Darbe apibendrinami duomenys apie cezio-137 kaupimąsi dirvoje ir jo perėjimą į augalus bei gyvulio organizmą. Pateikti šio izoztopo pasiskirstymo ir kaupimosi įvairiuose gyvulių organuose bei audiniuose dėsniai, apžvelgti įvairūs metodai, mažinantys cezio-137 kaupimąsi ir greitinantys jo pasišalinimą iš gyvulių organizmo bei gyvulininkystės produktų. Tirtas pienas, mėsa, bulvės, grūdai ir geriamasis vanduo iš Šakių rajono. Buvo nustatomas 137Cs savitasis aktyvumas ir bendrieji alfa ir beta aktyvumai. Radiometriniai tyrimai atlikti radiacinės saugos centre. / We have summarized the data concerning accumulation of 137Cs in soil and the transition of the radionuclides to plants and animals. The presented survey gives some information about the distribution and accumuliation of 137Cs in different organs and tissues of animals about the possible methods of reducing the amount of radionuclides in the organism of animals and in products of animal origin. There was tested milk, meat, potatoes, grain and drinking water from Šakiai region. There was instituted the specific activity of 137Cs and general alpha and beta activities. The radiometric tests were performed in the Radiation Protection Centre.

Maisto radiologinio monitoringo, nustatant 90Sr ir 137Cs savituosius ir tūrinius aktyvumus, optimizavimo būdai nėra nagrinėti. Nenustatyta kaip maisto mėginių radiologinių tyrimų rezultatai atspindi radionuklidų kiekį visame suvartotame maiste. Šiuo metu negalima atsakyti į klausimą, ar šalies gyventojų apšvita dėl 90Sr ir 137Cs maiste jonizuojančiosios spinduliuotės, įvertinta pagal atliktų maisto radiologinių tyrimų rezultatus, buvo ir yra tikrai tokia, kokia buvo nustatyta ar nustatoma, t. y. trūksta duomenų apie tyrimų rezultatų reprezentatyvumą. Aplinkosauginiu ir ekonominiu požiūriu įvertinti maisto radiologinio monitoringo optimalumą bei parengti jo keitimui rekomendacijas dėl taršos aplinkoje lygių ir maisto produktų importo kaitos tendencijų yra aktualu, vengiant nepagrįstai didelių radiologinių tyrimų apimčių. Optimalus mėginių kiekis ir tinkamos mėginių rūšys įgalintų išvengti nepagrįstai didelės apšvitos gyventojams, tinkamai įvertinus vidutines dozes dėl maiste esančių 90Sr ir 137Cs jonizuojančiosios spinduliuotės. Maisto radiologinio monitoringo optimizavimas svarbus ir dėl pastarųjų metų tendencijų atskirose valstybėse, taip pat ir Lietuvoje, planuojant plėtoti branduolinę energetiką. Įvertinus naujų technologijų su jonizuojančiosios spinduliuotės šaltiniais plėtrą atskirose socialinėse ekonominėse srityse yra būtina optimali radiologinio monitoringo programa, garantuojanti gyventojų apsaugą nuo jonizuojančiosios spinduliuotės. / Optimization methods of radiological monitoring of food for the measurements of 90Sr and 137Cs activity concentrations are not estimated. No determination is made in which extent the results of measurements of activity concentration in the samples reflect the amount of radionuclides in all food consumed. The estimation of the ways for the optimization of radiological monitoring of food and preparation of recommendations for the changes in the monitoring program according the levels of radioactivity in the environment and amount of food imported is relevant for the optimization of measurement program not to extend the program and to save allocations. Optimization of food radiological monitoring program should help for the protection of the public to avoid exposure due to 90Sr and 137Cs in food when the average annual dose estimation is made correctly. Optimization of food radiological monitoring is important in nowadays when the planning of development of nuclear energy is going on in different countries including Lithuania. To take into account the development of new technologies using sources of ionizing radiation the optimization of food radiological monitoring program should assure the radiation protection of public.

The acidification and metal contamination of freshwater resources are major environmental concerns in many areas, with Sudbury (Ontario, Canada) having been amongst the most severely impacted. Many scientific investigations have examined the effects of these environmental stressors on aquatic systems, but relatively little is known about the biological recovery process following smelter emission reductions. Therefore, paleolimnological techniques were utilized to determine if diatom and scaled chrysophyte assemblages have recovered toward their pre-disturbance conditions as a result of reduced anthropogenic inputs. Pre-industrial algal assemblages were primarily dominated by circumneutral to alkaline and pH-indifferent taxa. However, there was a shift toward acid-tolerant species in all study lakes with the onset of open pit roasting and smelting operations. Coinciding with emission reductions, scaled chrysophyte assemblages in two of the three study sites have shown evidence of biological recovery. Given the population growth of the city of Sudbury over the last century, and the lack of scientific information regarding cultural eutrophication trends in the region, paleolimnological techniques were also used to track long-term biological changes within diatom assemblages related to cultural disturbances. Historically, oligotrophic diatom taxa primarily dominated the algal assemblages in each of the four study lakes. With the onset of urban environmental stressors there was a shift toward taxa which thrive in more productive systems. In addition, diatom assemblages appear to track increased lakewater pH through time. Finally, geochemical analysis tracked the increase in copper and nickel concentrations in lake sediment with the onset of open pit roasting and smelting activities and the subsequent decline in concentration with emission controls. Metal concentrations in recently deposited lake sediments remain elevated compared to pre-industrial concentrations. Paleolimnological studies comparing pre- and post-disturbance algal assemblages are of interest to lake managers as these data will aid in setting realistic mitigation targets for freshwater systems impacted by acidification, cultural eutrophication, and metal contamination, and will help gauge biological recovery mechanisms. Furthermore, this study provides insight in to the role other environmental stressors (e.g., climate change) may play in the biological recovery process. / Thesis (Master, Biology) -- Queen's University, 2008-07-10 12:04:59.828

In response to sulphur dioxide emission reductions in North America and Europe, there has been a recent shift in research focus towards understanding ecosystem recovery. Evidence for reversibility in the effects of acidification on lake ecosystems within North America has been, for the most part, constrained to a single locality (Sudbury, Ontario). Lakes in a fume-kill area near Wawa, Ontario, present a new and rare opportunity for studying potentially rapid chemical and biological recovery patterns from extreme acidification. Several lakes acidified (pH ~3) during a period of local iron sintering from 1939 to 1998, and although minimal historical data are available, striking biological recovery has recently been observed. This study used paleolimnological techniques to track diatom (class Bacillariophyceae) responses to historical water quality changes in five fume-kill lakes near Wawa. Prior to the onset of iron sintering, the sediment-recorded diatom assemblages were dominated by species that are typically found in circumneutral or slightly alkaline lakes. Following the known occurrence of lake acidification, there was a striking shift in the sediment record towards dominance by acid- and metal-tolerant species. Water quality of the fume-kill lakes has since improved (i.e. pH has increased from ~3 to ~7 and metal concentrations have decreased). In four of the five lake cores, this was reflected by a decrease in the relative abundance of acid-tolerant species. Surprisingly, diatom communities were not progressing towards pre-disturbance species assemblages. Factors impeding the return of native species might include metal enrichment in surface sediment and potentially altered lake thermal regimes. Documenting and understanding recovery trajectories is necessary to help lake managers evaluate policy decisions regarding the efficacy of emission reduction programs and mitigation measures. This thesis provides evidence from one location in addition to Sudbury that the ecological effects of severe lake acidification can be reversed if SO2 emissions are sufficiently reduced. It also further demonstrates the complexity of recovery patterns in acidified and metal-contaminated lakes. / Thesis (Master, Biology) -- Queen's University, 2009-04-26 18:38:20.58

A rapid detection method combining immunomagnetic separation (IMS), PCR and slot blot detection was developed for the detection of Salmonella and Listeria monocytogenes in milk. Bacteria were first isolated and concentrated from phosphate-buffered saline (PBS) or milk by IMS. After extraction from diluted bacteria culture with the extraction buffer, bacterial DNA was subjected to PCR. Slot blot assay was optimized and used to measure PCR products. The lowest level of detection by this method was 40 cfu/ml in PBS or milk for both pathogens. The whole detection procedure could be completed within 7 h. Moreover, this detection method is simple and easy to handle for a large number of samples. Using multiplex PCR (amplification of two different bacterial DNA in the same PCR tube) and slot blot, simultaneous detection of both bacteria was also assessed. The detection sensitivities of 103 cfu/ml for both bacteria were the same as when PCR and slot blot were used for each bacterium separately. The combination of IMS, PCR and slot blot seems to give a highly sensitive and time-efficient procedure, which could be used for routine detection of Salmonella and L. monocytogenes in milk.

In this study, pollen contamination (measured by the number of seeds pollinated by pollen not belonging to any of the clones on the seed orchard) is compared between open pollination and isolated pollination environments in a Scots pine (Pinus sylvestris) seed orchard called Västerhus, located outside Önsköldsvik. In this seed orchard a tent experiment is taking place. Skogforsk has built six large tents covering 12-14 trees with each tent. Fertilization patterns were compared between one tree in a tent with a supplementation of pollen from five clones not represented in the tent and another tree of the same clone subject to open pollination outside the tents. By using DNA markers the paternity was determined for 48 seeds from each tree. The results show a big difference in pollen contamination between the two trees. The tree inside the tent showed a contamination rate of 0% and the tree from the open pollination had a contamination rate of 20,5%. No difference was found in the numbers of different fathers although the selfing rate of 4,26% was higher in the tent than the selfing rate of 2,56% observed in the open pollination environment. These results match the results of other studies done on the same orchard pretty well and therefore tent isolation with a supplementary pollination can be a good way to reduce unwanted pollen contamination.

In this study, pollen contamination (measured by the number of seeds pollinated by pollen not belonging to any of the clones on the seed orchard) is compared between open pollination and isolated pollination environments in a Scots pine (Pinus sylvestris) seed orchard called Västerhus, located outside Önsköldsvik. In this seed orchard a tent experiment is taking place. Skogforsk has built six large tents covering 12-14 trees with each tent. Fertilization patterns were compared between one tree in a tent with a supplementation of pollen from five clones not represented in the tent and another tree of the same clone subject to open pollination outside the tents. By using DNA markers the paternity was determined for 48 seeds from each tree. The results show a big difference in pollen contamination between the two trees. The tree inside the tent showed a contamination rate of 0% and the tree from the open pollination had a contamination rate of 20,5%. No difference was found in the numbers of different fathers although the selfing rate of 4,26% was higher in the tent than the selfing rate of 2,56% observed in the open pollination environment. These results match the results of other studies done on the same orchard pretty well and therefore tent isolation with a supplementary pollination can be a good way to reduce unwanted pollen contamination.

The incidences of diarrhoeal episodes in infants and children have mostly been associated with the consumption of contaminated weaning foods. This is especially true in developing countries where factors such as the lack of sanitation systems and electricity have been found to contribute to an increase in the incidence of microbiologically contaminated weaning foods. The process of fermentation has been found to reduce the amount of microbiological contamination in such foods as a result of the production of antimicrobial compounds such as organic acids, peroxides, carbon dioxide and bacteriocins. In this study, microbiological surveys were conducted on sorghum powder samples and their corresponding fermented and cooked fermented porridge samples collected from an informal settlement of the Gauteng Province of South Africa. The process of fermentation was found to result in significant decreases (P>0.05) in Gram-negative counts and spore counts, while aerobic plate counts decreased slightly. Lactic acid bacteria counts, however, increased significantly (P>0.05). The cooking process was found to result in further significant decreases (P>0.05) in all counts. Sorghum powder samples and fermented porridge samples were found to be contaminated with potential foodborne pathogens, including Bacillus cereus, Clostridium perfringens and Escherichia coli, however, none of the pathogens tested for were detected in any of the cooked fermented porridge samples. SDS-PAGE and phenotypic analysis of 180 lactic acid bacteria isolated from sorghum powder samples and their corresponding fermented and cooked fermented porridge samples showed that a majority of the isolates were lactobacilli and leuconostocs, however, some isolates were identified as pediococci and lactococci. These results demonstrated the heterogeneity of the lactic acid bacteria isolates that were associated with fermentation processes in this study. Of the lactic acid bacteria identified, Lactobacillus plantarum and Leuconostoc mesenteroides strains were found to have the highest distribution frequencies, being distributed in 87% and 73% of the households, respectively. Analysis of Lactobacillus plantarum (58) and Leuconostoc mesenteroides (46) strains isolated from sorghum powder samples and corresponding fermented and cooked fermented porridge samples by AFLP fingerprinting showed that they originated from a common source, which was sorghum powder. There was, however, evidence of strains that may have been introduced at household level. Antimicrobial activity of selected lactic acid bacteria was found to be mainly due to a decrease in pH in fermented and cooked fermented porridge samples. None of the lactic acid bacteria tested seemed to produce bacteriocins.

Casein – the main albumen constituent of milk. Food casein is used in the production of caseinat. Caseinats are used in the production of food concentrates, medicines, and cheese products. In addition, they may be used as casein glue. Goals of thesis. To determinate total bacterial contamination of acid casein edible, isolate and identify pathological microorganisms. 1. To determine the general bacterial contamination of edible acid casein samples. 2. To determine the influence of thermophylic bacteria on the general bacterial contamination. 3. To determine the general bacterial contamination of repeatedly researched edible acid casein samples and the presumable quantity of coliformic germs. 4. To define and identify the patological microorganisms out of edible acid casein samples. 5. To determine the chemical composition of edible acid casein samples. Results. Micro flora of crude milk constitutes certain part of micro flora, found in powdered milk. However, the increased level of general contamination and coliform germs shows the signs of secondary contamination. The enlarged bacteriological contamination, which exceeded the preset limit of 3.0x104 CFU/g, was identified in 3 per cent of analyzed acid casein edible samples. This was caused by impurity of crude milk. During the acid casein edible casein production process, the temperature of pasteurization was reached twice and in addition to that, comparatively low pH was maintained. These conditions are not hospitable for... [to full text]

Natural attenuation of trichloroethene (TCE) and technetium (99Tc) was studied for five consecutive seasons (from January 2002 to January 2003) in Little Bayou Creek. The stream receives ground water discharge from an aquifer contaminated by past waste disposal activities at the Paducah Gaseous Diffusion Plant (PGDP), a uranium enrichment facility near Paducah, Kentucky. Results from stream gaging, contaminant monitoring, tracer tests (with bromide, nitrate, rhodamine WT and propane) and simulation modeling indicate the TCE is naturally attenuated by volatilization and dilution, with volatilization rates related to the ambient temperature and surface discharge rate. The only apparent mechanism of 99Tc attenuation is dilution. Travel times of non-gaseous tracers were found to be similar and have highest values in October and lowest in June. It was also estimated from modeling that the transport of the solutes in the stream was mostly one-dimensional with insignificant secondary storage.