팔당호로의 질소와 황성분 침적 측정

김영성,진현철 한국대기환경학회 2005 한국대기환경학회지 Vol.21 No.1

Nitrogen and sulfur deposition was measured on Lake Paldang from March 2002 to October 2003. Wet and dry depositions were separately measured using wet- and dry-only samplers, respectively. In order to measure the dry deposition to the water body, a dry deposition sampler composed of three pans filled with pure water, called the deposition water, was used. Since ammonium was generally in excess in ambient air, more than half of ammonium was present in the gaseous form. Ammonium concentration was also generally higher than the sum of major anion concentrations in the deposition water because gaseous species were much easily deposited than the species in fine particles. Nevertheless, the contribution of gaseous ammonia to the deposition of ammonium was not high as well as that of particulate ammonium while the contribution of gaseous nitric acid was much higher than that of particulate nitrate. Annual wet deposition fluxes of nitrogen and sulfur were five and six times higher than their dry deposition fluxes, respectively. Except for ammonium, the dry deposition flux estimated in the present work was a half of the previous results. This was mainly caused by much smaller dry deposition velocities over the water than over the ground.

Evaluate Dry Deposition Velocity of the Nitrogen Oxides Using Noah-MP Physics Ensemble Simulations for the Dinghushan Forest, Southern China

Qi Zhang,Ming Chang,Shengzhen Zhou,Weihua Chen,Xuemei Wang,Wenhui Liao,Jianing Dai,ZhiYong Wu 한국기상학회 2017 Asia-Pacific Journal of Atmospheric Sciences Vol.53 No.4

There has been a rapid growth of reactive nitrogen (Nr) deposition over the world in the past decades. The Pearl River Delta region is one of the areas with high loading of nitrogen deposition. But there are still large uncertainties in the study of dry deposition because of its complex processes of physical chemistry and vegetation physiology. At present, the forest canopy parameterization scheme used in WRF-Chem model is a single-layer “big leaf” model, and the simulation of radiation transmission and energy balance in forest canopy is not detailed and accurate. Noah-MP land surface model (Noah-MP) is based on the Noah land surface model (Noah LSM) and has multiple parametric options to simulate the energy, momentum, and material interactions of the vegetation-soil-atmosphere system. Therefore, to investigate the improvement of the simulation results of WRF-Chem on the nitrogen deposition in forest area after coupled with Noah-MP model and to reduce the influence of meteorological simulation biases on the dry deposition velocity simulation, a dry deposition single-point model coupled by Noah- MP and the WRF-Chem dry deposition module (WDDM) was used to simulate the deposition velocity (Vd). The model was driven by the micro-meteorological observation of the Dinghushan Forest Ecosystem Location Station. And a series of numerical experiments were carried out to identify the key processes influencing the calculation of dry deposition velocity, and the effects of various surface physical and plant physiological processes on dry deposition were discussed. The model captured the observed Vd well, but still underestimated the Vd. The self-defect of Wesely scheme applied by WDDM, and the inaccuracy of built-in parameters in WDDM and input data for Noah-MP (e.g. LAI) were the key factors that cause the underestimation of Vd. Therefore, future work is needed to improve model mechanisms and parameterization.

Effect of particle size on various substrates for deposition of NiO film via nanoparticle deposition system

Kim, H.,Yang, S.,Ahn, S.H.,Lee, C.S. Elsevier Sequoia 2016 THIN SOLID FILMS - Vol.600 No.-

We report the deposition mechanism of NiO particles using a nanoparticle deposition system. To understand the effects of particle size and substrates on the deposition, nano-, 100-nm-, sub-micro-, and micro-sized NiO particles were deposited on Si wafers, Ni-coated Si wafers, and fluorine-doped tin oxide (FTO)-coated glass. It was found that 100-nm- and nano-sized NiO particles were deposited, forming loosely compacted coating layers, by the breaking up of agglomerates, regardless of the type of substrate. In contrast, sub-micro- and micro-sized NiO particles formed dense and compact coating layers by deformation and fracturing on the Si and Ni-coated Si wafers. Moreover, sub-micro- and micro-sized NiO particles were not deposited on FTO glass; this was likely attributable to the NiO being harder than FTO glass and the micro-sized NiO particles would likely have rebounded on impact, resulting in no deposition. Thus, the deposition mechanism of NiO particles may be greatly related to the relative hardness difference between the NiO particles and the substrate. Moreover, it was found that different particle sizes resulted in different friction and mobility, based on response angle measurements, influencing the deposition mechanism(s), especially at the interface. When the particle size was greater than 100nm, the deposition was due primarily to deformation and fracturing during the collision with the substrate. In particular, the 100-nm-sized NiO particles showed both mechanisms, a two-step process, with deformation or fracturing at the interface between the substrate and particles, followed by a loosely compacted coating layer forming, preserving the original particle shape. Thus, it was confirmed that the 100-nm-sized NiO particles were at or near a boundary for deposition mechanisms. The effects of particle size and substrate for dry deposition were explained successfully by assessing the deposition behavior using analytical tools.

Substrate-dependent deposition behavior of graphite particles dry-sprayed at room temperature using a nano-particle deposition system

Nasim, Mohammad Nur E Alam Al,Chun, Doo-Man Elsevier 2017 Surface & coatings technology Vol.309 No.-

<P><B>Abstract</B></P> <P>This work demonstrates the effect of the substrate upon the deposition of graphite microparticles during thin film preparation at room temperature using a nanoparticle deposition system (NPDS). NPDS is a dry spray deposition method, whereby various metal and ceramic powders can be deposited at room temperature without the use of any binders. Graphite powder was deposited on various substrates of different hardness, namely polystyrene, copper, glass, and sapphire, and the substrate-dependent deposition behaviors were investigated. For the soft polystyrene substrate, graphite particles fragmented into small pieces during deposition, but retained the original graphite crystal structure. For the copper substrate, which is of intermediate hardness, some areas of the deposited film showed fragmented particles that had undergone interlayer separation to yield few-layer graphene flakes, but in other areas of the film a fragmented graphite structure was observed, of particles that did not undergo interlayer separation. In contrast, intense fragmentation and interlayer separation of microscale graphite particles to form small and few-layer graphene flake structures were observed on the hardest substrates, glass and sapphire. The degree of fragmentation and interlayer separation of the microscale graphite particles were substrate-dependent: these phenomena increased as the hardness of the substrate was increased.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Dry spraying of microscale graphite particles on various substrates was performed. </LI> <LI> Substrate-dependent deposition behaviors were observed. </LI> <LI> Fragmentation and interlayer separation were considered as deposition behaviors. </LI> <LI> Graphene structures from the deposited films were observed on hard substrates. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Regional Scale 산성강하물의 장기변동 특성과 생태계 영향조사

신아윤(Ah-Yoon Shin),성민영(Min-Young Sung),안준영(Joon-Young Ahn),김종춘(Jong-Choon Kim),김정수(Jung-Soo Kim),이석조(Seok-Jo Lee),손정석(Jung-Seok Son),Arun Kumar Reddy Loka 한국환경관리학회 2010 環境管理學會誌 Vol.16 No.2

본 연구의 최종 목적은 전국적으로 지속적인 산성강하물질의 모니터링을 위한 표준화된 측정과 분석을 통한 자료 축적과 연구로 산성강하물에 대한 현상을 이해하고 원인을 규명하며, 산림 생태계를 중심으로 생태계에 미치는 영향을 평가할 수 있는 실측 농도를 근거로 한 국가자료를 지속적으로 확보하고, EANET 자료를 활용하여 우리나라 뿐만 아니라 동아시아 지역 산성강하물의 장기간 변화 경향을 파악하여 습성강하물의 분석 결과 2004~2009년 전국 연평균 pH는 4.8~4.9로 약산성이며 음이온 성분은 SO₄²?가 2.13~3.30 ㎎/L로 가장 높고 양이온 성분은 NH₄?가 0.63~0.85 ㎎/L로 가장 높은 농도로 나타났다. 산성(건성+습성)강하물 침적량 산정결과, 전체 황 침적량은 1.13~2.02 g/㎡ㆍyr이었으며 질소 침적량은 1.29~2.58 g/㎡ㆍyr로 나타났다. This study aims to understand chemical characteristics of wet and dry deposition, and trends of atmospheric concentration and deposition in Korea. To conduct long-term monitoring of acid deposition, rainfall and PM2.5 samples were collected at 38 monitoring sites and analyzed to detect pH, conductivity, and major ionic components including SO₄²?, Cl?, NO₃?, NH₄?, Na?, K?, Ca²? and Mg²?, as well as mass concentration of fine particles (PM2.5). From the analysis, we can observe the trends of acid deposition, deposition amount of each element, and total acid depositions in Korea. The volume weighted annual mean pH of precipitation in Korea was 4.9. The volume weighted annual mean concentrations of SO₄²?, NO₃?, Cl? were 2.21, 1.23, 1.39 ㎎/L respectively, indicating that SO₄²? was the major contributor, followed by NO₃? and Cl?. In the case of cation, annual mean concentration for NH₄?, Na?, K?, Ca²?, Mg²?, and H? are 0.66, 0.67, 0.28, 0.15, 0.11, 0.02 ㎎/L. Annual wet deposition rate for SO₄²?, NO₃?, and NH₄? were 2.61, 1.45, 0.77 g/㎡ㆍyr respectively. The results show that daily averaged mass concentration of PM2.5 is 27.5 ㎍/㎥ and mass concentrations for SO₄²?, NH₄?, and NO₃? are 4.94, 2.00, 2.08 ㎍/㎥ respectively, which account for 18.0%, 7.6% and 7.3% of the total PM2.5 mass concentration individually in the long term monitoring. During the measurement period, deposition velocity for SO₂, HNO₃, aerosol, NO₂, NH₃ was 0.24, 1.42, 0.17, 1.75, 1.75 ㎝/sec. The result shows that annual mean dry deposition rates for SO₂ in 2005~2009 were 0.32, 0.55, 0.56, 0.37, 0.27 S g/㎡ㆍyear, and for HNO₃ were 0.05, 0.11, 0.28, 0.22, 0.20 N g/m²ㆍyear, for NO₂ in 2007~2009 were 0.37, 0.41, 0.35 N g/㎡ㆍyear, and for NH₃ were 0.50, 0.43, and 0.59 N g/㎡ㆍyear. Dry deposition contributed about 29 percent of the total sulfur deposition, and 65 percent of the total nitrogen deposition. Critical load exceedance was estimated for three years (Oct. 2006~Oct. 2009) using mean depositions of nitrogen and sulfur, which shows that the impact of nitrogen was relatively higher than that of sulfur in the capital region and west coastal regions.

Numerical Simulations of Dry and Wet Deposition over Simplified Terrains

T. Michioka,H. Takimoto,A. Sato 한국대기환경학회 2017 Asian Journal of Atmospheric Environment (AJAE) Vol.11 No.4

To evaluate the deposition amount on a ground surface, mesoscale numerical models coupled with atmospheric chemistry are widely used for larger horizontal domains ranging from a few to several hundreds of kilometers; however, these models are rarely applied to high-resolution simulations. In this study, the performance of a dry and wet deposition model is investigated to estimate the amount of deposition via computational fluid dynamics (CFD) models with high grid resolution. Reynolds-averaged Navier-Stokes (RANS) simulations are implemented for a cone and a two-dimensional ridge to estimate the dry deposition rate, and a constant deposition velocity is used to obtain the dry deposition flux. The results show that the dry deposition rate of RANS generally corresponds to that observed in wind-tunnel experiments. For the wet deposition model, the transport equation of a new scalar concentration scavenged by rain droplets is developed and used instead of the scalar concentration scavenged by raindrops falling to the ground surface just below the scavenging point, which is normally used in mesoscale numerical models. A sensitivity analysis of the proposed wet deposition procedure is implemented. The result indicates the applicability of RANS for high-resolution grids considering the effect of terrains on the wet deposition.

지표 부근에서의 대기오염물질 건성 침적속도에 관한 모수화

이화운,박종길,장은숙,문난경 한국환경과학회 1994 한국환경과학회지 Vol.3 No.4

A predictive modal is demonstrated for gas removal rates from the atmosphere by dry deposition. Typical deposition velocities are complex functions of surface types, atmospheric stabilities, friction velocities, air pollutants, and so on. In this paper we simulated the calculation of dry deposition velocities near the earth surfaces, simultaneously we estimated real dry deposition velocities using the previous simulation. The measurement taken over a deciduous forest by Padro et al.(1988) were used to verify this model. In the comparison of the value of deposition velocity between numerical computation and observation, there are partially overestimations and underestimations between them, but we can speak that they are in a good accordance.

원자력 사고 중 핵종의 건·습침적에 따른 농작물 오염 영향

황원태,김은한,서경석,한문희,최용호,이창우 대한방사선 방어학회 2002 방사선방어학회지 Vol.27 No.3

핵종의 지표 침적 모델의 고찰과 함께 방사성물질의 공기중 농도로부터 건침적 뿐 아니라 습침적에 따른 농작물 오염 영향을 분석, 고찰하였다. 이를 위해 방사성물질의 지표 침적량으로부터 농작물의 오염을 평가하는 기존 동적 섭식경로모델을 공기중 농도 또는 지표 침적량으로부터 평가할 수 있도록 개선하였다. 평가결과, 방사성물질의 지표 침적량은 습침적에 의한 영향이 건침적에 의한 영향보다 뚜렷이 높으나, 농작물의 오염정도는 핵종, 강우율 등에 따라 다르게 나타났다. 이러한 현상은 방사성물질의 지표 침적과 농작물에로의 차단중 어느 과정이 농작물 오염에 보다 지배적으로 작용하는가에 기인한다. Combined with deposition model onto the ground of radionuclides, the influence of radioactive contamination to agricultural products was analyzed due to wet deposition as well as dry deposition from radioactive air concentration during a nuclear emergency. The previous dynamic food chain model, in which initial input parameter is only radionuclide concentrations on the ground, was improved for the evaluating of radioactive contamination to agricultural products from either radionuclide concentrations in air or radionuclide concentrations on the ground. As the results, in case of deposition onto the ground, wet deposition was more dominant process than dry deposition. While the contamination levels of agricultural products were dependent on the a variety of factors such as radionuclides and rainfall rate. It means that the contamination levels of agricultural products are determined from which is more dominant process between deposition on the ground and interception onto agricultural plants.

수체로의 대기오염물질 건식침적량 측정

김영성,진현철,김용표 한국대기환경학회 2004 한국대기환경학회지 Vol.20 No.3

Dry deposition fluxes or inorganic acidic species to the waterbody were measured by the dry deposition sampler (DDS). DDS was composed or three pans filled with pure water. An average concentration increase during the sampling time, after removing an abnormal value if existed, was considered as the input by deposition. Important operation parameters such as the amount of water used and sampling time were determined through a series of laboratory experiments. The deposition flux measured by DDS was compared with that by the water surface sampler developed by Yi et al. (1997a,b).

Highly stable barium zirconate supported nickel oxide catalyst for dry reforming of methane: From powders toward shaped catalysts

Seo, Minhye,Kim, Soong Yeon,Kim, Young Dok,Park, Eun Duck,Uhm, Sunghyun Elsevier 2018 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.43 No.24

<P><B>Abstract</B></P> <P>We report the barium zirconate supported NiO<SUB>x</SUB> catalysts (NiO<SUB>x</SUB>/BZO) for dry reforming of methane and feasibility test for their industrial application by using temperature-regulated chemical vapor deposition together with extrusion. Nickel oxide nanoparticles are well deposited and dispersed on BZO powders as well as structures in a gear form, showing high catalytic activity and extraordinary stability even at relatively lower temperature and higher space velocity. The NiO<SUB>x</SUB>/BZO catalyst are highly coke resistant for 50 h operation with almost negligible agglomeration of NiO<SUB>x</SUB> nanoparticles. Judging from XPS and high ion conducting properties of BZO supports, the –OH or –O species are expected to play an important role in promoting the self-decoking of surface carbon species to form CO and CO<SUB>2.</SUB> </P> <P><B>Highlights</B></P> <P> <UL> <LI> NiO<SUB>x</SUB>/BaZrO<SUB>3</SUB> are easily prepared by temperature-regulated chemical vapor deposition. </LI> <LI> The NiO<SUB>x</SUB> nanoparticles are well deposited and dispersed on BaZrO<SUB>3</SUB> powders. </LI> <LI> The NiO<SUB>x</SUB>/BZO catalysts have highly coke resistant for dry reforming reaction. </LI> <LI> Shaped catalysts are exhibited stable activity similar to that of powder catalysts. </LI> </UL> </P>