Pub Date : 2001-07-01DOI: 10.1016/S1465-9972(01)00009-5
B. Bonsang , M. Kanakidou
C2–C6 non-methane hydrocarbons (NMHC), including isoprene, were measured in a forested area of Portugal from June 20 to July 12, 1994 as part of the FIELDVOC'94 project. The day-to-day variability of the measured NMHC was clearly linked to the air mass origin. The longest-lived ethane did not show any significant diurnal variation. The diurnal variability of the C3–C5 alkanes and of acetylene presented low amplitude attributed to the changeable wind direction between northwest and southeast. The short-lived alkenes showed a well-defined diurnal variation with maximum mixing ratios during night-time and minimum during daytime resulting from both dynamical and photochemical sinks. Isoprene presented a very different trend with minima of 0.1 ppbv at night and maxima up to 12 ppbv occurring between 16:00 and 18:00 (UT). In continental air masses, the contribution of isoprene to the daytime ozone production was 3- to 6-fold greater than that of the other NMHC. In air masses of marine origin, the effect of isoprene on ozone and hydroxyl radicals was significantly reduced relative to the anthropogenic NMHC, which were dominating at night. In all cases, isoprene was a more efficient consumer of nitrate radicals than these NMHC. The observed decrease of isoprene at night was consistent with the measured nitrate radical mixing ratios of a few pptv.
{"title":"Non-methane hydrocarbon variability during the FIELDVOC'94 campaign in Portugal","authors":"B. Bonsang , M. Kanakidou","doi":"10.1016/S1465-9972(01)00009-5","DOIUrl":"10.1016/S1465-9972(01)00009-5","url":null,"abstract":"<div><p>C<sub>2</sub>–C<sub>6</sub> non-methane hydrocarbons (NMHC), including isoprene, were measured in a forested area of Portugal from June 20 to July 12, 1994 as part of the FIELDVOC'94 project. The day-to-day variability of the measured NMHC was clearly linked to the air mass origin. The longest-lived ethane did not show any significant diurnal variation. The diurnal variability of the C<sub>3</sub>–C<sub>5</sub> alkanes and of acetylene presented low amplitude attributed to the changeable wind direction between northwest and southeast. The short-lived alkenes showed a well-defined diurnal variation with maximum mixing ratios during night-time and minimum during daytime resulting from both dynamical and photochemical sinks. Isoprene presented a very different trend with minima of 0.1 ppbv at night and maxima up to 12 ppbv occurring between 16:00 and 18:00 (UT). In continental air masses, the contribution of isoprene to the daytime ozone production was 3- to 6-fold greater than that of the other NMHC. In air masses of marine origin, the effect of isoprene on ozone and hydroxyl radicals was significantly reduced relative to the anthropogenic NMHC, which were dominating at night. In all cases, isoprene was a more efficient consumer of nitrate radicals than these NMHC. The observed decrease of isoprene at night was consistent with the measured nitrate radical mixing ratios of a few pptv.</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"3 3","pages":"Pages 259-273"},"PeriodicalIF":0.0,"publicationDate":"2001-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(01)00009-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89232658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-07-01DOI: 10.1016/S1465-9972(01)00005-8
H. Harder , W. Pätz , A. Volz-Thomas , H. Fischer , T. Zenker
Measurements of NO,NOx,NOy,CO,O3,JNO2 (the photolysis frequency of NO2) and of meteorological parameters made during the FIELDVOC'94 campaign in Tábua, Portugal, are described. The situation at the site was dominated by a land–sea breeze system coupled with thermal up-slope on the mountain ridge, which caused northwesterly flow from the coastal area during daytime and southeasterly flow at night. O3 up to 100 ppbv was observed in photochemically aged air masses that reached the site in the afternoon from the coastal areas. At night, O3 mixing ratios at the surface dropped below 10 ppbv. NOx mixing ratios varied between 200 pptv during daytime and 3 ppbv at night with peaks up to 6 ppbv. NOy (the sum of NOx and its oxidation products) varied between 1 and 6 ppbv and CO between 100 and 280 ppbv. Simultaneous measurements of NO2 by photolytic conversion/NO-chemiluminescence and by tunable diode laser spectroscopy showed a tight correlation, in particular at night. Taking the identified difference in calibration between the two methods (8%) into account, the disagreement in the atmosphere, was ⩽2%, on average. Photochemical ozone formation in air transported from the coast was identified by a positive correlation between O3 and the oxidation products of NOx referenced as NOz. The slope of 16 represents an upper limit to the efficiency of NOx in catalyzing ozone formation in air. The relatively high ozone formation efficiency is supported by the large O3/CO ratio of about 0.4. The correlation between CO and NOy indicates an upper limit for the CO/NOx emission ratio of 28.
{"title":"Measurements of nitrogen oxides, ozone, and carbon monoxide during the FIELDVOC'94 campaign in Tábua","authors":"H. Harder , W. Pätz , A. Volz-Thomas , H. Fischer , T. Zenker","doi":"10.1016/S1465-9972(01)00005-8","DOIUrl":"10.1016/S1465-9972(01)00005-8","url":null,"abstract":"<div><p>Measurements of NO,NO<sub><em>x</em></sub>,NO<sub><em>y</em></sub>,CO,O<sub>3</sub>,<em>J</em><sub>NO<sub>2</sub></sub> (the photolysis frequency of NO<sub>2</sub>) and of meteorological parameters made during the FIELDVOC'94 campaign in Tábua, Portugal, are described. The situation at the site was dominated by a land–sea breeze system coupled with thermal up-slope on the mountain ridge, which caused northwesterly flow from the coastal area during daytime and southeasterly flow at night. O<sub>3</sub> up to 100 ppbv was observed in photochemically aged air masses that reached the site in the afternoon from the coastal areas. At night, O<sub>3</sub> mixing ratios at the surface dropped below 10 ppbv. NO<sub><em>x</em></sub> mixing ratios varied between 200 pptv during daytime and 3 ppbv at night with peaks up to 6 ppbv. NO<sub><em>y</em></sub> (the sum of NO<sub><em>x</em></sub> and its oxidation products) varied between 1 and 6 ppbv and CO between 100 and 280 ppbv. Simultaneous measurements of NO<sub>2</sub> by photolytic conversion/NO-chemiluminescence and by tunable diode laser spectroscopy showed a tight correlation, in particular at night. Taking the identified difference in calibration between the two methods (8%) into account, the disagreement in the atmosphere, was ⩽2%, on average. Photochemical ozone formation in air transported from the coast was identified by a positive correlation between O<sub>3</sub> and the oxidation products of NO<sub><em>x</em></sub> referenced as NO<sub><em>z</em></sub>. The slope of 16 represents an upper limit to the efficiency of NO<sub><em>x</em></sub> in catalyzing ozone formation in air. The relatively high ozone formation efficiency is supported by the large O<sub>3</sub>/CO ratio of about 0.4. The correlation between CO and NO<sub><em>y</em></sub> indicates an upper limit for the CO/NO<sub><em>x</em></sub> emission ratio of 28.</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"3 3","pages":"Pages 227-237"},"PeriodicalIF":0.0,"publicationDate":"2001-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(01)00005-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80041325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-04-01DOI: 10.1016/S1465-9972(00)00047-7
J Williams , H Fischer , P Hoor , U Pöschl , P.J Crutzen , M.O Andreae , J Lelieveld
Gradients of CO and CO2, taken between 12:00 and 15:00 local time, from the boundary layer over the tropical rainforest in Surinam were determined as 29 pmol/mol km−1 and −8.9 nmol/mol km−1, respectively, with a distance of south from the coast. For one CO2 molecule fixed in tropical forests 0.33% CO was produced. From an extrapolation of the CO gradient to the global scale we deduce that approximately 19% of C emitted as isoprene from tropical forests is converted to C in CO. From an extrapolation of the CO2 gradient we estimate that approximately 1.2% of the global atmospheric CO2 is converted each year into tropical seasonal and rainforests.
CO production from isoprene was calculated using an explicit gas-phase photochemical model but was found to be insufficient to account for the gradients measured. Diurnal variation in CO was controlled by a complex interplay between advection, chemical formation from natural NMHCs, direct soil emissions, removal by HO, and possible night-time uptake by soil. Diurnal variations of CO2 in the boundary layer were controlled by vegetation.
Over the 12.5 km altitude range of the aircraft, a high degree of variability was observed in CO, CO2 and northerly wind components. Two biomass burning events were identified and the ratio of delta CO and delta CO2 was determined in each case with a two-sided linear regression. A ratio of 12.1% was found in plumes from smouldering cooking or clearing fires at low-altitude. A ratio of 5.9% was found for a plume encountered between 10–12 km. The lower ratio of delta CO and delta CO2 indicates hotter, more complete, flame burning than the cooking or clearing fires. Emissions from savanna fires in the Brazil, Colombia and Venezuela regions coupled with deep convection and long-range advection are proposed to explain the observations.
在苏里南热带雨林上空的边界层上,当地时间12:00 - 15:00的CO和CO2梯度分别为29 pmol/mol km - 1和- 8.9 nmol/mol km - 1,距离海岸以南。固定在热带森林中的每一个CO2分子产生0.33%的CO。根据对全球尺度CO梯度的外推,我们推断出热带森林以异戊二烯形式排放的C中约有19%转化为CO中的C。根据对CO2梯度的外推,我们估计每年约有1.2%的全球大气CO2转化为热带季节性森林和雨林。使用明确的气相光化学模型计算异戊二烯的CO产量,但发现不足以解释测量的梯度。CO的日变化受平流、天然NMHCs的化学形成、土壤直接排放、HO的去除以及土壤夜间可能的吸收等因素的复杂相互作用控制。边界层CO2的日变化受植被控制。在飞机12.5公里高度范围内,观测到CO、CO2和北风分量的高度变化。确定了两个生物质燃烧事件,并通过双边线性回归确定了每种情况下δ CO和δ CO2的比例。在低海拔地区闷烧烹饪或清理火堆产生的烟雾中发现的比例为12.1%。在10-12公里之间遇到的羽流的比例为5.9%。较低的CO和CO2比值表明,与烹饪或清理火焰相比,火焰燃烧更热、更彻底。巴西、哥伦比亚和委内瑞拉地区热带稀树草原火灾的排放加上深对流和远距离平流被认为可以解释这些观测结果。
{"title":"The influence of the tropical rainforest on atmospheric CO and CO2 as measured by aircraft over Surinam, South America","authors":"J Williams , H Fischer , P Hoor , U Pöschl , P.J Crutzen , M.O Andreae , J Lelieveld","doi":"10.1016/S1465-9972(00)00047-7","DOIUrl":"10.1016/S1465-9972(00)00047-7","url":null,"abstract":"<div><p>Gradients of CO and CO<sub>2</sub>, taken between 12:00 and 15:00 local time, from the boundary layer over the tropical rainforest in Surinam were determined as 29 pmol/mol km<sup>−1</sup> and −8.9 nmol/mol km<sup>−1</sup>, respectively, with a distance of south from the coast. For one CO<sub>2</sub> molecule fixed in tropical forests 0.33% CO was produced. From an extrapolation of the CO gradient to the global scale we deduce that approximately 19% of C emitted as isoprene from tropical forests is converted to C in CO. From an extrapolation of the CO<sub>2</sub> gradient we estimate that approximately 1.2% of the global atmospheric CO<sub>2</sub> is converted each year into tropical seasonal and rainforests.</p><p>CO production from isoprene was calculated using an explicit gas-phase photochemical model but was found to be insufficient to account for the gradients measured. Diurnal variation in CO was controlled by a complex interplay between advection, chemical formation from natural NMHCs, direct soil emissions, removal by HO, and possible night-time uptake by soil. Diurnal variations of CO<sub>2</sub> in the boundary layer were controlled by vegetation.</p><p>Over the 12.5 km altitude range of the aircraft, a high degree of variability was observed in CO, CO<sub>2</sub> and northerly wind components. Two biomass burning events were identified and the ratio of delta CO and delta CO<sub>2</sub> was determined in each case with a two-sided linear regression. A ratio of 12.1% was found in plumes from smouldering cooking or clearing fires at low-altitude. A ratio of 5.9% was found for a plume encountered between 10–12 km. The lower ratio of delta CO and delta CO<sub>2</sub> indicates hotter, more complete, flame burning than the cooking or clearing fires. Emissions from savanna fires in the Brazil, Colombia and Venezuela regions coupled with deep convection and long-range advection are proposed to explain the observations.</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"3 2","pages":"Pages 157-170"},"PeriodicalIF":0.0,"publicationDate":"2001-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(00)00047-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87494149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In Japan, five types of vehicles, light-duty gasoline [(LDG); 550 cc < engine displacement (ED)], super-light-duty gasoline [(SLD); ED < 550 cc], liquid petroleum-fueled [(LPG); 550 cc < ED < 3000 cc], light-duty diesel [(LDD); 550 cc < ED < 5000 cc] and heavy-duty diesel [(HDD); 5000 cc < ED] cars have been used widely to give the complex influences on the hydrocarbon components at roadsides and in city areas, which have not been explained sufficiently. In this study, we investigated the ambient 16 hydrocarbon components at two roadsides in commercial and industrial areas of Osaka City along with the traffic densities of five types of vehicles to propose the significant effects of emissions from SLD and LPG cars besides that of LDG car through a comparison of the ambient [ethylene]/[acetylene] and [i-, n-pentanes]/[i-, n-butanes] ratios with those of the source profiles published in Japan.
在日本,五种类型的车辆,轻型汽油[(LDG);550 cc <发动机排量[ED]、超轻型汽油[SLD];ED & lt;550cc],液态石油燃料[(LPG)];550 cc <ED & lt;3000cc],轻型柴油[(LDD);550 cc <ED & lt;5000cc]和重型柴油[(HDD);5000毫升<汽车的广泛使用对路边和城市地区的碳氢化合物成分产生了复杂的影响,而这些影响尚未得到充分的解释。在本研究中,我们调查了大阪市商业区和工业区两个路边的16种碳氢化合物成分以及五种类型车辆的交通密度,通过将环境[乙烯]/[乙炔]和[i-,正戊烷]/[i-,正丁烷]比例与日本公布的来源概况进行比较,提出了除LDG汽车外,SLD和LPG汽车排放的显著影响。
{"title":"Effects of super-light-duty gasoline and LPG-fueled cars on 16 ambient hydrocarbons at roadsides in Japan","authors":"Masanobu Tanaka , Munehiro Warashina , Yasuyuki Itano , Yuji Tsujimoto , Shinji Wakamatsu","doi":"10.1016/S1465-9972(00)00051-9","DOIUrl":"10.1016/S1465-9972(00)00051-9","url":null,"abstract":"<div><p>In Japan, five types of vehicles, light-duty gasoline [(LDG); 550 cc<!--> <!--><<!--> <!-->engine displacement (ED)], super-light-duty gasoline [(SLD); ED<!--> <!--><<!--> <!-->550 cc], liquid petroleum-fueled [(LPG); 550 cc<!--> <!--><<!--> <!-->ED<!--> <!--><<!--> <!-->3000 cc], light-duty diesel [(LDD); 550 cc<!--> <!--><<!--> <!-->ED<!--> <!--><<!--> <!-->5000 cc] and heavy-duty diesel [(HDD); 5000 cc<!--> <!--><<!--> <span>ED] cars have been used widely to give the complex influences on the hydrocarbon components at roadsides and in city areas, which have not been explained sufficiently. In this study, we investigated the ambient 16 hydrocarbon components at two roadsides in commercial and industrial areas of Osaka City along with the traffic densities of five types of vehicles to propose the significant effects of emissions from SLD and LPG cars besides that of LDG car through a comparison of the ambient [ethylene]/[acetylene] and [</span><em>i</em>-, <em>n</em>-pentanes]/[<em>i</em>-, <em>n</em>-butanes] ratios with those of the source profiles published in Japan.</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"3 2","pages":"Pages 199-207"},"PeriodicalIF":0.0,"publicationDate":"2001-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(00)00051-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75824537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-04-01DOI: 10.1016/S1465-9972(00)00053-2
Charles D. Camp , Mark S. Roulston , Albert F.C. Haldemann , Yuk L. Yung
The dominant processes affecting the concentration of tropospheric methane on interannual timescales are the biospheric and anthropogenic sources and changes in the abundance of the hydroxyl radical caused by the changes in the UV flux which result from changes in stratospheric ozone abundance. We have carried out an empirical study of the sensitivity of the methane to fluctuations in ozone column abundance. This analysis was carried out using monthly mean surface methane concentrations measured by the National Oceanic and Atmospheric Administration – Climate Monitoring and Diagnostics Laboratory (NOAA-CMDL) Global Cooperative Air Sampling Network from 1983 to 1998 and ozone column abundances obtained by the Total Ozone Mapping Spectrometer (TOMS) and the EP TOMS instruments over the same time period. We focused on interannual variability with periods between 15 and 60 months, in which interval the dominant ozone fluctuation is the quasi-biennial oscillation (QBO), with a period of approximately 29 months. In order to isolate the response of methane to ozone from the effects of variability in the sources and transport of methane, we restricted our analysis to data at mid-latitudes in the southern hemisphere. A statistical study shows that the sensitivity factor α≡−d(ln[CH4])/d(ln[O3])=−0.038±0.009. The response of CH4 lags approximately 6 months behind the forcing by O3. A simple model was used to interpret the empirical results. Our results confirm that any mechanism that affects stratospheric ozone impacts the oxidizing potential of the troposphere. CH4 fluctuations provide a quantitative measure of this important effect linking the upper and the lower atmosphere.
{"title":"The sensitivity of tropospheric methane to the interannual variability in stratospheric ozone","authors":"Charles D. Camp , Mark S. Roulston , Albert F.C. Haldemann , Yuk L. Yung","doi":"10.1016/S1465-9972(00)00053-2","DOIUrl":"10.1016/S1465-9972(00)00053-2","url":null,"abstract":"<div><p>The dominant processes affecting the concentration of tropospheric methane on interannual timescales are the biospheric and anthropogenic sources and changes in the abundance of the hydroxyl radical caused by the changes in the UV flux which result from changes in stratospheric ozone abundance. We have carried out an empirical study of the sensitivity of the methane to fluctuations in ozone column abundance. This analysis was carried out using monthly mean surface methane concentrations measured by the National Oceanic and Atmospheric Administration – Climate Monitoring and Diagnostics Laboratory (NOAA-CMDL) Global Cooperative Air Sampling Network from 1983 to 1998 and ozone column abundances obtained by the Total Ozone Mapping Spectrometer (TOMS) and the EP TOMS instruments over the same time period. We focused on interannual variability with periods between 15 and 60 months, in which interval the dominant ozone fluctuation is the quasi-biennial oscillation (QBO), with a period of approximately 29 months. In order to isolate the response of methane to ozone from the effects of variability in the sources and transport of methane, we restricted our analysis to data at mid-latitudes in the southern hemisphere. A statistical study shows that the sensitivity factor <em>α</em>≡−<em>d</em>(ln[CH<sub>4</sub>])/<em>d</em>(ln[O<sub>3</sub>])=−0.038±0.009. The response of CH<sub>4</sub> lags approximately 6 months behind the forcing by O<sub>3</sub>. A simple model was used to interpret the empirical results. Our results confirm that any mechanism that affects stratospheric ozone impacts the oxidizing potential of the troposphere. CH<sub>4</sub> fluctuations provide a quantitative measure of this important effect linking the upper and the lower atmosphere.</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"3 2","pages":"Pages 147-156"},"PeriodicalIF":0.0,"publicationDate":"2001-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(00)00053-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85958026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vehicle exhaust has been a very important hydrocarbon source in a big city. In Japan, five types of vehicles, light-duty gasoline (LDG), super-light-duty gasoline (SLD), liquid petroleum gas-fueled (LPG), light-duty diesel (LDD) and heavy-duty diesel (HDD) cars have been used widely for a long time. These vehicles have different fuels and exhaust gas treatment systems, which have not changed so largely since the late 1980s. The hydrocarbons [total hydrocarbon (THC), methane and 16 speciated volatile hydrocarbon components] emitted from 12 cars (one LDG, two SLD, two LPG, three LDD and four HDD) were investigated. As a result, the remarkable peculiarities of hydrocarbon emissions from the five types of vehicles were observed. Especially, the emissions from SLD and LPG cars have the peculiarities of high concentrations of total hydrocarbon (THC) and C2 (ethylene and acetylene), C3 (propane or propylene) or C4 (i-, n-butanes) hydrocarbons in 16 components, which may be proposed to give a significant effect on 16 component hydrocarbons of the ambient air in big cities of Japan in addition to those from LDG and diesel (LDD and HDD) cars.
{"title":"Peculiarities of volatile hydrocarbon emissions from several types of vehicles in Japan","authors":"Masanobu Tanaka , Yuji Tsujimoto , Takeji Miyazaki , Munehiro Warashina , Shinji Wakamatsu","doi":"10.1016/S1465-9972(00)00052-0","DOIUrl":"10.1016/S1465-9972(00)00052-0","url":null,"abstract":"<div><p>Vehicle exhaust has been a very important hydrocarbon source in a big city. In Japan, five types of vehicles, light-duty gasoline (LDG), super-light-duty gasoline (SLD), liquid petroleum gas-fueled (LPG), light-duty diesel (LDD) and heavy-duty diesel (HDD) cars have been used widely for a long time. These vehicles have different fuels and exhaust gas treatment systems, which have not changed so largely since the late 1980s. The hydrocarbons [total hydrocarbon (THC), methane and 16 speciated volatile hydrocarbon components] emitted from 12 cars (one LDG, two SLD, two LPG, three LDD and four HDD) were investigated. As a result, the remarkable peculiarities of hydrocarbon emissions from the five types of vehicles were observed. Especially, the emissions from SLD and LPG cars have the peculiarities of high concentrations of total hydrocarbon (THC) and C<sub>2</sub> (ethylene and acetylene), C<sub>3</sub> (propane or propylene) or C<sub>4</sub> (<em>i</em>-, <em>n</em>-butanes) hydrocarbons in 16 components, which may be proposed to give a significant effect on 16 component hydrocarbons of the ambient air in big cities of Japan in addition to those from LDG and diesel (LDD and HDD) cars.</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"3 2","pages":"Pages 185-197"},"PeriodicalIF":0.0,"publicationDate":"2001-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(00)00052-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73802189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-04-01DOI: 10.1016/S1465-9972(00)00048-9
Tsun-Hsien Liu , Fu-Tien Jeng , Ho-Chun Huang , Erik Berge , Julius S. Chang
Influences of initial and boundary conditions were quantified by analysis of a simplified governing equation followed with a tracer and O3 simulations using a three-dimensional air quality transport model. The analytical solution derived from the governing equation indicated that the impacts of initial conditions on a given site decrease with simulation time and significantly affect the species concentrations before the arrival of the boundary conditions. Boundary influences, which decrease during the downwind transport, are significant to a selected site when the arrival time of boundary condition is short and the species lifetime is long.
Non-reactive tracers and O3 were then added to SARMAP Air Quality Model (SAQM), a three-dimensional transport model, and the results showed that tracer lifetime and arrival time determine the boundary influences on a given site consistent with the analysis obtained from the governing equation. Moreover, boundary conditions followed initial conditions to affect the calculated ozone concentrations at a given site and the influences are proportional to the magnitude of the prescribed boundary conditions, arrival time, and are more obvious at local nighttime. When the arrival time is 15 h, an average of 64% of initial ozone boundary conditions will contribute to the calculated ozone concentrations. For arrival times of 23, 20, and 7 h, the ratios are 26%, 34%, and 79%, respectively. This study indicated that the derived analytical solution could be used by air quality modelers in estimating the boundary influences as long as the species lifetime are known.
{"title":"Influences of initial conditions and boundary conditions on regional and urban scale Eulerian air quality transport model simulations","authors":"Tsun-Hsien Liu , Fu-Tien Jeng , Ho-Chun Huang , Erik Berge , Julius S. Chang","doi":"10.1016/S1465-9972(00)00048-9","DOIUrl":"10.1016/S1465-9972(00)00048-9","url":null,"abstract":"<div><p>Influences of initial and boundary conditions were quantified by analysis of a simplified governing equation followed with a tracer and O<sub>3</sub> simulations using a three-dimensional air quality transport model. The analytical solution derived from the governing equation indicated that the impacts of initial conditions on a given site decrease with simulation time and significantly affect the species concentrations before the arrival of the boundary conditions. Boundary influences, which decrease during the downwind transport, are significant to a selected site when the arrival time of boundary condition is short and the species lifetime is long.</p><p>Non-reactive tracers and O<sub>3</sub> were then added to SARMAP Air Quality Model (SAQM), a three-dimensional transport model, and the results showed that tracer lifetime and arrival time determine the boundary influences on a given site consistent with the analysis obtained from the governing equation. Moreover, boundary conditions followed initial conditions to affect the calculated ozone concentrations at a given site and the influences are proportional to the magnitude of the prescribed boundary conditions, arrival time, and are more obvious at local nighttime. When the arrival time is 15 h, an average of 64% of initial ozone boundary conditions will contribute to the calculated ozone concentrations. For arrival times of 23, 20, and 7 h, the ratios are 26%, 34%, and 79%, respectively. This study indicated that the derived analytical solution could be used by air quality modelers in estimating the boundary influences as long as the species lifetime are known.</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"3 2","pages":"Pages 175-183"},"PeriodicalIF":0.0,"publicationDate":"2001-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(00)00048-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79951458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-04-01DOI: 10.1016/S1465-9972(01)00002-2
Renjian Zhang, Mingxing Wang, Lixin Ren
A global two-dimensional chemistry model is used to study the long-term trends of CH4, CO, and OH from pre-industrial times to 2020 with given emission scenarios according to the increase of world population. The calculated global-averaged concentration of CO is 27 ppbv before 1840, the concentration of CO is 76 ppbv in 1991, and is estimated to be 105 ppbv in 2020. From 1840 to 1991, the concentration of OH changed from 7.17×105 to 5.79×105 molecules/cm3, i.e., decreased by 19%. The long-term trends of CH4 derived from the model are in good agreement with observation results. The annual increase of CH4 during 1983–1991 is 12.1–13.3 ppbv by this model and 11.1–11.6 ppbv by observation. The calculated growth rate of CO in 1980s is 1.03–1.06%/yr i.e., 6.9–7.9 ppbv/yr. The model is used to investigate why the CO concentration decreased at the beginning of 1990s. We find that the decrease of CO emissions and depletion of stratospheric ozone are the best explanation, which account for 70% and 30% of the decrease of CO concentration, respectively. The model results also show that possible reduction of CH4 emission has little influence on the change of CO concentrations though the reduction of CO emission can counteract the growth of CH4 significantly.
{"title":"Long-term trends of carbon monoxide inferred using a two-dimensional model","authors":"Renjian Zhang, Mingxing Wang, Lixin Ren","doi":"10.1016/S1465-9972(01)00002-2","DOIUrl":"10.1016/S1465-9972(01)00002-2","url":null,"abstract":"<div><p>A global two-dimensional chemistry model is used to study the long-term trends of CH<sub>4</sub>, CO, and OH from pre-industrial times to 2020 with given emission scenarios according to the increase of world population. The calculated global-averaged concentration of CO is 27 ppbv before 1840, the concentration of CO is 76 ppbv in 1991, and is estimated to be 105 ppbv in 2020. From 1840 to 1991, the concentration of OH changed from 7.17×10<sup>5</sup> to 5.79×10<sup>5</sup> molecules/cm<sup>3</sup>, i.e., decreased by 19%. The long-term trends of CH<sub>4</sub> derived from the model are in good agreement with observation results. The annual increase of CH<sub>4</sub> during 1983–1991 is 12.1–13.3 ppbv by this model and 11.1–11.6 ppbv by observation. The calculated growth rate of CO in 1980s is 1.03–1.06%/yr i.e., 6.9–7.9 ppbv/yr. The model is used to investigate why the CO concentration decreased at the beginning of 1990s. We find that the decrease of CO emissions and depletion of stratospheric ozone are the best explanation, which account for 70% and 30% of the decrease of CO concentration, respectively. The model results also show that possible reduction of CH<sub>4</sub> emission has little influence on the change of CO concentrations though the reduction of CO emission can counteract the growth of CH<sub>4</sub> significantly.</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"3 2","pages":"Pages 123-132"},"PeriodicalIF":0.0,"publicationDate":"2001-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(01)00002-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87063324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-04-01DOI: 10.1016/S1465-9972(01)00003-4
Prabhat K. Gupta , V. Krishna Prasad , C. Sharma , A.K. Sarkar , Yogesh Kant , K.V.S. Badarinath , A.P. Mitra
Context Abstract: Tropical deciduous fires from shifting cultivation process in India are characterized by the highly differential nature of fire behavior due to fragmented burning patterns. Our study from ground-based experiments from biomass burning of tropical deciduous forest fires suggests smoldering combustion as the dominating process during biomass burning which leads to evolution of more incompletely oxidized products such as Methane when compared to other ecosystems such as Savannas. In the study, we report emission ratios and emission factors for methane from biomass burning of tropical deciduous forests. As tropical deciduous forests in India cover more than 50% of overall forests, the emission factors obtained in the present study can be used widely for methane emission estimation from forest biomass burning studies in other parts of India and in modeling studies of Methane from forest biomass burning in India.
Main Abstract: Biomass burning is an important source of trace gas emissions to the atmosphere. Methane emitted from the biomass burning contributes to the atmospheric greenhouse effect and is sufficiently long-lived to enter the stratosphere and take part in the stratospheric ozone cycles. In India, though CH4 emissions from the different sources such as rice paddy fields and domestic animals have been well studied, there are relatively no field-based studies with respect to CH4 emissions from biomass burning. In the present study, we report for the first time, the CH4 emissions from biomass burning of tropical deciduous forests cleared for shifting cultivation purposes. Trace gas emissions from the biomass burning plumes have been collected through grab sampling in canisters as well as from online measurements through instruments. Site characteristics with respect to species composition, amount of biomass burnt and relative amounts of combustion, viz., flaming, mixed and smoldering have been determined. Modified combustion efficiency has been used to differentiate relative amounts of combustion. Emission ratios were calculated with respect to CO2 and emission factors based on the amount of biomass consumed. Results of the study with respect to biomass estimations prior to burning suggested values of 12–14 t ha−1 at the first site and 13.5–15.3 t ha−1 at the second site. The mean modified combustion efficiencies during flaming, mixed and smoldering combustion phases for the first site were found to be 95.7%, 91.1% and 74.4% and 95.31%, 90.63% and 72.89%, respectively, for the second site. The average biomass consumed during the fire ranged from 4.7 t ha−1 (site 1) to 3.4 t ha−1 (site 2), indicating low amount of biomass burnt during the first phase of burning in shifting cultivation areas. Results suggested the CH4 emission ratios of 1.29% at the first site and 1.59% at the second site. The CH
摘要:在印度,由于破碎的燃烧模式,热带落叶火灾的特征是火灾行为的高度差异。我们对热带落叶森林火灾生物质燃烧的地面实验研究表明,与稀树草原等其他生态系统相比,阴燃燃烧是生物质燃烧的主要过程,导致更多不完全氧化产物(如甲烷)的进化。在研究中,我们报告了热带落叶森林生物质燃烧产生的甲烷的排放比和排放因子。由于印度的热带落叶森林覆盖了整个森林的50%以上,本研究获得的排放因子可广泛用于印度其他地区森林生物质燃烧研究的甲烷排放估算以及印度森林生物质燃烧甲烷的建模研究。摘要:生物质燃烧是向大气排放微量气体的重要来源。生物质燃烧释放的甲烷有助于大气温室效应,并且寿命足够长,可以进入平流层并参与平流层臭氧循环。在印度,虽然对稻田和家畜等不同来源的甲烷排放进行了很好的研究,但相对而言,还没有关于生物质燃烧产生的甲烷排放的实地研究。在本研究中,我们首次报道了热带落叶森林转耕后生物质燃烧产生的CH4排放。通过罐中抓取取样以及通过仪器进行在线测量,收集了来自生物质燃烧羽流的微量气体排放。已经确定了有关物种组成、生物质燃烧量和相对燃烧量(即燃烧、混合和阴燃)的场地特征。改进的燃烧效率被用来区分相对的燃烧量。排放比是根据二氧化碳和基于生物质消耗量的排放因子计算的。研究结果表明,燃烧前的生物量估算值在第一个地点为12-14 t ha - 1,在第二个地点为13.5-15.3 t ha - 1。燃烧、混合和阴燃阶段的平均修正燃烧效率分别为95.7%、91.1%和74.4%和95.31%、90.63%和72.89%。火灾期间消耗的平均生物量在4.7 t ha - 1(站点1)至3.4 t ha - 1(站点2)之间,表明在移动耕作区域燃烧的第一阶段燃烧的生物量较少。结果表明,第1点和第2点的CH4排放比分别为1.29%和1.59%。本研究获得的CH4排放比更接近于其他地区热带森林获得的最广为接受的估计值1.2±0.5%。使用研究中获得的排放比并估计生物质燃烧产生的甲烷排放量表明,印度每年从轮作耕作过程中排放近0.99 Tg的甲烷。同时,对CH4的排放比和排放因子进行了详细的比较。
{"title":"CH4 emissions from biomass burning of shifting cultivation areas of tropical deciduous forests – experimental results from ground-based measurements","authors":"Prabhat K. Gupta , V. Krishna Prasad , C. Sharma , A.K. Sarkar , Yogesh Kant , K.V.S. Badarinath , A.P. Mitra","doi":"10.1016/S1465-9972(01)00003-4","DOIUrl":"10.1016/S1465-9972(01)00003-4","url":null,"abstract":"<div><p><em>Context Abstract</em>: Tropical deciduous fires from shifting cultivation process in India are characterized by the highly differential nature of fire behavior due to fragmented burning patterns. Our study from ground-based experiments from biomass burning of tropical deciduous forest fires suggests smoldering combustion as the dominating process during biomass burning which leads to evolution of more incompletely oxidized products such as Methane when compared to other ecosystems such as Savannas. In the study, we report emission ratios and emission factors for methane from biomass burning of tropical deciduous forests. As tropical deciduous forests in India cover more than 50% of overall forests, the emission factors obtained in the present study can be used widely for methane emission estimation from forest biomass burning studies in other parts of India and in modeling studies of Methane from forest biomass burning in India.</p><p><em>Main Abstract</em>: Biomass burning is an important source of trace gas emissions to the atmosphere. Methane emitted from the biomass burning contributes to the atmospheric greenhouse effect and is sufficiently long-lived to enter the stratosphere and take part in the stratospheric ozone cycles. In India, though CH<sub>4</sub> emissions from the different sources such as rice paddy fields and domestic animals have been well studied, there are relatively no field-based studies with respect to CH<sub>4</sub> emissions from biomass burning. In the present study, we report for the first time, the CH<sub>4</sub> emissions from biomass burning of tropical deciduous forests cleared for shifting cultivation purposes. Trace gas emissions from the biomass burning plumes have been collected through grab sampling in canisters as well as from online measurements through instruments. Site characteristics with respect to species composition, amount of biomass burnt and relative amounts of combustion, viz., flaming, mixed and smoldering have been determined. Modified combustion efficiency has been used to differentiate relative amounts of combustion. Emission ratios were calculated with respect to CO<sub>2</sub> and emission factors based on the amount of biomass consumed. Results of the study with respect to biomass estimations prior to burning suggested values of 12–14 t ha<sup>−1</sup> at the first site and 13.5–15.3 t ha<sup>−1</sup> at the second site. The mean modified combustion efficiencies during flaming, mixed and smoldering combustion phases for the first site were found to be 95.7%, 91.1% and 74.4% and 95.31%, 90.63% and 72.89%, respectively, for the second site. The average biomass consumed during the fire ranged from 4.7 t ha<sup>−1</sup> (site 1) to 3.4 t ha<sup>−1</sup> (site 2), indicating low amount of biomass burnt during the first phase of burning in shifting cultivation areas. Results suggested the CH<sub>4</sub> emission ratios of 1.29% at the first site and 1.59% at the second site. The CH<sub","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"3 2","pages":"Pages 133-143"},"PeriodicalIF":0.0,"publicationDate":"2001-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(01)00003-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77146481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}