• Fisheries and Aquatic Sciences
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• v.3 no.2
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• pp.126-134
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• 2000

We investigated the distribution of the marine cladoceran resting eggs in the intertidal sediments of Gomso Bay, Korea and compared the data with those in the subtidal sediments. The abundance of the eggs in the top 6cm of the sediments was higher than that in the other depths. The abundances of the eggs in seaward intertidal sediments below mean sea level (MSL) were higher than those in the sediments over MSL, but were not significantly different from those in the subtidal sediments. The distribution of the resting eggs of cladocerans in the intertidal sediments was affected by the grain-size and moisture content of sediments. The results of the present study suggest that the intertidal sediments as well as the subtidal sediments are a potential egg bank which plays important roles in population dynamics of zooplankton in coastal waters, in particular, recruitment of eggs into plankton.

• Journal of the korean society of oceanography
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• v.37 no.3
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• pp.108-115
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• 2002

To Investigate the distribution of resting eggs at the intertidal zone, Gomso Bay, samples were taken from the top of the sediments to 10 cm depth at four sites using a cylindrical corer in February, 1997. Additional samples were also taken from one station at subtidal zone to compare the distributions between the inter- and subtidal zones. The resting eggs of few copepods, Acartia pacifica, Centropages abdominalis, Calanopia thompsoni, and Tortanus forcipatus were studied. Mostly, the abundance of the resting eggs in the lower intertidal zone was greater than that in the upper intertidal zone, but was not significantly different from that in the subtidal zone. The abundance of the resting eggs in the intertidal sediments was related with the grain-size and moisture content of sediments. Intertidal sediments are potential egg banks like subtidal sediments.

• Ocean and Polar Research
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• v.30 no.1
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• pp.1-10
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• 2008

In order to find the effect of intertidal sediments on nutrient cycle in coastal environment, we measured ammonia, nitrate, phosphate, and silicate concentrations every hour during at least 12 hours in the entrance of Keunso Bay during four seasons. The content of ammonia and silicate do not change considerably with season, but nitrate shows large seasonal variation. In summer, nitrate concentration was much lower than in other seasons, which resulted from large biological uptake and active denitrification in intertidal sediments during summer. Phosphate also exhibit seasonal variations, but not that large like nitrate. N/P and N/Si ratios were lower in summer than in other seasons, which was due to active denitrification in the intertidal sediments during summer. For all seasons, ammonia concentrations were higher at low tide than at high tide, but nitrate concentrations were higher at high tide. Dissolved inorganic nitrogen concentrations measured in spring, summer, and winter were higher at high tide than at low tide, but in fall, they were higher at low tide than at high tide. For spring and winter, phosphate and silicate concentrations were higher at low tide than at high tide, while in summer and fall, they were higher at high tide than at low tide. In Keunso Bay, intertidal sediments affect significantly the nutrient cycle around the coastal areas. The intertidal sediments act as a source for ammonia and silicate, but as a sink for nitrate. However, phosphate is not considerably influenced by intertidal sediments.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.4
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• pp.555-563
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• 2015

Organic matter and trace metals were investigated in surface sediments of Gomso Bay, where there is dense Manila clam Ruditapes philippinarum farming activity, to evaluate contamination of sediments in intertidal shellfish farming area. We measured mean grain size (Mz), chemical oxygen demand (COD), ignition loss (IL), acid volatile sulfide (AVS), total organic carbon (TOC), and total nitrogen (TN), and trace metals (As, Cd, Cr, Cu, Fe, Hg, Mn, Pb and Zn) in intertidal and sublittoral sediments. The intertidal sediments were mainly composed of coarser sediments (sand, silty sand, and sandy silt), with Mz values ranging from 2.61 to 4.79 Ø. Mz and the content of organic matter in sediments were lower in the intertidal zone than in the sublittoral zone. The mean metal concentrations in surface sediments decreased in the order Fe > Mn > Zn > Cr > Pb > Cu > As > Cd > Hg. The metal concentrations in surface sediments showed a significant positive correlation with Mz and organic matter content, indicating that metal concentrations in the surface sediments of Gomso Bay are controlled by Mz and organic matter. The concentrations of organic matter and trace metals in the study region were lower than or similar to those in other intertidal zones in western coast and much lower than those reported in other shellfish farming areas in Korea. Our results suggest that intertidal Manila clam farming sediments from Gomso Bay are not contaminated by organic matter and trace metals.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.5
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• pp.638-648
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• 2013

To understand the geochemical characteristics of intertidal sediment in a semi-enclosed bay, we measured various geochemical parameters, including grain size, ignition loss (IL), chemical oxygen demand (COD), acid volatile sulfide (AVS), and trace metals (Al, Fe, Cu, Pb, Zn, Cd, Hg, and As), in intertidal sediment from three bays (Deukryang Bay, Yeoja Bay, and Gamak Bay) in the southern region of Jeollanam Province. The intertidal sediment in Deukryang Bay consisted of various sedimentary types, such as sand, gravelly muddy sand, mud, and silt, whereas the intertidal sediments in Yeoja and Gamak Bays were composed mainly of mud. The concentrations of IL, COD, AVS and trace metals in the intertidal sediments of the three study regions were relatively high near areas affected by input of stream waters and/or shellfish farming waste. The concentrations of organic matter and trace metals in Gamak Bay were much higher than those in Deukryang and Yeoja Bays, which appears to be due to the influence of anthropogenic pollutants, originating from the city and the industrial complex near Gamak Bay. The evaluation results of organic matter and metal pollution using the sediment quality guidelines showed that the intertidal sediments in the three study regions were not polluted in terms of organic matter and trace metals. In future, sustainable management for sources of organic matter and trace metal is necessary to conserve a healthy benthic ecosystem in intertidal sediments.

• 한국해양학회지
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• v.13 no.1
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• pp.9-18
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• 1978

The intertidal flat depositional environment of Southern Nam Yang Bay, west coast of Korea has been studied to understand textural, geochemical and mineralogical characteristics. The intertidal flat environment can be divided into two subenvironments, that is, the mud flat and the sand flat due to the sediment textures. From thd outer sand flat to the inner mud flat the grain size of the sediments decreases and the mud content increases. It is suggested that the intertidal flat environment is in the progradation of marsh deposits in the mud flat. The chemical composition of the sediments is related to the sediment textures. The chemical index of maturity of the mud flat sediments is higher than that of the sand flat sediments. The clay minerals of the sediments are chlorite, illite, montmorillonite and kaolinite.

• Journal of the Korean earth science society
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• v.37 no.2
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• pp.89-106
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• 2016

The Gochang open-coast intertidal flat is located in the southwestern coast of Korea (the eastern part of the Yellow Sea), characterized by macro-tidal range, an open-coast type, and sand substrates. This study has investigated seasonal variation in sedimentary facies of surface sediments in the Gochang intertidal flat. In the four seasons of February, May, August, and November, 2014, surface sediments of 252 sites in total were sampled and analyzed along three survey lines. The surface sediments of the Gochang intertidal flat in 2014 consisted mainly of fine-grained sand sediments showing a trend in grain size to be coarser in winter and finer in summer. Based on seasonal wave and tidal level data recorded near the study area, it was interpreted that the seasonal effects of wave were stronger than those of tide as a factor controlling surface sedimentation. High waves in winter resulted in the coarsening trend of grain size in surface sediments, whereas, during summer time, the sediments became finer by relatively low waves. Spatial sedimentary facies of the Gochang intertidal flat in 2014 represented that seasonal deviation of the upper tidal zone was larger than that of the lower tidal zone, hence sediments getting coarser in grain size and poorly sorted in the upper tidal zone. From upper to lower tidal zone, the grain size became finer and sediments were better-sorted, showing smaller seasonal deviations.

• Journal of Environmental Science International
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• v.8 no.6
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• pp.677-684
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• 1999

To investigate size distribution and metallic elements of surface sediments in Hampyong Bay, the southwestern coast of Korea, sedimentological and geochemical studies on surface sediments are carried out. The surface sediments of Hampyong Bay are classified into gravel, muddy sandy gravel, gravelly muddy sand, gravelly sandy mud, mud facies in accordance with areal characteristics. The coarse sediments are distributed on the subtidal zone along the main tidal channel and southeast intertidal flat of Hampyong Bay. On the other hand, the fine sediments are dominated in northeast and west intertidal flat of Hampyong Bay. Most metallic elements except for Ba in the sediments are closely interrelated with fine sediments and mutually with each element. Ba is maybe related with sandy sediments and inversely related with carbonate contents. Normalized by Al content, the sediment do not show any remarkable metal enrichments influenced by resonable artificial or environmental factors.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.6
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• pp.772-784
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• 2011

We measured grain size, organic matter, and metallic elements (Fe, Cu, Pb, Zn, Cd, Cr, Mn, Hg, and As) in intertidal sediments collected from six islands in the western part of Jellanam Province in order to evaluate heavy metal contamination in the tidal flat sediments of coastal islands. The evaluation of metal contamination was carried out using geochemical assessment techniques such as sediment quality guidelines (SQGs), enrichment factor (EF), and geoaccumulation index ($I_{geo}$). Surface sediments were classified into four sedimentary facies: sand, gravelly muddy sand, slightly gravelly mud, and silt. The concentrations of heavy metals in intertidal sediments from Jaeun, Amtae, Biguem, and Docho islands showed good positive correlations with mean grain size and ignition loss, indicating that the concentrations of metallic elements in these sediments were dependent on grain size and the organic matter content. The concentrations of heavy metals in sediments from almost all of the stations were lower than two criterion values proposed by the National Oceanic and Atmospheric Administration (NOAA) in the United States. Based on the EF and $I_{geo}$ results, surface sediments were a little polluted for Cr and were moderately polluted for As. Our results suggest that more intensive studies are necessary in the future in order to determine the major source of As in intertidal sediment and to evaluate the As pollution level in macrobenthos.

• Ocean and Polar Research
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• v.31 no.3
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• pp.247-255
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• 2009

We measured phosphate benthic fluxes and conducted phosphate adsorption experiments in order to find out the effects of adsorption on phosphate benthic fluxes in the intertidal sediments of Keunso Bay during summer and winter. Organic carbon contents showed little variation with season at St. S1, but noticeable changes were observed at St. S2, which were three times higher in winter than in summer. The higher organic carbon contents in winter resulted from the bloom of benthic algae in surface sediments. Pore water phosphate concentrations were much higher in summer than in winter. The higher phosphate concentration in summer was probably due to the faster remineralization rate of organic matter in summer. At St. S1, benthic fluxes of phosphate showed a negative value in summer and a positive value in winter. However, St. S2 had a negative benthic flux both in summer and winter. The negative benthic flux was ascribed to the phosphate adsorption on iron oxides in surface sediments. The equilibrium concentrations of phosphate obtained from the adsorption experiment were three times higher at St. S1 than at St. S2. The relatively high adsorption coefficient and low equilibrium concentration indicated that phosphate was strongly adsorbed on the surface sediments of Keunso Bay. The strong adsorption affinity significantly reduced benthic fluxes of phosphate in the intertidal sediments.