Past, present, and future for the study of Gamak Bay, Korea

Ock, Lee Moon; Kyu, Kim Jong; Kuk, Kim Byeong

doi:10.7846/jkosmee.2020.23.3.148

Cited by 6 publications

(7 citation statements)

References 48 publications

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“…It is characterized by a concaved bottom topography in the northwestern region with 9 m of mean water depth [38]. Typical semi-enclosed geography inhibits water circulation and induces stratification [39]. Nutrients and organic matter loaded from point/non-point sources surrounding Gamak Bay cause eutrophication and generate hypoxic waters [9,10,13].…”

Section: A Study Areamentioning

confidence: 99%

“…Nutrients and organic matter loaded from point/non-point sources surrounding Gamak Bay cause eutrophication and generate hypoxic waters [9,10,13]. In Gamak Bay, there are shellfish and fish farms that provide 30% of domestic oyster production [39]. Therefore, the Ministry of Oceans and Fisheries of Korea has conserved this bay as a marine protected area for cultivating and protecting fisheries resources [40].…”

Section: A Study Areamentioning

confidence: 99%

“…Although GA1 was characterized by the reducing conditions, concentrations of oxidation parameters such as NO 2 − (0.3 µM) and NO 3 − (2.1 µM) were relatively high compared to those in adjacent waters (Figure 4a,b). This might be associated with the incomplete reduction or the variation in hypoxic intensity due to factors such as meteorological conditions, relatively shallow water depth (4 m), daily tidal effects, and neap/spring tides [9,13,36,39]. For example, the DO concentration of bottom waters at GA1 was 6.95 mg/L on 8 August [9], but it was 2.5 mg/L a week later.…”

Section: Nutrient Elution and Diffusion Fluxes At The Bottom Seawater...mentioning

confidence: 99%

“…Thus, determining the nutrient mass balance before and after the reducing environment is also essential. In addition, the urban sewer pipes and aquaculture farms are also the major players in causing eutrophication in Gamak Bay [9,10,39]. Additionally, replicated sampling, current mass balances between the surface and bottom waters, excessive nutrient loading, and residence time of introduced nutrients should be examined to protect aquaculture organisms and marine organisms living in the bay and conserve the marine ecosystem and resources in Gamak Bay.…”

Section: C N and P Mass Balances Under The Effects Of The Reducing En...mentioning

confidence: 99%

“…The sewer pipes connecting to storm sewer pipes, designed as the combined sewer overflows, can be non-point sources when it rains [9]. Moreover, there are aquaculture farms for bivalves, fishes, and seaweed, and the shellfish production from this bay reaches 8300 tons/yr [39]. Interestingly, oligotrophic surface water is one of the main reasons for the decrease in annual oyster production [39,81].…”

Section: C N and P Mass Balances Under The Effects Of The Reducing En...mentioning

confidence: 99%

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C, N, and P Mass Balances in the Bottom Seawater–Surface Sediment Interface in the Reducing Environment due to Anoxic Water of Gamak Bay, Korea

Jeong

Kang

Cho

2022

Water

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Current mass balances of C, N, and P were estimated using a model (Fluxin = Fluxout + ΔFlux) from Gamak Bay, Korea, in August 2017, where eutrophication and reducing conditions are prevalent. To examine the current fluxes of particulate organic carbon (POC), nitrogen (PON), and phosphorus (POP), sinking and re-floating sediment traps were deployed, a sediment oxygen demand (SOD) chamber experiment and ex-situ nutrient incubation experiment were conducted, and Fick’s first law of diffusion was applied. The principal component analysis and cluster analysis were performed to identify the three groups of water masses based on the characteristics of the bay, including the effects of the reducing environment due to the anoxic water mass using 14 bottom water quality parameters. In the reducing environment (sampling point GA4), the SOD20 flux was 3047.2 mg O2/m2/d. Additionally, the net sinking POC flux was 861.0 mg C/m2/d, while 131.8% of the net sinking POC flux (1134.5 mg C/m2/d) was removed toward the overlying water. This indicates that the organic matter that had been deposited was decomposed as a flux of 273.6 mg C/m2/d. The net sinking PON flux was 187.9 mg N/m2/d, whereas 15.8% of the net sinking PON flux was eluted, and 84.2% remained in the surface sediments. The dissolved inorganic nitrogen (DIN) elution flux from the surface sediments consisted of NH4+ elution (33.7 mg N/m2/d) and NOx− elution (−4.1 mg N/m2/d) fluxes. Despite the net sinking POP flux being 26.0 mg P/m2/d, the 47.7 mg P/m2/d of DIP elution flux (179.5% of the net sinking POP flux) was eluted to the overlying water. Similar to C mass balance, the additional elution flux occurred. Therefore, severe eutrophication (16.5 of the Okaichi eutrophication index) with the lowest N:P ratio (2.6) in GA4 was noted. This indicates that not only the freshly exported organic matter to the surface sediments but also the biochemical processes under anoxic conditions played an essential role as a remarkable nutrient source–particularly P–for eutrophication in Gamak Bay, Korea.

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