当前世界环境

Introduction

The biogeochemical cycling of nitrogen is of vital importance due to the role of nitrogen in both aquatic and terrestrial ecosystems. However, global nitrogen cycle is being disturbed by the unchecked increase in food and energy production resulting in the accumulation of Reactive Nitrogen (Nr) in various environmental matrices. Generally, Nr refers to any formof nitrogen compound that is biologically active, photo chemically reactive and radioactively active in the biosphere and atmosphere of theearth.^1-2Nr includes inorganic reduced form of N (NH₃, NH₄⁺), inorganic oxidized forms (NO_x, NO₃^-, N₂O, HONO) & organic nitrogen compounds.³However, these Nr species are extremely important in atmospheric chemistry. Henceforth, the monitoring of Agricultural nitrogen air emissions and understanding their behaviour in atmosphere is crucial due to impending environmental and human health concern of the latter.One of the major sources of the incessant increase in the nitrogen air emissions is the agriculture activities followed by livestock, human waste, transport sector. Ammonia is one of the most important reactive Nitrogen (Nr) compounds emitted from agricultural sources. Other minor anthropogenic sources ofatmospheric NH₃emissions include animal manure, slash burning and industries⁴along with the natural sources such as forest fires, soils and oceans.^5-6. In India, IGP has been reported as hotspot of both NH₃and NH₄⁺emissions due to intense agricultural activities in the region.⁷The major contributor for NH₃emissions in agricultural systems includes inorganic fertilizers, livestock manure, increased biological N-fixation, biomass burning and residue added to the field after crop harvesting.For instance, as reported byMisselbrook et al.,⁸agricultural sector alone is responsible for about 90% of the total atmospheric NH₃emissions. According to Vitousek et al.,⁹human interventions have approximately doubled the fluxes of Nr species viz NH₃, NOx,NH₄⁺, NO₃⁻, and N₂O¹⁰.Human activities contribute approximately 170 Tg year^-1of Nr into agroecosystems, where inorganic fertilizer additions account for about 80 Tg Nr annually.¹¹For Indian Scenario, Aneja et al.,¹²reported the highest contribution of fertilizer application and livestock towards NH₃分别为1704.8 2696.6 Gg和Gg。在various inorganic fertilizers, urea isthe most widely used N fertilizer in south Asia.¹³Furthermore,urea is the highest contributor (~ 94%) of NH₃because of its large scale use and nitrogen content is maximum among all other fertilizers being used in India.¹⁴Urea alone contributes 2481.5 Gg NH₃whereas di-ammonium phosphate (DAP), NPK, ammonium phosphate contributes 124.8 Gg, 89.7 Gg and 0.6 Gg NH₃respectively, annually. Also, the rate of increase of urea in agricultural fields is estimated to be 92% per year, thus adding to the Nr budget.¹³45-55% of these Nr inputs are recovered by crop biomass whereas remaining is lost from agricultural systems via. leaching, erosion (32–45 Tg N year⁻¹) and denitrification(26–60 Tg N year⁻¹).^10-11Hence directly or indirectly influences the Nitrogen cycle.

A remarkable portion of N-fertilizer or excessreactive soil N (Nr) is lost through volatilization in the form of ammonia(NH₃) and surface run off which significantly contributes to the Nitrogen loss. Bouwman et al.,¹⁵reported that 10–30% of the applied N fertilizer is lost through volatilization process. Once NH₃is applied to the soil by fertilizer addition, NH₄⁺gets retained on the exchange sites. NH₄⁺is either nitrified to nitrate (NO₃^-), or decomposed to NH₃, depending on soil and environmental conditions. High temperature inhibits the nitrification process as reported by Grunditz and Dalhammar,¹⁶and hence, ammonia volatilization increases with increase in temperature.In agroecosystems, NH₃emissions can be reduced by minimizing the N input, increasing the efficiency of N fertilizers.¹⁷

Some studies have been carried out by research groups for NH₃inventories in Asian region¹⁸which mainly relied on emission factors. However, no country-specific emission factor for NH₃is available, there is high uncertainty in the emission estimates of NH₃in India.¹⁹As reported by Parashar et al²⁰NH₃emissions from fertilizers and livestock are estimated to be 1175 Gg and 1433 Gg, respectively. According to the estimates given by Yang et al,²¹the concentration of gaseous ammonia varied from 1.3 to 17.2 μg m⁻³throughout the year. These concentrations were observed at an agricultural field site which was remarkably higher in the summer than winter.

Fate of atmospheric ammonia (NH₃) is highly variable.NH₃is the most abundant alkaline constituent in theatmosphere²²and a precursor molecule for secondary aerosol formation causing severe air pollution in East and South Asia by contributing ambient levels of fine particulate matter (PM_2.5).²³Transformation of atmospheric NH₃into NH₄⁺via chemical processes of precursor gases (NH₃, SO₂, NO_x) occurs either by condensation or by direct nucleation. The major inorganic compounds formed through the gas-to-particle formation process are ammonium bisulfate (NH₄HSO₄), ammonium sulfate (NH₄)₂SO₄, ammonium nitrate (NH₄NO₃) and ammonium chloride (NH₄Cl).Due to the substantial increment in atmospheric NH₃emissions and its transformation, more ammonium (NH₄⁺) is returned to terrestrial and aquatic ecosystems via dry and wet deposition mechanisms.In temperate regions, precipitation is the main scavenging mechanism whereas in dry regions (with no or little rainfall) dry deposition is the dominating mechanism for the removal of atmospheric pollutants. Since, in India~ 90 % of precipitation occurs during monsoon period (June to September), dry deposition is the dominating mechanism for the scavenging of atmospheric pollutants throughout the year.²⁴Moreover, the fate of Nr species is determined by atmospheric acidity, particulate loading, land use dynamics, and photochemistry of the atmosphere.²⁵The deposition of NH₃and NH₄⁺in various compartments across the globe causes a cascade of environmental problems such as eutrophication of terrestrial and aquatic ecosystem, biodiversity loss,forest damage, water and soil acidification.^26-27Hence its role in atmospheric phenomenon such as neutralisation of cloud water, precipitation and aerosol formation typically in the fine particle size range is pivotal.²⁸

In addition, the formation of ammonium particulates increases the residence time of NH₃in the atmosphere thereby influencing the geographic distribution of acidic species. Also,deposition of these fine particles deep into the lungs causes morbidity and mortality in humans, alterations in visibility and climate.²⁹Henceforth,monitoring of atmospheric NH₃in agricultural fields is one of the decisive parameters needs to be considered. For this the study was conducted at a rural site in Jhajjar district of Haryana with the following objectives- i). to quantify the NH₃concentration and its variation during different growing stages of crops sown in our study area and ii).to study the effect of meteorological parameters in order to identify the possible transformations of NH₃.

NH₃emission rate from various agricultural activities and its downwind concentration mainly depends on meteorological conditions. There exists a positive relationship between incident solar radiation/air temperature and NH₃emission from surface-applied fertilizers.^30-32Solar radiation increases NH₃emission by increasing the atmospheric turbulence and hence,NH₃evaporates from the surface. Apart from that evaporation of water due to increasing air temperature increases the total N concentration at the surface. Consequently, the NH₃at the surface is transported upwards by atmospheric turbulence and sideways, by advection. Hence, NH₃emission levels are related to wind speed, relative humidity and temperature.³²Higher humidity and lower temperature favours the formation of NH₄⁺aerosols in presence of NO₂and SO₂.

Methodology

Site Description

一项研究是由农村Chhuchhak网站was village of Jhajjar district in Haryana (Fig. 1). It lies between 28°22’ - 28°49’ North latitudes, and 76°18’ -76°59’ East longitudes. The village is located at a distance of 13 kms from Jhajjar district which lies in the south-east part of the Haryana state covering total geographical area of 1834 sq.km. The climate characteristics of this area are hot summer, cold winter and moderate rainfall of about 444 mm. This area comprises approximately 87.03% land under agriculture and 6.77% build up area, indicating very less development in terms of urbanization. The district covers an forest area of 41 km², net sown area of 1670 km²and cultivable area of 1760 km²(Agriculture department Jhajjar). The sampling site represents a typical rural atmosphere surrounded by agricultural fields in all directions.

Figure 1: Map of the Sampling Site Click here to view figure

Meteorological Data

Temperature, relative humidity and wind data of the study region for every month (July to October) were downloaded from theworldweatheronline.com.Table 1 shows the mean values of all above mentioned meteorological parameters during the sampling period.

Table 1: Monthly Variation of Temperature, Wind Speed and Relative Humidity During the Sampling Period

Experimental Setup

Collection of gaseous NH₃samples was performed on 6 hr basis during both daytime and night time (8am-2pm and 10pm-4am) from July to October 2017 using a sampling assembly (Fig. 2) consisting of a low volume pump operating at a flow rate of 1 LPM. Ammonia gas was absorbed in absorbing solution (20 ml of 25 mM H₂SO₄)在一个6小时的标准撞击滤尘器。³³The aerosol samples were collected on thePTFE filters (diameter 47 mm and pore size 0.2µm) placed upstream to the impingers. Filter pack was connected to the impinger through silicon tubing. Collected gaseous NH₃样品在吸收溶液转移到into centrifuge tubes, preserved in refrigerator and analyzedby catalyzed Indophenol-blue method. It includes photometric determination of NH₃which is based on reaction with phenol and hypochlorite producing Indophenol, intensely blue in alkaline medium which is further analysed using spectrophotometer at 630nm.The collection efficiency of impinger technique for NH₃capture was estimated by using two impingers in series (Fig. 2), using the formula:

Collection efficiency = η₂∗100/(η₁+ η₂) - 1)

where η₁and η₂are the values of optical density in impingers 1 and 2, respectively (Fig. 2)

Figure 2: Flow Diagram of Sampling Assembly Click here to view figure

Hence, collection efficiency of the NH₃capture using this method was estimated as 67%.Furthermore, certainty and reliability in data collection was maintained by rejection of daily samples if any disruption was noted or post-sampling flow rate was reduced by more than 10% of the pre-sampling flow rate.

Agriculture and Cropping Pattern

Thefarming practices in Jhajjar district are dominated by agriculture activities and animal husbandry. The main crops sown in this region are Kharif cropsand Rabi crops.The word “Kharif” is Arabic for autumn since the season coincides with the beginning of autumn, also known asmonsoon crops. These are the crops that are cultivated at the onset of the monsoon season around June and harvested by September or Octobereg.Oryza Sativa (Paddy), pearl millet (bajra), gossypium (cotton), Cyamopsistetragonoloba(瓜尔胶)等和拉比作物s are agricultural crops that are sown in winter in month of November and harvested in Marcheg. Triticum aestivum (Wheat), Brassica juncea(mustard),Hordeum Vulgare(barley), etc.

Results and Discussion

Concentration of NH₃Over the Study Period

Table 2 gives the concentration of NH₃over the various periods (growing, post-fertilizer, grain filling, post-harvest) of thekharifcrop(mainly pearl millet in our study area). Growing time in the month of July shows the least NH₃concentration with an average value 29.68 µg m^-3as compared to all other time phases. These values can be assumed as background values. Nitrogen fertiliser can either be incorporated into the soil (basal dressing) before growing the crop or applied to the soil surface (top dressing). In basal dressing, nitrogen fertiliser is placed below the soil layer which limits the rates of nitrification, denitrification, volatilization and therefore, enhance efficiency of N fertilizer use.³⁴As Diammonium phosphate (DAP) fertilizer is mainly used in basal dressing (30 kg/hectare) prior to growing, the levels were very less as compared to the levels after top dressing (commonly urea) fertilizer application. The levels increased markedly after urea was applied on the soil surface on 1^stAugust with an application rate~100kg/hectare. Among various fertilizers being used in India, the NH₃concentrations peaked in conjunction with the application of urea. Contribution from urea is highest not only because of its excessive usage in Indian agriculture but also due to the large emission factor for NH₃emissions.³⁵The average concentrations during day and night time were measured as 96 µg m^-3and 149 µg m^-3respectively.The levels of NH₃are very high during grain filling and post-harvest period.As plant uptake of soil-Ndecreases towards maturity, NH₃volatilization from soil increases. This may be responsible for higher NH₃emissiontowards maturity.For further analysis during these months,variation of NH₃was related with wind directions as described below (Fig. 7).

Table 2: Day-Night Concentration of NH₃Over Various Time Periods of the Kharif Crop (Pearl Millet in our Study Area)

Diurnal Variation of NH₃Over the Study Period

Fig.3 shows the diurnal variability in NH₃concentration over the study period. NH₃concentration is higher during night time as compared to the day time. Similar variation in NH₃emissions were also reported by other researchers.³⁶During day time NH₃concentration varied from 1 to 187µgm^-3and during night time it lies in the range 88 to 249 µgm^-3. The mean concentration of NH₃for the day and night time was found to be 89 and 168µgm^-3respectively. Fig.4 shows the variation of average day and night time concentration of NH₃over the sampling months. Higher NH₃concentrations observed during night time might be due to stable atmospheric conditions (less turbulence) which resulted in reduced dispersion of gaseous NH₃in the atmosphere because of the accumulation and inefficient vertical mixing within a relative shallow boundary. This pattern is in consistent with the studies by other researchers.^37-38

Figure 3: Diurnal Variation of NH3Concentration Over the Study Period. Click here to view figure

Figure 4: Average Day- Night Time Variation of NH3Over the Sampling Months. Click here to view figure

Meteorological Data

Mean temperature during the sampling periods over the month of July, August, September, October were observed to be 37.4°C, 35.83°C, 35.28°C and 34.86^oC respectively whereas the average relative humidity levels were found to be 39.46%, 52.125%, 38.06% and 32.40% respectively.The prevailing wind speed and directions were mostly in the range 2–7 mphwith distinct patterns in W, E, NW and ESE directions.

Variation of NH₃with temperature and relative humidity is as represented in Fig. 5. There was no significant correlation observed betweenNH₃concentration with temperature and relative humidity in our catchment (Fig. 6). Levels of NH₃are negatively correlated with temperature and relative humidity during daytime. In contrast, NH₃concentration are positively correlated with temperature & negatively with relative humidity during night time.The relation can be explained on the fact that high temperature and low relative humidity conditionsfavours the formation of NH₃from NH₄⁺. The reason being, in summer, particulate ammonium nitrate is volatile, and hence, NH₄NO₃will be in gaseous phase.³⁹

Figure 5: Variation of NH3(µg m-3) with RH (%) and Temperature (0C) During Day Time and Night Time. Click here to view figure

Figure 6: Correlation of NH3(µg m-3) with RH (%) and Temperature (0C) During Day Time and Night Time. Click here to view figure

Possible Sources of NH₃

Since, NH₃is either subjected to dry deposition or readily converted to NH₄⁺. Therefore, high levels of gaseous NH₃are expected close to the surface and at less distance from the emission sources.^40-41Hence, there might be some local emission sources near the observation site. Wind rose plots suggested higher concentration from the west direction of the sampling site in the month of July and August (Fig.7). Application of large amount of inorganic nitrogen fertilizers in the nearby agricultural fields might be contributing to ambient NH₃concentration in these sampling months. Several researchers from various parts of the world also reported similar observations.^42-43During the grain filling period, in the month of September, the levels of ammonia were considerably high, and the prevailing wind direction was mainly northwest (Fig.7c). As this village is in the northwest direction of the sampling site, livestock population, solid waste generation might be contributing towards these high NH₃levels. In addition, winds were very diverse majorly from E and ESE direction during post harvest period in October. In addition to biomass burning, there may be various sources like animal waste, solid waste, etc. from nearby areas.

Figure 7:Wind Rose Plot (a) July 2017, (b) August 2017, (c) September 2017 and (d)October 2017. Click here to view figure

It is observed that the NH₃concentration during day & night time on 8 October, 2017 was 56µg m^-3& 176 µg m^-3(Table 3). Wind rose diagrams were plotted to understand the significant gap between the diurnal values on this particular day (Fig.8). It can be inferred that there were only minor changes in wind directions during day and night time. Hence, the high NH₃水平从晚上开始时间(10月8日,2017)can be attributed to the onset of biomass burning during post harvest period. However, to rule out any other possibility further investigation is required.

Figure 8:Day and Night Wind Rose Plots (e, f) 8 October 2017, (g,h) 9 October 2017, (i,j)10October 2017, (k, l)11 October 2017, respectively. Click here to view figure

Table 3: Comparison of Ambient NH₃Concentrations at Various Characteristic Sites Worldwide

Comparison of Concentrations of Gaseous NH₃Withother Studies

Generally, levels of atmospheric NH₃are high in tropical regions as compared to temperate regions. This is probably due to high temperature in tropical regions resulting in higher evaporation rates of gaseous NH₃from agricultural soils, animal waste and other sources.In addition, abundance of alkaline dust in tropics favours the existence of alkaline NH₃in its gaseous form. In contrast,dominance of H₂SO₄in acidified atmosphere in most of the temperate areas results in the formation of NH₄⁺and SO₄^2-aerosols.³⁸Table 4 gives a comparison of NH₃concentrations at various sites worldwide.

Conclusion

Average NH₃level in the growing period,when DAP was incorporated into the soil was very less i.e. 29.68µgm^-3. This is because addition into the soil increases the efficiency of fertilizer use. The concentration reached to considerably high levels, 96.53µgm^-3and 149.40µgm^-3during day and night time respectively, after addition of N-fertilizer (urea) on the soil surface. Wind direction indicated nearby agricultural fields to be the main source of these high levels. Average NH₃concentration during day and night time were observed to be 138.41µg m^-3and 144.01µg m^-3respectively prior to crop harvesting. Such high levels might be due to the contribution from livestock, sewage, etc. as the winds were predominantly from North-west (village) direction during this sampling period. Ambient NH₃concentration reached its maxima at night and minima during midday.

The study suggested that in order to reduce anthropogenic forcing of N cycle globally, there is need to address the inefficiency of N fertilization. In addition, there is a need to examine the formation of ammonium aerosols in the air around the agricultural areas in a comprehensive manner in order to address the health and climate issues related to ammonium aerosols.

Acknowledgement

Our sincere thanks to the University Grants Commission (UGC) for awarding the fellowship to Sudesh. We thank the Department of Science and Technology (DST) for extending their financial support through DST-PURSE programme. This work has been a part of DRSNet-India network.

References

1. Galloway, J. N., Dentener, F. J., Capone, D. G., Boyer, E. W., Howarth, R. W., Seitzinger, S. P., ... & Karl, D. M. Nitrogen cycles: past, present, and future.Biogeochemistry.2004;70(2):153-226.
   CrossRef
2. Phoenix, G. K., Hicks, W. K., Cinderby, S., Kuylenstierna, J. C., Stock, W. D., Dentener, F. J., ... & Ashmore, M. R. Atmospheric nitrogen deposition in world biodiversity hotspots: the need for a greater global perspective in assessing N deposition impacts.Global Change Biology. 2006;12(3): 470-476.
   CrossRef
3. Hertel, O., Skjoth, C. A., Reis, S., Bleeker, A., Harrison, R. M., Cape, J. N., ... &Kulmala, M. Governing processes for reactive nitrogen compounds in the European atmosphere. Biogeosciences. 2012; 9:4921–54.
   CrossRef
4. Sutton, M. A., Dragosits, U., Tang, Y. S., & Fowler, D. Ammonia emissions from non-agricultural sources in the UK.Atmospheric Environment. 2000;34(6):855-869.
   CrossRef
5. Bouwman, A. F., Lee, D. S., Asman, W. A. H., Dentener, F. J., Van Der Hoek, K. W., & Olivier, J. G. J. A global high‐resolution emission inventory for ammonia.Global biogeochemical cycles. 1997;11(4):561-587.
   CrossRef
6. Lee, S., Baumann, K., Schauer, J. J., Sheesley, R. J., Naeher, L. P., Meinardi, S., ... & Clements, M. Gaseous and particulate emissions from prescribed burning in Georgia.Environmental science & technology. 2005;39(23):9049-9056.
   CrossRef
7. Mishra, M., Kulshrestha, U.C. Extreme air pollution events spiking ionic levels at urban and rural sites of Indo-Gangetic plain.Aerosol and Air Quality Research.2020; 20:1266-1281.
   CrossRef
8. Misselbrook, T. H., Van Der Weerden, T. J., Pain, B. F., Jarvis, S. C., Chambers, B. J., Smith, K. A., Phillips, V.R&Demmers, T. G. M. Ammonia emission factors for UK agriculture.Atmospheric environment. 2000;34(6): 871-880.
   CrossRef
9. Vitousek, P. M., Aber, J. D., Howarth, R. W., Likens, G. E., Matson, P. A., Schindler, D. W., Schlesinger, W.H. & Tilman, D. G. Human alteration of the global nitrogen cycle: sources and consequences.生态应用程序. 1997;7(3):737-750.
   CrossRef
10. Galloway, J. N., & Cowling, E. B. Reactive nitrogen and the world: 200 years of change.AMBIO: A Journal of the Human Environment. 2002;31(2): 64-71.
    CrossRef
11. Smil, V. Nitrogen in crop production: An account of global flows.Global biogeochemical cycles. 1999;13(2): 647-662.
    CrossRef
12. Aneja、v P。施莱辛格,W·H。·埃里森曼,j . W。Behera, S. N., Sharma, M., &Battye, W. Reactive nitrogen emissions from crop and livestock farming in India.Atmospheric environment. 2012;47: 92 - 103。
    CrossRef
13. Schwab, G. J., & Murdock, L. W. Nitrogen transformation inhibitors and controlled release urea.Extension Report. Lexington, KY: University of Kentucky College of Agriculture. 2005.
14. Singh, S.,Kulshrestha, U.C. Rural versus urban gaseous inorganic reactive nitrogen in the Indo-Gangetic plains (IGP) of India.Environmental Research Letters. 2014;9(12):125004.
    CrossRef
15. Bouwman, A. F., Boumans, L. J. M., &Batjes, N. H. Estimation of global NH₃volatilization loss from synthetic fertilizers and animal manure applied to arable lands and grasslands.Global Biogeochemical Cycles. 2002;16(2):8-1.
    CrossRef
16. Grunditz, C., &Dalhammar, G. Development of nitrification inhibition assays using pure cultures of Nitrosomonas and Nitrobacter.Water research. 2001;35(2):433-440.
    CrossRef
17. Van Egmond, K., Bresser, T., &Bouwman, L. The European nitrogen case.AMBIO: A Journal of the Human Environment. 2002;31(2):72-78.
    CrossRef
18. Zhao, D. W., & Wang, A. P. (1994). Estimation of anthropogenic ammonia emissions in Asia. Atmospheric Environment, 28, 689–694. https://doi.org/10.1016/1352-2310(94)90045-0.
    CrossRef
19. Beusen, A. H. W., Bouwman, A. F., Heuberger, P. S. C., Van Drecht, G., & Van Der Hoek, K. W. (2008). Bottom-up uncertainty estimates of global ammonia emissions from global agricultural production systems.Atmospheric Environment,42(24), 6067-6077.
    CrossRef
20. Parashar, D. C., Kulshrestha, U. C., & Sharma, C. (1998). Anthropogenic emissions of NO x, NH 3 and N 2 O in India.Nutrient cycling in agroecosystems,52(2-3), 255-259.
    CrossRef
21. Yang, R., Hayashi, K., Zhu, B., Li, F., & Yan, X. (2010). Atmospheric NH3 and NO2 concentration and nitrogen deposition in an agricultural catchment of Eastern China.Science of the Total Environment,408(20), 4624-4632.
    CrossRef
22. Aneja, V.P., Schlesinger, W.H., Knighton, R., Jennings, G., Niyogi, D., Gillam, W., Duke, C. Proc. Of the workshop on agricultural air quality: State of Science; Potomac, MD, North Carolina state University, Releigh, NC. 2006.
23. Xu, R. T., Pan, S. F., Chen, J., Chen, G. S., Yang, J., Dangal, S. R. S., ... & Tian, H. Q. (2018). Half‐century ammonia emissions from agricultural systems in Southern Asia: Magnitude, spatiotemporal patterns, and implications for human health. GeoHealth, 2(1), 40-53.
    CrossRef
24. Naseem, M., &Kulshrestha, U. C. (2017). An Overview of Atmospheric Reactive Nitrogen Research: South Asian Perspective.当前世界环境,14(1), 10.
    CrossRef
25. Vet R., Artz R. S., Carou S., Shaw M., Ro C.U., Aas W. & Hou A. A global assessmentof precipitation chemistry and deposition ofsulfur, nitrogen, sea salt, base cations, organicacids, acidity and pH, and phosphorus.Atmospheric Environment. 2014;93:3-100.
    CrossRef
26. Bouwman, A. F., Van Vuuren, D. P., Derwent, R. G., &Posch, M. A global analysis of acidification and eutrophication of terrestrial ecosystems.Water, Air, and Soil Pollution. 2002;141(1-4):349-382.
    CrossRef
27. Bouwman, A. F., Lee, D. S., Asman, W. A. H., Dentener, F. J., Van Der Hoek, K. W., & Olivier, J. G. J. A global high‐resolution emission inventory for ammonia.Global biogeochemical cycles. 1997;11(4):561-587.
    CrossRef
28. Aneja, V. P., Chauhan, J. P., & Walker, J. T. Characterization of atmospheric ammonia emissions from swine waste storage and treatment lagoons.Journal of Geophysical Research: Atmospheres. 2000;105(D9):11535-11545.
    CrossRef
29. Asman, W. A., & van Jaarsveld, H. A. A variable-resolution transport model applied for NHχ in Europe.Atmospheric Environment. Part A. General Topics. 1992;26(3): 445-464.
    CrossRef
30. Sommer, S. G., Olesen, J. E., & Christensen, B. T. Effects of temperature, wind speed and air humidity on ammonia volatilization from surface applied cattle slurry.The Journal of Agricultural Science. 1991;117(1):91-100.
    CrossRef
31. Braschkat, J., Mannheim, T., &Marschner, H. Estimation of ammonia losses after application of liquid cattle manure on grassland.ZeitschriftfürPflanzenernährung und Bodenkunde. 1997;160(2):117-123.
    CrossRef
32. Sommer, S. G., Friis, E., Bach, A., &Schjørring, J. K. Ammonia volatilization from pig slurry applied with trail hoses or broadspread to winter wheat: effects of crop developmental stage, microclimate, and leaf ammonia absorption.Journal of Environmental Quality. 1997;26(4):1153-1160.
    CrossRef
33. Tiwari, R., Kulshrestha, U. Wintertime distribution and atmospheric interactions of reactive nitrogenspecies along the urban transect of Delhi – NCR.Atmospheric Environment. 2019; 209: 40-53.
    CrossRef
34. Linquist, B. A., Hill, J. E., Mutters, R. G., Greer, C. A., Hartley, C., Ruark, M. D., & Van Kessel, C. Assessing the necessity of surface-applied preplant nitrogen fertilizer in rice systems.Agronomy Journal. 2009;101(4):906-915.
    CrossRef
35. Sharma, C., Tiwari, M. K., & Pathak, H. Estimates of emission and deposition of reactive nitrogenous species for India. Current Science. 2008; 1439-1446.
36. Walker, J.T., Whitall, D.R., Robarge, W., &Paerl, H.W.Ambient ammonia and ammonium aerosol across a region ofvariable ammonia emission density. Atmospheric Environment. 2004; 38: 1235–1246.
    CrossRef
37. Burkhardt, J., Sutton, M. A., Milford, C., Storeton-West, R. L., & Fowler, D. Ammonia concentrations at a site in southern Scotland from 2 yr of continuous measurements.Atmospheric Environment. 1998;32(3):325-331.
    CrossRef
38. Singh, S., Kulshrestha, U. C. Abundance and distribution of gaseous ammonia and particulate ammonium at Delhi, India.Biogeosciences.2012; 9(12):5023-5029.
    CrossRef
39. Seinfeld, J.H., Pandis, S.N.Atmospheric Chemistry and Physics.Wiley-Interscience, New York. 1998.
40. Ferm, M. Atmospheric ammonia and ammonium transport in Europe and critical loads: a review.Nutrient Cycling in Agroecosystems. 1998;51(1):5-17.
    CrossRef
41. Lee, S., Baumann, K., Schauer, J. J., Sheesley, R. J., Naeher, L. P., Meinardi, S., Blake, D.R., Edgerton, E.S., Russell, A.G. and Clements, M. Gaseous and particulate emissions from prescribed burning in Georgia.Environmental science & technology. 2005;39(23):9049-9056.
    CrossRef
42. Sakurai, T., Fujita, S. I., Hayami, H., &Furuhashi, N. A case study of high ammonia concentration in the nighttime by means of modeling analysis in the Kanto region of Japan.Atmospheric Environment. 2003;37(31):4461-4465.
    CrossRef
43. Whitehead, J. D., Longley, I. D., & Gallagher, M. W. Seasonal and diurnal variation in atmospheric ammonia in an urban environment measured using a quantum cascade laser absorption spectrometer.Water, air, and soil pollution. 2007;183:317-329.
    CrossRef
44. Wilson, S. M., & Serre, M. L. Use of passive samplers to measure atmospheric ammonia levels in a high-density industrial hog farm area of eastern North Carolina.Atmospheric Environment. 2007;41(28):6074-6086.
    CrossRef
45. Shen, J. L., Tang, A. H., Liu, X. J., Fangmeier, A., Goulding, K. T. W., & Zhang, F. S. High concentrations and dry deposition of reactive nitrogen species at two sites in the North China Plain.Environmental Pollution. 2009;157(11):3106-3113.
    CrossRef
46. Ianniello, A., Spataro, F., Esposito, G., Allegrini, I., Rantica, E., Ancora, M. P.,Hu, M., & Zhu, T. Occurrence of gas phase ammonia in the area of Beijing (China).Atmospheric Chemistry and Physics. 2010;10(19):9487-9503.
    CrossRef
47. Carmichael, G. R., Ferm, M., Thongboonchoo, N., Woo, J. H., Chan, L. Y., Murano, K.,Viet, P.H., Mossberg, C., Bala, R., Boonjawat, J., &Upatum, P. Measurements of sulfur dioxide, ozone and ammonia concentrations in Asia, Africa, and South America using passive samplers.Atmospheric Environment. 2003;37(9-10):1293-1308.
    CrossRef
48. Parmar, R. S., Satsangi, G. S., Lakhani, A., Srivastava, S. S., & Prakash, S. Simultaneous measurements of ammonia and nitric acid in ambient air at Agra (27 10′ N and 78 05′ E)(India).Atmospheric Environment. 2001;35(34):5979-5988.
    CrossRef