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[en] To measure the nutrient leaching from canopy and the O layer in a natural oriental beech (Fagus orientalis Lipsky) forest and a Norway spruce (Picea abies) plantation. Materials and methods: From mid-July to early November, 2013, we measured throughfall (TF) (n=45), stemflow (SF) (n=12) and leaching from the O layer (n = 30) in a 0.5 ha sample plot in the Caspian region, Mazandaran province in northern Iran. Main results: Concentrations of PO43-, Na+, Mg2+, Ca2+ and K+ in the throughfall and the O layer in both beech and spruce forests significantly increased relative to gross rainfall. Concentrations of Ca2+ and Na+ in TF and SF were significantly higher in the spruce forest compared with the beech forest. Furthermore, in both forests, cumulative fluxes of all studied elements (with the exception of NH4+ and NO3-) during the study period were statistically different from those of GR (P<0.05). This study demonstrates that changing from a natural beech forest to a spruce plantation significantly alters nutrient fluxes exiting the canopy and the O layer. This information provides essential information on how planting exotic species will affect nutrient cycles in this region.
[en] Highlights: • Deep-seated smoldering fires in wood pellets generate pyrolysis gases. • Flammable pyrolysis gases can travel and accumulate, e.g. in the silo headspace. • Fires cannot be fought with water, novel approaches call for injection of inert gas. • Injection of carbon dioxide may generate static electricity, leading to silo explosion. • Industry standards and pellet handbooks largely silent on the hazard. - Abstract: Smouldering fires in wood pellet silos are not uncommon. The fires are often difficult to deal with and extinguishment is a lengthy process. Injection of inert gases to prevent oxygen from reaching the smouldering fire zone and suppress combustion is a new firefighting strategy. This article argues that injection of inert carbon dioxide (CO2) into the silo headspace is unsafe. Carbon dioxide is generally available as a liquid under high pressure. When discharged, small particles of dry ice are formed. The rapid flow of particles can generate considerable amounts of static electricity, which can act as a source of ignition if ignitable pyrolysis gases are present. This article discusses a serious wood pellet smouldering fire and silo explosion in Norway in 2010, which took place when firefighters discharged portable CO2 fire extinguishers into the headspace. The attempt to suppress the fire may have ignited pyrolysis gases. The article examines selected guidelines, standards, wood pellet handbooks and other literature and argues that the electrostatic hazard is widely under-appreciated. In the past, major explosions have been attributed to electrostatic ignition of flammable vapours during the release of CO2 for fire prevention purposes. There is evidence to suggest that those early lessons learned have at least partly passed out of sight.
[en] We will present the results from a study that was designed to map PM-concentrations and indoor climate in different areas of an underground railway environment, focusing on public areas and working environments. PM2.5 and PM10 were sampled at several sites at Norway‘s second most frequented railway station, including the platform in the basement and shops on the ground floor. During the same time, PM was monitored continuously at the platform. PM-levels above recommended standard values were observed especially at the platform and in shops which are not completely enclosed. Offices on the station‘s premises have satisfactory PM-levels. An important outcome from our study is that optical PM-monitors need to be specifically prepared for applications in the railway environment.
[en] One of the representative auroral emission lines that radiates from F-region heights and is measurable on the ground is the 777.4 nm line from excited atomic oxygen. This line has been adopted, along with another E-region emission line, for example 427.8 nm, to estimate the mean energy and total energy flux of precipitating auroral electrons. The influence of emissions from part of the molecular nitrogen band, which mainly radiate from E-region heights, should be carefully evaluated because it might overlap the 777.4 nm atomic oxygen line in the spectrum. We performed statistical analysis of auroral spectrograph measurements that were obtained during the winter of 2016–2017 in Tromsø, Norway, to derive the ratio of the intensity of the 777.4 nm atomic oxygen line to that of the net measurement through a typically used optical filter with a full width at half maximum of a few nm. The ratio had a negative trend against geomagnetic activity, with a primary distribution of 0.5–0.7 and a minimum value of 0.3 for the most active auroral condition in this study. This result suggests that the 30–50% emission intensities measured through the optical filter may be from the molecular nitrogen band. .
[en] Regional scale air quality models are regularly used for assessing health impacts over country or continental scales. However, these models lack sufficient resolution to represent pollution gradients near sources, particularly in the case of road traffic emissions, and are based mostly on top down emission inventories. From the regional modelling perspective it is therefore desirable to down scale gridded concentrations to a resolution that are sufficient to resolve these sources, approximately 50 m, for improved exposure assessment. At the same time local scale models, often based on Gaussian plume parameterisations and using bottom up emissions inventories, are also regularly applied for health impact assessments but are rarely used beyond the city scale. In this paper a methodology for downscaling regional scale concentrations from the EMEP/MSC-W model to local scales is presented, uEMEP (urban EMEP). The methodology requires bottom up emission proxy data, which is often incompatible with the top down inventories, for the redistribution of gridded concentrations. Results are presented for Norway and The Netherlands and the problems encountered when regional and local scales meet are discussed.
[en] Highlights: • Analyses of long term monitoring data reveals significant changes in benthic macrofaunal abundance, species richness, and community structure in the deep water of three west Norwegian sill fjords. • The macrofaunal changes were not reflected by changes in the Shannon-Wiener diversity index. • The observed changes are characterized by an increased abundance of opportunistic species, especially the polychaet Polydora sp. • The macrofaunal changes are significantly correlated to declining dissolved oxygen, rising temperature in the bottom water and increasing total organic matter in the sediment. - Abstract: Quantitative analyses of soft bottom invertebrate fauna from four Norwegian sill fjords show increased macrofaunal abundance, species richness, and a considerably changed benthic deep water macrofaunal composition in the inner parts of the fjord system. In retrospect, the analyses show significantly altered benthic macrofaunal community structure that was not reflected by the changes in the Shannon-Wiener diversity indices during regular monitoring. The observed changes are mainly due to an increased abundance of opportunistic species, especially of the polychaete Polydora sp. during the last 10–15 years which is correlated significantly to declining dissolved oxygen, rising temperature in the bottom water and increasing total organic matter in the sediment. Possible anthropogenic and climatic impact factors related to the observed macrofaunal changes and environmental consequences of the changes are discussed.
[en] Acid deposition has led to acidification and loss of fish populations in thousands of lakes and streams in Norway. Since the peak in the late 1970s, acid deposition has been greatly reduced and acidified surface waters have shown chemical recovery. Biological recovery, in particular fish populations, however, has lagged behind. Long-term monitoring of water chemistry and fish populations in Lake Langtjern, south-eastern Norway, shows that around 2008, chemical recovery had progressed to the point at which natural reproduction of brown trout (Salmo trutta) reoccurred. The stocked brown trout reproduced in the period 2008–2014, probably for the first time since the 1960s, but reproduction and/or early life stage survival was very low. The results indicate that chemical thresholds for reproduction in this lake are approximately pH = 5.1, Ali = 26 μg l−1, ANC = 47 μeq l−1, and ANCoaa = 10 μeq l−1 as annual mean values. These thresholds agree largely with the few other cases of documented recovery of brown trout in sites in Norway, Sweden, and the UK. Occurrence and duration of acidic episodes have decreased considerably since the 1980s but still occur and probably limit reproduction success.
[en] Highlights: • Simulation allows predicting the time of maximum energy content and the net present value of a forest fuel pile. • Optimizing the combustion sequence can improve the gained net present value of delivered biomass by 2.0%–6.4%. • The presented simulation and optimization method uses easily available input and is computationally efficient. - Abstract: We constructed a computation scheme that combines GIS, simulation and optimization techniques for assessing the moisture change, dry matter loss, transportation costs and net present value of solid forest fuel piles. This scheme was applied to predict the value of a stock composed of multiple piles, and to find the optimal feedstock allocation strategy, i.e. the selection of piles and the combustion time so that the total energy yield or the economic value of the energy production is maximized. According to the simulation, single Norway spruce energy wood piles reached their maximum energy content during July–August in boreal conditions in Finland. If a pile was created between January–September, the maximum energy content occurred in the same year, whereas for piles created between October–December, the maximum occurs in the summer of the following year. In the optimized combustion sequence, the piles generated in early Year 1 were combusted first. The main outcome of the study was that the simulation-optimization scheme can increase the gained net present value of the feedstock by 2.0%–6.4%, and the benefit increases with increasing heterogeneity of the feedstock. Forest fuel supplier can get considerable savings by applying the presented system to decide the combustion sequence of the existing feedstock. From practical point of view this is remarkable because the savings can be achieved without any investments only by arranging the transportation sequence. The presented computation system uses easily available input, can be modified to different condition, and can be run with standard IT-resources.
[en] Highlights: • Analysis of Ghana's offshore health and safety regulatory regime. • Comparison between regulatory frameworks in Norway and the United Kingdom. • Harmonisation of incoherent offshore health and safety provisions in Ghana. • Decoupling health and safety regulatory function of the Ghana Petroleum Commission. - Abstract: This paper assesses Ghana's offshore health and safety regulatory regime in the context of international best practice in the upstream oil and gas industry. It contributes to the discussion of the emerging issue of offshore risk regulation in new petroleum producing countries. We present a comparative analysis contrasting two leading safety regimes namely the United Kingdom and Norway to Ghana's emerging regime to benchmark common features as well as weaknesses. Our findings indicate that Ghana requires a robust regulatory regime that ensures that health and safety risks are properly delineated if the country is to avoid catastrophic accidents. This is especially important as these risks are more pronounced with deepwater operations such as those prevalent in the country's petroleum basins. We propose the enactment of a general Health & Safety at Work law in Ghana backed by subsidiary regulations to harmonise the disjointed and sometimes incoherent health and safety provisions. Additionally, we propose that the health and safety regulatory function of the Ghana Petroleum Commission should be decoupled to form an independent Competent Authority as activity levels and the degree of complexity of operations increase to prevent conflict of interest between its regulatory and licensing functions.