| 1. |
- Sutton, M. A., et al.
(författare)
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Towards a climate-dependent paradigm of ammonia emission and deposition
- 2013
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Ingår i: Philosophical Transactions of the Royal Society B: Biological Sciences. - : The Royal Society. - 1471-2970 .- 0962-8436. ; 368:1621
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Tidskriftsartikel (refereegranskat)abstract
- Existing descriptions of bi-directional ammonia (NH3) land-atmosphere exchange incorporate temperature and moisture controls, and are beginning to be used in regional chemical transport models. However, such models have typically applied simpler emission factors to upscale the main NH3 emission terms. While this approach has successfully simulated the main spatial patterns on local to global scales, it fails to address the environment-and climate-dependence of emissions. To handle these issues, we outline the basis for a new modelling paradigm where both NH3 emissions and deposition are calculated online according to diurnal, seasonal and spatial differences in meteorology. We show how measurements reveal a strong, but complex pattern of climatic dependence, which is increasingly being characterized using ground-based NH3 monitoring and satellite observations, while advances in process-based modelling are illustrated for agricultural and natural sources, including a global application for seabird colonies. A future architecture for NH3 emission-deposition modelling is proposed that integrates the spatio-temporal interactions, and provides the necessary foundation to assess the consequences of climate change. Based on available measurements, a first empirical estimate suggests that 5 degrees C warming would increase emissions by 42 per cent (28-67%). Together with increased anthropogenic activity, global NH3 emissions may increase from 65 (45-85) Tg N in 2008 to reach 132 (89-179) Tg by 2100.
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| 2. |
- Simpson, David, 1961, et al.
(författare)
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Impacts of climate and emission changes on nitrogen deposition in Europe: a multi-model study
- 2014
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 14:13, s. 6995-7017
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Tidskriftsartikel (refereegranskat)abstract
- The impact of climate and emissions changes on the deposition of reactive nitrogen (Nr) over Europe was studied using four offline regional chemistry transport models (CTMs) driven by the same global projection of future climate over the period 2000-2050. Anthropogenic emissions for the years 2005 and 2050 were used for simulations of both present and future periods in order to isolate the impact of climate change, hemispheric boundary conditions and emissions, and to assess the robustness of the results across the different models. The results from these four CTMs clearly show that the main driver of future N-deposition changes is the specified emission change. Under the specified emission scenario for 2050, emissions of oxidised nitrogen were reduced substantially, whereas emissions of NH3 increase to some extent, and these changes are largely reflected in the modelled concentrations and depositions. The lack of sulfur and oxidised nitrogen in the future atmosphere results in a much larger fraction of NHx being present in the form of gaseous ammonia. Predictions for wet and total deposition were broadly consistent, although the three fine-scale models resolve European emission areas and changes better than the hemisphericscale model. The biggest difference in the models is for predictions of individual N compounds. One model (EMEP) was used to explore changes in critical loads, also in conjunction with speculative climate-induced increases in NH3 emissions. These calculations suggest that the area of ecosystems that exceeds critical loads is reduced from 64% for year 2005 emissions levels to 50% for currently estimated 2050 levels. A possible climate-induced increase in NH3 emissions could worsen the situation, with areas exceeded increasing again to 57% (for a 30% NH3 emission increase).
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| 3. |
- Zweifel, Ulla Li, 1967, et al.
(författare)
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High bacterial 16S rRNA gene diversity above the atmospheric boundary layer
- 2012
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Ingår i: Aerobiologia. - : Springer Science and Business Media LLC. - 0393-5965 .- 1573-3025. ; 28:4, s. 481-498
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Tidskriftsartikel (refereegranskat)abstract
- The atmosphere is host to an omnipresent bacterial community that may influence fundamental atmospheric processes such as cloud formation and precipitation onset. Knowledge of this bacterial community is scarce, particularly in air masses relevant to cloud formation. Using a light aircraft, we sampled above the atmospheric boundary layer-that is, at heights at which cloud condensation occurs-over coastal areas of Sweden and Denmark in summer 2009. Enumeration indicated total bacterial numbers of 4 x 10(1) to 1.8 x 10(3) m(-3) air and colony-forming units of 0-6 bacteria m(-3) air. 16S rRNA gene libraries constructed from samples collected above the Baltic Sea coast revealed a highly diverse bacterial community dominated by species belonging to the genera Sphingomonas and Pseudomonas. Bacterial species known to carry ice-nucleating proteins were found in several samples. Modeled back trajectories suggested the potential sources of the sampled bacteria to be diverse geographic regions, including both marine and terrestrial environments in the northern hemisphere. Several samples contained 16S rRNA genes from plant chloroplasts, confirming a terrestrial contribution to these samples. Interestingly, the airborne bacterial community displayed an apparent seasonal succession that we tentatively ascribe to in situ succession in the atmosphere.
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| 4. |
- Geels, C., et al.
(författare)
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Improved modelling of atmospheric ammonia over Denmark using the coupled modelling system DAMOS
- 2012
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4189. ; 9:7, s. 2625-2647
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Tidskriftsartikel (refereegranskat)abstract
- A local-scale Gaussian dispersion-deposition model (OML-DEP) has been coupled to a regional chemistry-transport model (DEHM with a resolution of approximately 6 km x 6 km over Denmark) in the Danish Ammonia Modelling System, DAMOS. Thereby, it has been possible to model the distribution of ammonia concentrations and depositions on a spatial resolution down to 400 m x 400 m for selected areas in Denmark. DAMOS has been validated against measured concentrations from the dense measuring network covering Denmark. Here measured data from 21 sites are included and the validation period covers 2-5 years within the period 2005-2009. A standard time series analysis (using statistic parameters like correlation and bias) shows that the coupled model system captures the measured time series better than the regional- scale model alone. However, our study also shows that about 50% of the modelled concentration level at a given location originates from non-local emission sources. The local-scale model covers a domain of 16 km x 16 km, and of the locally released ammonia (NH3) within this domain, our simulations at five sites show that 14-27% of the locally (within 16 km x 16 km) emitted NH3 also deposits locally. These results underline the importance of including both high-resolution local-scale modelling of NH3 as well as the regional-scale component described by the regional model. The DAMOS system can be used as a tool in environmental management in relation to assessments of total nitrogen load of sensitive nature areas in intense agricultural regions. However, high spatio-temporal resolution in input parameters like NH3 emissions and land-use data is required.
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| 5. |
- Hansen, K., et al.
(författare)
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Ammonia emissions from deciduous forest after leaf fall
- 2013
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4189. ; 10:7, s. 4577-4589
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Tidskriftsartikel (refereegranskat)abstract
- The understanding of biochemical feedback mechanisms in the climate system is lacking knowledge in relation to bi-directional ammonia (NH3) exchange between natural ecosystems and the atmosphere. We therefore study the atmospheric NH3 fluxes during a 25-day period during autumn 2010 (21 October to 15 November) for the Danish beech forest Lille Bogeskov to address the hypothesis that NH3 emissions occur from deciduous forests in relation to leaf fall. This is accomplished by using observations of vegetation status, NH3 fluxes and model calculations. Vegetation status was observed using plant area index (PAI) and leaf area index (LAI). NH3 fluxes were measured using the relaxed eddy accumulation (REA) method. The REA-based NH3 concentrations were compared to NH3 de-nuder measurements. Model calculations of the atmospheric NH3 concentration were obtained with the Danish Ammonia MOdelling System (DAMOS). The relative contribution from the forest components to the atmospheric NH3 flux was assessed using a simple two-layer bi-directional canopy compensation point model. A total of 57.7% of the fluxes measured showed emission and 19.5% showed deposition. A clear tendency of the flux going from deposition of -0.25 +/- 0.30 mu gNH(3)-Nm(-2) s(-1) to emission of up to 0.67 +/- 0.28 mu gNH(3)-Nm(-2) s(-1) throughout the measurement period was found. In the leaf fall period (23 October to 8 November), an increase in the atmospheric NH3 concentrations was related to the increasing forest NH3 flux. Following leaf fall, the magnitude and temporal structure of the measured NH3 emission fluxes could be adequately reproduced with the bi-directional resistance model; it suggested the forest ground layer (soil and litter) to be the main contributing component to the NH3 emissions. The modelled concentration from DAMOS fits well the measured concentrations before leaf fall, but during and after leaf fall, the modelled concentrations are too low. The results indicate that the missing contribution to atmospheric NH3 concentration from vegetative surfaces related to leaf fall are of a relatively large magnitude. We therefore conclude that emissions from deciduous forests are important to include in model calculations of atmospheric NH3 for forest ecosystems. Finally, diurnal variations in the measured NH3 concentrations were related to meteorological conditions, forest phenology and the spatial distribution of local anthropogenic NH3 sources. This suggests that an accurate description of ammonia fluxes over forest ecosystems requires a dynamic description of atmospheric and vegetation processes.
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| 6. |
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| 7. |
- Langner, J., et al.
(författare)
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A multi-model study of impacts of climate change on surface ozone in Europe
- 2012
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 12:21, s. 10423-10440
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Tidskriftsartikel (refereegranskat)abstract
- The impact of climate change on surface ozone over Europe was studied using four offline regional chemistry transport models (CTMs) and one online regional integrated climate-chemistry model (CCM), driven by the same global projection of future climate under the SRES A1B scenario. Anthropogenic emissions of ozone precursors from RCP4.5 for year 2000 were used for simulations of both present and future periods in order to isolate the impact of climate change and to assess the robustness of the results across the different models. The sensitivity of the simulated surface ozone to changes in climate between the periods 20002009 and 2040-2049 differs by a factor of two between the models, but the general pattern of change with an increase in southern Europe is similar across different models. Emissions of isoprene differ substantially between different CTMs ranging from 1.6 to 8.0 Tg yr(-1) for the current climate, partly due to differences in horizontal resolution of meteorological input data. Also the simulated change in total isoprene emissions varies substantially across models explaining part of the different climate response on surface ozone. Ensemble mean changes in summer mean ozone and mean of daily maximum ozone are close to 1 ppb(v) in parts of the land area in southern Europe. Corresponding changes of 95-percentiles of hourly ozone are close to 2 ppb(v) in the same region. In northern Europe ensemble mean for mean and daily maximum show negative changes while there are no negative changes for the higher percentiles indicating that climate impacts on O-3 could be especially important in connection with extreme summer events.
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| 8. |
- Skjoth, Carsten, et al.
(författare)
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Identifying urban sources as cause of elevated grass pollen concentrations using GIS and remote sensing
- 2013
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4189. ; 10:1, s. 541-554
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Tidskriftsartikel (refereegranskat)abstract
- We examine here the hypothesis that during flowering, the grass pollen concentrations at a specific site reflect the distribution of grass pollen sources within a few kilometres of this site. We perform this analysis on data from a measurement campaign in the city of Aarhus (Denmark) using three pollen traps and by comparing these observations with a novel inventory of grass pollen sources. The source inventory is based on a new methodology developed for urban-scale grass pollen sources. The new methodology is believed to be generally applicable for the European area, as it relies on commonly available remote sensing data combined with management information for local grass areas. The inventory has identified a number of grass pollen source areas present within the city domain. The comparison of the measured pollen concentrations with the inventory shows that the atmospheric concentrations of grass pollen in the urban zone reflect the source areas identified in the inventory, and that the pollen sources that are found to affect the pollen levels are located near or within the city domain. The results also show that during days with peak levels of pollen concentrations there is no correlation between the three urban traps and an operational trap located just 60 km away. This finding suggests that during intense flowering, the grass pollen concentration mirrors the local source distribution and is thus a local-scale phenomenon. Model simulations aimed at assessing population exposure to pollen levels are therefore recommended to take into account both local sources and local atmospheric transport, and not to rely only on describing regional to long-range transport of pollen. The derived pollen source inventory can be entered into local-scale atmospheric transport models in combination with other components that simulate pollen release in order to calculate urban-scale variations in the grass pollen load. The gridded inventory with a resolution of 14m is therefore made available as supplementary material to this paper, and the verifying grass pollen observations are additionally available in tabular form.
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| 9. |
- Skjoth, Carsten, et al.
(författare)
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The effect of climate and climate change on ammonia emissions in Europe
- 2013
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7324. ; 13:1, s. 117-128
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Tidskriftsartikel (refereegranskat)abstract
- We present here a dynamical method for modelling temporal and geographical variations in ammonia emissions in regional-scale chemistry transport models (CTMs) and chemistry climate models (CCMs). The method is based on the meteorology in the models and gridded inventories. We use the dynamical method to investigate the spatiotemporal variability of ammonia emissions across part of Europe and study how these emissions are related to geographical and year-to-year variations in atmospheric temperature alone. For simplicity we focus on the emission from a storage facility related to a standard Danish pig stable with 1000 animals and display how emissions from this source would vary geographically throughout central and northern Europe and from year to year. In view of future climate changes, we also evaluate the potential future changes in emission by including temperature projections from an ensemble of climate models. The results point towards four overall issues. (1) Emissions can easily vary by 20% for different geographical locations within a country due to overall variations in climate. The largest uncertainties are seen for large countries such as the UK, Germany and France. (2) Annual variations in overall climate can at specific locations cause uncertainties in the range of 20 %. (3) Climate change may increase emissions by 0-40% in central to northern Europe. (4) Gradients in existing emission inventories that are seen between neighbour countries (e. g. between the UK and France) can be reduced by using a dynamical methodology for calculating emissions. Acting together these four factors can cause substantial uncertainties in emission. Emissions are generally considered among the largest uncertainties in the model calculations made with CTM and CCM models. Efforts to reduce uncertainties are therefore highly relevant. It is therefore recommended that both CCMs and CTMs implement a dynamical methodology for simulating ammonia emissions in a similar way as for biogenic volatile organic compound (BVOCs) - a method that has been used for more than a decade in CTMs. Finally, the climate penalty on ammonia emissions should be taken into account at the policy level such as the NEC and IPPC directives.
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| 10. |
- Xu, S. S., et al.
(författare)
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Long-term exposure to low-level air pollution and greenness and mortality in Northern Europe. The Life-GAP project
- 2023
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Ingår i: Environment International. - : Elsevier. - 0160-4120 .- 1873-6750. ; 181
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Tidskriftsartikel (refereegranskat)abstract
- Background: Air pollution has been linked to mortality, but there are few studies examining the association with different exposure time windows spanning across several decades. The evidence for the effects of green space and mortality is contradictory.Objective: We investigated all-cause mortality in relation to exposure to particulate matter (PM2.5 and PM10), black carbon (BC), nitrogen dioxide (NO2), ozone (O3) and greenness (normalized difference vegetation index NDVI) across different exposure time windows.Methods: The exposure assessment was based on a combination of the Danish Eulerian Hemispheric Model and the Urban Background Model for the years 1990, 2000 and 2010. The analysis included a complete case dataset with 9,135 participants from the third Respiratory Health in Northern Europe study (RHINE III), aged 40-65 years in 2010, with mortality follow-up to 2021. We performed Cox proportional hazard models, adjusting for potential confounders.Results: Altogether, 327 (3.6 %) persons died in the period 2010-2021. Increased exposures in 1990 of PM2.5, PM10, BC and NO2 were associated with increased all-cause mortality hazard ratios of 1.40 (95 % CI1.04-1.87 per 5 mu g/m3), 1.33 (95 % CI: 1.02-1.74 per 10 mu g/m3), 1.16 (95 % CI: 0.98-1.38 per 0.4 mu g/m3) and 1.17 (95 % CI: 0.92-1.50 per 10 mu g/m3), respectively. No statistically significant associations were observed between air pollution and mortality in other time windows. O3 showed an inverse association with mortality, while no association was observed between greenness and mortality. Adjusting for NDVI increased the hazard ratios for PM2.5, PM10, BC and NO2 exposures in 1990. We did not find significant interactions between greenness and air pollution metrics.Conclusion: Long term exposure to even low levels of air pollution is associated with mortality. Opening up for a long latency period, our findings indicate that air pollution exposures over time may be even more harmful than anticipated.
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