Reactive nitrogen fluxes and scavenging patterns through sequential sampling over Mathura, India.

Mapping Intimacies ◽

10.5194/egusphere-egu2020-21779 ◽

2020 ◽

Author(s):

Mudita Chaturvedi ◽

Umesh Kulshrestha

Keyword(s):

Wet Deposition ◽

Environmental Concern ◽

Sequential Sampling ◽

Nitrogen Concentration ◽

Behaviour Pattern ◽

Reactive Nitrogen ◽

Tropical Region ◽

Deposition Flux ◽

Remarkable Change ◽

Rain Events

In recent years, reactive nitrogen concentration and potentiality has been of environmental concern. India being the second largest populated country in world, huge amount of NH3+ emissions are expected from various activities of humans, agriculture and individual sources. This work has been carried out to calculate wet deposition fluxes of Nr species in rain water and to understand their scavenging behaviour at a typical residential site under semiarid tropical region. For this purpose, sequential sampling of rain events has been performed for determining Nr levels during monsoon 2015 and 2016. Samples were analysed for reactive nitrogen species. The wet deposition flux was observed to be 2.13 kg ha-1year-1 for NH4+-N and 3.62 kg ha-1year-1 for NO3- -N in 2015. However, significant increase in NO3--N was observed in 2016 where as there was no remarkable change for NH4+. This clearly indicates towards dynamic behaviour pattern showing sources of reactive nitrogen in air over the region. Scavenging patterns confirmed the presence of NH4NO3&#160;showing co-variations of NH4+&#160;and NO3-&#160;along with the rainfall intensity. Thereby, confirming the possible forms in which these Nr species are being deposited over the study area.

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Wet Deposition Fluxes of Nitrate and Ammonium at a Rural Agricultural Site in north India

10.5194/egusphere-egu21-9103 ◽

2021 ◽

Author(s):

Sudesh Yadav ◽

Umesh Kulshrestha

Keyword(s):

Wet Deposition ◽

Major Ions ◽

Monsoon Season ◽

North India ◽

Reactive Nitrogen ◽

Deposition Flux ◽

Deposition Fluxes ◽

Average Value ◽

Wet Deposition Flux ◽

Agricultural Site

The chemical composition of rainwater is an indicator of the air quality and sources of influence. In this study, pH and ionic concentrations were measured in rain samples collected during monsoon season of 2018 at a rural agricultural site located in northern part of India. Wet deposition fluxes of reactive nitrogen species NH4+ over NO3- were calculated to estimate their annual deposition. The pH of samples varied between 5.2 and 6.14, with an average value of 5.72 which is in alkaline range considering 5.6 as the neutral pH of cloud water with atmospheric CO2 equilibrium. These relatively high pH values indicate the neutralisation of acidity in precipitation. Samples were analysed for their cationic and anionic content using ion chromatography. The results showed that NH4+ concentrations were higher than NO3- with the VWM concentrations of 187.23 &#956;eql-1 and 26.79 &#956;eql-1 respectively. Furthermore, wet deposition flux of NH4+-N was calculated as 4.25 kg ha-1 yr-1 while that of NO3--N was as 2.10 kg ha-1 yr-1. VWM concentrations of major ions decreased in the following order NH4+ > Ca2+ > SO42- > NO3- > K+ > Cl- > Na+ > Mg2+. In this study, relatively high NH4+ concentrations in rainwater can be attributed to nearby agricultural activities, excreta and biomass burning.Keywords: Rainwater, Neutralisation, VWM concentration, Agricultural site, Reactive Nitrogen.

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A STUDY OF WET DEPOSITION FLUX USING THE SEQUENTIAL SAMPLING TECHNIQUE

SGEM2011 11th International Multidisciplinary Scientific GeoConference ◽

10.5593/sgem2011/s17.102 ◽

2011 ◽

Author(s):

O. Akkoyunlu

Keyword(s):

Wet Deposition ◽

Sequential Sampling ◽

Sampling Technique ◽

Deposition Flux ◽

Wet Deposition Flux

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Long term precipitation chemistry and wet deposition in a remote dry savanna site in Africa (Niger)

Atmospheric Chemistry and Physics ◽

10.5194/acp-9-1579-2009 ◽

2009 ◽

Vol 9 (5) ◽

pp. 1579-1595 ◽

Cited By ~ 50

Author(s):

C. Galy-Lacaux ◽

D. Laouali ◽

L. Descroix ◽

N. Gobron ◽

C. Liousse

Keyword(s):

Wet Deposition ◽

Ph Value ◽

Precipitation Chemistry ◽

Annual Rainfall ◽

Deposition Flux ◽

Air Concentration ◽

Ionic Charge ◽

Rainfall Gradient ◽

The Mean

Abstract. Long-term precipitation chemistry have been recorded in the rural area of Banizoumbou (Niger), representative of a semi-arid savanna ecosystem. A total of 305 rainfall samples ~90% of the total annual rainfall) were collected from June 1994 to September 2005. From ionic chromatography, pH major inorganic and organic ions were detected. Rainwater chemistry is controlled by soil/dust emissions associated with terrigeneous elements represented by SO42−, Ca2+, Carbonates, K+ and Mg2+. It is found that calcium and carbonates represent ~40% of the total ionic charge. The second highest contribution is nitrogenous, with annual Volume Weighed Mean (VWM) for NO3− and NH4+ concentrations of 11.6 and 18.1 μeq.l−1, respectively. This is the signature of ammonia sources from animals and NOx emissions from savannas soil-particles rain-induced. The mean annual NH3 and NO2 air concentration are of 6 ppbv and 2.6 ppbv, respectively. The annual VWM precipitation concentration of sodium and chloride are both of 8.7 μeq.l−1 which reflects the marine signature of monsoonal and humid air masses. The median pH value is of 6.05. Acidity is neutralized by mineral dust, mainly carbonates, and/or dissolved gases such NH3. High level of organic acidity with 8μeq.l−1 and 5.2 μeq.l−1 of formate and acetate were also found. The analysis of monthly Black Carbon emissions and Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) values show that both biogenic emission from vegetation and biomass burning could explain the rainfall organic acidity content. The interannual variability of the VWM concentrations around the mean (1994–2005) is between ±5% and ±30% and mainly due to variations of sources strength and rainfall spatio-temporal distribution. From 1994 to 2005, the total mean wet deposition flux in the Sahelian region is of 60.1 mmol.m−2.yr−1 ±25%. Finally, Banizoumbou measurements are compared to other long-term measurements of precipitation chemistry in the wet savanna of Lamto (Côte d'Ivoire) and in the forested zone of Zoétélé (Cameroon). The total chemical loading presents a maximum in the dry savanna and a minimum in the forest (from 143.7, 100.2 to 86.6 μeq.l−1), associated with the gradient of terrigeneous sources. The wet deposition fluxes present an opposite trend, with 60.0 mmol.m−2.yr−1 in Banizoumbou, 108.6 mmol.m−2.yr−1 in Lamto and 162.9 mmol.m−2.yr−1 in Zoétélé, controlled by rainfall gradient along the ecosystems transect.

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Estimate of changes in agricultural terrestrial nitrogen pathways and ammonia emissions from 1850 to present in the Community Earth System Model

Biogeosciences ◽

10.5194/bg-13-3397-2016 ◽

2016 ◽

Vol 13 (11) ◽

pp. 3397-3426 ◽

Cited By ~ 29

Author(s):

Stuart Riddick ◽

Daniel Ward ◽

Peter Hess ◽

Natalie Mahowald ◽

Raia Massad ◽

...

Keyword(s):

Agricultural Practices ◽

Animal Manure ◽

Fertilizer Application ◽

Global Scale ◽

Reactive Nitrogen ◽

Biogeochemical Model ◽

Community Land Model ◽

Synthetic Fertilizer ◽

Rain Events ◽

Percentage Basis

Abstract. Nitrogen applied to the surface of the land for agricultural purposes represents a significant source of reactive nitrogen (Nr) that can be emitted as a gaseous Nr species, be denitrified to atmospheric nitrogen (N2), run off during rain events or form plant-useable nitrogen in the soil. To investigate the magnitude, temporal variability and spatial heterogeneity of nitrogen pathways on a global scale from sources of animal manure and synthetic fertilizer, we developed a mechanistic parameterization of these pathways within a global terrestrial land model, the Community Land Model (CLM). In this first model version the parameterization emphasizes an explicit climate-dependent approach while using highly simplified representations of agricultural practices, including manure management and fertilizer application. The climate-dependent approach explicitly simulates the relationship between meteorological variables and biogeochemical processes to calculate the volatilization of ammonia (NH3), nitrification and runoff of Nr following manure or synthetic fertilizer application. For the year 2000, approximately 125 Tg N yr−1 is applied as manure and 62 Tg N yr−1 is applied as synthetic fertilizer. We estimate the resulting global NH3 emissions are 21 Tg N yr−1 from manure (17 % of manure production) and 12 Tg N yr−1 from fertilizer (19 % of fertilizer application); reactive nitrogen runoff during rain events is calculated as 11 Tg N yr−1 from manure and 5 Tg N yr−1 from fertilizer. The remaining nitrogen from manure (93 Tg N yr−1) and synthetic fertilizer (45 Tg N yr−1) is captured by the canopy or transferred to the soil nitrogen pools. The parameterization was implemented in the CLM from 1850 to 2000 using a transient simulation which predicted that, even though absolute values of all nitrogen pathways are increasing with increased manure and synthetic fertilizer application, partitioning of nitrogen to NH3 emissions from manure is increasing on a percentage basis, from 14 % of nitrogen applied in 1850 (3 Tg NH3 yr−1) to 17 % of nitrogen applied in 2000 (21 Tg NH3 yr−1). Under current manure and synthetic fertilizer application rates we find a global sensitivity of an additional 1 Tg NH3 (approximately 3 % of manure and fertilizer) emitted per year per °C of warming. While the model confirms earlier estimates of nitrogen fluxes made in a range of studies, its key purpose is to provide a theoretical framework that can be employed within a biogeochemical model, that can explicitly respond to climate and that can evolve and improve with further observation.

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Characteristics of atmospheric mercury deposition and size-fractionated particulate mercury in urban Nanjing, China

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-2233-2014 ◽

2014 ◽

Vol 14 (5) ◽

pp. 2233-2244 ◽

Cited By ~ 42

Author(s):

J. Zhu ◽

T. Wang ◽

R. Talbot ◽

H. Mao ◽

X. Yang ◽

...

Keyword(s):

Dry Deposition ◽

Wet Deposition ◽

Fine Particles ◽

Unit Area ◽

Atmospheric Mercury ◽

Anthropogenic Sources ◽

Deposition Flux ◽

Coarse Particles ◽

Mercury Deposition ◽

Particulate Mercury

Abstract. A comprehensive measurement study of mercury wet deposition and size-fractionated particulate mercury (HgP) concurrent with meteorological variables was conducted from June 2011 to February 2012 to evaluate the characteristics of mercury deposition and particulate mercury in urban Nanjing, China. The volume-weighted mean (VWM) concentration of mercury in rainwater was 52.9 ng L−1 with a range of 46.3–63.6 ng L−1. The wet deposition per unit area was averaged 56.5 μg m−2 over 9 months, which was lower than that in most Chinese cities, but much higher than annual deposition in urban North America and Japan. The wet deposition flux exhibited obvious seasonal variation strongly linked with the amount of precipitation. Wet deposition in summer contributed more than 80% to the total amount. A part of contribution to wet deposition of mercury from anthropogenic sources was evidenced by the association between wet deposition and sulfates, as well as nitrates in rainwater. The ions correlated most significantly with mercury were formate, calcium, and potassium, which suggested that natural sources including vegetation and resuspended soil should be considered as an important factor to affect the wet deposition of mercury in Nanjing. The average HgP concentration was 1.10 ± 0.57 ng m−3. A distinct seasonal distribution of HgP concentrations was found to be higher in winter as a result of an increase in the PM10 concentration. Overall, more than half of the HgP existed in the particle size range less than 2.1 μm. The highest concentration of HgP in coarse particles was observed in summer, while HgP in fine particles dominated in fall and winter. The size distribution of averaged mercury content in particulates was bimodal, with two peaks in the bins of < 0.7 μm and 4.7–5.8 μm. Dry deposition per unit area of HgP was estimated to be 47.2 μg m−2 using meteorological conditions and a size-resolved particle dry deposition model. This was 16.5% less than mercury wet deposition. Compared to HgP in fine particles, HgP in coarse particles contributed more to the total dry deposition due to higher deposition velocities. Negative correlation between precipitation and the HgP concentration reflected the effect of scavenging of HgP by precipitation.

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Characterization of S-Band Dual-Polarized Radar Data for the Convective Rain Melting Layer Detection in A Tropical Region

Remote Sensing ◽

10.3390/rs10111740 ◽

2018 ◽

Vol 10 (11) ◽

pp. 1740 ◽

Cited By ~ 1

Author(s):

Feng Yuan ◽

Yee Lee ◽

Yu Meng ◽

Jin Ong

Keyword(s):

Radar Data ◽

Tropical Region ◽

Rain Event ◽

Melting Layer ◽

Convective Rain ◽

Radar Measurements ◽

Dual Polarized ◽

Rain Events ◽

Differential Reflectivity

In the tropical region, convective rain is a dominant rain event. However, very little information is known about the convective rain melting layer. In this paper, S-band dual-polarized radar data is studied in order to identify both the stratiform and convective rain melting layers in the tropical region, with a focus on the convective events. By studying and analyzing the above-mentioned two types of rain events, amongst three radar measurements of reflectivity ( Z ), differential reflectivity ( Z DR ), and cross correlation coefficient ( ρ HV ), the latter one is the best indicator for convective rain melting layer detection. From two years (2014 and 2015) of radar and radiosonde observations, 13 convective rain melting layers are identified with available 0 °C isothermal heights which are derived from radiosonde vertical profiles. By comparing the melting layer top heights with the corresponding 0 °C isothermal heights, it is found that for convective rain events, the threshold to detect melting layer should be modified to ρ HV = 0.95 for the tropical region. The melting layer top and bottom heights are then estimated using the proposed threshold, and it is observed from this study that the thickness of convective rain melting layer is around 2 times that of stratiform rain melting layer which is detected by using the conventional ρ HV = 0.97 .

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Impacts of Anthropogenic Emissions and Meteorological Variation on Hg Wet Deposition in Chongming, China

Atmosphere ◽

10.3390/atmos11121301 ◽

2020 ◽

Vol 11 (12) ◽

pp. 1301

Author(s):

Yi Tang ◽

Qingru Wu ◽

Wei Gao ◽

Shuxiao Wang ◽

Zhijian Li ◽

...

Keyword(s):

Wet Deposition ◽

Warm Season ◽

Meteorological Condition ◽

Anthropogenic Emissions ◽

Deposition Flux ◽

Wet Deposition Flux ◽

Meteorological Variation ◽

Global Concern ◽

The Impact

Mercury (Hg) is a ubiquitous environmental toxicant that has caused global concern due to its persistence and bioaccumulation in the environment. Wet deposition is a crucial Hg input for both terrestrial and aquatic environments and is a significant indicator for evaluating the effectiveness of anthropogenic Hg control. Rainwater samples were collected from May 2014 to October 2018 in Chongming Island to understand the multi-year Hg wet deposition characteristics. The annual Hg wet deposition flux ranged from 2.6 to 9.8 μg m−2 yr−1 (mean: 4.9 μg m−2 yr−1). Hg wet deposition flux in Chongming was comparable to the observations at temperate and subtropical background sites (2.0–10.2 μg m−2 yr−1) in the northern hemisphere. Hg wet deposition flux decreased from 8.6 μg m−2 yr−1 in 2014–2015 to 3.8 μg m−2 yr−1 in 2016 and was attributed to a decrease in the volume-weighted mean (VWM) Hg concentration (−4.1 ng L−1 yr−1). The reduced VWM Hg was explained by the decreasing atmospheric Hg and anthropogenic emissions reductions. The annual Hg wet deposition flux further decreased from 3.8 μg m−2 in 2016 to 2.6 μg m−2 in 2018. The reduction of warm season (April–September) rainfall amounts (356–845 mm) mainly contributed to the Hg wet deposition flux reduction during 2016–2018. The multi-year monitoring results suggest that long-term measurements are necessary when using wet deposition as an indicator to reflect the impact of anthropogenic efforts on mercury pollution control and meteorological condition variations.

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Effects of aerosol dynamics and gas–particle conversion on dry deposition of inorganic reactive nitrogen in a temperate forest

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-4933-2020 ◽

2020 ◽

Vol 20 (8) ◽

pp. 4933-4949 ◽

Cited By ~ 1

Author(s):

Genki Katata ◽

Kazuhide Matsuda ◽

Atsuyuki Sorimachi ◽

Mizuo Kajino ◽

Kentaro Takagi

Keyword(s):

Dry Deposition ◽

Particle Deposition ◽

Chemical Transport ◽

Reactive Nitrogen ◽

Surface Model ◽

Deposition Flux ◽

Transport Models ◽

Inorganic Particles ◽

Aerosol Dynamics ◽

Chemical Transport Models

Abstract. Dry deposition has an impact on nitrogen status in forest environments. However, the mechanism for the high dry-deposition rates of fine nitrate particles (NO3-) observed in forests remains unknown and is thus a potential source of error in chemical transport models (CTMs). Here, we modified and applied a multilayer land surface model coupled with dry-deposition and aerosol dynamic processes for a temperate mixed forest in Japan. This represents the first application of such a model to ammonium nitrate (NH4NO3) gas–particle conversion (gpc) and the aerosol water uptake of reactive nitrogen compounds. Thermodynamics, kinetics, and dry deposition for mixed inorganic particles are modeled by a triple-moment modal method. Data for inorganic mass and size-resolved total number concentrations measured by a filter pack and electrical low-pressure impactor in autumn were used for model inputs and subsequent numerical analysis. The model successfully reproduces turbulent fluxes observed above the canopy and vertical micrometeorological profiles noted in our previous studies. The sensitivity tests with and without gpc demonstrated clear changes in the inorganic mass and size-resolved total number concentrations within the canopy. The results also revealed that within-canopy evaporation of NH4NO3 under dry conditions significantly enhances the deposition flux of fine-NO3- and fine-NH4+ particles, while reducing the deposition flux of nitric acid gas (HNO3). As a result of the evaporation of particulate NH4NO3, the calculated daytime mass flux of fine NO3- over the canopy was 15 times higher in the scenario of “gpc” than in the scenario of “no gpc”. This increase caused high contributions from particle deposition flux (NO3- and NH4+) to total nitrogen flux over the forest ecosystem (∼39 %), although the contribution of NH3 was still considerable. A dry-deposition scheme coupled with aerosol dynamics may be required to improve the predictive accuracy of chemical transport models for the surface concentration of inorganic reactive nitrogen.

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Studies on the Rain Scavenging Process of Tritium in a Tropical Site at Narora in India

Journal of Nuclear Chemistry ◽

10.1155/2013/849732 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6 ◽

Cited By ~ 2

Author(s):

Y. P. Gautam ◽

Saivajay Sharma ◽

A. K. Sharma ◽

Aviansh Kumar ◽

P. M. Ravi ◽

...

Keyword(s):

Wet Deposition ◽

Activity Ratio ◽

Specific Activity ◽

Deposition Velocity ◽

Ground Level ◽

Atomic Power Station ◽

Tropical Region ◽

Power Station ◽

Data Set ◽

Average Value

This study presents the results of systematic experiments on tritium (3H) concentrations in ground level air against those in rainwater near a pressurized heavy water reactor in a tropical region. The samples were collected over the rainy season of year 2011 from eight locations in the environment around Narora Atomic Power Station. The specific activity ratio of 3H between rainwater and air moisture at ground level was calculated for each data set. The average specific activity ratio was found to be ranged from 0.12 to 1.1. A correlation ( to 0.76, ) was observed between the total rain hours in a day and the rainwater 3H activity. Higher rain duration with slower rain rate yielded higher 3H concentrations as more time was available for the scavenging/wash-out process to take effect together with lower dilution. Annual tritium (HTO) wet deposition has been measured and calculated for the year 2011 within 0.8 km distance from 145 m high stack of Narora Atomic Power Station (NAPS) at nine locations in different directions. The range of deposition velocity, (m·s−1), at nine locations for the years 2011 is found to be from 4.43E − 04 to 6.42E − 03. The average value for wet deposition velocity for NAPS site is estimated as 3.17E − 03 m·s−1.

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Subtropical subsidence and surface deposition of oxidized mercury produced in the free troposphere

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-8999-2017 ◽

2017 ◽

Vol 17 (14) ◽

pp. 8999-9017 ◽

Cited By ~ 9

Author(s):

Viral Shah ◽

Lyatt Jaeglé

Keyword(s):

Boundary Layer ◽

Dry Deposition ◽

Wet Deposition ◽

Transport Model ◽

Lower Troposphere ◽

Deposition Flux ◽

Surface Deposition ◽

Middle Troposphere ◽

Western Us ◽

Wet Deposition Flux

Abstract. Oxidized mercury (Hg(II)) is chemically produced in the atmosphere by oxidation of elemental mercury and is directly emitted by anthropogenic activities. We use the GEOS-Chem global chemical transport model with gaseous oxidation driven by Br atoms to quantify how surface deposition of Hg(II) is influenced by Hg(II) production at different atmospheric heights. We tag Hg(II) chemically produced in the lower (surface–750 hPa), middle (750–400 hPa), and upper troposphere (400 hPa–tropopause), in the stratosphere, as well as directly emitted Hg(II). We evaluate our 2-year simulation (2013–2014) against observations of Hg(II) wet deposition as well as surface and free-tropospheric observations of Hg(II), finding reasonable agreement. We find that Hg(II) produced in the upper and middle troposphere constitutes 91 % of the tropospheric mass of Hg(II) and 91 % of the annual Hg(II) wet deposition flux. This large global influence from the upper and middle troposphere is the result of strong chemical production coupled with a long lifetime of Hg(II) in these regions. Annually, 77–84 % of surface-level Hg(II) over the western US, South America, South Africa, and Australia is produced in the upper and middle troposphere, whereas 26–66 % of surface Hg(II) over the eastern US, Europe, and East Asia, and South Asia is directly emitted. The influence of directly emitted Hg(II) near emission sources is likely higher but cannot be quantified by our coarse-resolution global model (2° latitude  ×  2.5° longitude). Over the oceans, 72 % of surface Hg(II) is produced in the lower troposphere because of higher Br concentrations in the marine boundary layer. The global contribution of the upper and middle troposphere to the Hg(II) dry deposition flux is 52 %. It is lower compared to the contribution to wet deposition because dry deposition of Hg(II) produced aloft requires its entrainment into the boundary layer, while rain can scavenge Hg(II) from higher altitudes more readily. We find that 55 % of the spatial variation of Hg wet deposition flux observed at the Mercury Deposition Network sites is explained by the combined variation of precipitation and Hg(II) produced in the upper and middle troposphere. Our simulation points to a large role of the dry subtropical subsidence regions. Hg(II) present in these regions accounts for 74 % of Hg(II) at 500 hPa over the continental US and more than 60 % of the surface Hg(II) over high-altitude areas of the western US. Globally, it accounts for 78 % of the tropospheric Hg(II) mass and 61 % of the total Hg(II) deposition. During the Nitrogen, Oxidants, Mercury, and Aerosol Distributions, Sources, and Sinks (NOMADSS) aircraft campaign, the contribution of Hg(II) from the dry subtropical regions was found to be 75 % when measured Hg(II) exceeded 250 pg m−3. Hg(II) produced in the upper and middle troposphere subsides in the anticyclones, where the dry conditions inhibit the loss of Hg(II). Our results highlight the importance the subtropical anticyclones as the primary conduits for the production and export of Hg(II) to the global atmosphere.

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