• Title/Summary/Keyword: Seasonal flux

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Effect of Rice Cultural Patterns on Methane Emission from a Korean Paddy Soil (벼 재배양식(栽培樣式)이 메탄가스 배출에 미치는 영향(影響))

  • Lee, Kyeong-Bo;Lee, Deog-Bae;Kim, Jong-Gu;Kim, Yong-Woong
    • Korean Journal of Soil Science and Fertilizer
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    • v.30 no.1
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    • pp.35-40
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    • 1997
  • This study was conducted to investigate methane emission under different rice cultural practices in paddy soil (Jeonbug Series, occurring on fluvio-alluvial plain). The rates of application of fresh rice straw were 5,000kg/ha in combination with 110 and 160kg N/ha as chemical fertilizer. The methane emission among the rice cultural practices was in the order of transplanting cultivation, direct seeding on flooded surface and direct seeding on dry paddy field. The average methane flux was $10.27mg/m^2/h$ in direct, seeding on dry paddy field and $24.1mg/m^2/h$ in transplanting cultivation. The diurnal variation of methane emission at heading stage was high from 9 a.m. till 7 p.m. and the methane emission rate was highly correlated with air temperature fluctuation and soil Eh. The seasonal change of methane flux was high from ear formation stage to heading stage.

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Chemical Composition of Rainwater in Chonju-city, Korea (전주시에서 채수된 강수의 화학적 조성)

  • 나춘기;정재일
    • Journal of Korean Society for Atmospheric Environment
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    • v.13 no.5
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    • pp.371-381
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    • 1997
  • Precipitation sampls were collected in Chonju-city during October 1994 to September 1995 and were analysed for major ions (N $a^{+}$, $K^{+}$, $Ca^{2+}$, $Mg^{2+}$, C $l^{[-10]}$ , NO/$_3$, S $O_4$$^{2-}$) and trace metals (Al, Cd, Ni, Pb, Sr, Zn) in addition to pH, in order to understand the chemical characteristics of acid rain and to estimate the origin of the determined ions. Most rain showed a neutral or alkaline character, and only 35% had a pH lower than 5.6. S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ are identified as the primary contributors to precipitation acidity in this region. Neutralization of precipitation acidity occurs as a result of the dissolution of alkaline compounds containing $Ca^{2+}$, $Mg^{2+}$ and $K^{+}$. S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ precipitation concentrations exhibit a seasonal pattern in which higher concentrations are observed during spring months and lower concentrations during summer months. However, the seasonal behavior of $H^{+}$ concentrations differs from this pattern, in that the highest concentrations occur during autumn months, owing to the different influence of neutralization processes. In all rain, S $O_4$$^{2-}$ concentration exceeded NO/$_3$$^{[-10]}$ concentration. The contribution of maritime sources to the total S $O_4$$^{2-}$ concentration was very low or negligible. For rain strongly affacted by yellow sand, $Ca^{2+}$, $Mg^{2+}$ and $K^{+}$ ions show a sharp increase in concentration, reflecting the increased amount of dust and soil suspended in atmosphere. At the same time, S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ concentrations are at their highest levels while $H^{+}$ values are not comparably elevated, presumably beacause much of the acidity has been neutralized by alkaline substances. The seasonal variance of trace metal concentrations in rainwater is similar to that of major cations. The annual wet flux of acidic pollutants and trace metals wat calculated to be as follows: N $O_3$$^{[-10]}$ ; 2.32 g/$m^2$, S $O_4$$^{2-}$, 5.34 g/$m^2$, Al; 6.30 mg/$m^2$, Cd; 0.62 mg/$m^2$, Ni; 4.08 mg/$m^2$, Pb: 9.76 mg/$m^2$, Sr; 5.94 mg/$m^2$, Zn; 111 mg/$m^2$./$m^2$.

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Mass Balance of Salts, DIP, DIN and DON in the Gomso Tidal Flat (곰소만 조간대에서 Salts, DIP, TDN의 물질 수지)

  • Jeong Yong-Hoon;Kim Yeong-Tae;Kim Ki-Hyun;Kim Soh-Young;Kim Byung-Hoon;Yang Jae-Sam
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.11 no.2
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    • pp.68-81
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    • 2006
  • As one of the on-going projects to investigate the biogeochemical characteristics of tidal flat, we develop seasonal mass balance calculations (or DIP, DIN and DON in Gomso Bay. We have obtained 13-hours time-series data of salinity, tidal current, nutrients, and chlorophyll-a of seawater for spring, dry summer, rainy summer and winter during $1999{\sim}2000$. DIP of $-1.10{\times}10^6g\;P\;day^{-1},\;-4.50{\times}10^5g\;P\;day^{-1}$ was out-fluxed from the bay to the bay proper for spring and dry summer, respectively. Whereas $1.06{\times}10^4g\;P\;day^{-1}$ of net influx of DIP was found during winter and $2.72{\times}10^6g\;P\;day^{-1}$ of net influx was also found during the rainy summer. Therefore we suggest the role of Gomso tidal flat as a source of DIP fur the seasons of spring and summer, but as an opposite role during the rainy summer and winter but much smaller in magnitude. Except winter, the advection process by tidal current is found the most dominant flux among the diverse fluxes of DIP in the bay. Whereas ground water is estimated as the strongest flux of TDN except winter. TDN of $1.38{\times}10^7g\;N\;day^{-1},\;2.45{\times}10^6g\;N\;day^{-1},\;and\;4.65{\times}10^7g\;N\;day^{-1}$ was in-fluxed to the bay from the bay proper far spring, rainy summer and summer, respectively. Only $-1.70{\times}10^7g\;N\;day^{-1}$ of net out-flux was found during the winter. Therefore we suggest the role of Gomso tidal flat as a sink of TDN far the year round except winter.

Design of Residual Treatment Process with Filter Backwash Recycle System (역세척수 회수시스템이 포함된 배출수처리공정의 설계)

  • Bae, Byung-Uk;Choi, Kyung-Hwan
    • Journal of Korean Society on Water Environment
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    • v.28 no.1
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    • pp.109-114
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    • 2012
  • In this study, both sedimentation and thickening experiments were conducted for residuals produced from an advanced water treatment plant for more accurate and practical design of residual treatment train. In order to design a backwashed residual sedimentation basin (SRSB) in the filter backwash water recycle system, two kinds of backwash waters, one from sand filter (SFBW) and the other from GAC adsorption bed (GACBW), were separately collected and their surface loading rate measured. In addition, in order to design a gravity thickener, batch thickening tests were conducted for concentrated residuals taken from sedimentation basin and their limiting solid flux ($SF_{L}$) measured. From the experimental results and consideration of the seasonal characteristics of the residual, surface loading rate of $70m^{3}/m^{2}{\cdot}d$ was proposed as a design parameter for SRSB and solid loading rate of 20 kg $TS/m^{2}{\cdot}d$ was proposed as a design parameter for gravity thickeners. Finally, the material mass-balance was made for the design of each unit process in the residual treatment train.

Net Ecosystem Productivity Determined by Continuous Measurement Using Automatic Sliding Canopy Chamber

  • Kim, Gun-Yeob;Lee, Seul-Bi;Lee, Jong-Sik;Choi, Eun-Jung
    • Korean Journal of Soil Science and Fertilizer
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    • v.45 no.6
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    • pp.1179-1186
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    • 2012
  • For better understanding of carbon cycle dynamics of an agro-ecosystem, an accurate assessment of seasonal and daily $CO_2$ flux is essential to understand the relationship between various environmental factors and crop productivity. We developed the automatic sliding canopy chamber (ASCC) system that measured continuous net ecosystem productivity (NEP) over whole growing season under the natural meteorological rhythm. The ASCC was composed of two main parts which were sliding part for measuring NEP, and automatic opening and closing chamber (AOCC) for measuring soil respiration (SR) on the soil surface. The ASCC was developed by using open flow method for measuring soil $CO_2$ efflux. The disturbance of natural meteorological condition was minimized by opening the base frames. In the field test with barley (Hordeum vulgare L.), NEP was calculated at $140mg\;CO_2\;m^{-2}h^{-1}$ on a clear day using continuous data and eliminated the possibility of overestimate about 16% using one hour data during the day time. Unlike other small scale chamber system, installation on cropping-field made it possible to take any modifications which might be caused by natural environmental condition.

Studies on Estimating Dry Deposition Velocities for Atmospheric Aerosol and Metal Elements in Korea (한국에서 분진 및 금속원소의 건식 침착속도 추정에 관한 연구)

  • 김성천;김동술
    • Journal of Korean Society for Atmospheric Environment
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    • v.12 no.1
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    • pp.101-112
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    • 1996
  • Dry and wet deposition is an impertant removal mechanism of the amobient aerosol in the atmospheric environment. Since the deposition flut provides adverse impacts on various encironmental media including aquatic and ecological system as well as human health, it is essential to quantitatively estimate the removal fluxes of many air pollutants. Thus, the purposes of this experimental study are to investigate seasonal deposition flux variations of the total dustfall and various inorganic elements in the local ambient air and then to finally estimate their dry deposition velocities. To perform the study, the total of 90 dustfall samples were collected from January, 1994 thru February, 1995 in 5 different cities of Korea including Seoul, Suwon, Daejon, Kwangju, and Kangrung. Each sample was analyzed by an AAS and an ICP to determine the quantities of the 11 inorganic elements, such as Zn, Cd, Cr, K, Na, Pb, Ca, Fe, Mn, Mi, and Cu. As results, deposition fluxes, soluble/insoluble fractions, and deposition velocities for each element were extensively investigated. The resulting dry deposition velocities of some elements in Suwon were estimated by ranges of 0.57 .sim. 0.87 cm/sec for Zn, 0.35 .sim. 0.45 cm/sec for Pb, 1.25 .sim. 3.52 cm/sec for Ca, 0.21 .sim. 0.48 cm/sec for Fe, 0.95 .sim. 9.31 cm/sec for Mn, and 2.08 cm/sec for Cu.

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Sensitivity of Indian Summer Monsoon Precipitation to Parameterization Schemes

  • Singh, G.P.
    • The Korean Journal of Quaternary Research
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    • v.24 no.1
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    • pp.1-10
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    • 2010
  • The Indian summer monsoon behaved an abnormal way in 2002 and as a result there was a large deficiency in precipitation (especially in July) over a large part of the Indian subcontinent. For the study of deficient monsoon of 2002, a recent version of the NCAR regional climate model (RegCM3) has been used to examine the important features of summer monsoon circulations and precipitation during 2002. The main characteristics of wind fields at lower level (850 hPa) and upper level (200 hPa) and precipitation simulated with the RegCM3 over the Indian subcontinent are studied using different cumulus parameterization schemes namely, mass flux schemes, a simplified Kuo-type scheme and Emanuel (EMU) scheme. The monsoon circulation features simulated by RegCM3 are compared with the NCEP/NCAR reanalysis and simulated precipitation is validated against observation from the Global Precipitation Climatology Centre (GPCC). Validation of the wind fields at lower and upper levels show that the use of Arakawa and Schubert (AS) closure in Grell convection scheme, a Kuo type and Emanuel schemes produces results close to the NCEP/NCAR reanalysis. Similarly, precipitation simulated with RegCM3 over different homogeneous zones of India with the AS closure in Grell is more close to the corresponding observed monthly and seasonal values. RegcM3 simulation also captured the spatial distribution of deficient rainfall in 2002.

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Simulation of anomalous Indian Summer Monsoon of 2002 with a Regional Climate Model

  • Singh, G.P.;Oh, Jai-Ho
    • The Korean Journal of Quaternary Research
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    • v.22 no.1
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    • pp.13-22
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    • 2008
  • The Indian summer monsoon behaved in an abnormal way in 2002 and as a result there was a large deficiency in precipitation (especially in July) over a large part of the Indian subcontinent. For the study of deficient monsoon of 2002, a recent version of the NCAR regional climate model (RegCM3) has been used to examine the important features of summer monsoon circulations and precipitation during 2002. The main characteristics of wind fields at lower level (850 hPa) and upper level (200 hPa) and precipitation simulated with the RegCM3 over the Indian subcontinent are studied using different cumulus parameterization schemes namely, mass flux schemes, a simplified Kuo-type scheme and Emanuel (EMU) scheme. The monsoon circulation features simulated by RegCM3 are compared with the NCEP/NCAR reanalysis and simulated precipitation is validated against observation from the Global Precipitation Climatology Centre (GPCC). Validation of the wind fields at lower and upper levels shows that the use of Arakawa and Schubert (AS) closure in Grell convection scheme, a Kuo type and Emanuel schemes produces results close to the NCEP/NCAR reanalysis. Similarly, precipitation simulated with RegCM3 over different homogeneous zones of India with the AS closure in Grell is more close to the corresponding observed monthly and seasonal values. RegcM3 simulation also captured the spatial distribution of deficient rainfall in 2002.

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A study of seasonal variation of the residual flow before and after Saemangeum reclamation (새만금간척전후의 잔차류의 계절변화에 관한연구(농지조성 및 농어촌정비))

  • 신문섭
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 2000.10a
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    • pp.47-53
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    • 2000
  • Saemangeum coastal area is being constructed the 33km sea dike and 40,000ha reclamation area. The purpose of this study is to find the residual circulations in spring before and after the dike construction by a robust diagnostic and prognostic numerical model. Heat flux at the sea surface in May was adopted on the basis of the daily inflow of solar radiation at the earth surface, assuming an average atmospheric transmission and no clouds, as a function of latitude and time of year(George L.P.,J. E. William,1990). The discharge from the Geum, the Mankyung and the Dongjin rivers was adopted on the basis of experience formula of river flow in May(The M. of C.,Korea, 1993). Water temperature and salinity along the open boundaries are obtained from the results of field observations. The results of spring of the residual flow in the Saemangeum coastal area by a prognostic numerical model lead to the following conclusions: Water temperature in spring is the highest, salinity is the lowest and density is the lowest at the upper layer near the coast after the dike construction. The flow pattern at the upper layer during spring is anti-clockwise circulation between Wi and Shinsi islands. The flow pattern at the lower layer is clockwise circulation between Wi and Shinsi islands.

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Behavior of Hydrogen and Organic Acids in Anaerobic Digestion of Food Wastewater (음폐수의 혐기성 소화 시 수소 및 유기산의 거동)

  • Cho, Kyungmin;Oh, Saeeun
    • New & Renewable Energy
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    • v.18 no.2
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    • pp.9-17
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    • 2022
  • In this study, we used the Flux Balance Analysis (FBA) program to examine the behavior of hydrogen and organic acids according to seasonal changes in food wastewater collected from D city. The results showed that average hydrogen conversion rates in spring, summer, autumn, and winter were 1.06, 0.71, 1.21, and 1.13 mol H2/mol of hexoseadded, respectively, indicating a significantly lower hydrogen conversion rate in summer than in other seasons. This phenomenon is believed to occur because the carbohydrate concentration of the incoming food wastewater is low. In addition, Lactobacillus, the lactic acid-producing bacterium, was 21.3% in spring, 27.2% in summer, 17.5% in autumn, and 22.6% in winter. The most distinctive feature of the microbial community in summer was that 15.3% of the Ilyobacter was analyzed. It was confirmed that Ilyobacter, which is involved in the production of acetic acid and propionic acid, is closely associated with the tendency of increasing acetic acid and propionic acid and thus contributes to organic acid change. Clostridium, a hydrogen-producing bacterium, was 76.2%, 50.8%, 78.3%, and 74%, in spring, summer, autumn, and winter, respectively. It was confirmed that Clostridium dominates the microbial community by approximately 70% or more in all seasons except summer.