• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.885-892
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• 2017

We estimated the limiting nutrient and DIP limiting history based on alkaline phosphatase (APase) activity during the spring of 2017 in the Southern Sea, Korea. In the frontal area, concentration of dissolved inorganic phosphorus (DIP), dissolved inorganic nitrogen (DIN): DIP ratio and Chlorophyll a (Chl-a) were < $0.2{\mu}M$, 23.2 and $2.2{\mu}g/L$, respectively, indicating high productivity despite DIP limiting. The relationship between APase and DIP indicates that the study area had limited DIP because of a strongly reverse correlation (r= -0.81; P<0.001). Relationship between APase and Chl-a (r=0.61, p<0.001) also indicated that APase may have been induced by phytoplankton (ca. 60 %) and bacteria (ca. 40 %). In DIP limiting history in this study area, frontal area and non-frontal areas might have induced long-term DIP limitation and the recent relief from DIP-limitation, respectively, based on distributions of dissolved APase and particulate APase. Thus, these results suggest that by measuring the enzyme that hydrolyzes organic matter such as APase in frontal area, it is possible to estimate temporal and spatial characteristics of limiting nutrient, thereby improving our understanding of biogeochemistry cycles.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.1
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• pp.56-62
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• 2009

Stable carbon isotope analysis was used to investigate the autotrophic carbon sources supporting fisheries in three coastal bay systems of the southern coast of Korea. Carbon isotope ratios (${\delta}^{13}C$) of 31 fish species were analysed and compared with those of a range of potential primary food sources [e.g., seagrass (Zostera marina), seagrass epiphytes, benthic microalgae, macroalgae, marine particulate organic matter (marine POM), marsh plant (Phragmites australis) and terrestrial POM]. ${\delta}^{13}C$ values (range, -16.2${\sim}$-8.3‰) of fishes from the coastal embayment systems were overlapped with those of seagrass (-8.3${\pm}$1.9‰), seagrass epiphytes (-12.4${\pm}$0.6‰), benthic microalgae (-15.4${\pm}$1.6‰) and macroalgae (-16.0${\pm}$1.8‰). In addition, fishes (-12.9${\pm}$1.5‰) from the study area had distinctly higher ${\delta}^{13}C$ values compared to those collected in offshore sites (-17.3${\pm}$0.8‰) of the southern sea of Korea and Nakdong River (-23.2${\pm}$1.6‰). This result indicates that carbon supporting fish communities of these coastal bay systems is mainly derived from the local benthic producers.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.3
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• pp.330-342
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• 1998

Benthic environmental parameters were analysed at 40 stations during the period from April 1995 to February 1996. such as water temperature, salinity, and dissolved oxygen (DO)-concentration in the surface and bottom water layers, grain size, chemical oxygen demand (COD), ignition loss, particulate organic carbon (POC) in the sediment of Youngsan River estuary. The water temperature ranged from 4.1 to $29.8^{\circ}C$ in the surface and 4.0 to $20.7^{\circ}C$ in the bottom layers. Salinity ranged from 15.1 to $33.6\%_{\circ}$ in the surface and 31.5 to $33.2\%_{\circ}$ in the bottom layer. The salinity in the outer pan of the study area was higher than that of inner area from autumn to spring, whereas they remained lower in summer. Dissolved oxygen concentration ranged from 5,1 to 11.2 $mg/\ell$ in the surface, and 0.79 to 10,2 $mg/{\ell}$ in the bottom layers. Hypoxic condition ($\le2.0mg/\ell$) was developed in the bottom water layer from Youngsan dike to Mokpo Harhour in summer due to the summer stratification. The surface sediment type was silty clay with a mean grain size of $9.12{\pm}0.45\phi$. The range of COD was from 6.15 to $15.49mgO_2/g$ with a mean of $10.59{\pm}12.64mgO_2/g$. The COD in the inner stations was relatively higher than that of outer stations, and decreased toward the outer part of the study area. Ignition loss (IL) ranged from 3.35 to $15.45\%$ with a mean of $5.96{\pm}1.91\%$. Principal component analysis was carried out from the following five environmental parameters: water temperature, dissolved oxygen in the bottom layer and mean grain size, clay content and COD in the sediment. The forty stations in the study area were classified into three stational groups. Group I was located in the inner part of the estuary characterised by relatively low surface salinity and bottom water temperature, fine sedimemt texture, high organic matter and low dissolved oxygen concentration during the summer. Meanwhile, Group III showing relatively high bottom salinity and water temperature was located in the outer part of the estuary characterising coarse sediment and low organic content in sediment. Group II was between Group I and Group III. The division of the areal groups had high correlations to the DO in the bottom layer and clay content in the sediment.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.587-597
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• 2023

We evaluated the eutrophication of Saemangeum Lake, which causes abnormal growth of algae, using the Carlson index. Eutrophication characteristics of Saemangeum Lake were analyzed. For the study, water quality surveys were conducted at 7 stations in Saemangeum Lake every month in 2021. The concentration of Chl.a was slightly higher in the Mankyeong water system in winter, and slightly higher in the Dongjin water system in spring and summer, but overall, except for some periods, the concentration was similar to or lower than the lake water quality environmental standard of class 3. COD showed water quality similar to or above the lake quality environmental standard of grade 4 in both the Mankyeong and Dongjin water systems in the summer and Autumn. TOC concentrations were within lake water quality standard 3 at all sites. Total phosphorus concentrations exceeded the lake water quality standard of Class 4 and were higher in January and August after rainfall. In the correlation analysis between water quality factors, the correlation of organic matter, total phosphorus, and total nitrogen to salinity was relatively high. This reflected the water quality characteristics of freshwater, brackish water, and seawater areas due to seawater inflow through the drainage gate and freshwater inflow through upstream rivers. According to the characteristics of eutrophication fluctuations in Saemangeum Lake by trophic state index, the indices of Chl.a, SD, and TN showed water quality in the early stage of eutrophication, while the TP index showed a severe eutrophication state. The magnitude of the eutrophication index among water quality components was TSI(TP) > TSI(TN) > TSI(SD) > TSI(CHL) in all water systems. Quadrant analysis of the deviation of TSI(CHL) from TSI(TP) and TSI(SD) on a two-dimensional plane showed that there was no limiting effect of total phosphorus on algal growth in all water systems. In addition, the factors af ecting light attenuation appeared to be dominated by small particulate matter from outside sources.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.4
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• pp.53-68
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• 2020

The concentrations of ammonia, hydrogen sulfide and fine dust were measured in the compost facility of a full-time Hanwoo breeding farms. The experiments were conducted in stack type composting facility(T1) and mechanical-stirred composting facilities(T2, T3). In the stack type composting facility, the highest temperature of compost pile was 46℃, and in the two mechanical-stirred composting facilities, it rose to 63℃ and 68℃, respectively. The concentrations of PM2.5 at T1, T2 were 15 ㎍/㎥ and 5~10 ㎍/㎥, respectively. And the concentration of PM2.5 at T3 was below 10 ㎍/㎥. The highest concentration of ammonia generated at T1 was 4 ppm, but no hydrogen sulfide was detected. The ammonia concentrations at T2 and T3 were 3 ppm and 4 ppm, respectively. However, hydrogen sulfide was not detected in both facilities. At T3, the ammonia concentration increased to 65 ppm at the point where the compost was stirred with a mechanical agitator. During composting period, the pH of the compost pile decreased from 9.06 to 8.94 and then increased to 9.14 as the composting period elapsed. The NaCl content of compost was 0.09% after composting process was complete. Moisture content of compost decreased from 65.9% to 62% as composting progressed. As composting proceeded, the content of volatile solids decreased from 65.6% to 64.7% and the content of TKN decreased from 1.327% to 1.095%.

• Korean Journal of Ecology and Environment
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• v.56 no.4
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• pp.281-302
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• 2023

Carbon is not only an essential element for life but also a key player in climate change. The radiocarbon (¹⁴C) analysis using accelerator mass spectrometry (AMS) is a powerful tool not only to understand the carbon cycle but also to track pollutants derived from fossil carbon, which have a distinct radiocarbon isotope ratio (Δ¹⁴C). Many studies have reported Δ¹⁴C of carbon compounds in streams, rivers, rain, snow, throughfall, fine particulate matter (PM_2.5), and wastewater treatment plant effluents in South Korea, which are reviewed in this manuscript. In summary, (1) stream and river carbon in South Korea are largely derived from the chemical weathering of soils and rocks, and organic compounds in plants and soils, strongly influenced by precipitation, wastewater treatment effluents, agricultural land use, soil water, and groundwater. (2) Unprecedentedly high Δ¹⁴C of precipitation during winter has been reported, which can directly and indirectly influence stream and river carbon. Although we cannot exclude the possibility of local contamination sources of high Δ¹⁴C, the results suggest that stream dissolved organic carbon could be older than previously thought, warranting future studies. (3) The ¹⁴C analysis has also been applied to quantify the sources of forest throughfall and PM_2.5, providing new insights. The ¹⁴C data on a variety of ecosystems will be valuable not only to track the pollutants derived from fossil carbon but also to improve our understanding of climate change and provide solutions.

• Korean Journal of Remote Sensing
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• v.14 no.4
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• pp.353-365
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• 1998

Light absorption coefficient per unit mass of particles, i.e., specific absorption coefficient, is important as one of the main parameters in developing algorithms for ocean color remote sensing. Specific absorption coefficient of chlorophyll ($a^*_{ph}$) and suspended sediment ($a^*_{ss}$) were analyzed with a spectrophotometer using the "wet filter technique" and "Kishino method" for the seawater collected in the Yellow and Mediterranean Sea. An improved data-recovery method for the filter technique was also developed using spectrum slopes. This method recovered the baselines of spectrum that were often altered in the original methods. High $a^*_{ph}({lambda})$ values in the oligotrophic Mediterranean Sea and low values in the Yellow Sea were observed, ranging 0.01 to 0.12 $m^2$/mg at the chlorophyll maximum absorption wavelength of 440 nm. The empirical relationship between $a^*_{ph}$(440nm) and chlorophyll concentrations () was found to fit a power function ($a^*_{ph}$=0.039 $^{-0.369}$), which was similar to Bricaud et al. (1995). Absorption specific coefficients for suspended sediment ($a^*_{ss}$) did not show any relationship with concentrations of suspended sediment. However, an average value of $a^*_{ss}$ ranging 0.005 - 0.08 $m^2$/g at 440nm, was comparable to the specific absorption coefficient of soil (loess) measured by Ahn (1990). The morepronounced variability of $a^*_{ss}$ than $a^*_{ph}$ was determined from the variable mixing ratio values between particulate organic matter and mineral. It can also be explained by a wide size-distribution range for SS which were determined by their specific gravity, bottom state, depth and agitation of water mass by wind in the sea surface.

• Journal of Korean Society of Forest Science
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• v.100 no.1
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• pp.112-117
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• 2011

This study was conducted for searching the functional feeding groups, and community stability of the macroinvertebrate on forest fire area of Uljin-gun. The samples were collected from 2 sites of control area and 2 sites of experimental area during 2007 to 2009. The identified species were 89 belonged to 47 families, 16 order, 6 class, and 4 phylum in control area. And 84 belonged to 43 families, 16 order, 6 class, and 4 phylum were identified in experimental area. As a result of changes in species and individuals of E.P.T. taxa investigated in experimental area by year, Ephemeroptera was 21 species, $2,434.6inds./m^2$, Plecoptera was 3 species, $199.8inds./m^2$, and Trichoptera 14 species, $540.2inds./m^2$ in 2007. And in 2009, Ephemeroptera was 9 species, $296inds./m^2$, Trichoptera was 4 species, $44.4inds./m^2$, and Plecoptera was none, showing that species and individuals belonging to E.P.T. taxa decrease rapidly every year. Community analysis by year, in 2008 when the water system started to be influenced by the fire directly, it showed a trend that H' and RI decreased in the experimental area. Functional feeding group by year, it showed a trend that species and individuals of GC type which is a functional group picking up and eating FPOM (fine particulate organic matter) from deposits in the bottom of water or benthic areas and performs an important function of material circulation in ecosystem decrease every year. Community stability by year, an environment of water system in forest fire area started to be somewhat destroyed, from 2008, it is shown that both species in I area which have great ability of resistance and recovery and species in III area which live in relatively stable water system decreased a little.