribution of the fresh groundwater origin to the drainage and coastal water samples appeared to be significant based on the statistically lower salinity and pH values.…”

“…The red circles represent the sampling stations in area Gueom, as the control group, which are located in more than 5 km distance from the aquafarms. The red triangles represent the study sites for physicochemical parameters of the coastal groundwater in previous studies (Cho et al 2021;Kim and Kim 2017a;Kim and Kim 2017b;Kim et al 2013;Song et al 2018) characteristics in aquaculture. Nimptsch et al (2015) revealed that large amounts of anthropogenic dissolved organic carbon (DOC) with the most biodegradable protein-like FDOM derived from land-based aquaculture facilities are being discharged into the river system in the North Patagonian region.…”

“…The red circles represent the sampling stations in area Gueom, as the control group, which are located in more than 5 km distance from the aquafarms. The red triangles represent the study sites for physicochemical parameters of the coastal groundwater in previous studies (Cho et al 2021 ; Kim and Kim 2017a ; Kim and Kim 2017b ; Kim et al 2013 ; Song et al 2018 ) …”

Does Nitrate Enrichment Accelerate Organic Matter Turnover in Subterranean Estuaries?

“…Previous studies have used FDOM humic-like components identified through PARAFAC analysis to quantify the transport of terrestrial DOM to the coast through SGD (Nelson et al, 2015; Leote et al (2008) and in this study. Kim and Kim, 2017;Cho et al, 2021). In our site, the relative abundances of FDOM humic-like components C3 and C5 were significantly correlated in water seeping out from stations A and B (Figure 4), suggesting that the relative abundances of C3 and C5 expressed as a ratio (FDOM C3/C5) could be a reliable tracer of SGD in the Ria Formosa lagoon.…”

A State-Of-The-Art Perspective on the Characterization of Subterranean Estuaries at the Regional Scale

“…At the coast, storms may, for instance, physically impact the freshwater input, the availability of substrates, or the seafloor morphology, which would change STE behavior. Due to storms, SGD rates can strongly change in a matter of days (Cho et al, 2021). More generally, hot moments in STE can be created through movements of the salinity gradient, when, e.g., phosphorus can desorb from aquifer sediment with increasing salinity and cause a spike of P fluxes to the ocean that is not directly connected to terrestrial or marine inputs (Flower et al, 2017).…”