In recent years, the production of pellets derived from forestry biomass to replace coal for electricity generation has been increasing, with over 10 million tonnes traded internationally—primarily ...between United States and Europe but with an increasing trend to Asia. Critical to this trade is the classification of woody biomass as ‘renewable energy’ and thus eligible for public subsidies. However, much scientific study on the net effect of this trend suggests that it is having the opposite effect to that expected of renewable energy, by increasing atmospheric levels of carbon dioxide for substantial periods of time. This review, based on recent work by Europe's Academies of Science, finds that current policies are failing to recognize that removing forest carbon stocks for bioenergy leads to an initial increase in emissions. Moreover, the periods during which atmospheric CO2 levels are raised before forest regrowth can reabsorb the excess emissions are incompatible with the urgency of reducing emissions to comply with the objectives enshrined in the Paris Agreement. We consider how current policy might be reformed to reduce negative impacts on climate and argue for a more realistic science‐based assessment of the potential of forest bioenergy in substituting for fossil fuels. The length of time atmospheric concentrations of CO2 increase is highly dependent on the feedstocks and we argue for regulations to explicitly require these to be sources with short payback periods. Furthermore, we describe the current United Nations Framework Convention on Climate Change accounting rules which allow imported biomass to be treated as zero emissions at the point of combustion and urge their revision to remove the risk of these providing incentives to import biomass with negative climate impacts. Reforms such as these would allow the industry to evolve to methods and scales which are more compatible with the basic purpose for which it was designed.
Trade in wood pellets from forestry biomass to replace coal for electricity generation is increasing dramatically. Critical to this trade is the classification of woody biomass as ‘renewable energy’ and thus eligible for public subsidies. However, scientific studies show that it is having the opposite effect and is increasing atmospheric levels of carbon dioxide for substantial periods of time. We argue that EU regulations and the current United Nations Framework Convention on Climate Change accounting, which both allow imported biomass to be treated as zero emissions at the point of combustion, should be revised to remove incentives to import biomass with negative climate impacts.
Carbon dioxide (CO2) is the main greenhouse gas released into the Earth’s atmosphere by human activities. The concentration of CO2 in the atmosphere depends on the balance of natural sources and ...sinks, which are being perturbed by anthropogenic forcing due to fossil fuel burning, uncontrolled urban development, deforestation and other land use changes. An improvement in our understanding of processes responsible for absorption of CO2 is urgently needed both for a reliable estimate of future CO2 levels, and for the enforcement of effective international agreements for its containment. ...
A new method for the data fusion of atmospheric vertical profiles, referred to as complete fusion, is presented. Using the measurements of the MIPAS instrument, the performance of the method is ...compared with those of weighted and arithmetic means. The complete fusion perfectly reproduces the results of the simultaneous retrieval with equal error estimates and number of degrees of freedom, while arithmetic and weighted means have relatively low vertical resolution and differ from the simultaneous retrieval by more than their errors. In addition the problem posed in this context by systematic errors is analyzed and alleviating procedures are considered.
MIPAS is a midinfrared Fourier Transform spectrometer that sounded the atmospheric emission at limb onboard the ENVISAT satellite. It was launched on 31 March 2002 in a sun-synchronous polar orbit of ...about 800 km altitude and operated until 8 April 2012. The limb scanning sequence observed by the instrument is made of spectra that sound the atmosphere at different tangent altitudes (the tangent altitude is the minimum altitude reached by the line of sight and is also the altitude from where most of the observed signal originates). The inversion of the measurements allows the determination of the vertical profiles of the atmospheric quantities of interest in the range of the tangent altitudes covered by the limb scanning sequence, which is 6-70 km for the nominal measurement mode. …
Studies on functional traits of aquatic communities are useful for understanding the ecosystem dynamics as well as the diversity of ecological niches. Here, we characterize zooplankton functional ...groups and which limnological factors are responsible to changes in traits. Water samples were collected to evaluate limnological parameters and vertical hauls with plankton net (68 μm) were performed to characterize the community in seven reservoirs (Itupararanga, Atibainha, Salto Grande, Rio Grande, Igaratá, Barra Bonita, and Broa, São Paulo state, Brazil). Each species identified was classified according to a trophic group, reproduction mode, body length, habitat, and feeding habitats. Our results showed a predominance of pelagic suspensory herbivores with cilia (31%) followed by pelagic herbivore suspension filter feeders (17%) and raptorial omnivores (15.38%). The other individuals were categorized as pelagic herbivore suspension with oral device (12.3%), littoral herbivores suspensive with cilia (12.3%), pelagic-sucking herbivores (9.2%), and littoral grazing herbivores (3%). The dominance of herbivores may be influenced by the availability of nutrients, influencing their food sources. The abundance of omnivores engaged in predatory behavior can be attributed to disponible prey, thereby exerting significant repercussions on the organization of biological communities.
RESUMO: As comunidades zooplanctônicas são importantes componentes na cadeia alimentar considerando os produtores primários e os demais níveis. Além disso, algumas espécies são sensíveis ou ...tolerantes à poluição orgânica. Aqui testamos a hipótese de que a composição de espécies varia conforme o gradiente de eutrofização. Buscou-se estabelecer os possíveis fatores ambientais responsáveis pela variação na distribuição das espécies. Esse estudo teve como objetivo caracterizar a comunidade zooplanctônica e relacionar os dados com a qualidade da água em reservatórios do Estado de São Paulo. Amostras foram coletadas através de arrasto vertical por meio de rede de plâncton (68 (m) em sete corpos d’água. Todos os espécimes foram identificados através de literatura específica e contados em camâra de Sedgwick rafter. Os dados bióticos e abióticos foram analisados através da análise de correspondência canônica. Um total de 67 táxons foram encontrados, sendo Rotifera o predominante. No geral, os reservatórios apresentaram condições eutróficas, principalmente Salto Grande, Barra Bonita e Broa. Os resultados apontaram que os rotíferos Trichocerca longiseta (Schrank, 1802), Hexarthra sp., Brachiounus spp. e Keratella tropica (Apstein, 1907) seguiram o gradiente de eutrofização. Além desses, microcrustáceos como Notodiaptomus, Mesocyclops, Metacyclops e Diaphanossoma ocorreram em reservatórios eutróficos. Por outro lado, os cládoceros Ceriodaphnia cornuta (Sars, 1886) e Bosminopsis deitersi Richard, 1895 foram considerados indicadores de melhor qualidade devido à relação com águas mais transparentes. Os resultados apontam que algumas espécies do zooplâncton são efetivas para o monitoramento ambiental sem descartar as análises físico-químicas e biológicas.
The complete data fusion is a method that combines independent measurements of atmospheric vertical profiles. Recently a new formula for the complete data fusion, which does not contain matrices that ...can be singular and overcomes the generalized inverse approximation used when singular matrices have to be inverted, has been proposed. We show that the new formula is a generalization of the original one and analyze the analytical relationship between the two formulas when generalized inverse matrices are used for the inversion of singular matrices. We extend the new formula to include interpolation and coincidence errors, which must be considered when the profiles to be fused are measured on different vertical grids and at different times and/or locations. Finally, we use a real measurement of the Infrared Atmospheric Sounding Interferometer (IASI) instrument to show the improved performances of the new formula with respect to the original one.
Biological fluid dynamics of airborne COVID-19 infection Seminara, Giovanni; Carli, Bruno; Forni, Guido ...
Atti della Accademia nazionale dei Lincei. Rendiconti Lincei. Scienze fisiche e naturali,
2020/9, Letnik:
31, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We review the state of knowledge on the bio-fluid dynamic mechanisms involved in the transmission of the infection from SARS-CoV-2. The relevance of the subject stems from the key role of airborne ...virus transmission by viral particles released by an infected person via coughing, sneezing, speaking or simply breathing. Speech droplets generated by asymptomatic disease carriers are also considered for their viral load and potential for infection. Proper understanding of the mechanics of the complex processes whereby the two-phase flow emitted by an infected individual disperses into the environment would allow us to infer from first principles the practical rules to be imposed on social distancing and on the use of facial and eye protection, which to date have been adopted on a rather empirical basis. These measures need compelling scientific validation. A deeper understanding of the relevant biological fluid dynamics would also allow us to evaluate the contrasting effects of natural or forced ventilation of environments on the transmission of contagion: the risk decreases as the viral load is diluted by mixing effects but contagion is potentially allowed to reach larger distances from the infected source. To that end, our survey supports the view that a formal assessment of a number of open problems is needed. They are outlined in the discussion.
Graphic abstract
The average of atmospheric vertical profiles Ceccherini, Simone; Carli, Bruno; Raspollini, Piera
Optics express,
2014-Oct-06, 2014-10-06, 20141006, Letnik:
22, Številka:
20
Journal Article
Recenzirano
Odprti dostop
A new method to perform averages of atmospheric vertical profiles is presented. The method allows changing a-posteriori the strength of the constraint used in the retrievals of the single profiles ...with the purpose of optimizing the trade-off between measurement error and vertical resolution. The method is used to calculate averages of HCFC-22 profiles retrieved from MIPAS observations, demonstrating the possibility of correctly obtaining retrievals with smaller constraints (that is: having at least a factor ten greater errors) and more degrees of freedom by up to a factor two.
The choice of the vertical grid of atmospheric profiles retrieved from remote sensing observations is discussed considering the two cases of profiles used to represent the results of individual ...measurements and of profiles used for subsequent data fusion applications. An ozone measurement of the MIPAS instrument is used to assess, for different vertical grids, the quality of the retrieved profiles in terms of profile values, retrieval errors, vertical resolutions and number of degrees of freedom. In the case of individual retrievals no evident advantage is obtained with the use of a grid finer than the one with a reduced number of grid points, which are optimized according to the information content of the observations. Nevertheless, this instrument dependent vertical grid, which seems to extract all the available information, provides very poor results when used for data fusion applications. A loss of about a quarter of the degrees of freedom is observed when the data fusion is made using the instrument dependent vertical grid relative to the data fusion made using a vertical grid optimized for the data fusion product. This result is explained by the analysis of the eigenvalues of the Fisher information matrix and leads to the conclusion that different vertical grids must be adopted when data fusion is the expected application.
•Data fusion application is taken into account for the choice of the vertical grid.•The study is performed using ozone profiles retrieved from MIPAS measurements.•A very fine vertical grid is not needed for the analysis of a single instrument.•The instrument dependent vertical grid is not the best choice for data fusion.•A data fusion dependent vertical grid must be used for profiles that will be fused.
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