| 1. |
- Monks, P. S., et al.
(författare)
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Atmospheric composition change : global and regional air quality
- 2009
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 43:33, s. 5268-5350
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Forskningsöversikt (refereegranskat)abstract
- Air quality transcends all scales with in the atmosphere from the local to the global with handovers and feedbacks at each scale interaction. Air quality has manifold effects on health, ecosystems heritage and, climate. In this review the state of scientific understanding in relation to global and regional air quality is outlined. The review discusses air quality, in terms of emissions, processing and transport of trace gases and aerosols. New insights into the characterization of both natural and anthropogenic emissions are reviewed looking at both natural (e.g. dust and lightning) as well as plant emissions. Trends in anthropogenic emissions both by region and globally are discussed as well as biomass burning emissions. In terms of chemical processing the major air quality elements of ozone, non-methane hydrocarbons, nitrogen oxides and aerosols are covered. A number of topics are presented as a way of integrating the process view into the atmospheric context; these include the atmospheric oxidation efficiency, halogen and HOx chemistry, nighttime chemistry, tropical chemistry, heat waves, megacities, biomass burning and the regional hot spot of the Mediterranean. New findings with respect to the transport of pollutants across the scales are discussed, in particular the move to quantify the impact of long-range transport on regional air quality. Gaps and research questions that remain intractable are identified. The review concludes with a focus of research and policy questions for the coming decade. In particular, the policy challenges for concerted air quality and climate change policy (co-benefit) are discussed.
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| 2. |
- Dedieu, K, et al.
(författare)
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Coupling of carbon, nitrogen and oxygen cycles in sediments from a Mediterranean lagoon: a seasonal perspective
- 2007
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Ingår i: Marine ecology progress series. - 0171-8630. ; 346, s. 45-59
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Tidskriftsartikel (refereegranskat)abstract
- Experimental data and simulations were used to investigate the seasonal coupling between carbon, nitrogen and oxygen cycles in marine sediments from a eutrophic shallow lagoon in the Mediterranean Sea area. A negative seasonal correlation was observed between oxygen consumption and coupled nitrification–denitrification rates in surface sediments. Elevated values of oxygen consumption rates were reached during warm periods (up to 87.7 mmol m–2 d–1) whereas nitrification and denitrification rates remained close to the lowest rates reported for coastal sediments (values around 0.021 to 0.35 mmol N m–2 d–1 for nitrification and 0.014 to 0.045 mmol N m–2 d–1 for denitrification). A steady-state diagenetic model closely represented the seasonal negative correlation of oxygen uptake, coupled nitrification–denitrification rates, the vertical distribution patterns of pore water oxygen and the solid phase distribution of organic carbon when nitrification inhibition by sulfide was included. Simulation adjusted to field data also highlighted the importance of oxygen penetration depth in the seasonal variation of nitrification. The modelling indicated that anaerobic metabolism was the most significant pathway (65 to 80%) during organic matter mineralization with a clear seasonal increase during warm periods. These warm periods were also characterized by the higher benthic demand of oxygen mostly used to re-oxidize the by-products from anaerobic reactions (from 57 to 82%), the other part being used for carbon mineralization.
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| 3. |
- Jimenez, J. L., et al.
(författare)
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Evolution of Organic Aerosols in the Atmosphere
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 326:5959, s. 1525-1529
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Tidskriftsartikel (refereegranskat)abstract
- Organic aerosol (OA) particles affect climate forcing and human health, but their sources and evolution remain poorly characterized. We present a unifying model framework describing the atmospheric evolution of OA that is constrained by high-time-resolution measurements of its composition, volatility, and oxidation state. OA and OA precursor gases evolve by becoming increasingly oxidized, less volatile, and more hygroscopic, leading to the formation of oxygenated organic aerosol (OOA), with concentrations comparable to those of sulfate aerosol throughout the Northern Hemisphere. Our model framework captures the dynamic aging behavior observed in both the atmosphere and laboratory: It can serve as a basis for improving parameterizations in regional and global models.
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