Found 2647 publications. Showing page 60 of 265:
2020
2020
The response of the atmosphere to solar irradiance and geomagnetic activity is analyzed in experiments with the Whole Atmosphere Community Climate Model (WACCM) under idealized forcings. Four experiments are carried out combining high (H) and low (L) solar radiative forcing with high (7) and low (3) geomagnetic activity: H7 (with high radiative forcing and high geomagnetic activity), H3, (high/low), L7 (low/high), and L3 (low/low). The comparison between these experiment is used to assess the effects of solar radiative forcing and geomagnetic activity mainly on the stratosphere. A two-step Monte Carlo-based statistical test, which defines an impact score, is used to assess statistically significant impacts on regional scales, on pressure levels, for a few key model variables, like NOx, ozone, and temperature.
Under low solar forcing (L7/L3), a statistically significant relationship between geomagnetic activity and NOx is found in both hemispheres and for all seasons. An equally strong relationship is lacking for ozone and temperature when analyzing these fields on isobaric levels. A statistically significant impact on stratospheric ozone is only seen in austral winter and spring. However, vertical cross sections show statistically significant impact on temperature and ozone mainly in the southern hemisphere (SH) during austral winter and the following spring.
Significant and persistent signals in both SH NOx and ozone concentrations are only produced when the effect of high solar forcing is added to high geomagnetic activity (H7). In this case, statistically significant differences are also found for mesospheric temperatures, ozone and NOx. This latter result appears also under low geomagnetic activity as a result of solar forcing alone, suggesting that solar irradiance significantly affects NOx, ozone and stratospheric temperatures and, in some seasons, even tropospheric temperature.
In summary, geomagnetic activity primarily affects NOx and ozone concentrations in the SH. Solar maximum conditions can reduce the amount of NOx in the stratosphere because of higher ozone production. Thus, we conclude that correlations between changes in solar irradiance and geomagnetic activity are important with respect to their effects on the atmosphere. In particular, geomagnetic activity can modulate atmospheric ozone concentrations and other associated stratospheric and tropospheric variables under conditions of high solar activity.
Elsevier
2020
2020
Car Tire Crumb Rubber: Does Leaching Produce a Toxic Chemical Cocktail in Coastal Marine Systems?
Crumb rubber granulate (CRG) produced from end of life tires (ELTs) is commonly applied to synthetic turf pitches (STPs), playgrounds, safety surfaces and walkways. In addition to fillers, stabilizers, cross-linking agents and secondary components (e.g., pigments, oils, resins), ELTs contain a range of other organic compound and heavy metal additives. While previous environmental impact studies on CRG have focused on terrestrial soil and freshwater ecosystems, many sites applying CRG in Norway are coastal. The current study investigated the organic chemical and metal additive content of ‘pristine’ and ‘weathered’ CRG and their seawater leachates, as well as uptake and effects of leachate exposure using marine copepods (Acartia and Calanus sp.). A combination of pyrolysis gas chromatography mass spectrometry (py-GC-MS) and chemical extraction followed by GC-MS analysis revealed similar organic chemical profiles for pristine and weathered CRG, including additives such as benzothiazole, N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine and a range of polycyclic aromatic hydrocarbons (PAHs) and phenolic compounds (e.g., bisphenols). ICP-MS analysis revealed g kg–1 quantities of Zn and mg kg–1 quantities of Fe, Mn, Cu, Co, Cr, Pb, and Ni in the CRG. A cocktail of organic additives and metals readily leached from the CRG into seawater, with the most abundant leachate components being benzothiazole and Zn, Fe, Co (metals), as well as detectable levels of PAHs and phenolic compounds. Concentrations of individual components varied with CRG source material and CRG to seawater ratio, but benzothiazole and Zn were typically the organic and metal components present at the highest concentrations in the leachates. While organic chemical concentrations in the leachates stabilized within days, metals continued to leach out over the 30-day period. Marine copepods exposed to high CRG leachate concentrations exhibited high mortalities within 48 h. The smaller lipid-poor Acartia had a higher sensitivity to leachates than the larger lipid-rich Calanus, indicating species-specific differences in vulnerability to leachates. The effect on survival was alleviated at lower leachate concentrations, indicating a dose-response relationship. Benzothiazole and its derivatives appear to be of concern owing to their proven toxicity, while bisphenols are also known to be toxic and were enriched in the leachates relative to the other compounds in the CRG.
Frontiers Media S.A.
2020
In the beginning of April 2020, large fires that started in the Chernobyl Exclusion Zone (CEZ) established after the Chernobyl accident in 1986 caused media and public concerns about the health impact from the resuspended radioactivity. In this paper, the emissions of previously deposited radionuclides from these fires are assessed and their dispersion and impact on the population is examined relying on the most recent data on radioactive contamination and emission factors combined with satellite observations. About 341 GBq of 137Cs, 51 GBq of 90Sr, 2 GBq of 238Pu, 33 MBq of 239Pu, 66 MBq of 240Pu and 504 MBq of 241Am were released in 1st–22nd April 2020 or about 1,000,000,000 times lower than the original accident in 1986 and mostly distributed in Central and East Europe. The large size of biomass burning particles carrying radionuclides prevents long-range transport as confirmed by concentrations reported in Europe. The highest cumulative effective doses (> 15 μSv) were calculated for firefighters and the population living in the CEZ, while doses were much lower in Kiev (2–5 μSv) and negligible in Belarus, Russia and Europe. All doses are radiologically insignificant and no health impact o
Nature Portfolio
2020
As part of the ongoing key comparison BIPM.QM-K1, a comparison has been performed between the ozone standard of Norway maintained by the Norwegian Institute for Air Research (NILU) and the common reference standard of the key comparison, maintained by the Bureau International des Poids et Mesures (BIPM). The instruments have been compared over a nominal ozone amount-of-substance fraction range from 0 nmol/mol to 500 nmol/mol.
2020
Air quality mitigation in European cities: Status and challenges ahead
Cities are currently at the core of air quality (AQ) improvement. The present work provides an overview of AQ management strategies and outcomes in 10 European cities (Antwerp, Berlin, Dublin, Madrid, Malmö, Milan, Paris, Plovdiv, Prague, Vienna) in 2018, and their evolution since 2013 (same cities, plus Ploiesti and Vilnius), based on first-hand input from AQ managers. The status of AQ mitigation in 2018, and its evolution since 2013, were assessed. While results evidenced that the majority of mitigation strategies targeted road traffic, emerging sources such as inland shipping, construction/demolition and recreational wood burning were identified. Several cities had in 2018 the ambition to continue decreasing air pollution concentrations to meet WHO guidelines, an ambition which had not yet been identified in 2013. Specific needs identified by all of the cities assessed were tools to quantify the effectiveness of mitigation strategies and for cost-benefit analysis, as well as specific and up to date technical guidance on real-world road vehicle emissions. The cities also requested guidance to identify mitigation measures promoting co-benefits, e.g., in terms of AQ, climate change, and noise. Support from administrations at local-regional-national-EU scales, and especially involving local policy-makers early on in the air quality management process, was considered essential. This work provides insight into the drivers of successful/unsuccessful AQ policies as well as on the challenges faced during their implementation. We identify knowledge gaps and provide input to the research and policy-making communities as to specific needs of cities.
Elsevier
2020
2020
2020