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| Open AccessIncrease in global emissions of HFC-23 despite near-total expected reductions
International agreements have been implemented to reduce emissions of hydrofluorocarbons (HFCs) to reduce their radiative forcing. Even though reported HFC-23 emissions are at a historical low, observations indicate that emissions have actually increased over recent years to higher levels than previously.
- K. M. Stanley
- , D. Say
- & M. Rigby
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Article
| Open AccessDelay in recovery of the Antarctic ozone hole from unexpected CFC-11 emissions
The Antarctic ozone hole is decreasing in size due to policies implemented following the Montreal Protocol. Here, model simulations show that if recently discovered increase in unreported CFC-11 emissions continue, they could delay the recovery of the ozone hole by well over a decade.
- S. S. Dhomse
- , W. Feng
- & M. P. Chipperfield
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Article
| Open AccessKey drivers of cloud response to surface-active organics
Aerosol-cloud interactions are a large source of uncertainty in radiative forcing estimates. Here, the authors show that the radiative effects of clouds are influenced by a combination of aerosol particle distribution, environmental conditions and atmosphere dynamics.
- S. J. Lowe
- , D. G. Partridge
- & I. Riipinen
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Article
| Open AccessConstraining the rise of oxygen with oxygen isotopes
The loss of anomalous sulfur isotope compositions from sedimentary rocks has been considered a symptom of permanent atmospheric oxygenation. Here the authors show sulfur and oxygen isotope evidence from < 2.31 Ga sedimentary barium sulphates (barites) from the Turee Creek Basin, W. Australia, demonstrating the influence of local non-atmospheric processes on anomalous sulfur isotope signals.
- B. A. Killingsworth
- , P. Sansjofre
- & S. V. Lalonde
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Article
| Open AccessMolecular identification of organic vapors driving atmospheric nanoparticle growth
Condensation of organic vapors is a main factor controlling the growth of atmospheric particles. Here the authors identify a distribution of organic vapors in a forested environment able to explain nanoparticle growth at the same location, contributing to understanding aerosol climate effects.
- Claudia Mohr
- , Joel A. Thornton
- & Taina Yli-Juuti
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Article
| Open AccessThe role of highly oxygenated organic molecules in the Boreal aerosol-cloud-climate system
Forests emit compounds into the atmosphere that are oxidized into highly oxygenated molecules that serve as precursors for cloud condensation nuclei–a process that impacts the climate, but is poorly represented in models. Here the authors create a new model that accurately depicts highly oxygenated molecule and climate dynamics over Boreal forests.
- Pontus Roldin
- , Mikael Ehn
- & Michael Boy
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Article
| Open AccessGigantic jet discharges evolve stepwise through the middle atmosphere
Gigantic jets, lightning discharges originating from tropical thunderstorms that can reach the base of the ionosphere at 90 km altitude, have not been captured using high-speed video cameras before. Here, the first such images are reported, showing a step-wise evolution of gigantic jets during their rising phase.
- Oscar A. van der Velde
- , Joan Montanyà
- & Steven A. Cummer
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Article
| Open AccessDeciphering key processes controlling rainfall isotopic variability during extreme tropical cyclones
“Reconstruction of precipitation variability from oxygen isotopes in the Mesoamerican and Caribbean region is made difficult by the occurrence of tropical cyclones. Here, the isotopic evolution of a tropical cyclone is studied in detail which helps disentangle the key processes governing rainfall isotope variability in the region.”
- Ricardo Sánchez-Murillo
- , Ana M. Durán-Quesada
- & Kim M. Cobb
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Article
| Open AccessDirect retrieval of isoprene from satellite-based infrared measurements
Isoprene is a key component of the atmosphere, with impacts on oxidation, ozone and organic aerosols, but in-situ measurements are limited. Here, the authors present a full-physics measurement framework based on satellite data that enables the direct observation of atmospheric isoprene from space.
- Dejian Fu
- , Dylan B. Millet
- & Annmarie Eldering
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Article
| Open AccessRainfall drives variation in rates of change in intrinsic water use efficiency of tropical forests
How the water use efficiency of trees changes with atmospheric CO2 variations has mostly been studied on short time scales. Here, a newly compiled data set covering 1915 to 1995 shows how rates of change in water use efficiency vary with location and rainfall over the global tropics on a decadal scale.
- Mark A. Adams
- , Thomas N. Buckley
- & Tarryn L. Turnbull
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Article
| Open AccessNet carbon emissions from African biosphere dominate pan-tropical atmospheric CO2 signal
Tropical land ecosystems contain vast carbon reservoirs, but their influence on atmospheric CO2 is poorly understood. Here the authors use new carbon-observing satellites to reveal a large emission source over northern tropical Africa, where there are large soil carbon stores and substantial land use changes.
- Paul I. Palmer
- , Liang Feng
- & Peter Somkuti
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Article
| Open AccessRevisiting enteric methane emissions from domestic ruminants and their δ13CCH4 source signature
Global average, geographical distribution and temporal variations of the 13C isotopic signature of enteric fermentation emissions are not well understood. Here the authors established a global dataset and show a larger emission increase between the two periods (2002–2006 and 2008–2012) than previous studies.
- Jinfeng Chang
- , Shushi Peng
- & Philippe Bousquet
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Article
| Open AccessReduced marine phytoplankton sulphur emissions in the Southern Ocean during the past seven glacials
Ice core derived marine biogenic sulphate does not agree with marine sediment records. Here based on new ice core records spanning the past 720,000 years obtained from Dome Fuji the authors propose that dust contributed a higher percentage of sulphate aerosols than previously thought.
- K. Goto-Azuma
- , M. Hirabayashi
- & Y. Fujii
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Article
| Open AccessTracing and constraining anthropogenic aerosol iron fluxes to the North Atlantic Ocean using iron isotopes
The relative importance of crustal vs. anthropogenic dust deposition for iron cycling in the surface ocean is unclear. Based on analysis of iron isotope data from North Atlantic aerosol samples, the authors can reveal the relative importance of anthropogenic iron emissions and its impact on marine biogeochemistry.
- Tim M. Conway
- , Douglas S. Hamilton
- & Seth G. John
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Article
| Open AccessRapid unimolecular reaction of stabilized Criegee intermediates and implications for atmospheric chemistry
Criegee intermediates have received much attention in atmospheric chemistry because of their importance in ozonolysis mechanisms. Here, using quantum mechanical kinetics, the authors reveal an unexpectedly fast mechanistic pathway for unimolecular reactions of large stabilized Criegee intermediates.
- Bo Long
- , Junwei Lucas Bao
- & Donald G. Truhlar
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Article
| Open AccessIn-situ aerosol nanoparticle characterization by small angle X-ray scattering at ultra-low volume fraction
State‐of‐the‐art aerosol nanoparticle techniques are limited by the shortcomings of removing the nanoparticles from their original environment. Here, the authors apply small angle X‐ray scattering as an in‐situ measurement technique, enabling the measurement of the primary particles and the aggregates.
- P. S. Bauer
- , H. Amenitsch
- & P. M. Winkler
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Article
| Open AccessUrban pollution greatly enhances formation of natural aerosols over the Amazon rainforest
It remains unclear how urban emissions influence the formation of secondary organic aerosols (SOA), including in the Amazon forest. Here, the authors simulate the formation of SOAs in the Amazon using a high-resolution regional chemical transport model. They find that urban emissions of NOx from Manaus enhance the production of biogenic SOA by 60–200%.
- Manish Shrivastava
- , Meinrat O. Andreae
- & Chun Zhao
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Article
| Open AccessChina’s coal mine methane regulations have not curbed growing emissions
Chinese government has implemented regulations to reduce mining-related methane emission since 2010. Here the authors estimated methane emissions in China using GOSAT satellite observation and results reveal a business-as-usual increase in methane emissions since 2010 despite those ambitious targets.
- Scot M. Miller
- , Anna M. Michalak
- & Stefan Schwietzke
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Article
| Open AccessDecrease in radiative forcing by organic aerosol nucleation, climate, and land use change
Organic nucleation is an important source of atmospheric aerosol number concentration, especially in pristine continental regions and during the preindustrial period. Here the authors find a 16% reduced radiative forcing associated with anthropogenic aerosols when including organic nucleation together with climate and land use change.
- Jialei Zhu
- , Joyce E. Penner
- & Hugh Coe
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Article
| Open AccessOrganic bromine compounds produced in sea ice in Antarctic winter
Short-lived natural bromocarbons, which contribute to ozone depletion in the atmosphere, are believed to be produced through light-driven processes, mainly in oceans. Here the authors present bromocarbon measurements in snow, sea ice, and air during polar winter that show an unexpected source of bromine to the polar atmosphere during periods of no sunlight.
- Katarina Abrahamsson
- , Anna Granfors
- & Alfonso Saiz-Lopez
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Article
| Open AccessFungal spores as a source of sodium salt particles in the Amazon basin
Salt particles in the Amazon basin are typically attributed to marine aerosols transported from the Atlantic Ocean. Here the authors show the potential importance of fungal spores as a source of sodium-salt particles in the Amazon rainforest.
- Swarup China
- , Susannah M. Burrows
- & Alexander Laskin
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Article
| Open AccessPhotoreduction of gaseous oxidized mercury changes global atmospheric mercury speciation, transport and deposition
Reduction of gaseous Hg(II) compounds drives atmospheric mercury wet and dry deposition to Earth surface ecosystems. Global Hg models assume this reduction takes place in clouds. Here the authors report a new gas-phase Hg photochemical mechanism that changes atmospheric mercury lifetime and its deposition to the surface.
- Alfonso Saiz-Lopez
- , Sebastian P. Sitkiewicz
- & Jeroen E. Sonke
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Article
| Open AccessThe reaction of hydroxyl and methylperoxy radicals is not a major source of atmospheric methanol
The reaction of hydroxyl and methylperoxy radicals has recently been suggested as the source of missing methanol in the remote troposphere. Here, the authors present direct experimental measurements demonstrating the reaction leads to further underprediction of modelled methanol.
- Rebecca L. Caravan
- , M. Anwar H. Khan
- & Craig A. Taatjes
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Review Article
| Open AccessEvaluating climate geoengineering proposals in the context of the Paris Agreement temperature goals
Research and debate are intensifying on complementing CO2 emissions reductions with hypothetical climate geoengineering techniques. Here, the authors assess their potentials, uncertainties and risks, and show that they cannot yet be relied on to significantly contribute to meeting the Paris Agreement temperature goals.
- Mark G. Lawrence
- , Stefan Schäfer
- & Jürgen Scheffran
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Article
| Open AccessTree rings reveal globally coherent signature of cosmogenic radiocarbon events in 774 and 993 CE
Despite their extensive use, the absolute dating of tree-ring chronologies has not hitherto been independently validated at the global scale. Here, the identification of distinct 14C excursions in 484 individual tree rings, enable the authors to confirm the dating of 44 dendrochronologies from five continents.
- Ulf Büntgen
- , Lukas Wacker
- & Giles H. F. Young
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Article
| Open AccessBlack carbon radiative effects highly sensitive to emitted particle size when resolving mixing-state diversity
Black carbon has a large but uncertain warming contribution to Earth’s climate. Here Matsui et al. show that black carbon mixing state and its interaction with aerosol size distribution are required for accurately estimating the radiative effect of black carbon.
- Hitoshi Matsui
- , Douglas S. Hamilton
- & Natalie M. Mahowald
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Article
| Open AccessBiogenic volatile release from permafrost thaw is determined by the soil microbial sink
Permafrost thaw allows biological activity in previously frozen ground, leading to a potential release of climate-relevant gases. Here the authors show that thawing permafrost emits volatile organic compounds but that their release to the atmosphere is limited by microbial consumption in the overlaying soil.
- Magnus Kramshøj
- , Christian N. Albers
- & Riikka Rinnan
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Article
| Open AccessReassessment of pre-industrial fire emissions strongly affects anthropogenic aerosol forcing
Several lines of evidence suggest that fire activity was much greater in the preindustrial era than currently assumed in climate models. Here the authors show that greater emission of aerosols from fires leads to a substantial reduction in the magnitude of aerosol radiative forcing over the Industrial Era.
- D. S. Hamilton
- , S. Hantson
- & K. S. Carslaw
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Article
| Open AccessObservational constraint on cloud susceptibility weakened by aerosol retrieval limitations
Cloud susceptibility to aerosols in models frequently exceeds satellite estimates. Here the authors show that the discrepancy can be explained by retrieval limitations especially in clean environments, suggesting that conventional comparison strategies may lead to misunderstanding.
- Po-Lun Ma
- , Philip J. Rasch
- & Steven J. Ghan
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Article
| Open AccessPhoto-tautomerization of acetaldehyde as a photochemical source of formic acid in the troposphere
The concentration of formic acid in Earth’s atmosphere is under-predicted by atmospheric models. Here the authors show that acetaldehyde photo-tautomerizes to vinyl alcohol under tropospheric conditions, with subsequent oxidation via OH radicals supplying up to 60% of total modeled formic acid production over oceans.
- Miranda F. Shaw
- , Bálint Sztáray
- & Scott H. Kable
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Article
| Open AccessStrong sesquiterpene emissions from Amazonian soils
Recent measurements in the Amazon rainforest indicate missing sources of volatile organic compounds (VOCs). Here the authors show that soil microorganisms are a strong, unaccounted source of highly reactive sesquiterpenes, a class of VOCs that can regulate ozone chemistry within the forest canopy.
- E. Bourtsoukidis
- , T. Behrendt
- & J. Williams
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Article
| Open AccessInterfacial photochemistry at the ocean surface is a global source of organic vapors and aerosols
Volatile organic compounds are photochemically produced in the ocean surface microlayer, but estimates are missing. Here the authors combine experiments and observations to quantify photochemical emissions of volatile organic compounds and show that they are comparable to biological production.
- Martin Brüggemann
- , Nathalie Hayeck
- & Christian George
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Article
| Open AccessTaxon-specific aerosolization of bacteria and viruses in an experimental ocean-atmosphere mesocosm
Factors controlling the transfer of microbes from the ocean to the atmosphere are unclear. Here, Michaud et al. study this process in an enclosed ocean-atmosphere facility, and show that the degree of aerosolization of bacteria and viruses is taxon-specific.
- Jennifer M. Michaud
- , Luke R. Thompson
- & Kimberly A. Prather
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Article
| Open AccessAnthropogenic combustion iron as a complex climate forcer
As a source of soluble iron, anthropogenic combustion iron is considered less important than natural sources. Here, the authors combine new measurements with a global aerosol model and show the atmospheric burden of anthropogenic combustion iron to be 8 times greater than previous estimates.
- Hitoshi Matsui
- , Natalie M. Mahowald
- & Mark G. Flanner
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Article
| Open AccessRapid increase in atmospheric iodine levels in the North Atlantic since the mid-20th century
Despite its chemical importance, the evolution of atmospheric iodine concentrations over time is unknown. Here, the authors show that North Atlantic atmospheric iodine levels have tripled since 1950, and propose ozone pollution and enhanced biological production Arctic sea ice thinning as a primary driver.
- Carlos A. Cuevas
- , Niccolò Maffezzoli
- & Alfonso Saiz-Lopez
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Article
| Open AccessResidential energy use emissions dominate health impacts from exposure to ambient particulate matter in India
Exposure to ambient particulate matter is a key contributor to disease in India and source attribution is vital for pollution control. Here the authors use a high-resolution regional model to show residential emissions dominate particulate matter concentrations and associated premature mortality.
- Luke Conibear
- , Edward W. Butt
- & Dominick V. Spracklen
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Article
| Open AccessCleaner fuels for ships provide public health benefits with climate tradeoffs
Aerosol pollution from shipping contributes to cooling but also leads to premature mortality and morbidity. Here the authors combine emission inventories, atmospheric models and health risk functions to show how cleaner marine fuels will reduce premature deaths and childhood asthma but results in larger warming.
- Mikhail Sofiev
- , James J. Winebrake
- & James J. Corbett
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Article
| Open AccessAmbient PM2.5 exposure and expected premature mortality to 2100 in India under climate change scenarios
Modulation of ambient PM2.5 exposure and premature mortality burden in India under climate change scenarios is unclear. Here the authors show that the premature mortality burden is projected to decrease in 2100 relative to present day under all possible combined climate change and socioeconomic pathways scenarios.
- Sourangsu Chowdhury
- , Sagnik Dey
- & Kirk R. Smith
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Article
| Open AccessGlobal and regional importance of the direct dust-climate feedback
Feedbacks between desert dust and climate might have amplified past climate changes, yet their role in future climate change is unclear. Here the authors find that dust feedbacks could play a key role in the future climates of Northern Africa, the Sahel, the Mediterranean, the Middle East, and Central Asia.
- Jasper F. Kok
- , Daniel S. Ward
- & Amato T. Evan
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Article
| Open AccessStratospheric ozone loss over the Eurasian continent induced by the polar vortex shift
Climate change can exert a significant effect on the ozone recovery. Here, the authors show that the Arctic polar vortex shift associated with Arctic sea-ice loss could slow down ozone recovery over the Eurasian continent.
- Jiankai Zhang
- , Wenshou Tian
- & Guang Zeng
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Article
| Open AccessImpact on short-lived climate forcers increases projected warming due to deforestation
The climate impacts of deforestation due to changes in biogenic volatile organic compound emissions, which act as short-lived climate forcers (SLCFs), are poorly understood. Here the authors show that including the impact SLCFs increases the projected warming associated with idealised deforestation scenarios.
- C. E. Scott
- , S. A. Monks
- & C. Wilson
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Article
| Open AccessIncreased ionization supports growth of aerosols into cloud condensation nuclei
Ions produced by cosmic rays have been thought to influence aerosol and cloud processes by an unknown mechanism. Here the authors show that the mass flux of ions to aerosols enhances their growth significantly, with implications for the formation of cloud condensation nuclei.
- H. Svensmark
- , M. B. Enghoff
- & J. Svensmark
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Article
| Open AccessComplex three-dimensional self-assembly in proxies for atmospheric aerosols
Nearly all atmospheric aerosols contain surface-active organic compounds; however, the nature of how they arrange remains poorly understood. Here, the authors show that fatty acids in atmospheric aerosol proxies self-assemble into highly ordered, viscous 3D nanostructures that undergo changes upon exposure to humidity and ozone.
- C. Pfrang
- , K. Rastogi
- & A. M. Squires
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Article
| Open AccessThe formation and evolution of Titan’s winter polar vortex
The polar hot-spot appeared in Titan after equinox in 2010 suddenly cooled in early 2012, which wasn’t predicted by models. Here the authors use observations to show that the increase in trace gases during the hot-spot resulted in radiative cooling feedback.
- Nicholas A. Teanby
- , Bruno Bézard
- & F. Michael Flasar
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Article
| Open AccessContribution of livestock H2S to total sulfur emissions in a region with intensive animal production
Hydrogen sulfide (H2S) from agricultural sources is generally omitted from sulfur emission estimates despite its abundance in livestock emissions. Here, the authors show that agriculture is the most important source of sulfur in Denmark using proton-transfer-reaction mass spectrometry measurements of H2S.
- Anders Feilberg
- , Michael Jørgen Hansen
- & Tavs Nyord
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Article
| Open AccessAtmospheric observations show accurate reporting and little growth in India’s methane emissions
India’s methane emissions have been quantified using atmospheric measurements to provide an independent comparison with reported emissions. Here Ganesan et al. find that derived methane emissions are consistent with India’s reports and no significant trend has been observed between 2010–2015.
- Anita L. Ganesan
- , Matt Rigby
- & Paul B. Krummel
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Article
| Open AccessTrade-driven relocation of air pollution and health impacts in China
International and domestic interprovincial trade of China are entangled, but their health impacts have been treated separately in earlier studies. Here Wang. quantify the complex impacts of trade on public health across China within an integrative framework.
- Haikun Wang
- , Yanxu Zhang
- & Michael B. McElroy
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Article
| Open AccessA surface-stabilized ozonide triggers bromide oxidation at the aqueous solution-vapour interface
Heterogeneous oxidation of bromide in atmospheric aqueous environments has long been suspected to be accelerated at the interface between aqueous solution and air. Here, the authors provide spectroscopic, kinetic and theoretical evidence for a rate limiting, surface active ozonide formed at the interface.
- Luca Artiglia
- , Jacinta Edebeli
- & Markus Ammann
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Article
| Open AccessAerosols as a source of dissolved black carbon to the ocean
The contribution of atmospheric deposition to the oceanic dissolved black carbon pool (DBC) is unclear. Here, the authors show that water-soluble black carbon is positively correlated with water-soluble organic carbon in marine aerosols, and that atmospheric deposition is a significant source of oceanic DBC.
- Hongyan Bao
- , Jutta Niggemann
- & Shuh-Ji Kao