213 research outputs found
COP-AQ - The UK-China Collaboration to Optimise Net Zero Policy options for Air Quality and Health
Clean Air policies in the UK and China have substantially improved air quality in recent years. However, reaching the new WHO guidelines on air pollution exposure to protect health remains a major challenge in both countries. Ambitious climate policies have already delivered significant co-benefits to air quality in the past. Future net zero or carbon neutrality policies may offer opportunities to contribute to improved air quality towards meeting the WHO guidelines. However, some climate policies have potentially negative impacts on air quality
Delivery of anthropogenic bioavailable iron from mineral dust and combustion aerosols to the ocean
Atmospheric deposition of anthropogenic soluble iron (Fe) to the ocean has
been suggested to modulate primary ocean productivity and thus indirectly
affect the climate. A key process contributing to anthropogenic sources of
soluble Fe is associated with air pollution, which acidifies Fe-containing
mineral aerosols during their transport and leads to Fe transformation from
insoluble to soluble forms. However, there is large uncertainty in our
estimate of this anthropogenic soluble Fe. In this study, for the first time,
we interactively combined laboratory kinetic experiments with global aerosol
modeling to more accurately quantify anthropogenic soluble Fe due to air
pollution. Firstly, we determined Fe dissolution kinetics of African dust
samples at acidic pH values with and without ionic species commonly found in
aerosol water (i.e., sulfate and oxalate). Then, by using acidity as a master
variable, we constructed a new empirical scheme for Fe release from mineral
dust due to inorganic and organic anions in aerosol water. We implemented
this new scheme and applied an updated mineralogical emission database in a
global atmospheric chemistry transport model to estimate the atmospheric
concentration and deposition flux of soluble Fe under preindustrial and
modern conditions. Our improved model successfully captured the inverse
relationship of Fe solubility and total Fe loading measured over the North
Atlantic Ocean (i.e., 1–2 orders of magnitude lower Fe solubility in
northern-African- than combustion-influenced aerosols). The model results
show a positive relationship between Fe solubility and water-soluble organic
carbon (WSOC)/Fe molar ratio, which is consistent with previous field
measurements. We estimated that deposition of soluble Fe to the ocean
increased from 0.05–0.07 Tg Fe yr<sup>−1</sup> in the preindustrial era to
0.11–0.12 Tg Fe yr<sup>−1</sup> in the present day, due to air pollution. Over
the high-nitrate, low-chlorophyll (HNLC) regions of the ocean, the modeled Fe
solubility remains low for mineral dust (< 1 %) in a base simulation
but is substantially enhanced in a sensitivity simulation, which permits the
Fe dissolution for mineral aerosols in the presence of excess oxalate under
low acidity during daytime. Our model results suggest that human activities
contribute to about half of the soluble Fe supply to a significant portion of
the oceans in the Northern Hemisphere, while their contribution to oceans in
high latitudes remains uncertain due to limited understanding of Fe source
and its dissolution under pristine conditions
Atmospheric delivery of anthropogenic bioavailable iron from mineral dust to the ocean
Atmospheric deposition of anthropogenic soluble iron (Fe) to the ocean has been suggested to modulate primary ocean productivity and thus indirectly affect the climate. A key process contributing to anthropogenic sources of soluble Fe is associated with air pollution, which acidifies Fe-containing mineral aerosols during their transport and leads to Fe transformation from insoluble to soluble forms. However, there is large uncertainty in our estimate of this anthropogenic soluble Fe. Here, we interactively combined laboratory kinetic experiments with global aerosol modeling to more accurately quantify anthropogenic soluble Fe due to air pollution. We firstly examined Fe dissolution kinetics of African dust samples at acidic pH values with and without ionic species commonly found in aerosol water (i.e., sulfate and oxalate). We then constructed a new empirical scheme for Fe release from mineral dust due to inorganic and organic anions in aerosol water, by using acidity as a master variable. We implemented this new scheme and applied an updated mineralogical emission database in a global atmospheric chemistry transport model to estimate the atmospheric concentration and deposition flux of soluble Fe under preindustrial and modern conditions. Our improved model successfully captured the inverse relationship of Fe solubility and total Fe loading measured over the North Atlantic Ocean. However, our modeled Fe solubility was significantly lower than that deduced from observations over the South Atlantic east downwind from the Patagonian dust source regions. Our modeled Fe solubility for dry deposition over the Atlantic is in good agreement the measurement, while that for wet deposition is significantly lower than the measurement. Our model results suggest that human activities contribute to about half of the soluble Fe supply to a significant portion of the oceans in the Northern Hemisphere, while their contribution to oceans in the high latitude remains highly uncertain due to limited understanding of dust blown off the coasts of Alaska, Iceland and the Patagonia desert.Poster abstract A23C-0310 presented at 2015 Fall Meeting, AGU, San Francisco, Calif., 14-18 Dec
Estimates of Future New Particle Formation under Different Emission Scenarios in Beijing
New particle formation
(NPF) is a leading source of particulate
matter by number and a contributor to particle mass during haze events.
Reductions in emissions of air pollutants, many of which are NPF precursors,
are expected in the move toward carbon neutrality or net-zero. Expected
changes to pollutant emissions are used to investigate future changes
to NPF processes, in comparison to a simulation of current conditions.
The projected changes to SO2 emissions are key in changing
future NPF number, with different scenarios producing either a doubling
or near total reduction in sulfuric acid-amine particle formation
rates. Particle growth rates are projected to change little in all
but the strictest emission control scenarios. These changes will reduce
the particle mass arising by NPF substantially, thus showing a further
cobenefit of net-zero policies. Major uncertainties remain in future
NPF including the volatility of oxygenated organic molecules resulting
from changes to NOx and amine emissions
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