Ammonium deficiency caused by heterogeneous reactions during a super Asian dust episode

Hsu, Shih-Chieh; Lee, Celine Siu Lan; Huh, Chih-An; Shaheen, R.; Lin, Fei-Jan; Liu, Shaw Chen; Liang, Mao‐Chang; Tao, Jun

doi:10.1002/2013jd021096

Cited by 23 publications

(24 citation statements)

References 84 publications

(161 reference statements)

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“…In the NWPac region, there was also good agreement between the 73 ship-based observations from 2005 to 2008 in the 25-30 • N, 120-125 • E cell and the 173 daily observations made during 2010 at Pengchiayu Island (25 • 37 44 N, 122 • 4 4 E) in the East China Sea (Hsu et al, 2014). The Pengchiayu dataset indicated that there was some seasonality in aerosol NO − 3 concentrations at this site ( Fig.…”

Section: Comparison To Concentrations At Island Monitoring Stationssupporting

confidence: 61%

“…Much of the observational work on dust has generated data on aerosol N concentrations, augmenting the data available in these regions, but the presence of dust adds extra complexity to the comparison performed here. Uptake of nitric acid onto suspended mineral dust particles alters the size distribution and deposition velocity of aerosol nitrate, and changes the gas-phase composition of N (Hanisch and Crowley, 2001;Rubasinghege and Grassian, 2009 (Lamarque et al, 2013b). In general, modelled dust deposition fluxes to remote ocean regions have been shown to vary by factors of 10 or more (Huneeus et al, 2011;Schulz et al, 2012) and to not reproduce key aspects of the dust cycle even in well-characterised regions (Prospero et al, 2010).…”

Section: Role Of Mineral Dust In Modifying N Deposition Fluxesmentioning

confidence: 99%

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Response to Reviewer 2

Baker¹

2017

Preprint

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Anthropogenic nitrogen (N) emissions to the atmosphere have increased significantly the deposition of nitrate (NO − 3 ) and ammonium (NH + 4 ) to the surface waters of the open ocean, with potential impacts on marine productivity and the global carbon cycle. Global-scale understanding of the impacts of N deposition to the oceans is reliant on our ability to produce and validate models of nitrogen emission, atmospheric chemistry, transport and deposition. In this work, ∼ 2900 observations of aerosol NO − 3 and NH + 4 concentrations, acquired from sampling aboard ships in the period 1995-2012, are used to assess the performance of modelled N concentration and deposition fields over the re-mote ocean. Three ocean regions (the eastern tropical North Atlantic, the northern Indian Ocean and northwest Pacific) were selected, in which the density and distribution of observational data were considered sufficient to provide effective comparison to model products. All of these study regions are affected by transport and deposition of mineral dust, which alters the deposition of N, due to uptake of nitrogen oxides (NO x ) on mineral surfaces. Assessment of the impacts of atmospheric N deposition on the ocean requires atmospheric chemical transport models to report deposition fluxes; however, these fluxes cannot be measured over the ocean. Modelling studies such as the Published by Copernicus Publications on behalf of the European Geosciences Union. 8190 A. R. Baker et al.: Particulate dry nitrogen deposition Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), which only report deposition flux, are therefore very difficult to validate for dry deposition. Here, the available observational data were averaged over a 5 • × 5 • grid and compared to ACCMIP dry deposition fluxes (Mod-Dep) of oxidised N (NO y ) and reduced N (NH x ) and to the following parameters from the Tracer Model 4 of the Environmental Chemical Processes Laboratory (TM4): Mod-Dep for NO y , NH x and particulate NO − 3 and NH + 4 , and surface-level particulate NO − 3 and NH + 4concentrations. As a model ensemble, ACCMIP can be expected to be more robust than TM4, while TM4 gives access to speciated parameters (NO − 3 and NH + 4 ) that are more relevant to the observed parameters and which are not available in ACCMIP. Dry deposition fluxes (CalDep) were calculated from the observed concentrations using estimates of dry deposition velocities. Model-observation ratios (R A,n ), weighted by gridcell area and number of observations, were used to assess the performance of the models. Comparison in the three study regions suggests that TM4 overestimates NO − 3 concentrations (R A,n = 1.4-2.9) and underestimates NH + 4 concentrations (R A,n = 0.5-0.7), with spatial distributions in the tropical Atlantic and northern Indian Ocean not being reproduced by the model. In the case of NH + 4 in the Indian Ocean, this discrepancy was probably due to seasonal biases in the sampling. Similar patterns were observed in the various comparisons of CalDep to Mod...

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Section: Comparison To Concentrations At Island Monitoring Stationssupporting

confidence: 61%

Section: Role Of Mineral Dust In Modifying N Deposition Fluxesmentioning

confidence: 99%

Response to Reviewer 2

Baker¹

2017

Preprint

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“…The second half of each PTFE filter was subjected to extraction with 20 mL of Milli-Q water (18.2 Ω) for 1 h, and ionic species concentration were determined through ion chromatography (Dionex ICS-90 for cations and ICS-1500 for anions), which was equipped with a conductivity detector (ASRSeULTRA). The water-soluble ionic species were K + , Na + , Mg 2+ , Ca 2+ , NH 4 + , SO 4 2-, NO 3 -, and Cl -, were analyzed with a precision better than 5% (Hsu et al, 2014). More information can be found in Lin et al (2016).…”

Section: Chemical Components Analysismentioning

confidence: 99%

Variations of Chemical Composition and Source Apportionment of PM2.5 during Winter Haze Episodes in Beijing

Tao

et al. 2017

Aerosol Air Qual. Res.

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PM 2.5 samples were collected in Beijing between February 24 and March 12 of 2014, and analyzed to examine chemical compositions and origins of the PM 2.5 at pollution levels of clean (PM 2.5 < 75 µg m -3 ), light-medium (75-150 µg m -3 ), heavy (150-250 µg m -3 ) and severe (> 250 µg m -3 ). The mean PM 2.5 concentration was 137.7 ± 124.8 µg m -3 during the observation period, accounting for 66% of PM 10. As all aerosol species concentrations increased with the pollution level, the contributions of secondary inorganic aerosols (SIA) to PM 2.5 continuously increased while the contributions of OC and EC decreased, indicating a substantial contribution from secondary formation to the elevation of PM 2.5 pollution. The acidity of PM 2.5 , the ratio of anion microequivalent concentration to cation, increased from 0.96 to 1.08 as pollution levels increased. Using a PMF model, secondary inorganic aerosols, industrial emissions, soil dust, traffic emissions, and coal combustion and biomass burning were identified as contributors to the PM 2.5 , and on average accounted 46%, 20%, 10%, 6% and 18% of the PM 2.5 , respectively, in the observation period. Industrial emissions were the dominant PM 2.5 source during the clean period (60%). Except for traffic emission, sources of PM 2.5 at the light-medium level were consistent, accounting for 17%-29%. Secondary inorganic aerosols were the largest origin of PM 2.5 at heavy and severe pollution levels, accounting for 40% and 78%, respectively. In addition, the 48 h transport distances of air masses decreased from 2000 km (clean) to 300 km (severe level) and the proportion of air masses from south pollution areas in the total air masses at each pollution level increased from 0% to 97%, indicating that the stability of near surface air and the northerly transport of pollutants from the south at local and regional scales played a the key role in the PM 2.5 elevation.

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“…Mineral aerosols contain soluble materials (slightly soluble calcium salts, such as CaCO 3 ). Additionally, heterogeneous reactions between acid gases and minerals lead to significant increases in water‐soluble calcium, magnesium, and aluminum [ Cao et al ., ; Duvall et al ., ; Hsu et al ., ]. The inclusion of water‐soluble minerals could increase the cloud water alkalinity, affecting SO 2 dissolution and the rate of aqueous‐phase oxidation of S(IV), especially for O 3 and NO 2 [ Seinfeld and Pandis , ].…”

Section: Model Descriptionmentioning

confidence: 99%

Pathways of sulfate enhancement by natural and anthropogenic mineral aerosols in China

et al. 2014

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China, the world's largest consumer of coal, emits approximately 30 million tons of sulfur dioxide (SO 2 ) per year. SO 2 is subsequently oxidized to sulfate in the atmosphere. However, large gaps exist between model-predicted and measured sulfate levels in China. Long-term field observations and numerical simulations were integrated to investigate the effect of mineral aerosols on sulfate formation. We found that mineral aerosols contributed a nationwide average of approximately 22% to sulfate production in 2006. The increased sulfate concentration was approximately 2 μg m À3 in the entire China. In East China and the Sichuan Basin, the increments reached 6.3 μg m À3 and 7.3 μg m À3, respectively. Mineral aerosols led to faster SO 2 oxidation through three pathways. First, more SO 2 was dissolved as cloud water alkalinity increased due to water-soluble mineral cations. Sulfate production was then enhanced through the aqueous-phase oxidation of S(IV) (dissolved sulfur in oxidation state +4). The contribution to the national sulfate production was 5%. Second, sulfate was enhanced through S(IV) catalyzed oxidation by transition metals. The contribution to the annual sulfate production was 8%, with 19% during the winter that decreased to 2% during the summer. Third, SO 2 reacts on the surface of mineral aerosols to produce sulfate. The contribution to the national average sulfate concentration was 9% with 16% during the winter and a negligible effect during the summer. The inclusion of mineral aerosols does resolve model discrepancies with sulfate observations in China, especially during the winter. These three pathways, which are not fully considered in most current chemistry-climate models, will significantly impact assessments regarding the effects of aerosol on climate change in China.

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Ammonium deficiency caused by heterogeneous reactions during a super Asian dust episode

Cited by 23 publications

References 84 publications

Response to Reviewer 2

Response to Reviewer 2

Variations of Chemical Composition and Source Apportionment of PM2.5 during Winter Haze Episodes in Beijing

Pathways of sulfate enhancement by natural and anthropogenic mineral aerosols in China

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