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1.
Aerosol and total vapor-phase Hg concentrations in air have been measured at Walker Branch Watershed, Tennessee for ≈ 2 yr. Airborne Hg at this site is dominated by vapor forms which exhibit a strong seasonal cycle, with summer maxima that correspond to elevated air temperature. Concentrations in this forest are near background levels; however, concentrations at a site within 3 km are significantly elevated due to emissions from Hg-contaminated soils. The concentration data have been combined with a recently modified dry deposition model to estimate dry deposition fluxes to the deciduous forest at Walker Branch. Weekly mean modeled Vd values for Hg° ranged from <0.01 (winter) to > 0.1 (summer) cm s1. Weekly dry deposition fluxes ranged from <0.1 μg m−2 during winter to > 1.0 μgg m−2 in the summer. Our dry deposition estimates plus limited measurements of wet deposition in this area indicate that dry deposition may be the dominant input process in this forest, at least during the summer.  相似文献   

2.
Anthropogenic and biogenic high molecular weight (C12–C32) hydrocarbons (HC) were deposited from the atmosphere in association with both wet and dry deposition. Wet deposition generally removes HC at a faster rate (22 to 670 μg m?2 day?1) than dry deposition (4 to 189 μg m?2 day?1). However, due to longer periods during which dry deposition occurred, the removal of atmospheric HC by wet and dry deposition is almost equal during this sampling period. Atmospheric HC concentrations ranged from 0.8 to 4.1 μg m?3 and show no simple relationship to wet or dry deposition rates. Large variabilities in deposition rates for individual events were found, but long-term average deposition was relatively constant.  相似文献   

3.
Long term continuous monitoring measurements of urban atmospheric concentrations of O3, NO2, NO, and SO2 were performed for the first time in Ciudad Real, a city in central-southern Spain. The measurements were carried out using the differential optical absorption spectroscopy (DOAS) technique, with a commercial system (OPSIS, Lund-Sweden), covering the summer and winter seasons (from 21st July 2000 to 23rd March 2001). Mean levels of O3, NO2 and SO2 monitored during this period were: 27 μg m?3, 50 μg m?3 and 7 μg m?3 respectively. The highest hourly averaged value of O3 (160 μg m?3) was measured during the summer period, while NO2 was enhanced in wintertime (highest values 90 μg m?3). In the coldest period, when central heating installations were operating, SO2 showed maximum levels of 20 μg m?3. The daily, weekly and seasonal analysis of the data shows that photochemical air pollution dominates in this urban atmosphere and is strongly influenced by levels of motor traffic and domestic heating system emissions. These measurements were compared with other studies in Spain and Europe. Also, the long path averaged DOAS measurements were compared with in situ observations made in Ciudad Real, from 23rd August 2000 to 25th September 2000, using a mobile air pollution control station. All gas concentrations reported in this paper are below the WHO guidelines and the different thresholds introduced by the European Environmental Legislation.  相似文献   

4.
The “Great Waters” program, established in the 1990 Clean Air Act Amendments, mandated that atmospheric deposition of hazardous air pollutants to Lake Champlain (including Hg) be assessed. An assessment of the magnitude and seasonal variation of atmospheric Hg deposition in the Lake Champlain basin was initiated in December 1992 with one year of event precipitation collection, as well as collection of vapor and particle phase Hg in ambient air. Samples were collected at the Vermont Monitoring Cooperative air monitoring site at the Proctor Maple Research Center in Underhill Center, VT. The average volume-weighted concentration for Hg in precipitation was 8.3 ng/L for the sampling year and the average amount of Hg deposited with each precipitation event was 0.069 μg/m2. The total amount of Hg deposited through precipitation during 1993 was 9.26 μg/m2/yr. A seasonal pattern for Hg in precipitation was evident, with increased concentrations and deposition during spring and summer months. Meteorological analysis indicated the highest levels of Hg in precipitation were associated with regional transport from the south regardless of season, and with transport from the west, southwest and northwest during spring and summer months. Concentrations of ambient vapor phase Hg were typical of rural locations and consistent across seasons. Ambient particulate Hg concentrations averaged 11 pg/m3 with highest concentrations during the winter months.  相似文献   

5.
To assess the sources, transport and deposition of atmospheric mercury (Hg) in Michigan, a multi-site network was implemented in which Hg concentrations in event precipitation and ambient samples (vapor and participate phases) were determined. Results from the analysis of 2 years of event precipitation samples for Hg are reported here. The volume-weighted average Hg concentration in precipitation was 7.9, 10.8 and 10.2 ng/L for the Pellston, South Haven and Dexter sites, respectively. Yearly wet deposition of Hg for 1992–93 and 1993–94 was 5.8 and 5.5 μg/m2 at Pellston, 9.5 and 12.7 μg/m2 at South Haven and 8.7 and 9.1 μg/m at Dexter. A spatial gradient in both the Hg concentration and wet deposition was observed. Northern Michigan received almost half the deposition of Hg recorded at the southern Michigan sites. The concentration of Hg in precipitation exhibited a strong seasonal behavior with low values of 1.0 to 2.0 ng/L in winter and maximum values greater than 40 ng/L in summer. The spring, summer and autumn precipitation accounted for 89 to 91% of the total yearly Hg deposition. Mixed-layer back trajectories were calculated for each precipitation event to investigate the meteorological history and transport from potential Hg source regions. Elevated Hg concentrations were observed with air mass transport from the west, southwest, south, and southeast. At each of the sites precipitation events for which the Hg concentration was in the 90th and 10th percentile were-analyzed for trace elements by ICP-MS to investigate source impacts.  相似文献   

6.
The city of Juarez is located in the northernpart of Mexico at the border with the United States. This reportinvestigates the mercury (Hg) contribution from atmosphericsources and its accumulation in the Juarez area estimated bymeasuring the concentration of total Hg in sediments of a smallartificial pond located within the urban area of the Juarez-ElPaso metroplex. The pond is intermittently fed by Hg-free(concentration below detection levels) groundwater from a privatewell, with sporadic input of storm overflow from a nearby watertreatment facility. Total Hg concentrations in the sedimentsvaried between 20 (detection level value) and 454 μg kg-1 dry wt, with an average value of 202.8±153.9 μg kg-1. Physicalcharacteristics of the sediments varied among samples, althoughnot as drastically as their Hg content did. Among the sedimentparameters, the organic matter content correlated best with theHg content. A simplified balance of total mercury supply in theaquatic system revealed a sediment Hg flux of 336.0 μg m-2 yr-1 and a maximum Hg atmospheric flux of 119 mg m-2 yr-1.Our unexpected finding of significant concentrations of Hg in thetreated wastewater and in the water column stresses the need ofcareful consideration of all possible sources in determiningmercury atmospheric deposition flux.  相似文献   

7.
Sulfur transport and deposition in Asia, on an annual andseasonal basis, is analyzed using the ATMOS model. Calculationsare performed for two complete years (1990 and 1995). Deposition amounts in excess of 0.5 g S m-2 yr-1 are estimated for large regions in Asia, with values as high as 10 g S m-2 yr-1 in southeastern China. Annual averaged SO2 concentrations in excess of 20 μg SO2 m-3 are calculated for many urban and suburban areas ofeastern China and S. Korea, with an average of 5 μg SO2 m-3 over most of the emitter regions. Sulfur deposition by major source categories is also studied. Southeast Asia (Indonesia, Malaysia, Philippines, Singapore)receives ～25% of its sulfur deposition from shipping activities. Sulfur deposition from bio-fuel burning is significant for most of the underdeveloped regions in Asia. Volcanoes are a major source of sulfur emissions in the PacificOcean, Papua New Guinea, Philippines and Southern Japan. Sulfur deposition is shown to vary significantly throughout the year.The monsoons are found to be the largest factor controlling sulfur transport and deposition in the Indian sub-continent andSoutheast Asia. India receives over 35% of its total depositionduring the summer months. In East Asia, sulfur deposition isestimated to be 10% higher during summer and fall than winterand spring. Model results are compared with observations from a number of monitoring networks in Asia and are found to be generally consistent with the limited observations.  相似文献   

8.
The greatest sources of atmospheric emissions of SO2 in Estonia are caused by power plants (TP) which use oil shale. Since 1990 the amount of SO 2 discharges has continuously decreased due to fall in production of electric energy, and it was from TP as follows: in 1990–1991 about 180–200 thousand tons, in 1992 about 140 and in 1993–1994 about 100 thousand tons. In 1990 the annual mean emission intensity of SO 2 from all North-East (NE) Estonian pollution sources was fixed to be about 6.kg/s, with a maximum of 9.5–11 kg/s in winter period. In 1992–1993 the corresponding values were 3.5–4.6 and 5.1–6.8 kg/s. The single maximum concentrations (MC, per 30 min.) of SO 2 in the overground air layer would be in the ranges 25–450 μg/m 3 depending on emission intensity and wind parameters. The annual mean concentrations are below 25 μg/m 3 on the main territory, but may be up to 50–75 μg/m 3 near the power plants. In Kohtla-Järve town the annual mean values of 15.8–19.1 μg/m 3 and MC values of 271–442 μg/m 3 were fixed during 1991–1994 by automatic air monitoring system. Many arable lands, forest areas and wild-life preserves are subjected to relatively high sulphur precipitation loads, exceeding 0.5 g S/m2 per year, of which the role of emissions from local sources is about 60–95%. On the basis of air pollution concentration maps, the landscape of NE Estonia is classified into zones of high, moderate and low pollution level.  相似文献   

9.
The environmental impact of arsenic and heavy metals on a 105 km2 area of the historical and recent mining site of Villa de la Paz-Matehuala, San Luis Potosí (Mexico) was evaluated. Results of soil samples reported concentrations between 19–17 384 mg kg-1 As, 15–7200 mg kg-1 Cu, 31–3450 mg kg-1 Pb and 26–6270 mg kg-1 Zn, meanwhile, the concentrations in dry stream sediment samples were found to vary between 29–28 600 mg kg-1 As, 50–2160 mg kg-1 Pb, 71–2190 mg kg-1 Cu, and 98–5940 mg kg-1 Zn. The maximum arsenic concentration in pluvial water storage ponds (265 μg L-1), near the main potential sources of pollution, exceed by 5 times the Mexican drinking water quality guideline (50 μg L-1). The arsenic concentrations in water storage ponds and stream sediments decrease as distance from the potential sources increase. A special case is the `Cerrito Blanco' area located 5 km east of Matehuala, where the highest arsenic concentration in water was found (>5900 μg L-1), exceeding by 100 times the established guideline, thus representing a severe health risk. The results suggest that arsenic and heavy metal dispersion from their pollution sources (historical and active tailings impoundments, waste rock dumps and historical slag piles), is mainly associated in this site with: (1) fluvial transportation of mine waste through streams that cross the area in W–E direction; and (2) aeolian transportation of mineral particles in SW–NE direction. Finally, control measures for pollution routes and remediation measures of the site are proposed.  相似文献   

10.
Deposition rates of trace metals (Pb, Cu, Zn, Cd) were determined at the Meteorological Station in New Belgrade (H s =74 m; φ=44°49′N and λ=20°24′E) in the hydrological year 1992/93 (1 November-31 October). The dominant characteristics of the observation period were strong drought and drastically reduced pollutant emissions. Traffic and local sources operated at 0–10% of their capacities. Samples of dry and wet precipitation were taken by an automatic collector at a height of 2 m at weekly intervals. Two petri polycarbonate dishes of 93.5 mm diameter, facing upward, and one, facing downward, were used for dry precipitation sampling. Determination in a ‘clean room’ by differential pulse stripping voltammetry provided the low detection thresholds of 0.1, 1.0, 0.5 and 2.0 ng mL-1,i.e. the measurement of minimal dry deposition rates of 0.02, 0.2, 0.1 and 0.4 μg m-2d-1 for Cd, Pb, Cu and Zn, respectively. The mean annual deposition rates, expressed in μg m-2d-1, were found to be as follows: 4.5 (down), 26 (up) and 37 (wet) for Pb, 2.1 (down), 13 (up) and 36 (wet) for Cu, and 3.1 (down), 26 (up) and 95 (wet) for Zn. No values above 0.2 μg m-2d-1 were found for the Cd dry deposition rate and no Cd concentration higher than 1 ng mL-1 for precipitation with an amount >0.5 mm at the weekly interval was detected. Using the XREDS method with a scanning electron microscope, Si, Al, Fe matrix elements and Mg, Ca, S, K, P, Cu, Zn. W were identified as minor constituents of the single spherical particles and of the agglomerates present. Pb could not be categorized as a minor constituent of the coarse particles suspended in the air of New Belgrade on the basis of the previous analysis. Analysis of meteorological data showed road dust transport by outgoing SE-ESE wind from the old city of Belgrade (H s =100–250 m) as a possible Pb source at the chosen site, which was located in a park. A comparative measurement of Pb deposition on linden leaves was carried out in the vegetation period (1 April–31 October) of 1993 and 1994. The Pb distribution on leaves differed in the two growing seasons, while the sum of Pb deposition rates on the downward and upward oriented petri dishes remained practically equal. The Pb accumulation on linden leaves was higher in 1994, first because of an intensive soil supply by rain water. Besides, ‘yellow’ rain was reported during the night 15/16 April, on 16 and 17 April 1994. A Fe concentration of 2.3 μg mL-1 and a Pb concentration of 312 ng mL-1 with a total precipitation of 12.6 mm were found in the weekly wet sample of 13–20 April. Dry deposition rates of 17 and 84 μg m-2d-1 for Cd and Pb, respectively, were measured on the upward facing dishes two weeks later (27 April–4 May). The synoptic analysis confirmed the development of the Saharan cyclogenesis and its influence on the Balkan peninsula in the period of 14 to 17 April 1994. In this region the impact of dustfall originating from the Saharan storm was evident either during wet deposition or through resuspension processes.  相似文献   

11.
To examine the spatial variation of airborne lead in Taipei, a field study was conducted during the summer and fall of 1991. Samples were collected 2–4 times daily at several sites for the determination of airborne lead. Results indicate that the average of air lead concentration of Taipei city is 0.70±0.39 μg/m3 and eighty-eight percent of particles are smaller than 10 pm. From high to low polluted area, the fine particle concentrations are 0.83, 0.51, 0.29 μg/m3 The lead concentration of particulates < 10 μm on 2nd, 7th, and 14th floors of a building are 0.75, 0.60, 0.55 μg/m3, and appears to be little difference among vertical dispersions. The air lead concentrations (da < 10 μm) on roadside, side walk and covered walk way from the vehicle emission source of a main road are 0.83, 0.78, 0.87 μg/m3 the highest is on the covered walk way. For lead concentrations (da < 10 μm) on the main street, side street and alley of an area are 0.34, 0.37, 0.35 μg/m3 the result indicates lead concentrations on these pathways are not significantly different.  相似文献   

12.
Gillett  R. W.  Ayers  G. P.  Selleck  P. W.  Tuti  MHW  Harjanto  H. 《Water, air, and soil pollution》2000,120(3-4):205-215
Gas mixing ratios of SO2, NO2 and HNO3 and nitrate and sulfate concentrations in rainwater have beenmeasured at six sites in Indonesia. The sites, Jakarta, Serang,Cilegon, Merak and Bogor, in Java, and Bukit Koto Tabang inSumatra, provide a range of pollution regimes in Indonesia.Jakarta and Bogor are heavily polluted sites in Java, whereasBukit Koto Tabang is a clean air station in a relativelyunpopulated area on the west coast of equatorial Sumatra. At thesesites rainwater was collected daily and gas samples weeklyduring 1996. The other three sites Serang, Cilegon and Merakrepresent smaller regional towns in west Java. At these sitesrainwater samples were collected weekly from June 1991 untilJune 1992.The results show that Jakarta has the highest volume-weightedmean sulfate concentrations in rainwater while the lowest weremeasured at Bukit Koto Tabang. Volume-weighted mean nitrateconcentration was about 24 μeq L-1 at Jakarta and Bogor,significantly higher than the 0.8 μeq L-1 measured atBukit Koto Tabang.Sulfur dioxide mixing ratios ranged from 4–7 ppbv in Jakarta toan average of 1.3 ppbv at Bukit Koto Tabang. Nitrogen dioxidemixing ratio was highest in Jakarta averaging 28 ppbv comparedwith the background mixing ratio of 1.2 ppbv at Bukit KotoTabang. Using dry deposition velocities estimated during aseparate study in the similar conditions of Malaysia enabled drydeposition estimates of SO2, HNO3 and NO2.Results of estimated total acidic S and N deposition (wet anddry) were greater than 250 meq m-2 yr-1 at the Jakartaand Bogor sites compared with about 23 meq m-2 yr-1 atBukit Koto Tabang. At Jakarta and Bogor dry deposition accountedfor more than 50% of the total deposition estimates compared with about 20% at Bukit Koto Tabang. Such deposition rates arehigh when compared to critical loads estimated for Indonesia bythe RAINS-Asia model. In this model, critical loads in western Java and equatorial western Sumatra fall into one of twoclasses: 50–100 and 20–50 meq m-2 yr-1. Thus acidic deposition flux at Jakarta and Bogor wasfound to be above the predicted critical loads even for the moreacid insensitive soils.  相似文献   

13.
Needles of Scots pine (Pinus sylvestris L.) from 25 and 40 sampling plots in southern and northern Finland, respectively, that had earlier been analysed for total sulphur concentration (St) were reanalysed for foliar sulphate sulphur (SO4–S) and total nitrogen (Nt). Organic sulphur content (So) was calculated as the difference between St and SO4–S. Current (c) and previous-year (c+1) needles were collected from southern Finland in December 1989 and c – c+2 needles from northern Finland in September-October 1990/September 1992. The results show that the St concentration and St/Nt ratio in Scots pine needles are good indices of dry deposition of SO2 in general, while SO4–S concentrations and SO4–S/So ratios can be used in areas with low N supply from the soil and/or low wet deposition of N. The normal St concentration in needles of Scots pines growing on a podzol with low N supply is considered to be 500–700 μg g-1 and that of SO4–S 100–200 μg g-1. An increase of 100 μg g-1 in needle St may be attributed to a rise of 1.4 μg m-3 in ambient SO2 concentration in areas with relatively low SO2 concentrations (>15 μg m-3). A critical level of 5 μg m-3 as an annual and growing season mean is proposed for forestry in northern Europe (north of 60°N).  相似文献   

14.
During the summer months, Nova Scotia is downwind of many of the large industrial areas of the eastern United States and central Canada. The studies described here were carried out in the summers of 1983 and 1984 in Antigonish, a small rural town in northeastern Nova Scotia with no local sources. Twenty-four hour samples were collected on Teflon filters using a dichotomous sampler, and were analyzed for sulphate, nitrate and chloride by ion chromatography and for strong acid using Gran titrations. Sulphate episodes (up to 27 μg m?3) were frequent. They usually occurred in warm, hazy weather and were often accompanied by strong acid (up to 9 μg m?3 as H2SO4).  相似文献   

15.
Results from the first study in Hong Kong, Southern China, to investigate the concentrations of organic acids in bulk deposition, aerosol and gas phase samples are presented. 57 daily bulk deposition samples were collected in central Kowloonand analyzed by ion chromatography, from May 1999 to May 2000. The volume-weighted (vw) mean concentrations for formate, acetate, propanoate and oxalate were 6.1, 4.5, 0.4 and 1.4 μeq dm-3, respectively, with vw mean pH being 4.65.The maximum acidity contributions by formic and acetic acidsfor bulk deposition samples collected on a daily basis, withpH < 5.0, were 17 and 14%, respectively. The concentrationsof these acids were significantly correlated with each other, butnot with pH. Higher organic acid concentrations were foundin the dry, winter season, and for the synoptic weather systemtypes: approaching cyclone and cold front. Oxalate levels weregenerally higher in bulk deposition samples for north/northeasterly air masses, higher surface windspeeds, and low rainfall amounts. Formic and acetic acids were present at higher concentrations in the gas phase (mean concentrations at two sites were in the range from 3.2 to 6.5 μg m-3, with formate usually < acetate), than in aerosols (mean concentration of formate, acetate or oxalate ≤2.2 μg m-3). Higher levels of organic acids both in aerosols and in the gas phase were found at a busy roadside site than at a residential site. Deposition fluxes for formic and acetic acidsare reported.  相似文献   

16.
Total S concentrations of Scots pine (Pinus sylvestris L.) needles studied in the Finnish subarctic (66–70°N, 24–30°E) in 1990/1992 ranged from 573 to 1153 μg g-1. Levels were found to be ≈ 900 μg g-1 (i.e. 1.3–1.8 times the ‘normal’ level of 500–700 μg g-1) in areas where the long-term ambient SO2 concentration was ≈ 2–5 μg m-3, particulate SO4 2- ≈ μg m-3 and total S deposition ≈ 0.5 g m-2. A statistically significant increase in needle total S concentrations was found towards the east, i.e. towards the smelters of the Kola Peninsula in Russia, which emit SO2. The increase in needle total S concentrations to over 900 μg g-1 close to the Russian border is thought to result mainly from exposure to high short-term SO2 concentrations. The results also suggest that wintertime S deposition may have an impact on the needle total S content. It is suggested that the UNECE long-term critical level of 15 μg SO2 m-3 for forestry in boreal and high mountain climates in Europe is too high for the pine forests in the extreme north, where the proportion of dry-deposited S may be 60–80%.  相似文献   

17.
Historical deposition rates of Hg were determined in 7 ombrotrophic bogs located far from direct sources in Sweden and Norway. The peat bog cores were dated using 210Pb. Based on the dating result 10 to 12 slices from each core were analyzed for Hg. In Southwestern Scandinavia (Rörvik) the deposition rate has increased from about 10 to about 30 μg Hg m?2 yr?1 since the beginning of this century. In Northwestern Norway (Överbygd) the deposition rate has increased from about 10 to about 35 μg Hg m?2 yr?1 since the 1960's. In Southeast Sweden (Aspvreten) the deposition rate decreased since the beginning of this century. There are no significant trends in the historical deposition rates at the two other stations in middle Scandinavia. A comparison between recent Hg deposition rates measured by peat bog analysis, wet precipitation and mosses shows good agreement at all stations except those in Northern Norway were local dry deposition of Hg may be an important source of Hg.  相似文献   

18.
The present study aims to establish the annual NH3 deposition to an inland heathland in Denmark using a micro-meterological approach with passive wind-vane flux samplers. The integrating samplers were replaced at weekly intervals from May 1995 to May 1996. The average concentration, 2.05 μg m-3 at the heathland is at a moderate level when compared to heathlands in other parts of Europe. The average deposition velocity was 0.83 cm s-1 which is within the range of depositon velocities found for other heathlands in Europe. The average canopy resistance was found to be relatively high, 61 s -1. The measurements yielded a total NH3-N deposition of 2.4 (± 0.9) kg ha-1 yr-1 with a data coverage of 71% for 1995/1996. In 40% of this time the flux is regarded as zero because the flux is not significant different from zero. In 60% of this time the significant fluxes varied from –0.052 μg m-2 s-1 (deposition equal 16.4 kg N ha-1 yr-1) to 0.089 μg m-2 s-1 (emission equal 28.2 kg N ha-1 yr-1). The method is only able to direct measure significant fluxes down to the equivalence of 0.010 μg m-2 s-1 (approximately 3.2 kg ha-1 yr-1). Therefore the exact deposition cannot be determined by the applied method at very low deposition sites such as a coastal heathland in Denmark. In a high-deposition area as in the central Netherlands the method gave significant fluxes with a 100% data coverage for a two month period.  相似文献   

19.
Atmospheric gases and particulates were collected using four-stage filter-pack in Chunchon from January through December in 1999. Particulate SO4 2? and NO3 ?, and gaseous HNO3, SO2 and NH3 were analyzed. Annual average concentration of SO4 2?(S), NO3 ?(S), HNO3 (g), SO2(g) and NH3(g) were 5.75µg/m3, 4.98µg/m3, 0.33ppb, 1.52ppb and 7.25ppb, respectively. Annual dry deposition fluxes were estimated using the measured concentration and dry deposition velocity published by other research group. Annual dry deposition of S was 287kg · (km)?2·y?1, which accounted for about 30% of total S deposition. For N deposition, dry deposition is predominant; about 70% of total N deposition was through dry process mostly as forms of NH3 and HNO3.  相似文献   

20.
This study investigated the relationship between exhaust emission from motorcycles and ambient air quality in Bangkok Metropolitan Region (BMR). The test result revealed that averagepollutant concentrations of the test motorcycles in terms of hydrocarbon, carbon monoxide and nitrogen dioxide were 8.38, 16.69 and 0.04 g km-1, respectively. The finding also indicated that two-stroke motorcycles emitted 1.5 and 5 times more carbon monoxide and hydrocarbon emission, respectively perkilometer driven than do four-stroke motorcycles. Four air sampling stations were strategically established to evaluate the air pollution problems in Bangkok arising from vehicle exhaust emission. Investigation was carried out to determine the correlation between average air pollutant concentration with different traffic configuration in each traffic zone of Bangkok Metropolitan Region (BMA) during peak/non peak hours, day/night times and weekday/weekend. The average concentrationsof PM10 particulate matter, carbon monoxide, nitrogen dioxide and sulphur dioxide in Bangkok street air were found tobe 84.33 μg m-3 (24 hr ave.), 7.05 mg m-3 (8 hr ave.), 56.74 μg m-3 (1 hr ave.) and 9.60 μg m-3 (24 hr ave.), respectively.  相似文献   

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