Reactive nitrogen and sulphate wet deposition at Zeppelin Station, Ny-Ålesund, Svalbard

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

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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Model Inter-Comparison Study for Asia (MICS-Asia) phase III: multimodel comparison of reactive nitrogen deposition over China

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-10587-2020 ◽

2020 ◽

Vol 20 (17) ◽

pp. 10587-10610

Author(s):

Baozhu Ge ◽

Syuichi Itahashi ◽

Keiichi Sato ◽

Danhui Xu ◽

Junhua Wang ◽

...

Keyword(s):

Air Quality ◽

Nitrogen Deposition ◽

Acid Deposition ◽

Dry Deposition ◽

Wet Deposition ◽

Monitoring Network ◽

Phase Iii ◽

Reactive Nitrogen ◽

Comparison Study ◽

Deposition Monitoring

Abstract. Atmospheric nitrogen deposition in China has attracted public attention in recent years due to the increasing anthropogenic emission of reactive nitrogen (Nr) and its impacts on the terrestrial and aquatic ecosystems. However, limited long-term and multisite measurements have restrained the understanding of the mechanism of the Nr deposition and the chemical transport model (CTM) improvement. In this study, the performance of the simulated wet and dry deposition for different Nr species, i.e., particulate NO3- and NH4+, gaseous NOx, HNO3 and NH3 have been conducted using the framework of Model Inter-Comparison Study for Asia (MICS-Asia) phase III. A total of nine models, including five Weather Research and Forecasting models coupled with the Community Multiscale Air Quality (WRF-CMAQ) models, two self-developed regional models, a global model and a Regional Atmospheric Modeling System coupled with the Community Multiscale Air Quality (RAMS-CMAQ) model have been selected for the comparison. For wet deposition, observation data from 83 measurement sites from the East Asia Acid Deposition Monitoring Network (EANET), Chinese Ecosystem Research Network (CERN), China Agricultural University Deposition Network (CAUDN), National Acid Deposition Monitoring Network (NADMN) and Department of Ecological Environment (DEE) of China have been collected and normalized for comparison with model results. In general, most models show the consistent spatial and temporal variation of both oxidized N (Nox) and reduced N (Nrd) wet deposition in China, with the normalized mean error (NME) at around 50 %, which is lower than the value of 70 % based on EANET observation over Asia. Both the ratio of wet or dry deposition to the total inorganic N (TIN) deposition and the ratios of TIN to their emissions have shown consistent results with the Nationwide Nitrogen Deposition Monitoring Network (NNDMN) estimates. The performance of ensemble results (ENMs) was further assessed with satellite measurements. In different regions of China, the results show that the simulated Nox wet deposition was overestimated in northeastern China (NE) but underestimated in the south of China, namely southeastern (SE) and southwestern (SW) China, while the Nrd wet deposition was underestimated in all regions by all models. The deposition of Nox has larger uncertainties than the Nrd, especially in northern China (NC), indicating the chemical reaction process is one of the most important factors affecting the model performance. Compared to the critical load (CL) value, the Nr deposition in NC, SE and SW reached or exceeded reported CL values and resulted in serious ecological impacts. The control of Nrd in NC and SW and Nox in SE would be an effective mitigation measure for TIN deposition in these regions. The Nr deposition in the Tibetan Plateau (TP) with a high ratio of TIN ∕ emission (∼3.0), indicates a significant transmission from outside. Efforts to reduce these transmissions ought to be paramount due the climatic importance of the Tibetan region to the sensitive ecosystems throughout China.

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MICS-Asia III: Multi-model comparison of reactive Nitrogen deposition over China

10.5194/acp-2019-1083 ◽

2020 ◽

Cited By ~ 2

Author(s):

Baozhu Ge ◽

Syuichi Itahashi ◽

Keiichi Sato ◽

Danhui Xu ◽

Junhua Wang ◽

...

Keyword(s):

Nitrogen Deposition ◽

Dry Deposition ◽

Wet Deposition ◽

Ecological Impacts ◽

Phase Iii ◽

Tibet Plateau ◽

Spatial And Temporal Variation ◽

Reactive Nitrogen ◽

Observation Data ◽

Public Attention

Abstract. Atmospheric nitrogen deposition in China has attracted huge public attention in recently years due to the increasing anthropogenic emission of reactive nitrogen (Nr) and its impacts on the terrestrial and aquatic ecosystems. However, limited long-term and multi-site measurements have restrained the understanding on the mechanism of the Nr deposition as well as the chemical transport model (CTM) improvement. In this study, the performance of the simulated wet and dry deposition for different Nr species, i.e., particulate NO3− and NH4+, gaseous NOx, HNO3 and NH3, have been conducted using the framework of Model Inter-Comparison Study for Asia (MICS-Asia) phase III. Nine Models, including 5 WRF-CAMQ models, 2 self-developed regional models, a global model and a RAMS-CMAQ model, have been selected for the comparison. For wet depositions, observation data from 83 measurement sites of EANET, CREN, CAUDN, NADMN and DEE of China have been collected and normalized to compare with model results. In general, most models showed the consistent spatial and temporal variation of both oxidized N (Nox) and reduced N (Nrd) wet depositions in China with the NME around at 50 %, which is lower than the value of 70 % based on EANET observation over Asia. Both the ratio of wet or dry deposition to the total inorganic N deposition (TIN) and the ratios of TIN to their emissions have shown the consistent results with the NNDMN estimations. The performance of ensemble results (ENM) was further assessed with the measurement from satellite. In different regions of China, the results showed that the simulated Nox wet deposition was overestimated in North East China (NE) but underestimated in south of China (SE+SW), while the Nrd wet deposition was underpredicted in all regions by all models. The deposition of Nox have large uncertainties than the Nrd especially in North China (NC), indicating chemical reaction process is one of the most importance factors that affecting the model performance. Compared to Critical load (CL) value, the Nr deposition in NC, SE and SW reached or exceeded the reported CL value and exerted serious ecological impacts. The control of Nrd in NC and SW and Nox in SE would be effective to mitigate the TIN deposition in these regions. More interestingly, the Nr deposition in Tibet plateau with the high ratio of TIN/emission (~3.0), indicating a significant import from outside should be focused in the future due to its climatical influence to the sensitive ecosystem in whole China.

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