• 한국대기환경학회지
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• 제31권3호
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• pp.239-254
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• 2015

Little information on HUmic-Like Substances (HULIS) in ambient particulate matter has been reported yet in Korea. HULIS makes up a significant fraction of the water-soluble organic mass in the atmospheric aerosols and influence their water uptake properties. In this study 24-hr $PM_{2.5}$ samples were collected between December 2013 and October 2014 at an urban site in Gwangju and analyzed for organic carbon (OC), elemental carbon (EC), water-soluble OC (WSOC), HULIS, and ionic species, to investigate possible sources and formation processes of HULIS. HULIS was separated using solid phase extraction method and quantified by total organic carbon analyzer. During the study period, HULIS concentration ranged from 0.19 to $5.65{\mu}gC/m^3$ with an average of $1.83{\pm}1.22{\mu}gC/m^3$, accounting for on average 45% of the WSOC (12~ 73%), with higher in cold season than in warm season. Strong correlation of WSOC with HULIS ($R^2=0.91$) indicates their similar chemical characteristics. On the basis of the relationships between HULIS and a variety of chemical species (EC, $K^+$, $NO_3{^-}$, $SO_4{^{2-}}$, and oxalate), it was postulated that HULIS observed during summer and winter were likely attributed to secondary formation and primary emissions from biomass burning (BB) and traffics. Stronger correlation of HULIS with $K^+$, which is a BB tracer, in winter ($R^2=0.81$) than in summer ($R^2=0.66$), suggests more significant contribution of BB emissions in winter to the observed HULIS. It is interesting to note that BB emissions may also have an influence on the HULIS in summer, but further study using levoglucosan that is a unique organic marker of BB emissions is required during summer. Higher correlation between HULIS and oxalate, which is mainly formed through cloud processing and/or photochemical oxidation processes, was found in the summer ($R^2=0.76$) than in the winter ($R^2=0.63$), reflecting a high fraction of secondary organic aerosol in the summer.

• 한국물환경학회지
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• 제36권4호
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• pp.284-299
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• 2020

Dam reservoirs play a particularly crucial role in processing the allochthonous and the autochthonous dissolved (DOC) and the particulate (POC) organic carbon and in the budget of global carbon cycle. However, the complex physical and biogeochemical processes make it difficult to capture the temporal and spatial dynamics of the DOC and the POC in reservoirs. The purpose of this study was to simulate the dynamics of the DOC and the POC in Daecheong Reservoir using the 3-D hydrodynamics and water quality model (AEM3D), and to quantify the mass balance through the source and sink fluxes analysis. The AEM3D model was calibrated using field data collected in 2017 and showed reasonable performance in the water temperature and the water quality simulations. The results showed that the allochthonous and autochthonous proportions of the annual total organic carbon (TOC) loads in the reservoir were 55.5% and 44.5%, respectively. In season, the allochthonous loading was the highest (72.7%) in summer, while in autumn, the autochthonous loading was the majority (77.1%) because of the basal metabolism of the phytoplankton. The amount of the DOC discharged to downstream of the dam was similar to the allochthonous load into the reservoir. However, the POC was removed by approximately 96.6% in the reservoir mainly by the sedimentation. The POC sedimentation flux was 36.21 g-C/㎡/yr. In terms of space, the contribution rate of the autochthonous organic carbon loading was high in order of the riverine zone, the transitional zone, and the lacustrine zone. The results of the study provide important information on the TOC management in the watersheds with extensive stagnant water, such as dam reservoirs and weir pools.

• Journal of Ecology and Environment
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• 제36권3호
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• pp.183-191
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• 2013

Dissolved organic carbon (DOC) concentrations and zooplankton and particulate organic matter (POM) ${\delta}^{13}C$ values were measured in five reservoirs in Korea. Zooplankton ${\delta}^{13}C$ and POM ${\delta}^{13}C$ showed large range from -33‰ to -22‰ and a significant difference among the reservoirs. One eutrophic reservoir, Lake Masan, showed unique characteristics with the highest zooplankton density, the highest ${\delta}^{13}C$, and the highest DOC. Zooplankton ${\delta}^{13}C$ was similar to POM ${\delta}^{13}C$, implying that zooplankton occupies substantial portion of POM or that zooplankton isotopic composition is related to selective grazing and assimilation of food sources from bulk POM. Except Lake Masan zooplankton ${\delta}^{13}C$ values were negatively correlated to DOC concentration in four reservoirs with mostly forest land use. This pattern can be probably attributed to intensive agricultural land use in the watershed of Lake Masan compared to the mostly forest land use in the other watersheds. Understanding the relationship between zooplankton ${\delta}^{13}C$ values and the origin of organic matter associated with watershed characteristics will be valuable to better understand trophic relationships in reservoirs in the summer monsoon region.

• 한국입자에어로졸학회지
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• 제16권1호
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• pp.19-30
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• 2020

The organic carbon in the ambient particulate matter (PM) is divided into primary organic carbon (POC) and secondary organic carbon (SOC) by their formation way. To regulate PM effectively, the estimation of the amount of POC and SOC separately is one of important consideration. Since SOC cannot be measured directly, previous studies have evaluated determination of SOC by the EC tracer method. The EC tracer method is a method of estimating the SOC value from calculating the POC by determining (OC/EC)pri which is the ratio of the measured values of OC and EC from the primary combustion source. In this study, three different ways were applied to OC and EC concentrations in PM_2.5 measured at Seoul for determining (OC/EC)pri: 1) the minimum value of OC/EC ratio during the measurement period; 2) regression analysis of OC vs. EC to select the lower 5-20% OC/EC ratio; 3) determining the OC/EC ratio which has lowest correlation coefficient value (R²) between EC and SOC which is reported as minimum R squared method (MRS). Each (OC/EC)pri ratio of three ways are 0.35, 1.22, and 1.77, respectively from the 1 hourly data. We compared the (OC/EC)pri ratio from 1hourly data with 24 hourly data and revealed that (OC/EC)pri estimated from 24 hourly data had twice larger than 1hourly data due to the low time resolution of sampling. We finally confirmed that the most appropriate value of (OC/EC)pri is that calculated by a regression analysis of 1 hourly data and estimated SOC amounts at PM_2.5 of the Seoul atmosphere.

• Journal of the korean society of oceanography
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• 제35권1호
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• pp.56-64
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• 2000

The importance of terrestrial organic matter as a food source for a brackish water clam Corbicula japonica was evaluated using stable carbon isotope ratios (${\delta}^{13}$C) in its tissues and potential food resources in an estuarine system of Youngil Bay, Korea. Suspended particulate organic matter (POM) had distinct ${\delta}^{13}$C values from riverine (-31.8 to -27.2%$_o$) to marine waters (-21.0 to -16.6%$_o$). Estuarine macroalgae had a wide ${\delta}^{13}$C range of -22.8 to -15.0%$_o$. The ${\delta}^{13}$C values of riverine POM were more negative than that of riverine phytoplankton (-26.5 to -24.2%$_o$) but similar to that of freshmarsh plant species (-29.1 to -27.5%$_o$ for Phragmites communis and -28.5 to -27.0%$_o$ for Salix gracilistyla), These ${\delta}^{13}$C values suggest that the POM transported by the Hyungsan River is predominantly of terrestrial origin rather than riverine autochthonous sources. The ${\delta}^{13}$C values of Corbicula japonica tissues (-28.7 to -27.2%$_o$) were most similar to values for riverine POM and freshmarsh plants. There was no significant difference in the isotopic composition of the clam individuals. The results indicate a predominant contribution of organic carbon derived from terrestrial and fresmarsh plant detritus to the diet of Corbicula japonica. Our results also confirm previous suggestion that terrestrial organic matter can be incorporated into estuarine food webs although its role is confined to the upper estuarine reaches.

• 한국대기환경학회지
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• 제18권6호
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• pp.487-501
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• 2002

The concentrations of gaseous (NO$_{x}$, SO$_2$, and $O_3$) and particulate (Elemental Carbon, EC and Organic Carbon, OC) pollutants were measured to evaluate the air quality of Kosan. Samples were taken at Kosan during ACE-Asia (Asian Pacific Regional Aerosol Characterization Experiment) IOP (Intensive Observation Period) (2001. 3. 21~2001. 5. 5). The mean concentrations of $O_3$(46.3$\pm$10.4 ppb) is higher than those at urban area such as Seoul and Busan in Korea. On the other hand, the mean concentrations of other gaseous species, NO$_{x}$(4.73$\pm$3.42 ppb) and SO$_2$(0.62$\pm$0.63 ppb) are lower than those at great cities. So we concluded that there are a few primary sources emitting atmospheric pollutants. The concentration of EC is higher and the concentration of OC is similar with or higher than those at other background sites. The recent EC concentration is higher than those measured before at Kosan. We concluded that there are more primary sources than other background sites and the amount of primary source have increased recently in Jeju. Backward trajectory and co..elation analysis were used to study where the air masses originated and distinguish the source of pollutants. While NO$_{x}$ and $O_3$ were mainly emitted and formed from Jeju inland area, concentrations of SO$_2$, OC and EC were affected by Asian Dust from China. Using the mean relative standard deviation of ozone, cleanness coefficient was obtained. The cleanness coefficient value, is 1.6 times larger than the value in 1992. Recently, the air quality of Kosan has been contaminated because of the Asian Dust events since spring and the rapid industrialization development.pment.

• Asian Journal of Atmospheric Environment
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• 제11권3호
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• pp.165-175
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• 2017

In Japan, the primary carbonaceous particles emitted from motor vehicles and waste incinerators have been reduced due to strict regulations against exhaust gas. However, the relative contribution of carbonaceous particles derived from plants and biomass has been increasing. Accordingly, compositional analysis of carbonaceous particles has become increasingly important to determine the sources and types of particles produced. To reveal the sources of the organic particles contained in particulate matter with diameters of ${\leq}2.5{\mu}m$ ($PM_{2.5}$) and the processes involved in their generation, we analyzed molecular marker compounds (2-methyltetrols, cis-pinonic acid, and levoglucosan) derived from the plants and biomass in the $PM_{2.5}$ collected during daytime- and nighttime-sampling periods in summer (July and August) and autumn (November) in Kazo, which is in the northern area of Saitama prefecture, Japan. We also measured $^{14}C$ carbonaceous concentrations in the same $PM_{2.5}$ samples. The concentrations of 2-methyltetrols were higher in the summer than in the autumn. Because the deciduous period overlaps with this decrease in the levels of 2-methyltetrols, we considered the emission source to broad-leaved trees. In contrast, the emission source of the cis-pinonic acid precursor was considered to be conifers, because its concentration remained almost constant throughout the year. The concentration of levoglucosan was considerably increased in the autumn due to frequent biomass open burning. The ratio of plant-derived carbon to total carbon, obtained by measuring of $^{14}C$, in summer $PM_{2.5}$ sample was higher in the nighttime, and could be influenced by anthropogenic sources during the daytime.

• 한국환경과학회지
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• 제13권12호
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• pp.1089-1102
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• 2004

Seasonal variation of biogeochemical characteristics was determined in Lake Shihwa from October 2002 to August 2003. When the lake was artificially constructed for the freshwater reservoir in 1988, the development of the strong haline density stratification resulted in two-layered system in water column and hypoxic/anoxic environment prevailed in the bottom layer due to oxidation of accumulated organic matters in the lake. Recently, seawater flux to the lake through the sluice has been increased to improve water quality in the lake since 2000, but seasonal stratification and hypoxic bottom layer of the lake still developed in the summer due to the nature of artificially enclosed lake system. As the lake is still receiving tremendous amount of organic matters and other pollutants from neighboring streams during the rainy summer season, limited seawater flux sluicing into the lake may not be enough for the physical and biogeochemical mass balance especially in the summer. The excess of accumulated organic matters in the bottom layer apparently exhausted dissolved oxygen and affected biogeochemical distributions and processes of organic and inorganic compounds in the stratified two-layered environment in the summer. During the summer, ammonia and dissolved organic carbon remarkably increased in the bottom layer due to the hypoxic/anoxic condition in the bottom layer. Phosphate also increased as the result of benthic flux from the bottom sediment. Meanwhile, dissolved organic carbon showed the highest value at the upstream area and decreased along the salinity gradient in the lake. In addition to the sources from the upstream, autochthonous origin of particulate organic carbon from algal bloom in the lake might be more important for sustaining aggravated water quality and development of deteriorated bottom environment in the summer. The removal of trace metals could be attributed to scavenging by strong insoluble metal-sulfide compounds in the hypoxic/anoxic bottom layer in the summer.

• 대한환경공학회지
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• 제33권3호
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• pp.202-211
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• 2011

본 연구는 소양호를 대상으로 장기간 동안 다매체 내 수은 농도 분포를 조사하였으며 소양호 총수은(TM; total mercury) 농도는 $1.17{\pm}1.09ng/L$ 나타났다. 표층수 총 수은 농도를 보면 시간적 및 공간적 변이에 대한 통계적 유의성을 찾아볼 수 없었으나, 탁도 및 입자성 유기탄소(particulate organic carbon; POC)의 농도와 뚜렷한 양의 상관성(P-value<0.01)이 있는 것으로 관측되었다. 또한 소양호의 경우 수은 유입원이 선행연구에서 언급된 대기 침적보다는 장마철 runoff로 인한 유입이 더 중요하다는 것을 나타낸다. 어류 내 수은은 한강과 소양호에서 총 22종의 어류를 채취하였으며, 어류 내 평균 총수은 농도는 0.073 ppm(습중량)으로 나타나, 우리나라의 기준치(0.5 ppm) 및 미국 EPA의 기준치(0.3 ppm)에 비해 낮은 농도를 보였다. 그러나 미국 EPA의 RfD(reference dose)를 바탕으로 본 연구에서 계산된 적정 기준치인 0.07 ppm을 상회하는 어류가 전체의 42%를 차지해 우리나라만의 어류섭취 관리대책이 필요하다. 어류를 채취한 세 지점, 한강, 신이리, 양구는 동일한 종에서 뚜렷하게 다른 농도 분포를 보였는데, 상류일수록 더 높은 농도를 나타냈다. 이는 호수의 부영양화 차이로 인한 지점별 어류 성장 속도의 차이가 원인인 것으로 생각된다. 소양호 저서퇴적물의 수은 농도 분포는 $69.9{\sim}98.3{\mu}g/kg$으로 나타나 미국 미네소타 주의 Voyageurs National Park에서의 연구 결과($102{\sim}364{\mu}g/kg$)보다 약간 낮게 나타났다.

• 한국환경농학회지
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• 제35권2호
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• pp.128-136
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• 2016

BACKGROUND: Hydrothermal carbonization reaction is the thermo-chemical energy conversion technology for producing the solid fuel of high carbon density from organic wastes. The hydrothermal carbonization reaction is accompanied by the thermal hydrolysis reaction which converse particulate organic matters to soluble forms (hydro-thermal hydrolysate). Recently, hydrothermal carbonization is adopted as a pre-treatment technology to improve anaerobic digestion efficiency. This research was carried out to assess the effects of hydro-thermal reaction temperature on the methane potential and anaerobic biodegradability in the thermal hydrolysate of organic sludge generating from the wastewater treatment plant of poultry slaughterhouse .METHODS AND RESULTS: Wastewater treatment sludge cake of poultry slaughterhouse was treated in the different hydro-thermal reaction temperature of 170, 180, 190, 200, and 220℃. Theoretical and experimental methane potential for each hydro-thermal hydrolysate were measured. Then, the organic substance fractions of hydro-thermal hydrolysate were characterized by the optimization of the parallel first order kinetics model. The increase of hydro-thermal reaction temperature from 170℃ to 220℃ caused the enhancement of hydrolysis efficiency. And the methane potential showed the maximum value of 0.381 Nm³ kg^-1-VS_added in the hydro-thermal reaction temperature of 190℃. Biodegradable volatile solid(VSB) content have accounted for 66.41% in 170℃, 72.70% in 180℃, 79.78% in 190℃, 67.05% in 200℃, and 70.31% in 220℃, respectively. The persistent VS content increased with hydro-thermal reaction temperature, which occupied 0.18% for 170℃, 2.96% for 180℃, 6.32% for 190℃, 17.52% for 200℃, and 20.55% for 220℃.CONCLUSION: Biodegradable volatile solid showed the highest amount in the hydro-thermal reaction temperature of 190℃, and then, the optimum hydro-thermal reaction temperature for organic sludge was assessed as 190℃ in the aspect of the methane production. The rise of hydro-thermal reaction temperature caused increase of persistent organic matter content.