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

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

<p>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 10–100 parts per billion by mass (ppb), have been shown to decrease its albedo by 1–5 %. 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.</p><p>We started a new research activity on BC and OC wet and dry deposition at Helsinki Kumpula SMEAR III station (60°12 N, 24°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’s aerosol laboratory, Helsinki, Finland. The special features in our deposition data are: </p><ul><li>seasonal BC, OC, and TC (total carbon, the sum of BC and OC) deposition data for an urban background station at 60 <sup>o</sup>N</li> <li>precipitation received as either water or snow  </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><p>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.</p><p><em>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).</em></p>

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

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.

scholarly journals Plant assemblages in atmospheric deposition

2019 ◽  
Author(s):  
Ke Dong ◽  
Cheolwoon Woo ◽  
Naomichi Yamamoto
Keyword(s):  
Atmospheric Deposition ◽  
Dry Deposition ◽  
Wet Deposition ◽  
High Throughput Sequencing ◽  
Sampling Site ◽  
Its2 Region ◽  
Dry And Wet Deposition ◽  
Custom Made ◽  
Plant Assemblages ◽  
Cloud Scavenging

Abstract. Plants disperse spores, pollen, and fragments into the atmosphere. The emitted plant particles return to the pedosphere by sedimentation (dry deposition) and/or by precipitation (wet deposition) and constitute part of the global cycle of substances. However, little is known regarding the taxonomic diversities and flux densities of plant particles deposited from the atmosphere. Here, plant assemblages were examined in atmospheric deposits collected in Seoul in South Korea. A custom-made automatic sampler was used to collect dry and wet deposition samples for which plant assemblages and quantities were determined using high-throughput sequencing and quantitative PCR with universal plant-specific primers targeting the internal transcribed spacer 2 (ITS2) region. Dry deposition was dominant for atmospheric deposition of plant particles (87 %). The remaining 13 % was deposited by precipitation, i.e., wet deposition, via rainout (in-cloud scavenging) and/or washout (below-cloud scavenging). Plant assemblage structures did not differ significantly between dry and wet deposition, indicating that washout, which is likely taxon-independent, predominated rainout, which is likely taxon-dependent, for wet deposition of atmospheric plant particles. A small number of plant genera were detected only in wet deposition, indicating that they might be specifically involved in precipitation through acting as nucleation sites in the atmosphere. Future interannual monitoring will control for the seasonality of atmospheric plant assemblages observed at our sampling site. Future global monitoring is also proposed to investigate geographical differences and investigate whether endemic species are involved in plant-mediated bioprecipitation in regional ecological systems.

scholarly journals Impact of dust deposition on carbon budget: a tentative assessment from a mesocosm approach

2014 ◽  
Vol 11 (19) ◽  
pp. 5621-5635 ◽  
Author(s):  
C. Guieu ◽  
C. Ridame ◽  
E. Pulido-Villena ◽  
M. Bressac ◽  
K. Desboeufs ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Atmospheric Deposition ◽  
Mediterranean Sea ◽  
Particulate Organic Carbon ◽  
Dry Deposition ◽  
Wet Deposition ◽  
Carbon Budget ◽  
Net Primary Production ◽  
Saharan Dust ◽  
Dust Deposition

Abstract. By bringing new nutrients and particles to the surface ocean, atmospheric deposition impacts biogeochemical cycles. The extent to which those changes are modifying the carbon balance in oligotrophic environments such as the Mediterranean Sea that receives important Saharan dust fluxes is unknown. The DUNE (DUst experiment in a low Nutrient, low chlorophyll Ecosystem) project provides the first attempt to evaluate the changes induced in the carbon budget of a large body of oligotrophic waters after simulated Saharan dust wet or dry deposition events, allowing us to measure (1) the metabolic fluxes while the particles are sinking and (2) the particulate organic carbon export. Here we report the results for the three distinct artificial dust seeding experiments simulating wet or dry atmospheric deposition onto large mesocosms (52 m3) that were conducted in the oligotrophic waters of the Mediterranean Sea in the summers of 2008 and 2010. Although heterotrophic bacteria were found to be the key players in the response to dust deposition, net primary production increased about twice in case of simulated wet deposition (that includes anthropogenic nitrogen). The dust deposition did not produce a shift in the metabolic balance as the tested waters remained net heterotrophic (i.e., net primary production to bacteria respiration ratio <1) and in some cases the net heterotrophy was even enhanced by the dust deposition. The change induced by the dust addition on the total organic carbon pool inside the mesocosm over the 7 days of the experiments, was a carbon loss dominated by bacteria respiration that was at least 5–10 times higher than any other term involved in the budget. This loss of organic carbon from the system in all the experiments was particularly marked after the simulation of wet deposition. Changes in biomass were mostly due to an increase in phytoplankton biomass but when considering the whole particulate organic carbon pool it was dominated by the organic carbon aggregated to the lithogenic particles still in suspension in the mesocosm at the end of the experiment. Assuming that the budget is balanced, the dissolved organic carbon (DOC) pool was estimated by the difference between the total organic carbon and the particulate organic carbon (POC) pool. The partitioning between dissolved and particulate organic carbon was dominated by the dissolved pool with a DOC consumption over 7 days of ∼1 μmol C L−1 d−1 (dry deposition) to ∼2–5 μmol C L−1 d−1 (wet deposition). This consumption in the absence of any allochthonous inputs in the closed mesocosms meant a small <10% decrease of the initial DOC stock after a dry deposition but a ∼30–40% decrease of the initial DOC stock after wet deposition. After wet deposition, the tested waters, although dominated by heterotrophy, were still maintaining a net export (corrected from controls) of particulate organic carbon (0.5 g in 7 days) even in the absence of allochthonous carbon inputs. This tentative assessment of the changes in carbon budget induced by a strong dust deposition indicates that wet deposition by bringing new nutrients has higher impact than dry deposition in oligotrophic environments. In the western Mediterranean Sea, the mineral dust deposition is dominated by wet deposition and one perspective of this work is to extrapolate our numbers to time series of deposition during similar oligotrophic conditions to evaluate the overall impact on the carbon budget at the event and seasonal scale in the surface waters of the northwestern Mediterranean Sea. These estimated carbon budgets are also highlighting the key processes (i.e., bacterial respiration) that need to be considered for an integration of atmospheric deposition in marine biogeochemical modeling.

Atmospheric deposition and canopy interactions of nitrogen in forests

1993 ◽  
Vol 23 (8) ◽  
pp. 1603-1616 ◽  
Author(s):  
Gary M. Lovett ◽  
Steven E. Lindberg
Keyword(s):  
Linear Function ◽  
Dry Deposition ◽  
Wet Deposition ◽  
Particle Deposition ◽  
Cloud Water ◽  
Organic N ◽  
Total System ◽  
Inorganic N ◽  
Deposition Rates ◽  
Total Deposition

Wet deposition of nitrogen compounds was measured and dry and cloud water deposition were estimated at 11 forested sites in North America and one site in Europe. Dry deposition was a significant pathway of N input to all the forests, averaging 46% of the total deposition. At most of these sites, NH4+ was the dominant form of fixed N in the air, but HNO3 vapor dominated the dry deposition of N. Coarse-particle deposition was often important, but fine-particle deposition usually contributed only a small amount of the dry-deposited N. The deposition rates of inorganic N, which ranged between 4.8 and 27 kg N•ha−1•year−1, were generally much higher than has been reported by other studies measuring only wet or bulk deposition. The highest deposition rates were at the high-elevation sites in the southeastern and northeastern United States and much of the deposition at these sites was attributed to cloud water. Throughfall and stemflow (TF + SF) flux was also measured at all sites, and the net canopy exchange (NCE = (TF + SF)–total deposition) was found to be negative (indicating consumption of N in the canopy) for NH4+ and NO3−, and positive (indicating canopy release) for organic N. Past reports of canopy release of NO3− can probably be attributed to washoff of dry-deposited NO3− species. Consumption of inorganic N in the canopy ranged from 1 to 12 kg N•ha−1•year−1, and was highest in the spruce and spruce–fir stands. When organic N was included in the canopy N balance, the net canopy uptake of N was generally < 15% of the total system N requirement. Total N deposition was a linear function of wet deposition for low-elevation sites, and dry deposition was a linear function of the net throughfall flux for NO3−.

scholarly journals Aerosol scattering and absorption during the EUCAARI-LONGREX flights of the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146: can measurements and models agree?

2012 ◽  
Vol 12 (15) ◽  
pp. 7251-7267 ◽  
Author(s):  
E. J. Highwood ◽  
M. J. Northway ◽  
G. R. McMeeking ◽  
W. T. Morgan ◽  
D. Liu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Organic Carbon ◽  
Black Carbon ◽  
Growth Curves ◽  
Temporal Variations ◽  
Mie Scattering ◽  
Chemical Components ◽  
Refractive Indices ◽  
Hygroscopic Growth ◽  
Atmospheric Measurements

Abstract. Scattering and absorption by aerosol in anthropogenically perturbed air masses over Europe has been measured using instrumentation flown on the UK's BAe-146-301 large Atmospheric Research Aircraft (ARA) operated by the Facility for Airborne Atmospheric Measurements (FAAM) on 14 flights during the EUCAARI-LONGREX campaign in May 2008. The geographical and temporal variations of the derived shortwave optical properties of aerosol are presented. Values of single scattering albedo of dry aerosol at 550 nm varied considerably from 0.86 to near unity, with a campaign average of 0.93 ± 0.03. Dry aerosol optical depths ranged from 0.030 ± 0.009 to 0.24 ± 0.07. An optical properties closure study comparing calculations from composition data and Mie scattering code with the measured properties is presented. Agreement to within measurement uncertainties of 30% can be achieved for both scattering and absorption, but the latter is shown to be sensitive to the refractive indices chosen for organic aerosols, and to a lesser extent black carbon, as well as being highly dependent on the accuracy of the absorption measurements. Agreement with the measured absorption can be achieved either if organic carbon is assumed to be weakly absorbing, or if the organic aerosol is purely scattering and the absorption measurement is an overestimate due to the presence of large amounts of organic carbon. Refractive indices could not be inferred conclusively due to this uncertainty, despite the enhancement in methodology compared to previous studies that derived from the use of the black carbon measurements. Hygroscopic growth curves derived from the wet nephelometer indicate moderate water uptake by the aerosol with a campaign mean f(RH) value (ratio in scattering) of 1.5 (range from 1.23 to 1.63) at 80% relative humidity. This value is qualitatively consistent with the major chemical components of the aerosol measured by the aerosol mass spectrometer, which are primarily mixed organics and nitrate and some sulphate.

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

2009 ◽  
Vol 9 (6) ◽  
pp. 23465-23504 ◽  
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.

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

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.

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

2018 ◽  
Vol 18 (9) ◽  
pp. 6381-6392 ◽  
Author(s):  
David M. Nelson ◽  
Urumu Tsunogai ◽  
Dong Ding ◽  
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 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.

scholarly journals Sampling, Filtering, and Analysis Protocols to Detect Black Carbon, Organic Carbon, and Total Carbon in Seasonal Surface Snow in an Urban Background and Arctic Finland (>60° N)

Atmosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 923
Author(s):  
Outi Meinander ◽  
Enna Heikkinen ◽  
Minna Aurela ◽  
Antti Hyvärinen
Keyword(s):  
Organic Carbon ◽  
Black Carbon ◽  
Laboratory Experiments ◽  
Elemental Carbon ◽  
Total Carbon ◽  
The Arctic ◽  
Urban Background ◽  
Wrong Side ◽  
Global Carbon ◽  
Snow Samples

Black carbon (BC), organic carbon (OC), and total carbon (TC) in snow are important for their climatic and cryospheric effects. They are also part of the global carbon cycle. Atmospheric black and organic carbon (including brown carbon) may deposit and darken snow surfaces. Currently, there are no standardized methods for sampling, filtering, and analysis protocols to detect carbon in snow. Here, we describe our current methods and protocols to detect carbon in seasonal snow using the OCEC thermal optical method, a European standard for atmospheric elemental carbon (EC). We analyzed snow collected within and around the urban background SMEARIII (Station for Measuring Ecosystem-Atmosphere Relations) at Kumpula (60° N) and the Arctic GAW (Global Atmospheric Watch) station at Sodankylä (67° N). The median BC, OC, and TC in snow samples (ntot = 30) in Kumpula were 1118, 5279, and 6396 ppb, and in Sodankylä, they were 19, 1751, and 629 ppb. Laboratory experiments showed that error due to carbon attached to a sampling bag (n = 11) was <0.01%. Sonication slightly increased the measured EC, while wetting the filter or filtering the wrong side up indicated a possible sample loss. Finally, we discuss the benefits and drawbacks of OCEC to detect carbon in snow.

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