The possibilities to use other media instead of the sand in the filters of vertical flow are analysed in the article. The media used has to be inexpensive and its possibilities to clean the wastewater have to surpass that of the sand. The modelling of the wastewater treatment in the vertical flow filters was carried out in 2008 at the Water Research Institute of the Faculty of Water and Land Management of Lithuanian University of Agriculture. Dolomite powder was chosen for the investigation. Two models of 0.2 square m filters were made: one was filled with the sand, but the other was filled with the dolomite powder. It was found that the dolomite filter was less reactive to the primary contamination of the wastewater with the organic pollutants: when their amount rose from 320 to 460 mg O2 LE-1 according to the BOD7 index, the amount of the pollutants in the wastewater cleaned with the dolomite powder filter rose from 1.4 to 3.1 and amount in the wastewater which passed the sand filter rose from 0.5 to 13.9 mg O2 LE-1. General phosphorus was removed with the efficiency of 99.9% in the dolomite powder filter (and only with the efficiency of 87.0% in the sand filter). Therefore the dolomite powder filter will be removing phosphorus from the wastewater to the allowable contamination level for a much longer period. General nitrogen was cleaned with the effectiveness of 13.0% in the dolomite powder filter. Therefore, it is necessary to use additional means for its removal from the wastewater in the vertical filters with the output higher than 5 m**3 dE-1.

In order to avoid the problem of stoppage in the filters of vertical filtration, we tried to search for the filter media which was coarse and could clean the wastewater to the allowable contamination level. For this purpose the dolomite chippings were chosen and the modelling investigation was performed. Two modelled filters taking 0.2 square m area each were equipped: one was filled with the sand and the other was filled with the dolomite chippings. The results revealed that the initial contamination of the wastewater had a much bigger influence on the wastewater cleaning process than the hydraulic load. The wastewater was cleaned with the efficiency of 95.9% and never exceeded the allowable level of 30 mg O2 LE-1 in the dolomite chippings filter during the trial with the hydraulic load 0.03 m**3 mE-2 dE-1. When the hydraulic load was doubled the efficiency of the wastewater cleaning process decreased to 80.5% and the dependence of the cleaning process on the initial contamination of the wastewater increased. In order to ensure the successful removal of the easily decomposing organic pollutants from the wastewater up to their allowable contamination level, the quantity of the pollutants in the untreated wastewater must not exceed 220 mg O2 LE-1.

Due to the recently increasing frequency of extreme changes in river runoff regime, scientific literature deals with the characteristics of runoff formation. Works are carried out in analyzing climate changes and a lot of attention falls on land–use structures. Following thorough analysis of the lithological structure of river basins in separate costal zones, this article aims at evaluating river runoff formation characteristics. The basin lithological factor was calculated based on Quaternary map of Lithuania M 1:200000 and Lithuanian river map M 1:50000 using ArcGis software. In order to carry out more thorough analysis of the influence of lithology in given territories, sections of 0–20 m, 50–200 m, 200–500 m, 500–800 m, 800–1000 m and is greater than 1000 m were established, calculating the distance in meters from the riverbank. Eight river basins of typical lithological structure (sandy, loamy, argillaceous) were selected and examined. The period of the years 1960–2007 was analyzed as this period saw the greatest amount of precipitation (up to 33% probability), and relation between the runoff and precipitation was established as well as that with the lithological structure, established following the derivation of a hydromodule.

The pollution of the river water with organic matter deteriorates the chemical, biological and microbiological quality of the water and has a negative effect upon the biological variety of the water environment. The paper analyses the study period (1996-2000) seasonal change of organic matter in the upper reaches of the River Nevezis (study sites upstream and downstream Panevezys). The highest amount of organic matter (according to chemical oxygen demand and biochemical oxygen demand) got into the river under the influence of concentrated pollution, the fewer amount - under the influence of agricultural pollution and in the course of natural processes. The concentration of organic substances in the river water had a seasonal character: rivers with a better ecological state (the Juosta) were more polluted with organic matter in spring, when water temperature was below 10 deg C, but rivers with a worse ecological state (the Nevezis upstream and downstream Panevezys) – in summer (water temperature was higher than 10 deg C). This may be related with fresh pollution; in the former case organic matter might have come from the environment together with the runoff, in the latter case - due to decomposition of water vegetation and fauna residues in the river itself. In all rivers water temperature was by 0.1-4.4 deg C higher in 1996-2000 in comparison to that in 1986-1989, a significant temperature increases were observed in winter and autumn. The water temperature arose mostly below the town.

Global warming undoubtedly influences the flow of rivers. It is essential to observe the climate changes, trace, analyse and forecast how they could influence the environment and, especially, how it can influence the flow of rivers. In this article two maximum flows of basins of two different rivers are analyzed: the river Venta (above Papile) and the river Krazante (above Pluskiai) during the period 1968–2008. Climatic parameters, such as the precipitation and the average air temperature, observed in the weather stations of Siauliai and Laukuva, influence the changes in flows the most. The correlation between the precipitation and maximum change of the flow was estimated though it was not strong: the ratio of correlation in the river Venta was 0.66, in the river Krazante the same ratio was 0.72. Significant negative trends of the both analyzed rivers during the spring period and significant negative trends of the river Venta during the period of winter have been established by the use of statistical analysis of the results obtained from a non-parametric Mann-Kendall test and linear regression test. This specific analysis is performed by using TREND programme. The collected data which were obtained to show that the most watery decade of the rivers Venta and Krazante were during the period 1978–1987, which formed 36% flow in the river of Venta and 35% in the river of Krazante for the whole period of forty years.

Approach of white box mathematical modelling was used to develop dynamic mathematical model of glycerol cycle in baker's yeast Saccharomyces cerevisiae and by deterministic simulations explore an interaction between glycerol cycle and glycolysis. The key process in research was reaction of artificially expressed glycerol-2-dehydrogenase (Gld2) which catalyses glycerol transition into dihydroxyacetone and reduced nicotinamide adenine dinucleotide phosphate (NADPH). We put forward hypothesis that expression of Gld2 in S. cerevisiae could increase concentration of reduced cytosolic NADPH. Michaelis-Menten equation was used to describe a rate law of reactions of the model of glycerol cycle. Kinetic parameters Km (Michaelis - Menten constant) and Vmax (maximal velocity of reaction) were taken from BRENDA database and publications. To perform deterministic simulations of the model of glycerol cycle and glycolysis, an accomplished model of glycerol cycle was introduced into the mathematical model of glycolysis of Nielsen et al. (1998). Results suggested that Gld2 reaction could run even without glycolysis as long as glycerol and oxidized nicotinamide adenine dinucleotide phosphate (NADP+) was present in the system. Intracellular concentration of glycerol had a direct impact on formation and acumulation of dihydroxyacetone. Reduced nicotinamide adenine dinucleotide (NADH) concentration decreased significantly and rapidly when glycerol cycle was switched on suggesting that it could be a limiting factor of the system.

Informatics is profoundly reshaping social relations and changing pupils’ education. A goal was set to offer the pupils an integrated informatics learning content, orientated to develop an emotionally and intellectually equilibrated and harmonic personality. The aim of the paper is to characterize the integration in the content of the subject of informatics and research the realisation of integrated learning material in educational practice. Subjects in the school curricula provide concrete guidelines on knowledge, skills and attitudes that should be taught and what goals and purposes their education program follows. To establish the understanding of pupils on development of taste in integrated informatics subject, an educational experimentation was conducted. The data are obtained by using a pretest-post-test design and analysis of teaching-learning informatics in classroom. Pupils at Lielvarde secondary school were asked to involve for learning a new integrated informatics material for developing their understanding of taste. The method of analysis of aesthetic and pedagogical literature and data processing and analysis by Wilcoxon signed-rank Test and Chi-square test are used. Pupils undertook independent practical tasks at the computer with the aim of developing their knowledge and cognitive skills (understanding, selection, reflection). Learning integrated informatics material is a pedagogical condition for fostering the development of pupils’ understanding of taste. Learning integrated informatics material executed diverse practical tasks with choice of color match, ethnographic characters and making a portfolio which enriched pupils' experience of taste and effectuated as acquisition of their cognitive skills.

Grain after enzymatic treatment, which is a starch-containing raw material, is used for ethanol production. Bioethanol production in Latvia began in 2006. Extraction of biofuels is a clean process, because the byproduct is used in various sectors of the economy. The bioethanol in Latvia was derived primarily from winter wheat, winter rye, and winter triticale. The objective of the research is to determine the different nitrogen fertiliser rates required for winter cereal crop yields and bioethanol outcome. The trials were carried out from 2005 to 2008 in Agricultural Science Centre of Latgale (Latvia). The method (ethanol outcome) is based on fermentation of saccharified cereal samples by yeast Saccharomyces cerevisiae followed by the calculation of ethanol outcome and speed of fermentation. The highest starch content was in winter wheat and winter triticale grain, but the lowest - in winter rye grains. A close negative correlation (p is less than 0.05) was found for winter triticale and winter wheat between the ethanol outcome and thousand grain weight. Production of bioethanol from rye starch content is used with full utilisation of grain. The winter wheat has the largest ethanol outcome from one hectare.

Maize (Zea mays L.) is one of the agricultural plants that is suitable substrate for biogas production. Fresh as well as ensiled maize can be used as biogas substrate. Practically, mainly maize silage is used because fresh maize is available only for short term during the vegetative period. The paper is aimed to determine the impact of ensiling on substrate composition of maize hybrids. A field trial was carried out in the Research and Study farm ''Vecauce'' of the Latvia University of Agriculture (LLU) in 2008 and 2009. Ten (in 2008) to eleven (2009) maize hybrids with different maturity rating according to FAO numbers (FAO 180 – 340) were harvested at three different times beginning on 5 September at fourteen-day intervals. Chopped maize samples of 1-3 kg were ensiled in plastic silos. Samples of fresh and ensiled (for at least 90 days) maize were analyzed detecting 14 parameters in the Scientific Laboratory of Agronomy Research of LLU using standard methods. Our results showed that ensilaging influence on organic dry matter and hemi-cellulose content was not substantial. High (p is less than 0.05) correlation between organic dry matter content of fresh and ensiled samples was noted. The crude protein, crude fibre, ash and cellulose concentration was greater in the ensiled samples if compared with fresh maize samples in 2008 and 2009. After ensilaging process neutral detergent fibre (NDF) concentration was higher compared with fresh samples in 2009 but lower in 2008.

The investigation was done at the Latvia State Institute of Fruit-Growing in Dobele in 2009, on the basis of an established field experiment planted in 1997 with apple (Malus domestica Borh.) cultivar 'Melba' (rootstock B9) trees spaced at 1.5 × 4 m distances. Three different treatments of soil moisture management were compared: control, sawdust mulch and fertigation. Soil of the experimental plot was Haplic Luvisol (Hypereutric), sandy loam, interspaced with Cutanic Luvisol, sandy loam. Organic matter – 25 g kgE-1, soil reaction pH – 6.5. Plant available P was 130.9, K – 157.7, and Mg – 102.2 mg kgE-1. The aim of the investigation was to determine nitrogen removal with fruit yield taking into consideration the used soil moisture regulation method – sawdust mulch or fertigation. The applied soil moisture regulation methods (mulch and fertigation) had significant influence on the content of dry matter in apple fruits (p is less than 0.05). The highest content of dry matter was found in the control treatment. A significantly higher nitrogen concentration (47 g kgE-1) in apple dry matter was in the control treatment, whereas in mulch and fertigation treatments nitrogen concentrations were lower (36 and 42 g kgE-1). The highest nitrogen concentration in dry matter was found in fruits with the biggest mass (r=0.61). A negative significant (p is less than 0.05) correlation was found between nitrogen concentration and trunk diameter (r=–0.85), and between nitrogen concentration and yield (r=–0.84). Removal of N was 24.4 kg haE-1 in the control, 22.3 kg haE-1 in the mulch, and 25.0 kg haE-1 in the fertigation treatment.