Source Of NH3 Research Articles

Do N-isotopes in atmospheric nitrate deposition reflect air pollution levels?

Dry and wet deposition of atmospheric reactive nitrogen compounds mostly originate from anthropogenic NH3 and NOX sources. Regarding land-borne pollutants, coastal environments usually have a lower pollution level than terrestrial/urban areas, which have a greater anthropogenic imprint. To investigate this spatial characteristic, we measured NO3− and NH4+ deposition and N isotopes of NO3− (δ15N–NO3−) in 94 and 88 wet and dry deposition samples, respectively, at a coastal (List on Sylt) and a terrestrial/urban site (Geesthacht) in Germany from May 2012 to May 2013. A higher total N deposition rate was observed in Geesthacht (10.4 vs. 8.9 kg N ha−1 yr−1) due to higher NH4+ deposition, which can be explained by more agricultural influence. Surprisingly, overall NO3− fluxes were higher at the coastal site than at the terrestrial/urban site. We assume that sea-salt aerosols and the increased influence of NOX emissions from ships in most recent times compensate the higher terrestrial/urban pollution level and thus lead to higher NO3− fluxes in dry and comparable fluxes in wet deposition at the coastal site, despite a much lower impact of land-based sources. In line with this, overall mean N isotopes values of NO3− show higher values in List than in Geesthacht in dry (+3.1 vs. +1.9‰) as well as in wet deposition (−0.1 vs. −1.0‰). This surprising result can mainly be attributed to an emerging source of NOX, ship emissions, which have a distinctly higher impact at the coastal site. The usage of heavy oil and possibly new technologies in marine engines, which emit more enriched 15N in comparison to older engines, caused the spatial isotopic differences.

Satellite observations of tropospheric ammonia and carbon monoxide: Global distributions, regional correlations and comparisons to model simulations

Ammonia (NH3) and carbon monoxide (CO) are primary pollutants emitted to the Earth's atmosphere from common as well as distinct sources associated with anthropogenic and natural activities. The seasonal and global distributions and correlations of NH3 and CO from the Tropospheric Emission Spectrometer (TES) satellite observations and GEOS-Chem model simulations for 2007 are investigated to evaluate how well the global and seasonal pollutant sources are prescribed in the model. Although the GEOS-Chem simulations of NH3 and CO atmospheric mixing ratio values are lower than the TES satellite observations, the global distribution patterns from the model reasonably agree with the observations, indicating that the model represents the general location of the source regions and the seasonal enhancements of NH3 and CO globally over large regional scales. In regions and seasons where biomass burning is the dominant source of both NH3 and CO emissions into the atmosphere, there are strong NH3:CO correlations, which is consistent with the relationship demonstrated by surface measurements over fires. In regions where the enhanced NH3 and CO are known to be produced by different sources, the NH3:CO correlations from TES observations and model simulations are weak or non-existent. For biomass burning regions the NH3:CO ratios are 0.015 (TES) and 0.013 (GEOS-Chem). In regions of high-population density, known heavy traffic, and limited biomass burning sources, such as the rapidly developing areas of South Asia and northern China, which include mixtures of megacities, industrial, and agricultural areas, the two species show weaker but still positive correlations and NH3:CO ratios of 0.051 (TES) and 0.036 (GEOS-Chem). These enhancement ratios of NH3 relative to CO are useful in constraining NH3 emission inventories when CO emission inventories are better known for some events or regions (i.e. biomass burning).

Static Chamber Measurements of Ammonia Volatilization from Manured Soils: Impact of Deployment Duration and Manure Characteristics

Static chambers (SC) are a simple low-cost option for measuring NH₃ volatilization from agricultural soils. However, it is uncertain how their estimates relate to more sophisticated methods. In this study, we compared SCs and wind tunnels (WT) for the field measurement of NH₃ volatilization during 22 d following surface application of seven solid poultry manures to a bare agricultural soil. Our objective was to determine the impact of SC deployment duration and manure characteristics on the emission estimates. Total NH₃ losses measured using SCs were on average 23% lower than using WTs. This bias varied with deployment time as the SC/WT emission ratio increased from a value of 0.2 immediately following deployment to a plateau of 1.6, 8 d later. The performance of SCs was also influenced by manure type, with the SC/WT ratio ranging from 0.40 to 1.30 after 22 d. Globally we found that (i) shortly after deployment, absence of air movement inside SCs results in an underestimation of soil-surface NH₃ volatilization (≈80%) compared with WT; (ii) this initial bias appears independent of the NH₃ source intensity; (iii) the underestimation decreases with deployment duration; and (iv) the cumulative bias after 22 d is impacted by the modified transformations of manure organic N (MON) inside SCs. We conclude that SCs yield biased absolute estimates of NH₃ volatilization rates in most situations. Furthermore, their use for comparing relative emission potential between various surface-applied solid manures is also limited to periods during which the transformation of the manure N is not affected by SC deployment.

Sulfate-reducing anammox for sulfate and nitrogen containing wastewaters

In a moving bed biofilm reactor (MBBR) at moderate temperature of 20°C sulfate reduction along with ammonium oxidation were established. In an upflow anaerobic sludge blanket reactor (UASBR), the same process took place at 36°C. Sulfate-reducing ammonium oxidation (SRAO) was performed using reject water as a substrate for micro-organisms and a source of NH4+, with SO42- being added as an electron acceptor. Bacterial strains belonging to the phylum Planctomycetales were detected from the biofilm of the MBBR; from the UASBR species representing phylum Verrucomicrobia were found. Average volumetric TN removal rates were 0.03 kg-N/m3/d in the MBBR and 0.04 kg-N/m3/d in the UASBR. HCO3- concentrations exceeding 1000 mg/l had an inhibiting effect on the SRAO process. The stoichiometric ratio of NH4+ removal was significantly higher than that expected from the extent of SO42- reduction. This phenomenon can primarily be attributed to complex interactions between nitrogen and sulfur compounds and organic matter present in the wastewater. Addition of hydrazine and hydroxylamine up to 12.5 mg/l had a positive effect on SRAO process performance, particularly in the UASBR. Hydrazine was naturally present in the reaction medium, indicating occurrence of the anammox process.

Variability of atmospheric ammonia related to potential emission sources in downtown Toronto, Canada

The variability of atmospheric ammonia (NH3) in downtown Toronto was investigated through the analysis of 24 hr integrated denuder NH3 samples collected at a site above a street canyon every third day from July 2003 to September 2011 (Dataset 1). The measured NH3 mixing ratios ranged from below the detection limit to 14.7 ppb during the eight-year period. Distinctive seasonal variations were observed with summer averages (±standard deviation) of 3.9 ± 1.6 ppb and winter averages of 1.1 ± 0.6 ppb. Two other datasets, weekly/biweekly passive samples of NH3 monitored at 74 agricultural and remote sites across southern Ontario during the period of June 2006 to March 2007 (Dataset 2) and semi-continuous measurements of NH3 and ammonium (pNH4+) in PM2.5 collected at a site inside a street canyon approximately 170 m away from the downtown site in December 2008 and February, March and May 2009 (Dataset 3), were further used to evaluate the potential NH3 sources in downtown Toronto. The NH3 mixing ratios at the downtown location were higher than those at the surrounding agricultural sites, and the mixing ratios within the street canyon were almost double those measured above it. These results suggested that the observed NH3 at the downtown location was mainly from local sources within the street canyon. Analysis of Dataset 3 showed that the diurnal cycles of NH3 at the downtown location cannot be simply explained by traffic and water consumption patterns. A green space inside the street canyon was identified as a potential important source contributing to the observed NH3 when T > 0 °C. However, the major NH3 emission sources at T ≤ 0 °C are yet to be investigated.

Urban NH3 levels and sources in six major Spanish cities

A detailed spatial and temporal assessment of urban NH3 levels and potential emission sources was made with passive samplers in six major Spanish cities (Barcelona, Madrid, A Coruña, Huelva, Santa Cruz de Tenerife and Valencia). Measurements were conducted during two different periods (winter–autumn and spring–summer) in each city. Barcelona showed the clearest spatial pattern, with the highest concentrations in the old city centre, an area characterised by a high population density and a dense urban architecture. The variability in NH3 concentrations did not follow a common seasonal pattern across the different cities. The relationship of urban NH3 with SO2 and NOX allowed concluding on the causes responsible for the variations in NH3 levels between measurement periods observed in Barcelona, Huelva and Madrid. However, the factors governing the variations in A Coruña, Valencia and Santa Cruz de Tenerife are still not fully understood. This study identified a broad variability in NH3 concentrations at the city-scale, and it confirms that NH3 sources in Spanish urban environments are vehicular traffic, biological sources (e.g. garbage containers), wastewater treatment plants, solid waste treatment plants and industry. The importance of NH3 monitoring in urban environments relies on its role as a precursor of secondary inorganic species and therefore PMX. Further research should be addressed in order to establish criteria to develop and implement mitigation strategies for cities, and to include urban NH3 sources in the emission inventories.

Examining the transport of ammonia emissions across landscapes using nitrogen isotope ratios

The proportion of reactive nitrogen in wet deposition attributable to ammonium (NH4+) has increased over the last three decades in the U.S. due to steadily increasing NH3 emissions and concomitant reductions in NOx emissions. The importance of examining NH3 emission sources and transport is amplified as the fraction of NH3 contributing to reactive nitrogen budget increases. Presented here is a study illustrating how the nitrogen stable isotopic composition of NH3 (δ15N–NH3) can be used to characterize the transport of NH3 emissions at the landscape-scale. To accomplish this, ambient NH3 was sampled across varying land use types (e.g. conventionally managed cornfield, tallgrass prairie, concentrated animal feeding operation (CAFO), dairy operation, urban setting) and analyzed for δ15N–NH3 values. Ambient δ15N–NH3 values at a conventionally managed cornfield were used in an isotope mixing model to make first order approximations of NH3 source contributions to ambient air over the cornfield. Results suggest that while volatilized fertilizer is a primary contributor to ambient NH3 after fertilizer application, during periods of low or no fertilization, vehicle NH3 emissions can be a substantial contributor to ambient NH3 over cornfields that are adjacent to roadways. These source approximations can aid in evaluating NH3 emission abatement techniques to local landscapes. Modeled NH3 deposition flux at a CAFO was found to contribute a considerable amount of nitrogen to the landscape and δ15N–NH3 values were used to trace the livestock source contributing to this flux. Ambient NH3 concentrations and δ15N–NH3 values were measured across an urban region and δ15N–NH3 values indicated primarily fossil fuel-based emissions and large spatial variations in NH3 concentrations.

Sources and processes governing rainwater chemistry in New Delhi, India

Rainwater plays an important role in scavenging of aerosols and gases from atmosphere, and its chemistry helps to understand the relative contributions of atmospheric pollution sources. The present work is aimed to understand and explain the sources, seasonal patterns and the processes thereof affecting rainwater chemistry in an urban environment of Delhi, India. Rainwater samples (n = 111) collected throughout the year in New Delhi showed alkalinity in general. Eight rainwater samples, collected in late monsoon and winter season, had pH less than 5.6 indicating that Delhi continues to face the prospects of acid rain despite the introduction of compressed natural gas as the clean fuel in city transport. Organic acids could be the possible contributors of acidity in rainwater samples having the fractional acidity (FA) value of 0.174, which is greater than the annual average FA (0.011) and the (Ca2+ + Mg2+ + NH4 +)/(SO4 2− + NO3 −) ration of more than one. Average acid neutralization factors of cations decrease in the order Ca2+ (1.01) > NH4 + (0.77) > Mg2+ (0.10). However, neutralization by Ca2+ dominates only in summer season as cation-rich dust is transported from the Great Indian Thar Desert to this region by strong summer S–SW winds, while NH4 + dominates in rainwater of other three sampling seasons. Identified dominant sources for soluble ions in rainwater are (1) non-silicate crustal source for carbonates and sulfates of Ca and Mg, (2) emissions from catalytic convertor-fitted vehicles and agriculture fields for NH3 and (3) mixed anthropogenic sources for SO4 2−, NO3 − and Cl−. Rainwater chemistry showed significant seasonal variations. This could be due to the changes in relative proportions of natural and anthropogenic sources of soluble ions to rainwater. Dominance of anthropogenic sources over crustal sources can result in acidic rains, which can adversely affect the environment and human health in this region.

결정질 실리콘 태양전지의 패시베이션 적용을 위한 Al2O3/SiON 적층구조의 열적 안정성에 대한 연구

We investigated the influence of blistering on Al₂O₃/SiON stacks and Al₂O₃/SiNx:H stacks passivation layers. Al₂O₃ film provides outstanding Si surface passivation quality. Al₂O₃ film as the rear passivation layer of a p-type Si solar cell is usually stacked with a capping layer, such as SiO₂, SiNx, and SiON films. These capping layers protect the thin Al₂O₃ layer from an Al electrode during the annealing process. We compared Al₂O₃/SiON stacks and Al₂O₃/SiNx:H stacks through surface morphology and minority carrier lifetime after annealing processes at 450℃ and 850℃. As a result, the Al₂O₃/SiON stacks were observed to produce less blister phenomenon than Al₂O₃/SiNx:H stacks. This can be explained by the differences in the H species content. In the process of depositing SiNx film, the rich H species in NH₃ source are diffused to the Al₂O₃ film. On the other hand, less hydrogen diffusion occurs in SiON film as it contains less H species than SiNx film. This blister phenomenon leads to an increase insurface defect density. Consequently, the Al₂O₃/SiON stacks had a higher minority carrier lifetime than the Al₂O₃/SiNx:H stacks.

Comparison of sulfate-reducing and conventional Anammox upflow anaerobic sludge blanket reactors

Autotrophic NH4(+) removal has been extensively researched, but few studies have investigated alternative electron acceptors (for example, SO4(2-)) in NH4(+) oxidation. In this study, sulfate-reducing anaerobic ammonium oxidation (SRAO) and conventional Anammox were started up in upflow anaerobic sludge blanket reactors (UASBRs) at 36 (±0.5)°C and 20 (±0.5)°C respectively, using reject water as a source of NH4(+). SO4(2-) or NO2(-), respectively, were applied as electron acceptors. It was assumed that higher temperature could promote the SRAO, partly compensating its thermodynamic disadvantage comparing with the conventional Anammox to achieve comparable total nitrogen (TN) removal rate. Average volumetric NH4(+)-N removal rate in the sulfate-reducing UASBR1 was however 5-6 times less (0.03kg-N/(m(3) day)) than in the UASBR2 performing conventional nitrite-dependent autotrophic nitrogen removal (0.17kg-N/(m(3) day)). However, the stoichiometric ratio of NH4(+) removal in UASBR1 was significantly higher than could be expected from the extent of SO4(2-) reduction, possibly due to interactions between the N- and S-compounds and organic matter of the reject water. Injections of N2H4 and NH2OH accelerated the SRAO. Similar effect was observed in batch tests with anthraquinone-2,6-disulfonate (AQDS). For detection of key microorganisms PCR-DGGE was used. From both UASBRs, uncultured bacterium clone ATB-KS-1929 belonging to the order Verrucomicrobiales, Anammox bacteria (uncultured Planctomycete clone Pla_PO55-9) and aerobic ammonium-oxidizing bacteria (uncultured sludge bacterium clone ASB08 "Nitrosomonas") were detected. Nevertheless the SRAO process was shown to be less effective for the treatment of reject water, compared to the conventional Anammox.

Chemical composition and sources of coastal marine aerosol particles during the 2008 VOCALS-REx campaign

Abstract. The chemical composition of aerosol particles (Dp ≤ 1.5 μm) was measured over the southeast Pacific Ocean during the VAMOS (Variability of the American Monsoon Systems) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-Rex) between 16 October and 15 November 2008 using the US Department of Energy (DOE) G-1 aircraft. The objective of these flights was to gain an understanding of the sources and evolution of these aerosols, and of how they interact with the marine stratus cloud layer that prevails in this region of the globe. Our measurements showed that the marine boundary layer (MBL) aerosol mass was dominated by non-sea-salt SO42−, followed by Na+, Cl−, Org (total organics), NH4+, and NO3−, in decreasing order of importance; CH3SO3− (MSA), Ca2+, and K+ rarely exceeded their limits of detection. Aerosols were strongly acidic with a NH4+ to SO42− equivalents ratio typically < 0.3. Sea-salt aerosol (SSA) particles, represented by NaCl, exhibited Cl− deficits caused by both HNO3 and H2SO4, but for the most part were externally mixed with particles, mainly SO42−. SSA contributed only a small fraction of the total accumulation mode particle number concentration. It was inferred that all aerosol species (except SSA) were of predominantly continental origin because of their strong land-to-sea concentration gradient. Comparison of relative changes in median values suggests that (1) an oceanic source of NH3 is present between 72° W and 76° W, (2) additional organic aerosols from biomass burns or biogenic precursors were emitted from coastal regions south of 31° S, with possible cloud processing, and (3) free tropospheric (FT) contributions to MBL gas and aerosol concentrations were negligible. The very low levels of CH3SO3− observed as well as the correlation between SO42− and NO3− (which is thought primarily anthropogenic) suggest a limited contribution of DMS to SO42− aerosol production during VOCALS.

H2CO and H110α observations towards NH3 sources

We observed the H2CO(110–111) absorption lines and H110α radio recombination lines (RRL) toward 180 NH3 sources using the Nanshan 25-m radio telescope. In our observation, 138 sources were found to have H2CO lines and 36 have H110α RRLs. Among the 138 detected H2CO sources, 38 sources were first detected. The detection rates of H2CO have a better correlation with extinction than with background continuum radiation. Line center velocities of H2CO and NH3 agree well. The line width ratios of H2CO and NH3 are generally larger than unity and are similar to that of 13CO. The correlation between column densities of H2CO and extinction is better than that between NH3 and extinction. These line width relation and column density relation indicate H2CO is distributed on a larger scale than that of NH3, being similar to the regions of 13CO. The abundance ratios between NH3 and H2CO were found to be different in local clouds and other clouds.

Optimization Study: Biological Removal of Inorganic Nitrogen along with Chemical Oxygen Demand from Wastewater Using Response Surface Methodology

A comparative optimization study using response surface methodology (RSM) was carried out for biological removal of various inorganic N–NH3 sources (NH4OH, (NH4)2SO4, NH4NO3) along with chemical oxygen demand (COD; glucose: C6H12O6) from synthetic wastewater and consequently minimizing the N–N2O emission. Heterotrophic biomass conversion (HBC) process was used for wastewater treatment. Central composite design (CCD) method was used to optimize various experimental parameters using RSM. During the experiment biomass (total volatile suspended solids) was kept constant, while varying nitrogen and carbon concentration, respectively. Alkalinity consumption results in pH decrease during the HBC process. N–NH3 and COD depletion rates were higher in NH4OH in comparison to the other two nitrogen sources. Analyses of variance observed highly significant differences. Models obtained through CCD method were checked and tested via experiments and statistics. Having optimum value, i.e., 210 mg/L N–NH3, 2.90 g/L COD and 38 h; higher COD (94.1%) and N–NH3 (82.72%) removal was observed in (NH4)2SO4 and NH4OH. Higher desirability factor was obtained in NH4OH.

Polarized XAFS study of Al K-edge for m-plane AlGaN films

Local structures around Al atoms in high-quality m-plane AlxGa1-xN films (x=0.32 and 0.58) deposited on m-plane GaN substrates by the NH3 source molecular beam epitaxy method were investigated by Al K-edge X-ray absorption fine structure (XAFS) for the first time. XAFS spectra were measured using a linearly-polarized X-ray source from synchrotron radiation for three different directions; along the c-, a-, and m-axes. The interatomic distances along the a-axis are close to Ga-Ga distance in GaN, indicating that the local structures are strongly affected by GaN substrates. The localization of Al atoms was observed for the Al0.32Ga0.68N film.

Measurement of Ambient Ammonia over the National Capital Region of Delhi, India

Mixing ratio of ambient ammonia (NH3) was measured at various locations of the National Capital Region (NCR) of Delhi, India using a NH3-analyzer during January 2010 to June 2012 in campaign mode. The present study has been carried out on campaign based measurement of mixing ratios of NH3 and NOx for short period of time over the NCR of Delhi represent the indicative values over the region. The average mixing ratio of ambient NH3 was 20.9 ± 1.6 ppb during the period. The maximum average mixing ratio of ambient NH3 (28.8 ± 3.0 ppb) was recorded in an industrial area surrounded by intensive vehicular traffic followed by an agricultural farm (27.5 ± 2.1 ppb), whereas the minimum (6.4 ± 1.2 ppb) was recorded in the semi-urban area. The diurnal trend of NH3 depended on the ambient temperature at most of the sites and was affected by wind direction. Ambient NH3 was correlated with the NOx mixing ratio suggesting that the vehicular emission may be one of the sources of ambient NH3 in the NCR of Delhi. However, long-term measurements of ambient NH3 and their precursors will lead to seasonal variation of source apportionment over the NCR, Delhi, India.

Seasonal and geomorphic controls on N and P removal in riparian zones of the US Midwest

Riparian zones are an important strategy to mitigate N and P export to streams. However, their efficiency with respect to nitrate (NO3 −), ammonium (NH4 +), or soluble reactive phosphorus (SRP) in groundwater remains uncertain in the US Midwest. This study investigates water table fluctuations and NO3 −, NH4 +, and SRP concentration dynamics in two riparian zone types (outwash vs. glacial till) common in the upper US Midwest. During low water table periods, NO3 − removal was 93 % at WR (outwash site), and 75 % at LWD (glacial till site); but during high water table periods, NO3 − removal efficiencies dropped to 50 % at WR, and 14 % at LWD. Median seasonal mass fluxes of NO3 − removed at WR (9.4–21.7 mg N day−1 m−1 of stream length) and LWD (0.4–1.9 mg N day−1 m−1) were small compared to other riparian zones in glaciated landscapes. The WR site was a small SRP sink (0.114 and 0.118 mg day−1 m−1 during the dry period and wet period, respectively), while LWD acted as a small SRP source to the stream (0.004 mg day−1 m−1 during the dry period; 0.075 mg day−1 m−1 during the wet period). Both LWD and WR acted as sources of NH4 + to the stream with mass fluxes ranging from 0.17 to 7.75 mg N day−1 m−1. Although riparian zones in the US Midwest provide many ecosystem services, results suggest they are unlikely to efficiently mitigate N and P pollution in subsurface flow.

Physicochemical Assessment of Rain Water of Karachi, Pakistan

Local Precipitation (Rain) is a good source of surface water and could be a safe source of drinking water if it is free from contaminants. Many Asian countries do not have access to safe drinking water; therefore, they have no alternative but to use water from contaminated sources that poses a health hazard. In the present study, thirty three rain water samples were collected from Karachi, Pakistan during monsoon season of year 2007. The pH, electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO) and hardness were immediately monitored after sample collections and possible sources of NH4, Na, K, Mg, Ca, F- , Cl- , NO3 - , CO3 -2 and SO4 -2 concentrations in rain water of Karachi city, Sindh, Pakistan were analyzed in order to distinguish safe source of drinking water. All samples were completely free from fluoride contamination while the concentration of chloride and sulfate was in range of 15.11-125 mg/l and 10.02- 72.02 mg/l indicate their presence from air pollution. Moreover, the study showed that the rain water can be harvested to extend potable and non-potable water supplies in this city.

Optical bleaching of perovskite (CH3NH3)PbI3 through room-temperature phase transformation induced by ammonia

Ammonia induces a phase transformation of perovskite (CH3NH3)PbI3, leading to a rapid (<1 s) change in its color from brown to colorless (400-800 nm). This color change is reversed within seconds upon removing the NH3 source.

Characteristics of ambient ammonia over Delhi, India

In the present paper, we have characterized the ambient ammonia over Delhi along with other trace gases (NH3, NO, NO2, SO2 and CO) and particulates (PM2.5 and PM10) measured during December 2011 to June 2012. The average mixing ratios of ambient NH3, NO, NO2, SO2 and CO were recorded as 21.2 ± 5.4, 19.5 ± 4.9, 17.4 ± 1.4, 1.7 ± 0.5 ppb and 1.6 ± 0.7 ppm, respectively, during winter, whereas the average mixing ratios of ambient NH3, NO, NO2, SO2 and CO were recorded as 20.8 ± 4.7, 21.7 ± 6.3, 16.8 ± 3.1, 2.2 ± 0.8 ppb and 1.8 ± 0.9 ppm, respectively, during summer. In the present case, non-significant seasonal and diurnal variations of NH3, NO, NO2, SO2 and CO were observed during both the seasons. The average monthly NH3/NH4 + ratios varied from 0.28 to 2.56 with an average value of 1.46 in winter. The higher NH3/NH4 + ratio (3.5) observed in summer indicates the abundance of NH3 in the atmosphere during summer. The higher fraction of particulate NH4 + observed in winter than summer attributes to the conversion of gaseous NH3 into NH4 +. The results emphasized that the traffic could be one of the significant sources of ambient NH3 at the urban site of Delhi as illustrated by positive correlations of NH3 with traffic-related pollutants (NO, NO2 and CO). Surface wind analysis and wind directions also support the roadside traffic and agricultural activities at the nearby area indicating possible major sources of ambient NH3 at the study site.

Locating sources of hazardous gas emissions using dual pollution rose plots and open path Fourier transform infrared spectroscopy

A new approach employing two pollution rose plots to locate the sources of multiple hazardous gas emissions was proposed and tested in an industrial area. The data used for constructing the pollution rose plots were obtained from two side-by-side measurements of open-path Fourier Transform Infrared (OP-FTIR) spectrometers during one week of continuous analysis on the rooftop of a semiconductor plant. Hazardous gases such as CF4, C2F6, CH3OH, NH3, NO2, and SF6 were found and quantified at the ppb level by both OP-FTIR measurement sites. The data of the top 20% highest concentrations and associated wind directions were used to construct the pollution rose plots. Pollution source probability contours for each compound were constructed using the probability-product of directional probability from two pollution rose plots. Hot spots for SF6, CF4, NO2, and C2F6 pointed to the stack area of the plant, but the sources of CH3OH and NH3 were found outside of this plant. The influences of parameters for this approach such as the variation in wind direction, lower limit concentration threshold and the nearby buildings were discussed.