Experimental research of oily sawdust air gasification

This article shows oily sawdust gasification research on countercurrent installation. Experimental research was on a laboratory scale. The main purpose of the experiment was combustible gas production with higher CH₄ concentration. Gas concentrations like CO, CO₂, CH₄, H₂, and C_nH_m determine syngas composition. The technological parameter’s value defines experimental conditions. Value of this was fuel to air ratio. With fuel to air ratio change, syngas composition was a differential phenomenon where it depended on the process parameters like temperature. Additionally, evaluation of methane formation from CO, H₂, and CO₂ was done. Methanization coefficients were based on CO and CO₂ hydrogenation reactions. Component’s activity was in analogs way to syngas components changed.

     

Concentrations of selected trace elements in surface soils near crossroads in the city of Bratislava (the Slovak Republic)

Environmental Science and Pollution Research - It is well known that road transport emits various trace elements into the environment, which are deposited in soils in the vicinity of roads,...     

Bark removal and population structure of Taxus wallichiana Zucc. in a temperate mixed conifer forest of western Himalaya

Taxus wallichiana Zucc. (Himalayan yew) represents one of the most threatened medicinal tree species of the Himalayan region. Heavy exploitation of its bark and leaves for taxol® has resulted in decline in its population. Generating quantitative information on Himalayan yew has therefore been stressed. The present paper provides information on the population and bark removal of Himalayan yew from one of the interior areas of Himalaya. Total count and quadrat method were deployed to generate quantitative information on its population while bark removal was estimated based on depth and extent of bark removed. After analyzing the existing information and the results of the study, a rapid vulnerability assessment (RVA) of the species was carried out. Taxus reported a density of 72 individuals/ha and was present as an under canopy of Picea smithiana. Complete stripping of bark was observed in 11 % of the Taxus population which amounted to ca. 18,152.86 cm³ of bark removed. The age class distribution showed complete absence of seedlings and saplings. RVA scores also reported higher values (26) thereby pointing toward the high vulnerability of this species. Across its entire distributional range, Taxus population is under severe pressure. It is high time when few patches of Taxus are demarcated as Medicinal Plant Conservation Areas, and detailed studies on its autecology are initiated.     

Mineralisation of Monuron photoinduced by Fe(III) in aqueous solution

The degradation of Monuron (3-(4-chlorophenyl)-1,1-dimethylurea) photoinduced by Fe(III) in aqueous solution has been investigated. The rate of degradation depends on the concentration of Fe(OH)2+, the most photoreactive species in terms of *OH radical formation. These *OH radicals are able to degrade Monuron until total mineralisation. The primordial role of the speciation of Fe(III)-hydroxy complex in aqueous solution, for the efficiency of the elimination of pollutant, was shown and explained in detail. The formation of Fe(II) in the irradiated solution was monitored and correlated with the total organic carbon evolution. Degradation photoproducts were identified and a mechanism of degradation is proposed.     

Communities of different plant diversity respond similarly to drought stress: experimental evidence from field non-weeded and greenhouse conditions

Accelerating rate of species loss has prompted researchers to study the role of species diversity in processes that control ecosystem functioning. Although negative impact of species loss has been documented, the evidence concerning its impact on ecosystem stability is still limited. Here, we studied the effects of declining species and functional diversity on plant community responses to drought in the field (open to weed colonization) and greenhouse conditions. Both species and functional diversity positively affected the average yields of field communities. However, this pattern was similar in both drought-stressed and control plots. No effect of diversity on community resistance, biomass recovery after drought and resilience was found because drought reduced biomass production similarly at each level of diversity by approximately 30?%. The use of dissimilarity (characterized by Euclidean distance) revealed higher variation under changing environments (drought-stressed vs. control) in more diverse communities compared to less species-rich assemblages. In the greenhouse experiment, the effect of species diversity affected community resistance, indicating that more diverse communities suffered more from drought than species-poor ones. We conclude that our study did not support the insurance hypothesis (stability properties of a community should increase with species richness) because species diversity had an equivocal effect on ecosystem resistance and resilience in an environment held under non-weeded practice, regardless of the positive relationship between sown species diversity and community biomass production. More species-rich communities were less resistant against drought-stressed conditions than species-poor ones grown in greenhouse conditions.     

Passive air sampler as a tool for long-term air pollution monitoring: Part 1. Performance assessment for seasonal and spatial variations

The potential of passive air sampling devices (polyurethane foam disks) to assess the influence of local sources on the quality of the surrounding environment was investigated. DEZA Valasske Mezirici, a coal tar and mixed tar oils processing plant, and Spolana Neratovice, a chemical factory with the history of high production of organochlorinated pesticides (OCPs), were selected as the point sources of PAHs, and OCPs, respectively. Levels of PCBs, OCPs and PAHs were determined for all sampling sites and sampling periods. The study brought useful data about the air concentrations of POPs in the investigated regions. More important, it provided information on the transport and fate of POPs in the vicinity of local sources of contamination useful for the estimation of their influence. Very good capability of passive samplers to reflect temporal and spatial fluctuation in concentrations of persistent organic pollutants in the ambient air was confirmed which makes them applicable for monitoring on the local scale.