Deposition flux of dioxin-like polychlorinated biphenyls (DLPCBs) in urban environment of Busan

Moon, Hyo-Bang,Lee, Su-Jeong,Choi, Hee-Gu,Ok, Gon 한국환경과학회 2004 한국환경과학회지 Vol.13 No.5

Atmospheric bulk (wet and dry) samples were monthly collected in an urban environment (Daeyeon-dong) of Busan over a year, to assess the deposition flux and seasonality of dioxin-like polychlorinated biphenyls (DLPCBs) using stainless steel pots. Deposition fluxes of DLPCBs in bulk samples were determined using high resolution gas chromatography coupled to high resolution mass spectrometry (HRGC/HRMS). Particle deposition fluxes in the urban environment varied from 23 to 98 g/m²/year (mean 41 g/m²/year). DLPCB deposition fluxes in atmospheric bulk samples ranged from 0.09 to 0.77 ng-TEQ/m²/year (mean 0.35 ng-TEQ/m²/year). Seasonal atmospheric deposition fluxes of DLPCBs were high in winter and low in summer. Atmospheric deposition fluxes of particles and DLPCBs in this study were comparable to or slightly lower values than those of different locations in the world. Monthly DLPCB profiles in deposition bulk samples were similar over a year. Non-ortho PCBs were higher contributions to the total DLPCBs fluxes than mono-ortho PCBs. In particular, PCB 126 had the highest concentrartion (>75%) in all deposition samples, followed by PCB 169 and PCB 156. A highly positive correlation was found among the deposition fluxes of DLPCB species, suggesting the possibility of that the DLPCB contamination originated from one source. The deposition fluxes of DLPCBs were not significantly correlated with temperature and the amount of precipitation even though the summer season with the highest temperature and the largest amount of precipitation showed the lowest DLPCB deposition flux.

대전지역 자연환경림 관리 및 기능평가를 위한 물질순환 모델화

장관순(Gwan-Soon Jang),정헌준(Heon-Jun Jeong) 한국환경관리학회 2006 環境管理學會誌 Vol.12 No.1

대전지역에서 생물지화학적 물질순환 관점으로 대기오염물질이 생태계로 유입되는 강우(WD)로부터 시작하여 삼림수관으로 통과하는 임내우(TF)와 수간류(SF) 그리고 토양배출수(DS)로 거동하는 이온 flux를 측정하여 산성강하 물질에 대한 삼림의 산 정화능력을 평가하였다. 평가는 H?와 양이온 flux를 주요 인자로 취급하였고, 두개의 삼림지역에서 2002년 4월부터 12월까지 조사가 이루어졌다. 조사 기간동안, 활엽수림지역에서 H? flux는 WD가 0.1kmolc h?¹, TF+SF로는 0.03 이었으며, 양이온 flux는 WD가 1.96 kmolc ha?¹ 그리고 TF+SF로는 3.36으로 측정되어 WD로부터 유입된 H?는 수관을 통과하면서 0.07 kmolc ha?¹이 소비되었다. 반면에 수관으로부터 용탈되어 나온 양이온은 1.40kmolc ha?¹에 해당되었다. 침엽수림지역에서 H?의 유입량은 1.1 kmolc ha?¹, TF+SF로는 0.09로 측정되었고, 수관에 의한 H? 소비는 0.01 kmolc h?¹로서 활엽수림보다 약 7배 낮았다. 양이온 flux는 유입량이 2.05 kmolc h?¹, TF+SF에서는 2.93, 그리고 수관으로부터 용탈은 0.89 kmolc ha?¹로 활엽수림보다 낮았다. DS에 대한 양이온 flux는 침엽 수림지역에서 3.41kmolc ha?¹ 그리고 활엽수림지역에서 2.16으로 이들 지역에서 유입량 1.96~2.05 kmolc ha?¹보다 배출량이 많아 양이온 flux 수지는 모두 음(-)의 균형을 나타내고 있었다. 조사지역에서 보이는 있는 음(-)의 물질수지는 영양염류가 토양에 축적되는 것보다 토양으로부터 유실되는 양이 더 많아 산성강하물에 의한 토양산성화를 방지하고 토양 양료보전을 위한 노력이 필요함을 의미한다. To verify acid neutralization capacity against atmospheric deposition in two forest ecosystem, Taejeon, biogeochemical proton and base cation fluxes were estimated using data on wet deposition(WD), throughfall(TF), stemflow(SF), and discharge from soils(DS) from April to December 2002. In deciduous ecosystem during investigation period, proton flux was 0.1 kmolc ha?¹ for WD, 0.03 for TF+SF, and base cation flux was 1.96 kmolc ha?¹ for WD, 3.36 for TF+SF, indicating that atmospheric acid input was neutralized through forest canopy. In deciduous canopy proton consumption was 0.07 kmolc ha?¹ and net canopy leaching of base cation was 1.40 kmolc ha?¹. In coniferous ecosystem, proton flux was kmolc ha?¹ for WD, 0.09 for TF+SF and base cation flux was 2.05 kmolc ha?¹ for WD, 2.93 for TF+SF. Proton consumption in coniferous canopy appeared 7 times lower than one in deciduous canopy and net canopy leaching of base cation was 0.89 kmolc ha?¹, indicating that acid neutralization capacity for atmospheric acid input in two forest ecosystem excelled in decidous ecosystem. DS fluxes in deciduous and in coniferous were 3.4 1kmolc ha?¹ and 2.16 kmolc ha?¹, respectively and base cation budgets in two ecosystem showed negative balance of loss nutrient element from soil.

Measurement of Atmospheric Dry Deposition and Size Distribution of Particulate PCBs in 1999 at Seoul

Park, Seong-Suk,Shin, Hye-Joung,Yi, Seung-Muk,Kim, Yong-Pyo Korean Society for Atmospheric Environment 2006 한국대기환경학회지 Vol.22 No.E1

Ambient particle size distributions of PCBs and their dry deposition fluxes were measured at a site in Seoul to quantify dry deposition fluxes of PCBs and size characteristics of PCBs in the air, and to estimate ambient concentrations of gaseous PCBs and dry deposition fluxes. The dry deposition plate was used to measure dry deposition fluxes of particulate mass and PCBs and a cascade impactor and rotary impactor were used to measure ambient particle size distributions for small ($D_p<9{\mu}m$) and large ($D_p>9{\mu}m$) particles, respectively. Six sample sets were collected from April to July 1999. The fluxes of particulate total PCBs (the sum of 43 congeners) ranged from 160 to $607ng\;m^{-2}day^{-1}$. The size distribution of total PCBs was bimodal with two peaks in small particle size ($D_p{\sim}0.6\;and\;6{\mu}m$, respectively) and, thus, mass concentration being dominant in small particles. The mean particulate PCBs concentration was $6.9{\mu}g$ PCBs/g. The concentrations of PCB homologues in the gas phase were estimated based on the particle/gas partition coefficient ($K_p$) with the measured values of particulate PCBs in this study and they were comparable to those observed in other previous studies. Dry deposition fluxes were estimated by calculating dry deposition velocities.

Wet Deposition Fluxes of Ions Contributed by Cyclone-, Stationary Front- and Typhoon-associated Rains at the Southwestern Japan Coast

Satoshi Toyonaga,Daizhou Zhang 한국대기환경학회 2016 Asian Journal of Atmospheric Environment (AJAE) Vol.10 No.2

Wet deposition fluxes of ions at a coastal site in southwestern Japan in the period 1996-2003 were investigated to quantify the respective contributions of cyclone-, stationary front- and typhoon-associated rains. On average, the deposition fluxes of terrigenous- origin ions, nss-SO4 2-, NO3 -, NH4 + and nss-Ca2+ were 37.6±7.3, 16.3±4.2, 19.0±3.4 and 9.6±4.8 meq m-2 yr-1, and those of Na+ and Cl-, the major ions in sea water, were 97.0±38.2 and 115.2±48.2 meq m-2 yr-1, respectively. Cyclone-associated rain constituted more than 50% of the fluxes of the terrigenous ions in almost all years. Stationary frontassociated rain also contributed significantly, although the contribution was lower than the contribution by Cyclone-associated rain in almost all years. In particular, the wet deposition flux of nitrogen compounds of NO3 - and NH4 +, which are important nutrients for micro-bioactivities in sea surface water, was dominated by cyclone-associated rain. Due to the extreme abundance of Na+ and Cl- in the rainwater of typhoons, the fluxes of Na+ and Cl- were contributed substantially by typhoons in years with typhoons’ passage although cyclones were still the largest contributor to the fluxes. These results indicate the dominance of cyclones in the wet deposition to the East China Sea areas and the necessity to take rain types into account for a more accurate elucidation of the temporal and spatial variation of the wet deposition.

Wet Deposition Fluxes of Ions Contributed by Cyclone-, Stationary Front- and Typhoon-associated Rains at the Southwestern Japan Coast

Toyonaga, Satoshi,Zhang, Daizhou Korean Society for Atmospheric Environment 2016 Asian Journal of Atmospheric Environment (AJAE) Vol.10 No.2

Wet deposition fluxes of ions at a coastal site in southwestern Japan in the period 1996-2003 were investigated to quantify the respective contributions of cyclone-, stationary front- and typhoon-associated rains. On average, the deposition fluxes of terrigenous-origin ions, nss-$SO_4{^{2-}}$, $NO_3{^-}$, $NH_4{^+}$ and nss-$Ca^{2+}$ were $37.6{\pm}7.3$, $16.3{\pm}4.2$, $19.0{\pm}3.4$ and $9.6{\pm}4.8meq\;m^{-2}yr^{-1}$, and those of $Na^+$ and $Cl^-$, the major ions in sea water, were $97.0{\pm}38.2$ and $115.2{\pm}48.2meq\;m^{-2}yr^{-1}$, respectively. Cyclone-associated rain constituted more than 50% of the fluxes of the terrigenous ions in almost all years. Stationary front-associated rain also contributed significantly, although the contribution was lower than the contribution by Cyclone-associated rain in almost all years. In particular, the wet deposition flux of nitrogen compounds of $NO_3{^-}$ and $NH_4{^+}$, which are important nutrients for micro-bioactivities in sea surface water, was dominated by cyclone-associated rain. Due to the extreme abundance of $Na^+$ and $Cl^-$ in the rainwater of typhoons, the fluxes of $Na^+$ and $Cl^-$ were contributed substantially by typhoons in years with typhoons' passage although cyclones were still the largest contributor to the fluxes. These results indicate the dominance of cyclones in the wet deposition to the East China Sea areas and the necessity to take rain types into account for a more accurate elucidation of the temporal and spatial variation of the wet deposition.

기상요소에 의한 대기오염물의 건성침적량 추정 : 황산화물을 중심으로

박종길 인제대학교기초과학연구소 1998 자연과학 Vol.2 No.-

본 연구의 목적은 미국 플로리다 북중부 지방에 있는 G ainesville의 Austin Cary Forest에서 관측되어진 대기 오염물 (Sulfur dioxide, particulate sulfate)의 농도 특성을 밝히고자 하며 동일 지역에서 관측되어진 기상요소(1990. 7. ∼ 1991. 6)에 의한 대기 침적속도 및 플럭스를 Hicks 다층모델을 이용하여 추정하고자 한다. 연구 기간동안 추정된 연 평균 건성 침적속도는 SO₂(g)가 SO₄²-(s)0.860.07 [㎝/s]이며 SO₄²-(s)는 0.0980.014 [㎝/s]이였다. 일 평균 침적 속도의 경향은 하계에 크고 동계에 작아지는 계절적인 변화를 가지며 침적 속도의 월 평균 값은 큰 차이를 보이지 않으나, 하계에 증가하고 동계에 감소하는 경향을 보여준다. 건성 침적속도의 일변화는 일사량이 강한 한 낮에는 크며 밤에는 작아진다. 침적 Flux는 SO₂(g)가 SO₄²-(s)보다 크며 동계에 크게 나타났으나 SO₄²- 는 반대 경향을 나타내었다. The objectives of this paper are to analysis the characteristics of the concentration of air pollutant observed at the Gainesville, north central part of Florida, to estimate atmospheric deposition velocities and fluxes from the local meteological elements using the Hicks model that being compute from the concentration data and meteorological data observed at the same site. The model that was used for these calculations is the multiple layer resistance model developed by Hicks et al. [13, 14]. Meteorological data were recorded on an hourly basis from July, 1990 to June, 1991 at the Austin Cary forest site, near Gainesville FL. Or the study period at this site annual average dry deposition velocities were estimated to be: 0.860.07 [㎝/s] for SO₂(g) and 0.0980.014 [㎝/s] for SO₄²-(s). Trends observed in daily mean deposition velocities are largely seasonal, indicated by larger depositon velocities for the summer season and smaller deposition velocities for the winter season. Monthly averaged values for deposition velocities do not show large differences over the year but do show a tendency for increased deposition velocities in summer and decreased values in winter. Diurnal variations of dry deposition velocities show large deposition velocities for strong solar irradiance during day time and small depositon velocities at night.

Characteristics of total mercury (TM) wet deposition: Scavenging of atmospheric mercury species

Seo, Y.S.,Han, Y.J.,Choi, H.D.,Holsen, T.M.,Yi, S.M. Pergamon Press ; Elsevier [distribution] 2012 Atmospheric environment Vol.49 No.-

Total mercury (TM) in precipitation samples were collected with a modified MIC-B sampler on the roof of Graduate School of Public Health building in Seoul, Korea from January 2006 to December 2007 to determine the seasonal variations in TM wet deposition and to identify the contribution of reactive gaseous mercury (RGM) and particulate mercury (Hg<SUB>p</SUB>) scavenging to mercury wet deposition. The volume weighted mean (VWM) TM concentrations in 2006 and 2007 were 10.1+/-17.0ngL<SUP>-1</SUP> and 16.3+/-16.5ngL<SUP>-1</SUP>, respectively and the TM wet deposition flux in 2006 and 2007 were 16.8μgm<SUP>-2</SUP> and 20.2μgm<SUP>-2</SUP>, respectively. Seasonal VWM TM concentrations in 2006 were highest in fall followed by winter, spring, and summer. In 2007, VWM TM concentrations were greatest in winter, followed by spring, summer, and fall. Nonparametric Mann-Whitney test revealed that there was no statistical difference between fall and summer in 2006 (p=0.10), however, there was a statistical difference between winter and fall in 2007 (p<0.01). The high VWM TM concentration in spring was probably due to the yellow sand events suggesting that RGM and Hg<SUB>p</SUB> present in the rain were long-range transported from China during this period. The large wet deposition fluxes observed in summers were possibly due to the intense rainfall. Overall there was a significant positive correlation between rainfall depth and wet deposition flux (r<SUP>2</SUP>=0.22) (p<0.01) and a significant negative correlation between rainfall depth and TM concentration in precipitation (r<SUP>2</SUP>=0.20) (p<0.01) due to dilution effects. In addition, a weak positive correlation between TM concentration and wet deposition flux was shown (r<SUP>2</SUP>=0.10) (p<0.05). Multiple linear regression showed that scavenging coefficient (SC) for RGM was much higher than SC for Hg<SUB>p</SUB> suggesting that RGM was more effectively scavenged by wet deposition than Hg<SUB>p</SUB> (SC<SUB>RGM</SUB>=750 and SC<SUB>Hg'p</SUB>=380).

Effects of spray-deposited oxidized multi-wall carbon nanotubes and graphene on pool-boiling critical heat flux enhancement

박성식,김용환,전용한,현명택,김남진 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.24 No.-

This paper examines the differences in critical heat flux (CHF) based on multi-wall carbon nanotubes and graphene have been found as new heat-transfer materials which are carbon allotropes with different shapes. The analysis of experimental data and results of calculations in pool-boiling critical heat flux experiments by spray-depositing oxidized multi-wall carbon nanotubes and graphene onto heat- transfer samples have been done to improve the economic efficiency and safety of the heat-transfer apparatus. The results show that the contact angle of the heat-transfer surface linearly decreased with spray deposition time, which resulted in an increased critical heat flux. The oxidized multi-wall carbon nanotubes and graphene showed maximum pool-boiling heat-transfer coefficients at 19.88 and 21.78, respectively, while the pool-boiling heat-transfer coefficients decreased at angles of 9.98 or less and 12.58 or less, respectively. Also, the following new correction formula has been derived and compared with a current model by introducing a correction factor to Kandlikar’s prediction model.

Effect of Ionic Strength and Permeate Flux on Membrane Fouling: Analysis of Forces acting on Particle Deposit and Cake Formation

S Vigneswaran,권대영 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.6

In Cross-Flow Microfiltration (CFMF), suspended particles deposit to form a cake layer on the membrane surface, which provides a resistance to permeate flow. The cake resistance, which plays an important role on the performance of CFMF, is mainly determined by the packing porosity of the cake and, the physical and chemical properties of particles. This study aimed at understanding the porosity and the specific filtration resistance of the cake for a given condition. These properties have been studied using experiments under a constant permeate flux. Factors such as permeate flux and ionic strength were investigated in terms of the particles deposition and cake formation. This study also adopted a force balance model to predict the deposit rate of particles and then compare with the experimental results. Inter-particle forces (electric double layer repulsion force and Van der Waals attraction force) were incorporated into the calculation of cake structure (cake porosity and specific resistance) together with the equilibrium condition of hydrodynamic forces. The experimental results showed that the higher the permeate flux led to the greater amount of particles deposit and the denser structure of cake. The porosity of cake decreased with the increase in ionic strength (0~0.01M) and then increased sharply afterwards (0.01~0.1M). The hydrodynamic force balance model estimated well the tendency of variation in cake structure depending on the ionic strength.

나노유체의 풀비등 임계열유속에 대한 실험적 연구

김형대(Hyung Dae Kim),김무환(Moo Hwan Kim) 대한기계학회 2007 大韓機械學會論文集B Vol.31 No.11

Pool boiling critical heat flux (CHF) of nanofluids with oxide nanoparticles of TiO₂ or Al₂O₃ was experimentally investigated under atmospheric pressure. The results showed that a dispersion of oxide nanoparticles significantly enhances the CHF over that of pure water. Moreover it was found that nanoparticles were seriously deposited on the heater surface during pool boiling of nanofluids. CHF of pure water on a nanoparticle-deposited surface, which is produced during the boiling of nanofluids, was not less than that of nanofluids. The result reveals that the CHF enhancement of nanofluids is absolutely attributed to modification of the heater surface by the nanoparticle deposition. Then, the nanoparticle-deposited surface was characterized with parameters closely related to pool boiling CHF, such as surface roughness, contact angle, and capillary wicking. Finally, reason of the CHF enhancement of nanofluids is discussed based on the changes of the parameters.