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1.
Some metal etching operations emit limited flow rates of waste gases with reddish-brown NO 2 fume, which may cause visual and acidic-odor complaints, as well as negative health effects. In this study, tests were performed by passing caustic-treated waste gases vented from Al-etching operations through columns packed either with virgin or regenerated granular activated carbon (GAC) to test their adsorptive conversion performance of NO 2 in the gases. The gases contained 5–55 ppm NO 2 and acetic and nitric acids of below 3 ppm. Exhausted carbon was regenerated by scrubbing it with caustic solution and water, and dried for further adsorption tests. Results indicate that with an (empty bed residence time (EBRT) of 0.15 sec for the gas through the GAC-packed space, around 60% of the influent NO 2 of 54 ppm could be removed, and 47% of the removed NO 2 was converted by and desorbed from the carbon as NO. GAC used in the present study could be regenerated at least twice to restore its capacity for NO 2 adsorption. Within EBRTs of 0.076–0.18 sec, the adsorptive conversion capacity was linearly varied with EBRT. In practice, with an EBRT of 0.20 sec, a conversion capacity of 0.80 kg NO 2 (kg GAC) ?1 with an influent NO 2 of 40 ppm can be used as a basis for system design. Implications: Some metal etching operations emit waste gases with reddish-brown (yellow when diluted) NO 2 fume which may cause visual and acidic-odor complaints, as well as negative health effects. This study provides a simple process for the adsorptive conversion of NO 2 in caustic-treated waste gases vented from metal-etching operations through a GAC column. With an EBRT of 0.20 sec, a conversion capacity of 0.80 kg NO 2 (kg GAC) ?1 with an influent NO 2 of 40 ppm can be used as a basis for system design. Saturated GAC can be regenerated at least twice by simply scrubbing it with aqueous caustic solution. 相似文献
2.
The study reported by this paper involves the use of the Controlled Condensation System (Goksoyr/Ross Coil) for flue gas S0 3 measurements in both the laboratory and the field, under low and high mass loadings. The Controlled Condensation System cools the flue gas to below the dewpoint of H 2S0 4 but above the H 20 dewpoint. The resulting aerosol is collected either on the coil walls or on the back-up glass frit. The laboratory recovery of the H 2S0 4 in streams of varying S0 2, H 20, and H 2S0 4 content was found to be 95 ± 6%. A new quartz filter holder was designed to meet the filtration problems encountered in collecting S0 3 from particle laden flue gas streams. This quartz system, when heated to above 250°C, quantitatively passed the H 2S0 4 into the condensation coil. Later studies with this filter system preloaded with fly ash equivalent to a mass loading of 1.3 g/m 3 yielded a 80-85% recovery of H 2S0 4. The laboratory system was simultaneously tested at a 150 megawatt, pulverized coal-fired power plant prior to and after a wet limestone FGD. The inlet grain loading to the FGD ranged from 0.06 g/m 3 to 11.4 g/m 3 with S0 2 concentrations as high as 4000 ppm. The average inlet H 2S0 4 value was 8.3 ppm and the outlet from the FGD was 3.1 ppm. The source fluctuation value was determined to be ±65%. 相似文献
3.
The biochar derived from rice hull was evaluated for its abilities to remove hydrogen sulfide (H 2S) from gas phase. The surface area and pH of the biochar were compared. The biochar derived from rice hull was evaluated for its abilities to remove hydrogen sulfide (H 2S) from gas phase. The surface area and pH of the biochar were compared. The different pyrolysis temperature has great influence on the adsorption of H 2S. At the different pyrolysis temperature, the H 2S removal efficiency of rice hull-derived biochar was different. The adsorption capacities of biochar were 2.09 mg·g –1, 2.65 mg·g –1, 16.30 mg·g –1, 20.80 mg·g –1, and 382.70 mg·g –1, which their pyrolysis temperatures were 100 °C, 200 °C, 300 °C, 400 °C and 500 °C respectively. Based on the Yoon-Nelson model, it analyzed the mass transfer mechanism of hydrogen sulfide adsorption by biochar. Implications: The paper focuses on the biochar derived from rice hull–removed hydrogen sulfide (H 2S) from gas phase. The surface area and pH of the biochar were compared. The different pyrolysis temperatures have great influence on the adsorption of H 2S. At the different pyrolysis temperatures, the H 2S removal efficiency of rice hull–derived biohar was different. The adsorption capacities of biochar were 2.09, 2.65, 16.30, 20.80, and 382.70 mg·g ?1, and their pyrolysis temperatures were 100, 200, 300, 400, and 500 °C, respectively. Based on the Yoon-Nelson model, the mass transfer mechanism of hydrogen sulfide adsorption by biochar was analyzed. 相似文献
4.
The mass concentration of carbonaceous species, organic carbon (OC), and elemental carbon (EC) using a semicontinuous thermo-optical EC-OC analyzer, and black carbon (BC) using an Aethalometer were measured simultaneously at an urban mega city Delhi in Ganga basin from January 2011 to May 2012. The concentrations of OC, EC, and BC exhibit seasonal variability, and their concentrations were ~2 times higher during winter (OC 38.1?±?17.9 μg m ?3, EC 15.8?±?7.3 μg m ?3, and BC 10.1?±?5.3 μg m ?3) compared to those in summer (OC 14.1?±?4.3 μg m ?3, EC 7.5?±?1.5 μg m ?3, and BC 4.9?±?1.5 μg m ?3). A significant correlation between OC and EC ( R?=?0.95, n?=?232) indicate their common emission sources with relatively lower OC/EC ratio (range 1.0–3.6, mean 2.2?±?0.5) suggests fossil fuel emission as a major source of carbonaceous aerosols over the station. On average, mass concentration of EC was found to be ~38 % higher than BC during the study period. The measured absorption coefficient (b abs) was significantly correlated with EC, suggesting EC as a major absorbing species in ambient aerosols at Delhi. Furthermore, the estimated mass absorption efficiency (σ abs) values are similar during winter (5.0?±?1.5 m 2 g ?1) and summer (4.8?±?2.8 m 2 g ?1). Significantly high aerosol loading of carbonaceous species emphasize an urgent need to focus on air quality management and proper impact assessment on health perspective in these regions. 相似文献
5.
In order to remove high concentrations of hydrogen sulfide (H 2S) gas from anaerobic wastewater treatments in livestock farming, a novel process was evaluated for H 2S gas abatement involving the combination of chemical absorption and biological oxidation processes. In this study, the extensive experiments evaluating the removal efficiency, capacity, and removal characteristics of H 2S gas by the chemical absorption reactor were conducted in a continuous operation. In addition, the effects of initial Fe 2 + concentrations, pH, and glucose concentrations on Fe 2 + oxidation by Thiobacillus ferrooxidans CP9 were also examined. The results showed that the chemical process exhibited high removal efficiencies with H 2S concentrations up to 300 ppm, and nearly no acclimation time was required. The limitation of mass‐transfer was verified as the rate‐determining step in the chemical reaction through model validation. The Fe 2 + production rate was clearly affected by the inlet gas concentration as well as flow rate and a prediction equation of ferrous production was established. The optimal operating conditions for the biological oxidation process were below pH 2.3 and 35°C in which more than 90% Fe 3 + formation ratio was achieved. Interestingly, the optimal glucose concentration in the medium was 0.1%, which favored Fe 2 + oxidation and the growth of T. ferrooxidans CP9. 相似文献
6.
Abstract Simultaneous removal of NH 3 and H 2S was investigated using two types of biofilters—one packed with wood chips and the other with granular activated carbon (GAC). Experimental tests and measurements included analyses of removal efficiency (RE), metabolic products, and results of long-term operation (around 240 days). The REs for NH 3 and H 2S were 92 and 99.9%, respectively, before deactivation. After deactivation, the RE for NH 3 and H 2S were decreased to 30–50% and 75%, respectively. The activity of nitrifying bacteria was inhibited by high concentrations of H 2S (over 200 ppm) but recovered gradually after H 2S addition was ceased. However, the Thiobacillus thioparus as sulfur oxidizing bacteria did not show inhibition at the NH 3 concentration under 150-ppm conditions. The deactivation of the biofilter was caused by metabolic products [elemental sulfur and (NH 4) 2SO 4] ac-cumulating on the packing materials during the extended operation. The removal capacities for NH 3 and H 2S were 6.0–8.0 and 45–75 mg N, S/L/hr, respectively. 相似文献
7.
以木屑为填料,采用多层生物滤塔净化H2S气体,研究其适宜的工艺条件及生物降解宏观动力学.结果表明,填料分层可提高H2S去除率,当进气容积负荷<153.2 g H2S/(m3·d)时,H2S的去除率保持在90%以上;进气浓度低于70 mg/m3,下层200mm填料对H2S总去除率的贡献在50%以上;填料含水率为50%~6... 相似文献
8.
The anaerobic activities in swine slurry storage and treatment generate biogas containing gaseous ammonia component which is a chemical agent that can cause adverse environmental impacts when released to the atmosphere. The aim of this pilot plant study was to remove ammonia from biogas generated in a covered lagoon, using a sulfuric acid wet scrubber. The data showed that, on average, the biogas contained 43.7 ppm of ammonia and its concentration was found to be exponentially related to the air temperature inside the lagoon. When the air temperature rose to 35°C and the biogas ammonia concentration reached 90 ppm, the mass transfer of ammonia/ammonium from the deeper liquid body to the interface between the air and liquid became a limiting factor. The biogas velocity was critical in affecting ammonia removal efficiency of the wet scrubber. A biogas flow velocity of 8 to 12 mm s ?1 was recommended to achieve a removal efficiency of greater than 60%. Stepwise regression revealed that the biogas velocity and air temperature, not the inlet ammonia concentration in biogas, affected the ammonia removal efficiency. Overall, when 73 g L ?1 (or 0.75 M) sulfuric acid solution was used as the scrubber solution, removal efficiencies varied from 0% to 100% with an average of 55% over a 40‐d measurement period. Mass balance calculation based on ammonium–nitrogen concentration in final scrubber liquid showed that about 21.3 g of ammonia was collected from a total volume of 1169 m 3 of biogas, while the scrubber solution should still maintain its ammonia absorbing ability until its concentration reaches up to 1 M. These results showed promising use of sulfuric acid wet scrubber for ammonia removal in the digester biogas. 相似文献
9.
An indoor/outdoor monitoring programme of PM 10 was carried out in two sports venues (a fronton and a gymnasium). Levels always below 50 μg m ?3 were obtained in the fronton and outdoor air. Due to the climbing chalk and the constant process of resuspension, concentrations above 150 μg m ?3 were registered in the gymnasium. The chalk dust contributed to CO 3 2? concentrations of 32?±?9.4 μg m ?3 in this sports facility, which represented, on average, 18 % of the PM 10 mass. Here, the carbonate levels were 128 times higher than those registered outdoors. Much lower concentrations, around 1 μg m ?3, were measured in the fronton. The chalk dust is also responsible for the high Mg 2+ concentrations in the gym (4.7?±?0.89 μg m ?3), unfolding a PM 10 mass fraction of 2.7 %. Total carbon accounted for almost 30 % of PM 10 in both indoor spaces. Aerosol size distributions were bimodal and revealed a clear dependence on physical activities and characteristics of the sports facilities. The use of climbing chalk in the gymnasium contributed significantly to the coarse mode. The average geometric mean diameter, geometric standard deviation and total number of coarse particles were 0.77 μm, 2.79 cm ?3 and 28 cm ?3, respectively. 相似文献
10.
Simultaneous sludge reduction and malodor abatement in humus soil cooperated an anaerobic/anoxic/oxic (A2O) wastewater treatment were investigated in this study. The HSR-A2O was composed of a humus soil reactor (HSR) and a conventional A2O (designated as C-A2O).The results showed that adding HSR did not deteriorate the chemical oxygen demand (COD) removal, while total phosphorus (TP) removal efficiency in HSR-A2O was improved by 18 % in comparison with that in the C-A2O. Both processes had good performance on total nitrogen (TN) removal, and there was no significant difference between them (76.8 and 77.1 %, respectively). However, NH 4 +–N and NO 3 ?–N were reduced to 0.3 and 6.7 mg/L in HSR-A2O compared to 1.5 and 4.5 mg/L. Moreover, adding HSR induced the sludge reduction, and the sludge production rate was lower than that in the C-A2O. The observed sludge yield was estimated to be 0.32 kg MLSS/day in HSR-A2O, which represent a 33.5 % reduction compared to a C-A2O process. Activated sludge underwent humification and produced more humic acid in HSR-A2O, which is beneficial to sludge reduction. Odor abatement was achieved in HSR-A2O, ammonium (NH 3), and sulfuretted hydrogen (H 2S) emission decreased from 1.34 and 1.33 to 0.06 mg/m 3, 0.025 mg/m 3 in anaerobic area, with the corresponding reduction efficiency of 95.5 and 98.1 %. Microbial community analysis revealed that the relevant microorganism enrichment explained the reduction effect of humus soil on NH 3 and H 2S emission. The whole study demonstrated that humus soil enhanced odor abatement and sludge reduction in situ. 相似文献
11.
To investigate the spatial and seasonal variations of nitrous oxide (N 2O) fluxes and understand the key controlling factors, we explored N 2O fluxes and environmental variables in high marsh (HM), middle marsh (MM), low marsh (LM), and mudflat (MF) in the Yellow River estuary throughout a year. Fluxes of N 2O differed significantly between sampling periods as well as between sampling positions. During all times of day and the seasons measured, N 2O fluxes ranged from ?0.0051 to 0.0805 mg N 2O m ?2 h ?1, and high N 2O emissions occurred during spring (0.0278 mg N 2O m ?2 h ?1) and winter (0.0139 mg N 2O m ?2 h ?1) while low fluxes were observed during summer (0.0065 mg N 2O m ?2 h ?1) and autumn (0.0060 mg N 2O m ?2 h ?1). The annual average N 2O flux from the intertidal zone was 0.0117 mg N 2O m ?2 h ?1, and the cumulative N 2O emission throughout a year was 113.03 mg N 2O m ?2, indicating that coastal marsh acted as N 2O source. Over all seasons, N 2O fluxes from the four marshes were significantly different ( p?<?0.05), in the order of HM (0.0256?±?0.0040 mg N 2O m ?2 h ?1)?>?MF (0.0107?±?0.0027 mg N 2O m ?2 h ?1)?>?LM (0.0073?±?0.0020 mg N 2O m ?2 h ?1)?>?MM (0.0026?±?0.0011 mg N 2O m ?2 h ?1). Temporal variations of N 2O emissions were related to the vegetations ( Suaeda salsa, Phragmites australis, and Tamarix chinensis) and the limited C and mineral N in soils during summer and autumn and the frequent freeze/thaw cycles in soils during spring and winter, while spatial variations were mainly affected by tidal fluctuation and plant composition at spatial scale. This study indicated the importance of seasonal N 2O contributions (particularly during non-growing season) to the estimation of local N 2O inventory, and highlighted both the large spatial variation of N 2O fluxes across the coastal marsh (CV?=?158.31 %) and the potential effect of exogenous nitrogen loading to the Yellow River estuary on N 2O emission should be considered before the annual or local N 2O inventory was evaluated accurately. 相似文献
12.
Introduction The removal of heavy metals by natural adsorbent has become one of the most attractive solutions for environmental remediation. Natural clay collected from the Late Cretaceous Aleg formation, Tunisia was used as a natural adsorbent for the removal of Hg(II) in aqueous system. Methods Physicochemical characterization of the adsorbent was carried out with the aid of various techniques, including chemical analysis, X-ray diffraction, Fourier transform infrared and scanning electron micrograph. Batch sorption technique was selected as an appropriate technique in the current study. Method parameters, including pH, temperature, initial metal concentration and contact time, were varied in order to quantitatively evaluate their effects on Hg(II) adsorption onto the original and pillared clay samples. Adsorption kinetic was studied by fitting the experimental results to the pseudo-first-order and pseudo-second-order kinetic models. The adsorption data were also simulated with Langmuir, Freundlich and Temkin isotherms. Results Results showed that the natural clay samples are mainly composed of silica, alumina, iron, calcium and magnesium oxides. The sorbents are mainly mesoporous materials with specific surface area of <250 m 2 g ?1. From the adsorption of Hg(II) studies, experimental data demonstrated a high degree of fitness to the pseudo-second-order kinetics with an equilibration time of 240 min. The equilibrium data showed the best model fit to Langmuir model with the maximum adsorption capacities of 9.70 and 49.75 mg g ?1 for the original and aluminium pillared clays, respectively. The maximum adsorption of Hg(II) on the aluminium pillared clay was observed to occur at pH 3.2. The calculated thermodynamic parameters (? G°, ? H° and ? S°) showed an exothermic adsorption process. The entropy values varied between 60.77 and 117.59 J?mol ?1 K ?1, and those of enthalpy ranged from 16.31 to 30.77 kJ mol ?1. The equilibrium parameter ( R L) indicated that the adsorption of Hg(II) on Tunisian smectitic clays was favourable under the experimental conditions of this study. Conclusion The clay of the Aleg formation, Tunisia was found to be an efficient adsorbent for Hg(II) removal in aqueous systems. 相似文献
13.
Carbonized wood is a biofuel from cellulose pyrolysis with frequent smoke and life-threatening carcinogenic emissions. Carbon monoxide (CO), particulate matter (PM2.5), metalloids and trace elements from charcoals from six commonly used tropical timbers for carbonization in Donkorkrom (Ghana) were assessed. During combustion, Anogeissus leiocarpa charcoal emitted the least CO (4.28 ± 1.08 ppm) and PM2.5 (3.83 ± 1.57 μg/m3), while particulate matter was greatest for Erythrophleum ivorense (28.05 ± 3.08 ppm) and Azadirachta indica (27.67 ± 4.17 μg/m3) charcoals. Erythrophleum ivorense charcoal produced much lead (16.90 ± 0.33 ppm), arsenic (1.97 ± 0.10 ppm) and mercury (0.58 ± 0.003 ppm) but the least chromium (0.11 ± 0.01 ppm) and zinc (2.85 ± 0.05 ppm). Nickel was greatest for A. indica charcoal (0.71 ± 0.01 ppm) and least for Vitellaria paradoxa (0.07 ± 0.004 ppm). Trace elements ranged from 342.01 ± 2.54 ppm (A. indica) to 978.47 ± 1.80 ppm (V. paradoxa) for potassium and 1.74 ± 0.02% (V. paradoxa) to 2.24 ± 0.10% (A. indica) for sulphur. Besides A. leiocarpa charcoal, which ranked safest during combustion, the high PM2.5 and CO emissions make the other biofuels hazardous indoors. Kitchens need air filters to absorb these emissions together with the use of improved cook stoves. These carcinogenic metalloids would necessitate that their ashes be properly discarded without human contact. Yet, the charcoals would be much suitable as soil amendment bio-char for plant growth quality improvement. 相似文献
14.
Methane (CH 4) removal in the presence of ethanol vapors was performed by a stone-based bed and a hybrid packing biofilter in parallel. In the absence of ethanol, a methane removal efficiency of 55 ± 1% was obtained for both biofilters under similar CH 4 inlet load (IL) of 13 ± 0.5 g CH4 m ?3 h ?1 and an empty bed residence time (EBRT) of 6 min. The results proved the key role of the bottom section in both biofilters for simultaneous removal of CH 4 and ethanol. Ethanol vapor was completely eliminated in the bottom sections for an ethanol IL variation between 1 and 11 g ethanol m ?3 h ?1. Ethanol absorption and accumulation in the biofilm phase as well as ethanol conversion to CO 2 contributed to ethanol removal efficiency of 100%. In the presence of ethanol vapor, CO 2 productions in the bottom section increased almost fourfold in both biofilters. The ethanol concentration in the leachate of the biofilter exceeding 2200 g ethanol m ?3 leachate in both biofilters demonstrated the excess accumulation of ethanol in the biofilm phase. The biofilters responded quickly to an ethanol shock load followed by a starvation with 20% decrease of their performance. The return to normal operations in both biofilters after the transient conditions took less than 5 days. Unlike the hybrid packing biofilter, excess pressure drop (up to 1.9 cmH 2O m ?1) was an important concern for the stone bed biofilter. The biomass accumulation in the bottom section of the stone bed biofilter contributed to 80% of the total pressure drop. However, the 14-day starvation reduced the pressure drop to 0.25 cmH 2O m ?1. 相似文献
15.
The rate of production of SO 2 from H 2S was measured in a series of experiments in a broad, ground-level plume from geothermal vents in New Zealand. The mean rate constant for the reaction was 3.5 ± 1.3 × 10 −3 min −1 which produced a mean lifetime for H 2S oxidation of 500 ± 240 min. It is likely that the major oxidant of H 2S in the atmosphere is the OH radical, but it is also necessary to consider additional unknown mechanisms to fully explain the results. 相似文献
16.
Agra, one of the oldest cities “World Heritage site”, and Delhi, the capital city of India are both located in the border of Indo-Gangetic Plains (IGP) and heavily loaded with atmospheric aerosols due to tourist place, anthropogenic activities, and its topography, respectively. Therefore, there is need for monitoring of atmospheric aerosols to perceive the scenario and effects of particles over northern part of India. The present study was carried out at Agra (AGR) as well as Delhi (DEL) during winter period from November 2011 to February 2012 of fine particulate (PM 2.5: d?<?2.5 μm) as well as associated carbonaceous aerosols. PM 2.5 was collected at both places using medium volume air sampler (offline measurement) and analyzed for organic carbon (OC) and elemental carbon (EC). Also, simultaneously, black carbon (BC) was measured (online) at DEL. The average mass concentration of PM 2.5 was 165.42?±?119.46 μg m ?3 at AGR while at DEL it was 211.67?±?41.94 μg m ?3 which is ~27 % higher at DEL than AGR whereas the BC mass concentration was 10.60 μg m ?3. The PM 2.5 was substantially higher than the annual standard stipulated by central pollution control board and United States Environmental Protection Agency standards. The average concentrations of OC and EC were 69.96?±?34.42 and 9.53?±?7.27 μm m ?3, respectively. Total carbon (TC) was 79.01?±?38.98 μg m ?3 at AGR, while it was 50.11?±?11.93 (OC), 10.67?±?3.56 μg m ?3 (EC), and 60.78?±?14.56 μg m ?3 (TC) at DEL. The OC/EC ratio was 13.75 at (AGR) and 5.45 at (DEL). The higher OC/EC ratio at Agra indicates that the formation of secondary organic aerosol which emitted from variable primary sources. Significant correlation between PM 2.5 and its carbonaceous species were observed indicating similarity in sources at both sites. The average concentrations of secondary organic carbon (SOC) and primary organic carbon (POC) at AGR were 48.16 and 26.52 μg m ?3 while at DEL it was 38.78 and 27.55 μg m ?3, respectively. In the case of POC, similar concentrations were observed at both places but in the case of SOC higher over AGR by 24 in comparison to DEL, it is due to the high concentration of OC over AGR. Secondary organic aerosol (SOA) was 42 % higher at AGR than DEL which confirms the formation of secondary aerosol at AGR due to rural environment with higher concentrations of coarse mode particles. The SOA contribution in PM 2.5 was also estimated and was ~32 and 12 % at AGR and DEL respectively. Being high loading of fine particles along with carbonaceous aerosol, it is suggested to take necessary and immediate action in mitigation of the emission of carbonaceous aerosol in the northern part of India. 相似文献
17.
Experiments were conducted to assess the impact of citric acid (CA) and rhizosphere bacteria on metal uptake in Phragmites australis cultured in a spiked acid mine drainage (AMD) soil. Rhizosphere iron-oxidizing bacteria (Fe(II)OB) enhanced the formation of Fe plaque on roots, which decreased the uptake of Fe and Mn. CA inhibited the growth of Fe(II)OB, decreased the formation of metal plaque, raised the metal mobility in soil, and increased the accumulation of metals in all tissues of the reeds. The higher the CA dosage, the more metals accumulated into reeds. The total amount of metals in reeds increased from 7.8?±?0.5?×?10 ?6 mol plant ?1 (Mn), 1.4?±?0.1?×?10 ?3 mol plant ?1 (Fe), and 1.0?±?0.1?×?10 ?4 mol plant ?1 (Al) in spiked soil without CA to 22.2?±?0.5?×?10 ?6 mol plant ?1 (Mn), 3.5?±?0.06?×?10 ?3 mol plant ?1 (Fe), and 5.0?±?0.2?×?10 ?4 mol plant ?1 (Al) in soil added with 33.616 g C 6H 8O 7·H 2O for per kilogram soil. CA could be effective at enhancing the phytoremediation of metals from AMD-contaminated soil. 相似文献
18.
In an effort to assess the occurrence and sources of polycyclic aromatic hydrocarbons (PAHs) in the ambient air of Riyadh, Saudi Arabia, PM 10 samples were collected during December 2010. Diagnostic PAH concentration ratios were used as a tool to identify and characterize the PAH sources. The results reflect high PM 10 and PAH concentrations (particulate matter (PM)?=?270–1,270 μg/m 3). The corresponding average PAH concentrations were in the range of 18?±?8 to 1,003?±?597 ng/m 3 and the total concentrations (total PAHs (TPAHs) of 17 compounds) varied from 1,383 to 13,470 ng/m 3 with an average of 5,871?±?2,830 ng/m 3. The detection and quantification limits were 1–3 and 1–10 ng/ml, respectively, with a recovery range of 42–80 %. The ratio of the sum of the concentrations of the nine major non-alkylated compounds to the total (CPAHs/TPAHs) was 0.87?±?0.10, and other ratios were determined to apportion the PM sources. The PAHs found are characteristic for emissions from traffic with diesel being a predominant source. 相似文献
19.
The concentrations of ambient total suspended particulates (TSP) and PM 2.5, and the dry depositions at a sample site at Luliao Junior High School (Luliao) in central Taiwan were measured during smog and non-smog days between December 2017 and July 2018. The results are compared to those obtained during non-smog periods in the years 2015–2017. The mean TSP and PM 2.5 concentrations and dry deposition flux were 72.41?±?26.40, 41.88?±?23.51?μg/m 3, and 797.57?±?731.46?μg/m 2 min, respectively, on the smog days. The mean TSP and PM 2.5 concentrations and dry deposition flux on the non-smog days were 56.39?±?18.08, 34.81?±?12.59?μg/m 3 and 468.93?±?600.57?μg/m 2 min, respectively. The mean TSP concentration in the smog period was 28% greater than that in the non-smog period, and the mean PM 2.5 concentration was 20% higher. The mean dry deposition flux in the smog period was 70% higher than that in the non-smog period at Luliao. The PM 2.5 concentrations exceeded the standards set by the Taiwan EPA (35?μg/m 3 daily, and 15?μg/m 3 annually). Therefore, the TSP and PM 2.5 concentrations and dry deposition must be reduced in central Taiwan on smog days. In addition, atmospheric TSP and PM 2.5 concentrations at various sampling sites were compared, and those herein were not higher than those measured in other countries. Finally, apart from the local traffic emissions, during smog periods, the other pollution source originated from the transportation process of traffic pollutants emitted in the northwest side of Taiwan. 相似文献
20.
Particulate matter is an important air pollutant, especially in closed environments like underground subway stations. In this study, a total of 13 elements were determined from PM 10 and PM 2.5 samples collected at two subway stations (Imam Khomeini and Sadeghiye) in Tehran’s subway system. Sampling was conducted in April to August 2011 to measure PM concentrations in platform and adjacent outdoor air of the stations. In the Imam Khomeini station, the average concentrations of PM 10 and PM 2.5 were 94.4?±?26.3 and 52.3?±?16.5 μg m ?3 in the platform and 81.8?±?22.2 and 35?±?17.6 μg m ?3 in the outdoor air, respectively. In the Sadeghiye station, mean concentrations of PM 10 and PM 2.5 were 87.6?±?23 and 41.3?±?20.4 μg m ?3 in the platform and 73.9?±?17.3 and 30?±?15 μg m ?3, in the outdoor air, respectively. The relative contribution of elemental components in each particle fraction were accounted for 43 % (PM 10) and 47.7 % (PM 2.5) in platform of Imam Khomeini station and 15.9 % (PM 10) and 18.5 % (PM 2.5) in the outdoor air of this station. Also, at the Sadeghiye station, each fraction accounted for 31.6 % (PM 10) and 39.8 % (PM 2.5) in platform and was 11.7 % (PM 10) and 14.3 % (PM 2.5) in the outdoor. At the Imam Khomeini station, Fe was the predominant element to represent 32.4 and 36 % of the total mass of PM 10 and PM 2.5 in the platform and 11.5 and 13.3 % in the outdoor, respectively. At the Sadeghiye station, this element represented 22.7 and 29.8 % of total mass of PM 10 and PM 2.5 in the platform and 8.7 and 10.5 % in the outdoor air, respectively. Other major crustal elements were 5.8 % (PM 10) and 5.3 % (PM 2.5) in the Imam Khomeini station platform and 2.3 and 2.4 % in the outdoor air, respectively. The proportion of other minor elements was significantly lower, actually less than 7 % in total samples, and V was the minor concentration in total mass of PM 10 and PM 2.5 in both platform stations. 相似文献
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