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Open access

Václav Šimůnek, Zdeněk Vacek, Stanislav Vacek, Ivo Králíček and Karel Vančura

Abstract

Long-term temporal development of beech stands in relation to climatic conditions is well documented by dendrochronological analyses. The study aims to identify and describe growth factors affecting natural European beech stands (Fagus sylvatica L.) on permanent research plots in the eastern Krkonoše Mountains, the Czech Republic. The paper focus on radial growth dynamics, frequency and cyclicity, and the effect of climatic factors on diameter increment of beech stands since 1850. The growth development of beech stands was significantly affected by air pollution load in 1977–1989, and increasingly frequent climate extremes in recent years (since 2010). Periodic increment events recurred in approximately 10–18 years’ periods. Stands on research plots responded differently to climatic factors, the main limiting factor being low temperatures during the growing season, frost damages and extreme droughts. The positive influence of temperatures on beech increments was recorded in winter, early spring, and especially in July and August of the current year. Conversely, precipitation in the previous year had higher impact on radial increment, with prevailing negative correlation. The plots were negatively affected by the decrease in sum of precipitation in February and March, but it was the temperature that influenced the beech increment most significantly. Dendrochronological analysis of close-to-nature beech stands provides valuable information on radial forest growth in response to changing climatic conditions.

Open access

Amina Malek, Mohamed Kahoul and Hamza Bouguerra

Abstract

Drinking water is a possible source of humans’ illness when it contains chemicals and microorganisms especially from anthropogenic activities. The water supply from groundwater remains very important in Algeria. To assess the quality of groundwater in the region of Sedrata, analyses were carried out on 26 wells belonging to two neighbouring areas: one urban and the other rural. A study of physicochemical parameters has focused on the measurement of in situ temperature, electrical conductivity, pH and turbidity. Then the following parameters were analysed: hardness, and the elements: Ca2+, Mg2+, SO4 2−, PO4 3−, Cl, NO2 , NO3 , NH4 + as well as metal trace elements Fe2+, Mn2+, Al3+. The samples taken for the bacteriological study were filtered and introduced into growth medium for the research and enumeration of total germs, faecal coliforms, faecal streptococci and sulphite reducing Clostridium. As a result, the contamination of the studied waters is almost general. Some of the most important obtained values are ranging from 4.8 to 76 mg∙dm−3 for nitrates, the recorded values for mesophilic germs vary from 1 to 1100 CFUs∙cm−3. Agricultural activity and livestock products on the one hand and the use of fertilizers on the other hand are the main sources of physicochemical and bacteriological pollution. Contaminated wells should be treated as soon as possible to limit contamination before spreading in the deep aquifers. In the future, it will be necessary not only to assess the health risks related to the level of contamination of these waters, but also to proceed with their treatment before supplying them to consumers.

Open access

Megersa Olumana Dinka

Abstract

Wonji Shoa Sugar Estate (WSSE), located in the flood plain of the Awash River (Ethiopia), has been under long-term (>60 years) irrigation, industrial activities and agro-chemical usage. In this study, the hydrochemical properties of groundwater bodies available at WSSE have been characterized for quality compositions. Water samples were collected from groundwater monitoring piezometers distributed in the sugarcane plantation and then analysed for physico-chemical quality parameters (pH, EC, major cations and anions) following standard procedures. Other chemical indices (e.g., total dissolved solids (TDS), total hardness (TH), magnesium absorption ratio (MAR), base exchange (r 1), meteoric genesis (r 2)) were derived from the measured water quality parameters. The compositional variability and groundwater classification has been presented using the Box and Piper plots. The potential sources of minerals were suggested for each of the considered water sources based on their quality characteristics. Both trilinear Piper plot and meteoric genesis index revealed that groundwater of the area is shallow meteoric water percolation type with a changing of hydrochemical facies and mixing trend. Groundwater of the area, is group 1 (Ca-Mg-HCO3) type, with no dominant cations and HCO3 are the dominant anions. Overall, the study result elucidates that the chemical composition of GW of the area showed spatial variability depending upon the variations in hydrochemical inputs from natural processes and/or anthropogenic activities within the region. The local anthropogenic processes could be discharges from sugar factory, domestic sewage and agricultural activities.

Open access

M. R. Werneck, A. Mastrangelli, R. Velloso, P. Baldassin, H. Jerdy and E. C. Q. Carvalho

Summary

The present note describes the occurrence of Rhytidodoides intestinalis and Rhytidodoides similis (Digenea: Rhytidodidae) in the gallbladder of two juvenile green turtles (Chelonia mydas - Testu- dines, Cheloniidae) found on the coast of Brazil. Both were detected in gallbladder and intestine of green turtles: Rhytidodoides similis (United States, Panama, Costa Rica and Brazil) and R. intestinais (United States, Panama and Costa Rica). This note is the first report of R. intestinalis in Brazil and South-West Atlantic Ocean. Also the histological lesions caused by the parasites in one gallbladder are described.

Open access

Zeqir Hashani, Qenan Maxhuni, Rrahman Ferizi, Almir Abdurrahmani and Xhavit Mala

Abstract

Flora of the southern part of Kosovo has previously been studied in a limited way due to the difficult terrain and the fact that up to the 1990s it was a military area. In this paper we report Galanthus elwesii Hook for the first time from Kosovo. This species is found in different habitats, mainly in siliceous substrate or wet meadows of the Dragash Municipality, South Kosovo. This species was collected in the Vraça Mountains, near Restelica, (part of National Park ‘Sharri’) on the road leading to the border with Macedonia. The study area consists of territories belonging to the phytogeographic system Skardon-Pindik (Sharri-Pindi) and includes the mountain ranges of Sharri. This research comprises the presence, description, spread and mapping of the species.

Open access

Abdelhalim Yahiaoui

Abstract

Extreme streamflow drought is the direct problem of serious on damaging and on social impacts, so the frequency analysis of hydrological drought is an important work can be done to studying the drought phenomenon in catchments. So the hydrometric data for a river conducts to the establishment of the flow duration curve (FDC) as an important index of streamflow drought regime, from this characteristic, a threshold level can be defined for both perennial or intermittent streams. Well, two partial duration series can be derived for each year; the deficit volume and drought duration series. In the catchment of Wadi Mekerra in the North-West of Algeria, the minimum value estimated from the Pareto’s annual maximum instantaneous flood population (0.60 m3∙s−1) is considered as the threshold level index where, the largest deficit volume and the largest drought duration occurring in a given year are taken into consideration. Hence, the frequency analysis of the streamflow drought regime of the catchment is analysed with Weibull distribution for both deficit volume and drought duration combined with the probability of occurrence which is determined under some criterion in order to forecasting the streamflow drought in the catchment.

Open access

Jun Wang, Yifan Wu, Jueyi Sui and Bryan Karney

Abstract

Ice jams in rivers often arise from the movement of frazil ice as cover-load under ice cover, a process which is conceptually similar to the movement of sediment as bed-load along a river bed. The formation and movement of an ice-accumulation wave is one facet of a larger class of cover-load movements. The movement of an ice-accumulation wave obviously plays a crucial role in the overall process of ice accumulation. In the present study, experiments under different flow and ice conditions help reveal the mechanics of formation and evolution of ice-accumulation waves. In particular, suitable criteria for formation of an ice-accumulation wave are investigated along with the resulting speed of wave propagation. The transport capacity of frazil ice under waved accumulation is modeled by comparing those of experiments collected in laboratories, and the resulting equation is shown to be in good agreement with measured experimental results.

Open access

Rudolf Navrátil, Yvonne Brodrechtová, Róbert Sedmák and Ján Tuček

Abstract

Scenarios modelling offers to forest management an option how to envision complex future associated with various natural, social, or economic uncertainties. The challenge is what modelling method to choose as many methodological approaches to scenario building exists. Morphological analysis is a basic modelling method for structuring and analysing a whole set of relationships existing in multi-dimensional, non-quantifiable, and complex topics. Especially, its application is relevant when abstract policy or market-driven challenges need to be investigated. In this study, we demonstrated the usefulness of the morphological analysis with an example case taken from forest management in Slovakia. The use of the method has enabled, from a number of uncertain futures, to identify three possible, plausible and consistent future scenarios of possible forest management direction in the regions of Podpoľanie and Kysuce. Additionally, the future scenario modelling as prognostic method of qualitative research supported by quantitative models or forestry DSS could introduce participation and more dimensions into forest management modelling. Thus, the future scenarios modelling offers new methodological possibilities to how to deal with increasing uncertainties associated with increasing demands for various ecosystem services or negative impacts of climate change, that forest management in Slovakia will face in the near future.

Open access

Mahsa Jahadi, Hossein Afzalimehr and Paweł M. Rowinski

Abstract

Investigation of the interactions between submerged vegetation patch and flow structure is of crucial importance for river engineering. Most of hydraulic models have been presented for fully developed flows over uniform vegetation in the laboratory conditions; however, the mentioned interactions are complex in river flows where the flow is not developed along small patch. This reveals a gap between developed and non-developed flow along the vegetation patch. This study was conducted in a gravel-bed river in the central Iran. The results reveal that the flow structure in evolving flow (non-developed flow) along the patch resembles that in shallow mixing layer. Accordingly, a shallow mixing layer model and modified equations are combined to quantify evolving area along the patch. The evolving shallow mixing layer equations for the flow along a non-uniform vegetation patch reach a reasonable agreement with field data. However, the spreading coefficient of this model less than one was reported in literature, 0.06 and 0.12. In addition, the flow immediately downstream the vegetation patch behaves similar to a jet and is parameterized by two conventional models, conventional logarithmic law and mixing layer theory. These models present a reasonable agreement with the measured velocity profiles immediately downstream the patch.

Open access

O. Košulič and Š. Mašová

Summary

Details about the record of a juvenile mermithid roundworm parasitizing the bark spider Caerostris sumatrana Strand, 1915 from Thailand are presented. The morphology and ecology of both organisms is discussed. Morphological features suggest this juvenile nematode belongs to the genus cf. Aranimermis. Due to the subadult stage of parasite, identification to species-level was not possible. This first report of a nematode infection in C. sumatrana with several recent findings from other studies significantly adds to the current inventory of mermithids parasitizing spiders. Moreover, our finding is among the first record of this host-parasite interaction from Southeast Asia.