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Wind-wave relationship: a case of the Lithuanian coast of the Baltic Sea Full text
2013
Kasiulis, E., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania) | Punys, P., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania)
In this paper regression analysis was adopted to assess the wind-wave relationship between wind speeds and wave heights on the Lithuanian coast of the Baltic Sea. In the coastal observations register missing data of visual wave observations occur because of the fog, ice, evaporation or other meteorological phenomenon. There is also inconsistency in instrumental measurements of wave heights in the Lithuanian coast due to technical issues. First step to fill the gaps in the wave height data is to find a strong relationship between wind speeds and wave heights. In this study correlation coefficients for Nida and Klaipeda coastal hydrometeorological stations data both taking and not taking into consideration wind blowing directions were calculated. Every data set used in this study was treated separately and it was revealed that applying nonlinear regression the most common model for wind-wave relationship analysis on Lithuanian coast is DR-Hill model, while applying multivariable regression it is Full Cubic model. Relationship between wind speeds and wave heights always can be improved by removing swell waves from correlation.
Show more [+] Less [-]Advantages of the pneumatic pulse method for dehydration of the sewage sludge Full text
2013
Gusarevs, I., Latvia Univ. of Agriculture, Jelgava (Latvia)
Utilization of the sewage sludge is pressing and crucial environmental and economic challenge. High moisture content of the sludge is one of the main difficulties during the process of the sewage sludge utilization. Experimental drying module has been designed and manufactured to identify and verify effectiveness of the main parameters of the thermal drying of the sewage sludge with application of the pneumatic pulse method. The pulser is supposed to be part of the technological scheme in order to speed up the process of drying and saving energy. The pulser supplies hot air into the drying chamber with time intervals by pulse. In the drying chamber the airflow dislodges water molecules from the material by means of pulses and then they are taken away from the drying chamber. For the convenience of the comparison and evaluation of the executed experiment the following general characteristics were selected: drying rate – i – kg minE-1; power consumption – q – kWh kgE-1. The greatest effect in application of the pneumatic pulse method for dehydration of the sewage sludge was achieved at the angle of incidence equal to nearly 90° of the airflow on the dried sample and higher temperature. The experiment showed that application of the pneumatic pulse method for dehydration of the sewage sludge allows to reduce power consumption and speed up the process of drying. The process of drying can be executed at lower temperatures.
Show more [+] Less [-]The change of water quality in the sinkholes in Lithuanian karst zone Full text
2013
Rudzianskaite, A., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania)
The paper overviews the research material related to occurrence of sinkholes and change of their water quality in the conditions of increasingly natural environment and minimal anthropogenic impact. Sinkholes create favourable conditions for interaction of surface and groundwater. Identification of possible sources of sinkholes pollution is very important in solution of groundwater safety problems. Water quality investigations are carried out in 4 sinkholes, which are of different age and have differently overgrown slopes. Sinkhole water quality may worsen due to accumulation of organic materials (increasing peat content) or natural changes of environment (abrasion of slopes, overgrowth, etc.), while anthropogenic impact is minimal. Water quality in peat-filled sinkholes and young sinkholes with mineral slopes is different. Water of peat-filled sinkholes has bigger amounts of N-NO3, PTotal, SO4 and BOD7 than water in young sinkholes. The highest N-NO3 and SO4 concentration is observed in the sinkhole that is overgrown with trees and shrubs.
Show more [+] Less [-]Impact of the fields, fertilized with manure from big livestock companies on drainage water quality Full text
2013
Miseviciene, S., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania)
The paper presents data on the water quality in drainage from manure-fertilized areas in a large livestock company (629 conditional livestock) from 2008 to 2012. The scheme of investigation consists of two field variants: manure fertilized and non-fertilized. Researches are carried out in drained areas, where the drainage water is drained away through outlets. The nitrogen rate 170 kg haE-1 is used annually to fertilize fields in spring. The aim of the research was to ascertain the impact of large livestock company fields fertilized annually with manure on the water quality in drainage. For the purpose of chemical investigations, water samples from drainage were taken once per month. Water analyses were carried out by the accredited Chemical Analytical Laboratory of the Water Management Engineering Institute of Aleksandras Stulginskis University according to specified methods. Investigation results have demonstrated that fields fertilized annually with manure raised the contents of Nmin and P2O5 in the soil by 1.5 and 2.2 times respectively in comparison to the non-fertilized ones. The increase in these contents was conditioned by the higher air temperature and the lower rainfall. The seasonality of Ntotal concentrations in drainage water was discovered: higher concentrations were identified in autumn and winter, lower concentrations – in spring and summer. Due to low dissolubility in the soil, low Ptotal concentrations were identified in drainage water. The highest concentrations were identified with the start of drainage operation.
Show more [+] Less [-]Food wastage problems in a perspective of eating habits: a review paper Full text
2013
Tokareva, T., Latvia Univ. of Agriculture, Jelgava (Latvia)
Even though thousands of people suffer from hunger each day, there are people that simply throw away their food, imposing serious environmental, social and economic consequences. Food waste concept, however, is not as strictly defined as it varies from research to research. The classification itself can be specific to certain regions and cultures, and it can even be affected by the eating habits of the researchers. This review paper aims to unify the theoretical knowledge of food wasting with examples from actual research, evaluating data from the perspective of eating habits and finding motives for such an action, such as family and friends’ influence, incomes, lifestyle, religion, mass media etc. Previously done studies show that people are less concerned about reducing food wastage when it comes to environmental and social problems, but are the most motivated if they see a real opportunity to save money.
Show more [+] Less [-]The potential influence of social networks on the adoption of breeding strategies Full text
2013
Pali, Pamela N. | Zaibet, L. | Mburu, S.K. | Ndiwa, Nicholas N. | Rware, H.I.
Smallholder livestock farmers face challenges such as lack of appropriate fora and networks which can motivate and influence the adoption of breeding strategies in West Africa. Efforts to ensure participation of livestock owners in breeding programs such as performance recording, the use of village herd stocks for breeding programs have been documented as has the creation of livestock producer organizations to enhance effective participation of farmers in breeding programs. The study was conducted in southern Mali where livestock such as the N’dama cattle are endemic. We explored baseline characteristics from a household and community survey to determine the potential effects of individual, household and network characteristics on the knowledge and use of livestock breeding strategies. We assume that interaction amongst stakeholders results in transfer of knowledge between stakeholders. Results from the stakeholder analysis of the types of stakeholders present at the site level were used in the Probit and Seemingly Unrelated Regression (SUR) models. Farmers’ organisations were commonly found at the village level. However, despite the presence of these organizations across sites, they do not interact with the technical organisations as often as they should hence a lower incidence of use of livestock breeding technologies across sites. Results from the models confirm the importance of networks as key determinants to improve the adoption of breeding technologies.
Show more [+] Less [-]Evaluation of European pear rust severity depending on agro-ecological factors Full text
2013
Lace, B., Latvia Univ. of Agriculture, Jelgava (Latvia);Latvia State Inst. of Fruit-Growing, Dobele (Latvia) | Bankina, B., Latvia Univ. of Agriculture, Jelgava (Latvia)
Pear (Pyrus communis L.) fruits in Latvia are very popular, although orchard areas are not large. In the commercial orchards the control of plant pathogens mainly is performed using a plant protection plan, based on long-term observations. European pear rust caused by Gymnosporangium sabinae (Dicks.) G. Winter has become during recent years one of the most important diseases in Latvian pear orchards. Pathogen G. sabinae has a complex development cycle, with four types of spores on two different plants: pear and junipers. Favourable development of each stage depends on the specific environmental conditions. The aim of the study was field evaluation of the disease severity depending on agro-ecological factors. The study was performed at the Latvia State Institute of Fruit-Growing from 2008 to 2012. The severity of European pear rust infection on leaves of cultivars was evaluated in points 0–5, where: 0 – a tree has no infected leaves; 5 – 81% to 100% infected leaves. The disease severity during these years, impact of tree planting year, rootstock, cultivar and tree location in the plot were analyzed. Results gave the opportunity to determine which factors have positive influence on the development of pathogen and severity of disease. Severity of disease was not directly dependent on cultivar, their country of origin, rootstock and planting year. Severity of disease was influenced by tree location in the orchard; higher severity was observed on larger and more vigorous trees, located in outer rows, exposed to the prevailing wind carrying pathogen spores.
Show more [+] Less [-]Metal uptake from contaminated soils by some plant species - radish, lettuce, dill Full text
2013
Stapkevica, M., University of Latvia, Riga (Latvia) | Vincevica-Gaile, Z., University of Latvia, Riga (Latvia) | Klavins, M., University of Latvia, Riga (Latvia)
Plants are components of ecosystem that transfer elements from abiotic to biotic environments. Several elements, such as As, Cd, Hg, Pb, can be considered as food chain contaminants. Simultaneously, some essential micronutrients (e.g., Cu, Cr, Ni, Zn) at high concentrations may become toxic to both, plants and animals. To secure the aim to describe the uptake of metals by food crop species such vegetables, as radish Raphanus sativus L., leafy lettuce Lactuca sativa L. and dill Anethum graveolens L., were grown in soils of various grading composition and type. There were five soil types selected. A part of soils was contaminated with copper sulphate solution at different target concentrations, while another part was contaminated with mixture of metal (Pb, Cd, Cu, Zn) compounds. In half of treated soil samples the solution of humic substances was added. Harvested vegetables were dried, and after wet digestion with nitric acid quantitative analysis of metal concentrations was performed by use of atomic absorption spectrometry. The highest concentration of copper was detected in vegetable samples grown in soils with less organics, thereby indicating the importance of soil organic matter to metal transfer routes and accumulation rates in plants. Analysis of lettuce grown in soils contaminated with the mixture of metal compounds revealed that zinc was a metal absorbed more intensively, but metal uptake and accumulation was less intensive from peat if compared with other soils.
Show more [+] Less [-]Effect of hydrogen peroxide on the quality parameters of shredded carrots Full text
2013
Augspole, I., Latvia Univ. of Agriculture, Jelgava (Latvia) | Rakcejeva, T., Latvia Univ. of Agriculture, Jelgava (Latvia)
The main purpose of the present experiments was to investigate the effect of various hydrogen peroxide (H2O2) concentrations and for various lengths of treatment on the total carotenoid, β–carotene content, colour intensity and microbiological safety on the fresh shredded carrots. Shredded carrots were dipped in 0.5, 1.0 and 1.5% H2 O2 water solution for 30 ± 1s, 60 ± 1s and 90 ± 1s. Negative effect of H2 O2 on β–carotene content and colour parameters of analyzed shredded carrots samples was not detected. In carrots treated with H2 O2 (p = 0.008) for 60 – 90s the total content of carotenoids significantly decreased during treatment compared to untreated carrot samples. There was significant difference (p is less than 0.05) observed between treated and non–treated shredded carrot samples on the total bacteria count. It was possible to reduce significantly (p is less than 0.05) the content of yeasts and mould up to 99.99% by shredded carrots treatment with 1.5% hydrogen peroxide water solution for 30 ± 1s. In the non–processed carrots E.coli was detected; however, it was possible to destroy E.coli by treating carrots with 0.5% H2 O2 water solution for 30 ± 1s. Considering all experimentally obtained results, we have concluded that fresh shredded carrots could be treated in water with the addition of hydrogen peroxide 1.5% for 30 ± 1s to maintain quality.
Show more [+] Less [-]Comparison of different solvents for isolation of phenolic compounds from horseradish (Armoracia rusticana L.) leaves Full text
2013
Tomsone, L., Latvia Univ. of Agriculture, Jelgava (Latvia) | Kruma, Z., Latvia Univ. of Agriculture, Jelgava (Latvia)
Horseradish (Armoracia rusticana L.) is a perennial herb belonging to the Brassicaceae family and contains biologically active substances. The aim of the current research was to determine the most suitable extraction method and solvent for obtaining horseradish leaf extracts with high antiradical activity. For experiments fresh leaves of horseradish were extracted with seven different solvents: n-hexane, diethyl ether, 2-propanol, acetone, ethanol (95%), ethanolwater/acetic acid (80/20/1 v/v/v) and ethanol / water (80/20 by volume) using two extraction methods (conventional and Soxhlet). For all extracts, total phenolic, flavonoid content and DPPH˙, ABTS radical scavenging activity, and reducing power were determined using a spectrophotometric method. As the best solvent can be used ethanol. Total phenolic content and total flavonoid content was higher in Soxhlet extracts. Comparing to other plants, the proportion of flavonoids in the amount of total phenolics is average, and it increases by increasing the polarity of used solvent. It can be concluded that by using Soxhlet extraction method it is possible to obtain extracts that are effective antioxidants. A very strong and a strong correlation has been identified between levels of phenolic compounds and antioxidant capacities of the extracts.
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