Triple oxygen isotopes indicate urbanization affects sources of nitrate in wet and dry atmospheric deposition

Abstract. Atmospheric nitrate deposition resulting from anthropogenic activities negatively affects human and environmental health. Identifying deposited nitrate that is produced locally vs. that originating from long-distance transport would help inform efforts to mitigate such impacts. However, distinguishing the relative transport distances of atmospheric nitrate in urban areas remains a major challenge since it may be produced locally and/or be transported from upwind regions. To address this uncertainty we assessed spatiotemporal variation in monthly weighted-average Δ17O and δ15N values of wet and dry nitrate deposition during one year at urban and rural sites along the western coast of the northern Japanese island of Hokkaido, downwind of the East Asian continent. Δ17O values of nitrate in wet deposition at the urban site mirrored those of wet and dry deposition at the rural site, ranging between ∼  +23 and +31 ‰ with higher values during winter and lower values in summer, which suggests the greater relative importance of oxidation of NO2 by O3 during winter and OH during summer. In contrast, Δ17O values of nitrate in dry deposition at the urban site were lower (+19 – +25 ‰) and displayed less distinct seasonal variation. Furthermore, the difference between δ15N values of nitrate in wet and dry nitrate deposition was, on average, 3 ‰ greater at the urban than rural site, and Δ17O and δ15N values were correlated for both forms of deposition at both sites with the exception of dry deposition at the urban site. These results suggest that, relative to nitrate in wet and dry deposition in rural environments and wet deposition in urban environments, nitrate in dry deposition in urban environments forms from relatively greater oxidation of NO by peroxy radicals and/or oxidation of NO2 by OH. Given greater concentrations of peroxy radicals and OH in cities, these results imply that dry nitrate deposition results from local NOx emissions more so than wet deposition, which is transported longer distances. These results illustrate the value of stable isotope data for distinguishing the transport distances and reaction pathways of atmospheric nitrate pollution.

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Triple oxygen isotopes indicate urbanization affects sources of nitrate in wet and dry atmospheric deposition

10.5194/acp-2017-1071 ◽

2018 ◽

Author(s):

David M. Nelson ◽

Urumu Tsunogai ◽

Ding Dong ◽

Takuya Ohyama ◽

Daisuke D. Komatsu ◽

...

Keyword(s):

Dry Deposition ◽

Wet Deposition ◽

Urban Environments ◽

Rural Site ◽

Urban Site ◽

Peroxy Radicals ◽

Long Distance ◽

Wet And Dry Deposition ◽

Atmospheric Nitrate ◽

Nitrate Deposition

Abstract. Atmospheric nitrate deposition resulting from anthropogenic activities negatively affects human and environmental health. Identifying deposited nitrate that is produced locally vs. that originating from long-distance transport would help inform efforts to mitigate such impacts. However, distinguishing the relative transport distances of atmospheric nitrate in urban areas remains a major challenge since it may be produced locally and/or come from upwind regions. To address this uncertainty we assessed spatiotemporal variation in monthly weighted-average Δ17O and δ15N values of wet and dry nitrate deposition during one year at urban and rural sites along the western coast of the northern Japanese island of Hokkaido, downwind of the East Asian continent. Δ17O values of nitrate in wet deposition at the urban site mirrored those of wet and dry deposition at the rural site, ranging between ~ +22 and +30 ‰ with higher values during winter and lower values in summer, which suggests greater relative importance of oxidation of NO2 by O3 during winter and OH during summer. In contrast, Δ17O values of nitrate in dry deposition at the urban site were lower (+19–+25 ‰) and displayed less distinct seasonal variation. Furthermore, the difference between δ15N values of nitrate in wet and dry nitrate deposition was, on average, 3 ‰ greater at the urban than rural site, and Δ17O and δ15N values were correlated for both forms of deposition at both sites with the exception of dry deposition at the urban site. These results suggest that, relative to nitrate in wet deposition in urban environments and wet and dry deposition in rural environments, nitrate in dry deposition in urban environments forms from relatively greater oxidation of NO by peroxy radicals and/or oxidation of NO2 by OH. Given greater concentrations of peroxy radicals and OH in cities, these results imply that dry nitrate deposition results from local NOx emissions more so than wet deposition, which is transported longer distances. These results illustrate the value of stable isotope data for distinguishing the transport distances and reaction pathways of atmospheric nitrate pollution.

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Seasonal variations in black and organic carbon wet and dry deposition rates at SMEAR III station (60oN), Finland

10.5194/egusphere-egu21-5362 ◽

2021 ◽

Author(s):

Outi Meinander ◽

Enna Heikkinen ◽

Jonas Svensson ◽

Minna Aurela ◽

Aki Virkkula ◽

...

Keyword(s):

Organic Carbon ◽

Black Carbon ◽

Dry Deposition ◽

Wet Deposition ◽

Total Carbon ◽

Sampling Location ◽

Atmospheric Measurements ◽

Deposition Rates ◽

Wet And Dry Deposition ◽

Custom Made

Black carbon (BC) and organic carbon (OC, including brown carbon BrC) aerosols in the atmosphere, and their wet and dry deposition, are important for their climatic and cryospheric effects. Seemingly small amounts of BC in snow, of the order of 10&#8211;100 parts per billion by mass (ppb), have been shown to decrease its albedo by 1&#8211;5 %. Due to the albedo-feedback mechanism, surface darkening accelerates snow and ice melt. In snow, the temporal variability of light absorbing aerosols, such as BC, depends both on atmospheric and cryospheric processes, mostly on sources and atmospheric transport, and dry and wet deposition processes, as well as post-depositional snow processes.We started a new research activity on BC and OC wet and dry deposition at Helsinki Kumpula SMEAR III station (60&#176;12 N, 24&#176;57 E, Station for Measuring Ecosystem-Atmosphere Relations, https://www.atm.helsinki.fi/SMEAR/index.php/smear-iii). The work included winter, spring, summer and autumn deposition samples during January 2019 - June 2020 (sampling is currently on hold). In winter, wet deposition consisted of snowfall and rainwater samples. Dry deposition samples were separately collected in 2020. For sample collection, a custom-made device, including a heating-system, was applied. The samples were analyzed using the OCEC analyzer of the Finnish Meteorological Institute&#8217;s aerosol laboratory, Helsinki, Finland. The special features in our deposition data are:&#160;<ul><li>seasonal BC, OC, and TC (total carbon, the sum of BC and OC) deposition data for an urban background station at 60 oN</li> <li>precipitation received as either water or snow &#160;</li> <li>dry deposition samples included (only in 2020)</li> <li>data as wet and dry deposition rates [concentration/time/area]</li> <li>simultaneous atmospheric measurements of the SMEAR III station</li> </ul>Since our deposition samples are collected manually, the data are non-continuous, yet they allow us to provide deposition rates. Such data can be utilized in various modeling approaches including, for example, climate and long-range transport and deposition modeling. According to our knowledge, these data are the first BC (determined as elemental carbon, EC), OC and TC wet and dry deposition data to represent Finland. Our sampling location, north of 60 deg. N, can be useful for other high-latitude studies and Arctic assessments, too.Acknowledgements. We gratefully acknowledge support from the Academy of Finland NABCEA-project of Novel Assessment of Black Carbon in the Eurasian Arctic (no. 296302) and the Academy of Finland Flagship funding (grant no. 337552).

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Mercury deposition in Southern New Hampshire, 2006–2009

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-7657-2011 ◽

2011 ◽

Vol 11 (15) ◽

pp. 7657-7668 ◽

Cited By ~ 49

Author(s):

M. A. S. Lombard ◽

J. G. Bryce ◽

H. Mao ◽

R. Talbot

Keyword(s):

New Hampshire ◽

Dry Deposition ◽

Wet Deposition ◽

Winter Precipitation ◽

Rural Site ◽

Mercury Deposition ◽

Mixing Ratios ◽

Order Of Magnitude ◽

Aqueous Mercury ◽

Event Based

Abstract. The atmospheric deposition of mercury (Hg) occurs via several mechanisms including wet, dry, and occult processes. In an effort to understand the atmospheric cycling and seasonal depositional characteristics of Hg, event-based wet deposition samples and reactive gaseous Hg (RGM) measurements were collected for approximately 3 years at Thompson Farm (TF), a near-coastal rural site in Durham, NH, part of the University of New Hampshire AIRMAP Observing Network. Total aqueous mercury exhibited seasonal patterns in Hg wet deposition at TF. The lowest Hg wet deposition was measured in the winter with an average total seasonal deposition of 1.56 μg m−2 compared to the summer average of 4.71 μg m−2. Inter-annual differences in total wet deposition are generally linked with precipitation volume, with the greatest deposition occurring in the wettest year. Relationships between surface level RGM and Hg wet deposition were also investigated based on continuous RGM measurements at TF from November 2006 to September 2009. No correlations were observed between RGM mixing ratios and Hg wet deposition, however the ineffective scavenging of RGM during winter precipitation events was evidenced by the less frequent depletion of RGM below the detection level. Seasonal dry deposition of reactive gaseous Hg (RGM) was estimated using an order-of-magnitude approach. RGM mixing ratios and dry deposition estimates were greatest during the winter and spring. The seasonal ratios of Hg wet deposition to RGM dry deposition vary by up to a factor of 80.

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Atmospheric total gaseous mercury (TGM) concentrations and wet and dry deposition of mercury at a high-altitude mountain peak in south China

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-23465-2009 ◽

2009 ◽

Vol 9 (6) ◽

pp. 23465-23504 ◽

Cited By ~ 11

Author(s):

X. W. Fu ◽

X. Feng ◽

Z. Q. Dong ◽

R. S. Yin ◽

J. X. Wang ◽

...

Keyword(s):

South China ◽

Dry Deposition ◽

Urban Areas ◽

Wet Deposition ◽

Ambient Air ◽

Total Gaseous Mercury ◽

Deposition Fluxes ◽

Wet And Dry Deposition ◽

Gaseous Mercury ◽

Seasonal And Diurnal Variations

Abstract. China is regarded as the largest contributor of mercury (Hg) to the global atmospheric Hg budget. However, concentration levels and depositions of atmospheric Hg in China are poorly known. Continuous measurements of atmospheric total gaseous mercury (TGM) were carried out from May 2008 to May 2009 at the summit of Mt. Leigong in south China. Wet and dry deposition fluxes of Hg were also calculated following collection of precipitation, throughfall and litterfall. Atmospheric TGM concentrations averaged 2.80±1.51 ng m−3, which was highly elevated compared to global background values but much lower than semi-rural and industrial/urban areas in China, indicating great emissions of Hg in central, south and southwest China. Seasonal and diurnal variations of TGM were observed, which reflected variations in source intensity, deposition processes and meteorological factors. Wet deposition of Hg was quite low, while its dry deposition of Hg (litterfall + throughfall-direct wet deposition) constituted a major portion of total deposition (~88% for total mercury (THg) and 84% for methyl mercury (MeHg)). This highlights the importance of vegetation to Hg atmospheric cycling. In a remote forest ecosystem of China, dry deposition of TGM, especially gaseous elemental mercury (GEM), was very important for the depletion of atmospheric Hg. Elevated TGM level in ambient air may accelerate the foliar uptake of Hg through air which may partly explain the elevated Hg dry deposition fluxes observed in Mt. Leigong.

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Wet Deposition of Total Dissolved Nitrogen in Indo-Gangetic Plain (India)

10.21203/rs.3.rs-365097/v1 ◽

2021 ◽

Author(s):

Manisha Mishra ◽

Umesh Chandra Kulshrestha

Keyword(s):

Wet Deposition ◽

Animal Husbandry ◽

Rural Site ◽

Urban Site ◽

Organic N ◽

Major Influence ◽

Limited Information ◽

Monsoon Period ◽

Gangetic Plain ◽

Indo Gangetic Plain

Abstract Very limited information on the magnitude and environmental impacts of both inorganic as well as organic forms of Nitrogen (N) wet deposition is available in India. Molar concentrations of inorganic (NH4+ and NO3−) and organic N in rainwater were monitored at three different land-use sites in Indo-Gangetic Plain (IGP) during the monsoon period (June-September) of 2017. It has been observed that dissolved organic N (DON) contributed significantly to the total dissolved N (TDN) ranging from 5–60%. Dissolved inorganic N (DIN = NH4+ + NO3−) concentration was recorded as high as 221.0 µmol L− 1 at urban site to as low as 65.9 µmol L− 1 at the rural site. A similar pattern was also observed for DON. NH4+ contribution to TDN had the order: urban megacity (65%) > urban (70%) > rural (75%). Agriculture and animal husbandry are the primary sources of NH4+ emissions in the rural site. However, NO3− has shown a contrasting trend at these sites (25%, 15% and 8%, respectively). Wet deposition fluxes of atmospheric TDN was observed to be higher at urban sites. This can attributed to a variety of local sources such as vehicular emission, microbial emissions, biomass burning, human excreta due to higher population density, and transportation from surrounding areas, as observed from concentration weighted trajectories (CWT) model and cluster analysis. Upwind region of IGP has experienced major influence of air mass transported from agriculturally rich northwest part of India. However, both the downwind sites have experienced by-and-large the influence of south-westerly air-masses originated over the Arabian Sea. Study has found that the DON contributes significantly to TDN and need to be included for budget assessment in South Asia.

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Regional effect on urban atmospheric nucleation

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-8715-2016 ◽

2016 ◽

Vol 16 (14) ◽

pp. 8715-8728 ◽

Cited By ~ 26

Author(s):

Imre Salma ◽

Zoltán Németh ◽

Veli-Matti Kerminen ◽

Pasi Aalto ◽

Tuomo Nieminen ◽

...

Keyword(s):

Particle Production ◽

Large City ◽

Urban Environments ◽

Rural Site ◽

Urban Site ◽

Atmospheric Conditions ◽

Regional Effect ◽

Atmospheric Nucleation ◽

Timing Properties

Abstract. Secondary aerosol particle production via new particle formation (NPF) has been shown to be a major contributor to the global aerosol load. NPF has also been observed frequently in urban environments. Here, we investigate the effect of regional NPF on urban aerosol load under well-defined atmospheric conditions. The Carpathian Basin, the largest orogenic basin in Europe, represents an excellent opportunity for exploring these interactions. Based on long-term observations, we revealed that NPF seen in a central large city of the basin (Budapest) and its regional background occur in a consistent and spatially coherent way as a result of a joint atmospheric phenomenon taking place on large horizontal scales. We found that NPF events at the urban site are usually delayed by > 1 h relative to the rural site or even inhibited above a critical condensational sink level. The urban processes require higher formation rates and growth rates to be realized, by mean factors of 2 and 1.6, respectively, than the regional events. Regional- and urban-type NPF events sometimes occur jointly with multiple onsets, while they often exhibit dynamic and timing properties which are different for these two event types.

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Mercury distribution in surface soil of China is potentially driven by precipitation, vegetation cover and organic matter

10.21203/rs.3.rs-21590/v1 ◽

2020 ◽

Author(s):

Zhao-Yang Zhang ◽

Gang Li ◽

Lei Yang ◽

Guo-Xin Sun

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Solar Radiation ◽

Dry Deposition ◽

Vegetation Cover ◽

Wet Deposition ◽

Surface Soil ◽

Wet And Dry Deposition ◽

Continental Scale ◽

Low Emission

Abstract Background Mercury (Hg) distribution in surface soil in China is quite uneven with relatively high concentrations in southeastern China and low concentrations in northwestern China. The reason for this is inconclusive so far, especially on the continental scale. In the present study we used the multiple linear regression model to evaluate the relative importance of these different factors and elucidate the contribution on soil Hg of major factors, such as dry and wet precipitations, vegetation cover, soil organic matter and solar radiation. Results Wet and dry deposition associated with precipitation and vegetation cover, and emissions influenced by soil organic matter (SOM), are key factors controlling Hg distribution in surface soil. In southeast China, high wet deposition associated with south Asia monsoon and dry deposition, enhanced by vegetation canopies, together with low emission caused by high vegetated surface and solar radiation, are responsible for high Hg in soil (> 0.08 mg/kg). In northeast China, medium wet Hg deposition and high dry deposition via throughfall and litterfall, low emission due to weak solar radiation and high SOM are responsible for high Hg accumulation in soil. In northwest China, low wet deposition, together with high emission by low vegetation cover (bare soil), SOM and strong solar radiation contributed to low Hg in surface soil (< 0.03 mg/kg). Conclusions We suggest that wet deposition derived from Asian monsoon, dry deposition linked to vegetated surfaces and Hg emission associated with vegetation cover, SOM and solar radiation play key roles in Hg balance in other terrestrial environments worldwide, especially in those regions with significantly high wet and dry deposition and high vegetation cover.

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Regional effect on urban atmospheric nucleation

10.5194/acp-2016-115 ◽

2016 ◽

Cited By ~ 1

Author(s):

Imre Salma ◽

Zoltán Németh ◽

Veli-Matti Kerminen ◽

Pasi Aalto ◽

Tuomo Nieminen ◽

...

Keyword(s):

Particle Production ◽

Large City ◽

Urban Environments ◽

Rural Site ◽

Urban Site ◽

Atmospheric Conditions ◽

Regional Effect ◽

Atmospheric Nucleation ◽

Timing Properties

Abstract. Secondary aerosol particle production via new particle formation (NPF) has been shown to be a major source for global aerosol load. It has been also observed frequently in urban environments affecting the human health. Here, we investigate the effect of regional NPF on urban aerosol load under well-defined atmospheric conditions. The Carpathian Basin, the largest orogenic basin in Europe, represents an excellent opportunity for exploring these interactions. Based on long-term observations, we revealed that NPF seen in a central large city of the basin (Budapest) and its regional background occur in a consistent and spatially coherent way as result of a joint atmospheric phenomenon taking place over large horizontal scales. We found that NPF events at the urban site are usually delayed by > 1 hour relative to the rural site or even inhibited above a critical condensational sink level. The urban processes require higher formation rates and growth rates to be realised, by mean factors of 2 and 1.6, respectively, than the regional events. Regional- and urban-type NPF events sometimes occur jointly with multiple onsets, while they often exhibit dynamic and timing properties which are different for these NPF types.

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Influence of summer and winter climate variability on nitrogen wet deposition in Norway

Hydrology and Earth System Sciences ◽

10.5194/hess-12-405-2008 ◽

2008 ◽

Vol 12 (2) ◽

pp. 405-414 ◽

Cited By ~ 5

Author(s):

L. R. Hole ◽

H. A. de Wit ◽

W. Aas

Keyword(s):

Wet Deposition ◽

Winter Precipitation ◽

Climate Indices ◽

Winter Climate ◽

Nitrate Concentrations ◽

Northern Regions ◽

Atmospheric Nitrate ◽

Nitrate Deposition ◽

Highly Correlated ◽

Southern Norway

Abstract. Dominating wind patterns around Norway may change due to climate warming. This could affect transport of polluted air masses and precipitation. Here, we study relations between reactive nitrogen wet deposition and air mass transport during summer and winter expressed in the form of climate indices, at seven sites in Southern Norway for the period 1980–2005. Atmospheric nitrate concentrations decreased with 0 to 50% in the period, particularly at sites with little precipitation, and mostly during 1990–2005. For comparison, reported reductions in emissions of oxidised nitrogen in Europe in 1989–2003 were 23%. Climate indices explained up to 36% of the variation in winter nitrate deposition at the western and northern sites – and also explained 60% of the variation in winter precipitation (R=0.77). This suggests that the variation in nitrate wet deposition is closely related to variation in precipitation, and that the climate indices seem to also partly control the variation in atmospheric nitrate concentrations (R=−0.45 at coastal sites). At the coastal sites, local air temperature was highly correlated (R=0.84) with winter nitrate deposition, suggesting that warm, humid winter weather results in increased wet nitrate deposition. For ammonia the pattern was similar, but this compound is more influenced by local sources. Expected severe increase in precipitation in western and northern regions as a consequence of climate change suggest that nitrogen deposition in these areas will increase under global warming if emissions are held constant.

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