Aerosols in atmospheric chemistry and biogeochemical cycles of nutrients

Kanakidou, Maria; Myriokefalitakis, Stelios; Tsigaridis, Kostas

doi:10.1088/1748-9326/aabcdb

Cited by 95 publications

(82 citation statements)

References 238 publications

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“…For example, the global trend appears to be strongly driven by sharp increases in the proportion of chemically reduced nitrogen deposited over the United States (Figure 4), in accord with reports by Du et al (2014) and Li et al (2016). The continuation of this trend toward an increased proportion of chemically reduced nitrogen in IN deposition is likely to impact the competitive balance among plants with differing affinities for various nitrogen forms (Choudhary et al, 2016;Kahmen et al, 2006;Kanakidou et al, 2018;Liu et al, 2018). The continuation of this trend toward an increased proportion of chemically reduced nitrogen in IN deposition is likely to impact the competitive balance among plants with differing affinities for various nitrogen forms (Choudhary et al, 2016;Kahmen et al, 2006;Kanakidou et al, 2018;Liu et al, 2018).…”

Section: Discussionsupporting

confidence: 59%

“…The United States has implemented controls on the emission of oxidized nitrogen, primarily caused by combustion processes, but not on the emission of reduced nitrogen, primarily caused by volatilization from livestock waste and fertilizer (Li et al, 2016;Reis et al, 2009). The continuation of this trend toward an increased proportion of chemically reduced nitrogen in IN deposition is likely to impact the competitive balance among plants with differing affinities for various nitrogen forms (Choudhary et al, 2016;Kahmen et al, 2006;Kanakidou et al, 2018;Liu et al, 2018).…”

Section: 1029/2018gb005990mentioning

confidence: 99%

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Global Estimates of Inorganic Nitrogen Deposition Across Four Decades

Ackerman

Millet

Chen

2019

Global Biogeochemical Cycles

276

201

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Atmospheric deposition of inorganic nitrogen is critical to the function of ecosystems and elemental cycles. During the industrial period, humans have doubled the amount of inorganic nitrogen in the biosphere and radically altered rates of atmospheric nitrogen deposition. Despite this rapid change, estimates of global nitrogen deposition patterns generally have low, centennial‐scale temporal resolution. Lack of information on annual‐ to decadal‐scale changes in global nitrogen deposition makes it difficult for scientists researching questions on these finer timescales to contextualize their work within the global nitrogen cycle. Here we use the GEOS‐Chem Chemical Transport Model to estimate wet and dry deposition of inorganic nitrogen globally at a spatial resolution of 2° × 2.5° for 12 individual years in the period from 1984 to 2016. During this time, we found an 8% increase in global inorganic nitrogen deposition from 86.6 to 93.6 TgN/year, a trend that comprised a balance of variable regional patterns. For example, inorganic nitrogen deposition increased in areas including East Asia and Southern Brazil, while inorganic nitrogen deposition declined in areas including Europe. Further, we found a global increase in the percentage of inorganic nitrogen deposited in chemically reduced forms from 30% to 35%, and this trend was largely driven by strong regional increases in the proportion of chemically reduced nitrogen deposited over the United States. This study provides spatially explicit estimates of inorganic nitrogen deposition over the last four decades and improves our understanding of short‐term human impacts on the global nitrogen cycle.

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Section: Discussionsupporting

confidence: 59%

Section: 1029/2018gb005990mentioning

confidence: 99%

Global Estimates of Inorganic Nitrogen Deposition Across Four Decades

Ackerman

Millet

Chen

2019

Global Biogeochemical Cycles

276

201

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“…TM4-ECPL explicitly accounts for interconversion of Fe (II) and Fe (III) and formation of oxalate (the partitioning of which is also pH-sensitive, e.g., Nah et al, 2018) that acts as a ligand and contributes to secondary organic aerosol. This chemistry has been used to understand changes in oceanic deposition of Fe and P from preindustrial, present-day, and future atmospheres (Myriokefalitakis et al, 2015 as well as with regional focus on the Mediterranean region (Kanakidou et al, 2020). The CMAQ v5.1+ , and GEOS-Chem v11-02+ (Marais et al, 2016) models use particle acidity, although in slightly different forms, to mediate the uptake of isoprene epoxydiols and resulting production of secondary organic aerosol in PM 2.5 .…”

Section: Aerosol Ph Fmentioning

confidence: 99%

The acidity of atmospheric particles and clouds

et al. 2020

Self Cite

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Abstract. Acidity, defined as pH, is a central component of aqueous chemistry. In the atmosphere, the acidity of condensed phases (aerosol particles, cloud water, and fog droplets) governs the phase partitioning of semivolatile gases such as HNO3, NH3, HCl, and organic acids and bases as well as chemical reaction rates. It has implications for the atmospheric lifetime of pollutants, deposition, and human health. Despite its fundamental role in atmospheric processes, only recently has this field seen a growth in the number of studies on particle acidity. Even with this growth, many fine-particle pH estimates must be based on thermodynamic model calculations since no operational techniques exist for direct measurements. Current information indicates acidic fine particles are ubiquitous, but observationally constrained pH estimates are limited in spatial and temporal coverage. Clouds and fogs are also generally acidic, but to a lesser degree than particles, and have a range of pH that is quite sensitive to anthropogenic emissions of sulfur and nitrogen oxides, as well as ambient ammonia. Historical measurements indicate that cloud and fog droplet pH has changed in recent decades in response to controls on anthropogenic emissions, while the limited trend data for aerosol particles indicate acidity may be relatively constant due to the semivolatile nature of the key acids and bases and buffering in particles. This paper reviews and synthesizes the current state of knowledge on the acidity of atmospheric condensed phases, specifically particles and cloud droplets. It includes recommendations for estimating acidity and pH, standard nomenclature, a synthesis of current pH estimates based on observations, and new model calculations on the local and global scale.

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“…67 Iron oxidation state can affect iron solubility, and iron can bind with organic ligands in atmospheric or oceanic particles influencing bioavailability in aquatic ecosystems. [68][69][70][71][72][73][74][75] Moffet et al 62 used STXM/NEXAFS to quantify the Fe 2+ fraction, a, out of the total iron in ambient particles and calculated an average mass weighted value of a = 0.33 AE 0.08 during a pollution transport event from China to Japan, of which B5% of particles contained detectable iron. As a polysaccharide and biopolymer, XG is a unique model compound of marine derived organic matter in atmospheric aerosol.…”

Section: Introductionmentioning

confidence: 99%

Visualizing reaction and diffusion in xanthan gum aerosol particles exposed to ozone

Alpert

Arroyo

Dou

et al. 2019

Phys. Chem. Chem. Phys.

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Atmospheric aerosol particles with a high viscosity may become inhomogeneously mixed during chemical processing. Models have predicted gradients in condensed phase reactant concentration throughout particles as the result of diffusion and chemical reaction limitations, termed chemical gradients. However, these have never been directly observed for atmospherically relevant particle diameters. We investigated the reaction between ozone and aerosol particles composed of xanthan gum and FeCl 2 and observed the in situ chemical reaction that oxidized Fe 2+ to Fe 3+ using X-ray spectromicroscopy. Iron oxidation state of particles as small as 0.2 mm in diameter were imaged over time with a spatial resolution of tens of nanometers. We found that the loss off Fe 2+ accelerated with increasing ozone concentration and relative humidity, RH. Concentric 2-D column integrated profiles of the Fe 2+ fraction, a, out of the total iron were derived and demonstrated that particle surfaces became oxidized while particle cores remained unreacted at RH = 0-20%. At higher RH, chemical gradients evolved over time, extended deeper from the particle surface, and Fe 2+ became more homogeneously distributed. We used the kinetic multi-layer model for aerosol surface and bulk chemistry (KM-SUB) to simulate ozone reaction constrained with our observations and inferred key parameters as a function of RH including Henry's Law constant for ozone, H O 3 , and diffusion coefficients for ozone and iron, D O 3 and D Fe , respectively. We found that H O 3 is higher in our xanthan gum/FeCl 2 particles than for water and increases when RH decreased from about 80% to dry conditions. This coincided with a decrease in both D O 3 and D Fe . In order to reproduce observed chemical gradients, our model predicted that ozone could not be present further than a few nanometers from a particle surface indicating near surface reactions were driving changes in iron oxidation state. However, the observed chemical gradients in a observed over hundreds of nanometers must have been the result of iron transport from the particle interior to the surface where ozone oxidation occurred. In the context of our results, we examine the applicability of the reacto-diffusive framework and discuss diffusion limitations for other reactive gas-aerosol systems of atmospheric importance.

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Aerosols in atmospheric chemistry and biogeochemical cycles of nutrients

Cited by 95 publications

References 238 publications

Global Estimates of Inorganic Nitrogen Deposition Across Four Decades

Global Estimates of Inorganic Nitrogen Deposition Across Four Decades

The acidity of atmospheric particles and clouds

Visualizing reaction and diffusion in xanthan gum aerosol particles exposed to ozone

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