• Journal of the korean society of oceanography
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• v.33 no.4
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• pp.157-167
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• 1998

The distribution of particulate organic carbon and nitrogen (POC and PON) and chlorophyll a of particulate organic matter was investigated in the southwestern East Sea in August and October 1995. The upwelled 'cold water mass' with temperature less than 14$^{\circ}$C occurred near the Campo coast in August. At most of the onshore stations, concentrations of POC and PON were high in surface water, rapidly decreased with depth down to 30 m and then remained constant. Differences in their concentrations between surface and bottom waters were larger in August than in October. At the offshore stations, POC and PON were higher in surface than in deep waters though the differences in concentration were small. The highest, vertically integrated inventories of POC, PON and phytoplanktonic carbon in the upper mixed waters of the onshore stations occurred in August. The mixed layers at onshore stations showed relatively high percentages of POC, PON and chlorophyll a in total suspended matter, low ratios of POC to chlorophyll a and high inventories of phytoplanktonic carbon, compared with the values at offshore stations. These phenomena were more obvious in August, when cold water mass developed strongly, than in October. These results indicate that primary production plays a significant role for the budget of particulate organic matter in the upwelled cold water mass of the southwestern East Sea.

• Korean Journal of Environmental Agriculture
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• v.39 no.3
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• pp.237-245
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• 2020

BACKGROUND: The closed chamber method is the most commonly used for measuring greenhouse gas emissions from upland fields. This method has the advantages of being simple, easily available and economical. However, uncertainty estimation is essential for accurate assessment of greenhouse gas emissions and verification of emission reductions. The nitrous oxide emissions from upland field is very important for the nitrogen budget in the agriculture sectors. Although assessment of uncertainty components affecting nitrous oxide emission from upland field is necessary to take account of dispersion characteristics, research on these uncertainty components is very rare to date. This study aims at elucidation of influencing factors on measurement uncertainty of nitrous oxide concentrations measured by an automated open closed chamber method from upland field. METHODS AND RESULTS: The nitrous oxide sampling system is located in the upland field in Gyeonggi-do Agricultural Research and Extension Services (37°13'22"N, 127°02'22"E). The primary measurement uncertainty components influencing nitrous oxide concentrations (influencing factors) investigated in this research are repeatability, reproducibility and calibration in the aspects of nitrous oxide sampling and analytical instrumentation. The magnitudes of the relative standard uncertainty of each influencing factor are quantified and compared. CONCLUSION: Results of this study show what influencing factors are more important in determination of nitrous oxide concentrations measured using the automated open closed chambers located in the monitoring site. Quantifying the measurement uncertainty of the nitrous oxide concentrations in this study would contribute to improving measurement quality of nitrous oxide fluxes.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.3
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• pp.221-231
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• 1993

WASP4. an estuarine or lake water quality model, wat applied to simulate future water qualities at alternative withdrawal sites for capital areas. Simulated water quality constituents were Chlorophyll a, nitrogen cycles, Phosphorus, BOD End DO. A Water budget analysis Using the monthly records of reservoir inflows and outflows between 1986 and 1990 was made to determine seasonally-averaged flowrates at model boundaries. Estimated flowrates were used. together with the seasonal water quality inputs simulated by the QUAL2E model, for the simulation of future water qualities. Sensitivities to the future pollutant inputs and possible future withdrawal alternatives were also analyzed. From simulations or future water qualities it is found that among the candidate withdrawal sites. the one located at the downstream end of the North Han River has the best future water quality in all quality constituents and the one at the downstream end of the South Han River has the worst Possible future withdrawal from the North Han River brings a slight increase or pollutant concentrations at existing withdrawal sites. but the aggravation of water quality is not significant.

• Journal of Korean Society for Atmospheric Environment
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• v.10 no.E
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• pp.311-324
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• 1994

The quantitative knowledge of N $O_{\gamma}$ (＝N $O_{x}$ ＋HN $O_3$＋/PAN＋N $O_3$ ＋$N_2$ $O_{5}$ ＋HN $O_2$＋N $O_3$$^{-10}$ ＋organic nitrates＋......)distribution is essential in tropospheric chemistry, especially, especially that related to understanding the processes leading to ozone production. Ambient concentrations of NO, N $O_2$, HN $O_3$ and PAN as well as total N $O_{\gamma}$ were measured during June and early July 1992 at a rural site(Candor, NC), in the central Piedmont region of NC. The measurements of N $O_{\gamma}$ species were made in an effort to provide a comprehensive understanding of nitrogen chemistry and to investigate the total nitrogen budget at the site. N $O_{\gamma}$, N $O_2$, and NO showed diurnal variations with maxima in the morning. The maximum N $O_{\gamma}$ concentration reached was 14.5 ppbv, and the maximum concentrations of NO and N $O_2$ were 5.4 and 7.8 PPbv, respectively. The mean N $O_{\gamma}$ concentration as found to be 2.88$\pm$1.58 ppbv(n=743). The mean concentrations of NO and N $O_2$, were found to be 0.15 $\pm$ 0.29 ppbv(n＝785) and 1.31 $\pm$ 0.99 ppbv(n＝769). Products of photochemical oxidants, (N <$O_{\gamma}$-N $O_{x}$ ), such as HN $O_3$ and PAN, as well as ozone showed diurnal variation with maxima in the afternoon and minima at night The fractions of individual reactive nitrogen species to total N $O_{\gamma}$ were investigated and contrasted to the results from remote marine site and rural continental sites. N $O_{x}$ was the major species to total N $O_{\gamma}$(45%). NO concentrations appeared to be nearly constant whether the Prevailing winds were from continental areas or from oceanic areas. Linear regression of $O_3$ with (N $O_{\gamma}$- N $O_{x}$ )/N $O_{\gamma}$ (i.e. percent N $O_{x}$ converted to the photochemical products of N $O_{\gamma}$) yielded ( $O_3$) ＝25.8 〔 N $O_{\gamma}$-N $O_{x}$ 〕/(N $O_{\gamma}$) ＋27, ( $r^{2}$＝0.58). The regression intercept is interpreted as the ozone back ground (intercept=27ppbv) and the slope suggests that 8.6 molecules of ozone are formed per molecule of N $O_{x}$ oxidized products (when the average N $O_{\gamma}$ concentration, about 3 ppbv at the site, is used). The N $O_{x}$ N $O_{\gamma}$ ratio was used as an indicator of the chemical age of airmasses and the ratio showed strong positive correlations with HN $O_3$( $r^{2}$=0.58), PAN ( $r^{2}$=0.46) and $O_3$( $r^{2}$=0.62). Larger N $O_{\gamma}$ and N $O_{x}$ N $O_{\gamma}$ ratio were found when winds came from continental sides. It may suggest that synoptic meteorological conditions and transport of N $O_{x}$ are important in the distribution of N $O_{\gamma}$ and its relationship with photochemical oxidants at the site.

• Korean Journal of Environmental Agriculture
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• v.27 no.4
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• pp.343-348
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• 2008

To investigate the effects of incorporation of green manures (GM) into a sandy loam soil on growth, yield, and nutrient uptake of tomato (Lycoperiscon esculentum Mill.) and nutrient balances (input minus offtake of nutrients), five tomato production systems were compared under the condition of plastic film house: 1) a no input system (no additional amendment or inputs, 0-To-0-To); 2) a conventional system (application of N-P-K chemical fertilizers, Cf-To-Cf-To); 3) a leguminous GM-containing system (hairy vetch-tomato-soybean-tomato, Hv-To-Sb-To); 4) a graminaceous GM-containing system (rye-tomato-sudan grass-tomato, Ry-To-Sd-To); and 5) system mixed with leguminous and graminaceous GMs (rye-tomatosoybean- tomato, Ry-To-Sb-To). Here, hairy vetch and rye were cultivated as winter cover crops during late $Dec{\sim}late$ Feb and soybean and sudan grass were cultivated as summer cover crops during late $Jun{\sim}mid$ Aug. All of them cut before tomato planting and then incorporated into soil. Biomass of GMs was greater in summer season than that of winter season. Nitrogen amount fixed by a leguminous plants was about $126\;kg\;ha^{-1}$ per a cropping season, corresponding to 60% N level needed for tomato production, which was comparable to 50 and $96\;kg\;ha^{-1}$ fixed by rye and sudan grass. As a result, tomato yield of Hv-To-Sb-To system (legume GM treatment) was similar to Cf-To-Cf-To (conventional), but that in Ry-To-Sd-To system (graminaceous GM treatment) was not attained to a half level of conventional treatment. Nutrient budgets for N, P and K on the conventional farm were balanced or somewhat positive exception for minus-balanced K. Ry-To-Sd-To system showed a positive N, P and K budgets due to the depressed growth of tomato which is caused by high C/N ratio and low N-fixing capacity of the GMs. Inversely, those of Hv-To-Sb-To system were negative in all of N, P and K budgets because of increased growth and yield of tomato with high nitrogen-supplying capacity as well as low C/N ratio of leguminous GM. In conclusion, although conventional cultivation has an advantage in relation to N, P and K nutrient budgets rather than GM-incorporated systems, a leguminous GMs could be recommended as nitrogen reservoir and soil amendment because the yield of tomato between use of leguminous GM and conventional cultivation was not only significantly difference, but also GMs commonly reduce nutrient loss and improve microbial communities.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.6
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• pp.708-722
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• 2016

Land-Ocean Interactions in the Coastal Zone (LOICZ) models for nutrient budgets were used to estimate the seasonal capacity of the Youngsan Estuary and Youngam-Geumho Estuary to sink and/or supply nutrients such as dissolved inorganic phosphorus (DIP) and nitrogen (DIN) to provide an understanding of the behavior of the coupled biogeochemical cycles of phosphorus and nitrogen in the estuaries (Youngsan Estuary, Youngam-Geumho Estuary) near Mokpo Harbor. During non-stratified periods (May, September, and November, 2008), simple three-box models were applied in each sub-region of the system, while a two-layer box model was applied during on-site observation of stratification development (July, 2008). The resulting mass-balance calculation indicated that even after large discharges from artificial lakes (in May and July), DIP influxes due to a mixing exchange ($V_{X-3}$, or $V_{deep}$) were more than terrigenous loads, indicating the backward transportation of nutrients from a marine source. The model results also indicated that for nutrient loads (DIP and DIN fluxes) in September, an extreme congestion of nutrients occurred around the mouths (sub-region III of the model) of the estuaries, possibly due to an imbalance in physical circulations between the estuaries and offshore locations. In November, the Youngam-Geumho Estuary, into which freshwater was discharged from artificial lakes (Youngam and Geumho Lake), showed nutrient enrichment in the water column, but the Youngsan Estuary showed nutrient depletion. In conclusion, to efficiently control water quality in the estuaries near Mokpo Harbor, integrated environmental management programs should be implemented. I.e., the reduction of nutrient loads from land basins as well as the deposit of nutrient loads into adjacent coastal lines.

• Korean Journal of Weed Science
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• v.30 no.4
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• pp.330-339
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• 2010

In order to suggest correct direction of researches on Miscanthus spp. which are promising bioenergy crop, authors had reviewed and summarized various literature about botanical taxonomy, morphology and present condition of breeding, cultivation and utilization of miscanthus. Among the genus of Miscanthus which are known 17 species, the most important species are M. sinensis and M. sacchariflorus which origin are East Asia including Korea, and M. x giganteus which is inter-specific hybrid of tetraploid M. sacchariflorus and diploid M. sinensis. Miscanthus is superior to other energy crops in resistance to poor environments including cold, saline and damp soil, nitrogen utilization efficiency, budget of input energy and carbon which are required for producing biomass and output which are stored in biomass. The major species for production of energy and industrial products including construction material in Europe, USA and Canada is M. x giganteus which was introduced from Japan in 1930s. In present, many breeding programs are conducted to supplement demerits of present varieties and to develop "Miscanes" which is hybrid of miscanthus and sugar cane. In Korea, the researches on breeding and cultivation of miscanthus were initiated in 2007 by collecting germplasms, and developed "Goedae-Uksae 1" which is high biomass yield and "mass propagation method of miscanthus" which can improve propagation efficiency in 2009. In order to develop "Korean miscanthus industry" in future, the superior varieties available not only domestic but also foreign market should be developed by new breeding method including molecular markers. Researches on production process of cellulosic bio-ethanol including pre-treatment and saccharification of miscanthus biomass also should be strengthen.