Floc-pathogen interactions are important determinants of the fate of pathogens in aquatic systems. The dissociation of bacteria from particles due to shear stress can significantly increase the presence of free-floating pathogenic bacteria in the aqueous phase. This has implications for pathogen transport and water quality. This study evaluated the interactions of water-borne pathogens with particles in selected aquatic ecosystems. Three experimental chapters and one concluding chapter is presented. Chapter 3 assesses the strength of the floc-microorganism association under different energy levels in relation to the physico-chemical properties and the bioorganic content of flocs from six different aquatic environments (SB, CSO, RF, AG, ML, MN); Chapter 4 evaluates how energy dissociates bacteria and affects microbial diversity in free-floating and particle-associated fractions in cohesive bed sediments (BedS) and suspended flocs (SusF) of three sites (SB, CSO, RF). Chapter 5 studies the diversity and succession among free-floating and particle-associated bacteria at different energy levels and the abundance of antibiotic resistance genes and Class 1 integrons (intI1) as a result of ecosystem perturbation in the six initial sites. Different strategies, such as standard laboratory analytical methods, as well as techniques based on analytical chemistry, biochemistry and molecular biology were used to accomplish these objectives. The bioorganic and physico-chemical properties of flocs and sediments, and the energy effects these structures are exposed to, play a role in the assessment of pathogen risk in water systems. Molecular approaches showed a significant difference in the composition of free-floating and particle-associated assemblages after simulated flow conditions and detected earlier differences in the dissociation of bacteria, compared to plating techniques. The analysis of integrons provided evidence for horizontal gene transfer events. Free-floating and particle-associated bacterial assemblages are potential genetic reservoirs for antibiotic resistance genes. This research shows that particles act as reservoirs for microorganisms, providing an early warning for potential indicators of human health risk in water systems and could determine the presence of future clinically relevant antibiotic resistance mechanisms and/or pathogenic microbial gene transfer in sediments, demonstrating the need to improve the existing protocols and methodologies that assess water quality. / Natural Sciences and Engineering Research Council of Canada (NSERC)

Intensity and types of land use have changed rapidly in the last century and in north-western Alberta this has coincided with the decline of Wapiti River watershed Arctic Grayling (<italic>Thymallus arcticus</italic>) populations. Data on diurnal dissolved oxygen (DO), chemical and physical stream habitat data were collected in nine sub-watersheds of the Wapiti River with historically abundant Arctic Grayling populations. Levels and fluctuations of DO and temperature were related to the status of populations; five of the nine streams had higher temperatures and lower DO during summer, anoxic conditions during winter and extirpated populations. Amount of disturbed land and road density within sub-watersheds were inversely related to DO levels and population status. Cumulative effects modelling suggests a possible mechanism for these relationships is increased phosphorous runoff, leading to impaired habitat. These relationships and thresholds may be used as a management tool to maintain or restore Arctic Grayling and other stream fishes.

Lietuvoje kaip ir daugelyje pasaulio šalių dedama daug pastangų, kad vandenų tarša mažėtų. Pagal valstybinio monitoringo duomenis nustatyta, kad Lietuvos upėse vis dar išlieka didelės biogeninių medžiagų koncentracijos. Vandens tarša yra viena iš pagrindinių ES aplinkosaugos problemų. Norint išsiaiškinti pagrindines vandens taršos problemas, būtina atlikti nagrinėjamos upės vandens kokybės parametrų matavimus. Tam tikslui nuo 2010-11-06 iki 2013-05-07 buvo atliekami vandens kokybės tyrimai, kurių metu buvo fiksuojami šie parametrai: vandens lygis, ištirpusio deguonies koncentracijos, aktyvi vandens reakcija (pH), bendrosios mineralizacijos, elektrinio laidžio, nitratų ir vandens temperatūros kaita. Vandens kokybės parametrai matuoti aukščiau ir žemiau Akademijos tvenkinio, kuris susidarė 1968 m. ant Dotnuvėlės upės ties Akademijos gyvenviete. Pagal minėtus duomenis buvo nustatyta vandens kokybė atskiruose Dotnuvėlės ir jos intako Kačiupio upių taškuose. Atlikus tyrimą buvo nustatyta, kad Akademijos tvenkinys sąlygoja nitratų pasiskirstymą upėje, t. y. pastebėtas nedidelis nitratų padidėjimas upėje žemiau tvenkinio. Nustatyta, kad bendroji mineralizacija rudenį didėjo, žiemos metu svyravo, o pavasarį mažėjo. Pagal ištirpusio deguonies kiekį visose matavimo stotyse vanduo atitiko labai blogą, blogą, vidutinę, gerą arba labai gerą būklę. Vandens lygis Akademijos tvenkinyje tiriamuoju laikotarpiu svyravo 0−19 cm ribose stoties „O“ atskaitos atžvilgiu. Kitų išmatuotų vandens... [toliau žr. visą tekstą] / In Lithuania, as well as in other countries of the world, great efforts are made to reduce water pollution. According to the national monitoring data, there is still a high concentration of biogenic substance in Lithuanian rivers. Water pollution problem is one of the key EU environmental issues. In order to find out the main water pollution problems, it is necessary to conduct the measurements of water quality parameters of the investigated River. For this purpose, from 06/11/2010 to 07/05/2013 water quality measurements were carried out, during which values of the following parameters were recorded: water level fluctuations, dissolved oxygen concentration, pH, total dissolved solids, the variation of nitrates and water temperature. Water quality parameters were measured upstream and downstream the pond at Akademija settlement. In accordance with the given data, water quality was identified in several points of Dotnuvėlė and Kačiupio rivers. The research revealed that the pond of Akademija determines nitrate distribution in the river, i.e. a slight nitrate increase was observed in the river below the pond. It was disclosed that in autumn total dissolved solids increased, in winter the concentration varied and it decreased in spring. According to the amount of dissolved oxygen at all measurement stations, water corresponded to a poor, extremely poor, moderate, good or extremely good condition. During the research period, water level in the pond of Akademija ranged from 0-19... [to full text]

Lietuvoje ežerų vandens kokybė kasmet kinta. Joje pastebimi gerėjimo ir blogėjimo pokyčiai. Darbe pateikti 2001-2010 m. monitoringo duomenys, iš Lietuvos Respublikos aplinkos apsaugos ministerijos Aplinkos apsaugos agentūros apie (pH; T°C; O2; BDS7; NH4; NO3; Min N; Bendr. N; PO4-P; P bendr.; Savitasis elektros laidis) koncentracijas ir dydžius Platelių, Lūksto, Rėkyvos, Kirkilų, Švento, Drūkšių, Alnio, Žuvinto, Dusios, Vištyčio, Balsio, Rubikių, Tauragno ežeruose. Nors vandens telkinių kokybė Lietuvoje nėra prasta, 6 proc. šalies ežerų būklė laikoma net labai bloga ir ją būtina gerinti. Specialistai aiškina, kad ežerų valymas - brangus, todėl daugiau dėmesio skiriama ne teršalams šalinti, o taršos prevencijai. Duomenims apibendrinti taikytas klasterinės analizės metodas. Šis metodas leidžia nustatyti koncentracijų variacijos panašumus ir skirtumus skirtinguose ežeruose. Tyrimai parodė, kad daugiausia panašumų pagal pH; T°C; O2; BDS7; NH4; NO3; Min N; Bendr. N; PO4-P; P bendr.; Savitasis elektros laidis kaitą turi Kirkilų, Rėkyvos, Lūksto, Vištyčio, Žuvinto ežerai. / Lithuania Lakes water quality varies year to year. It noticeable improvement and deterioration of the changes. The work presented in 2001-2010. monitoring data from to Lithuanian Republic the Ministry of Environment The Environment Protection agency about (hydrogen ions, temperature, oxygen, biochemical oxygen demand, ammonium nitrogen, nitrates, mineral nitrogen, total nitrogen, phosphate phosphorus, the total phosphorus, specific electrical conductivity) concentrations and sizes Platelių, Lūksto, Rėkyvos, Kirkilų, Švento, Drūkšių, Alnio, Žuvinto, Dusios, Vištyčio, Balsio, Rubikių, Tauragno lakes. Although water quality in Lithuania is not poor, 6 percent. status of a lake, even very bad and needs to be improved. Experts argue that lakes treatment - expensive, so the focus shifted to remove contaminants and pollution prevention. The data summarized in applied cluster analysis method. This method allows determining the variation in the concentrations of similarities and differences between the different lakes. Studies have demonstrated that the similarity between the (active water reaction, temperature, oxygen, biochemical oxygen demand, ammonium nitrogen, nitrates, mineral nitrogen, total nitrogen, phosphate phosphorus, the total phosphorus, specific electrical conductivity) change have Kirkilų, Rėkyvos, Lūksto, Vištyčio, Žuvinto lakes.

Land use/land cover (LULC) change and variations in precipitation can alter the quantity and quality of freshwater flows. The Mission-Aransas (M-A) estuary depends on inputs of freshwater and material from streams in order to maintain its ecological integrity. Freshwater inflow estimates for the M-A estuary have been established, but no analyses using scenarios of LULC change and precipitation variability have been conducted that inform how freshwater inflows could be impacted. A land change analysis for the M-A region was conducted by classifying two Landsat images for the years 1990 and 2010. A large degree of LULC change occurred within the M-A region during this time; with 27.1% of the land area experiencing LULC change. Furthermore, developed land increased by 44.9%. A SWAT hydrological model was developed to model the quantity and quality of freshwater inflows. SWAT was calibrated at a monthly scale using data from a stream gage. Model evaluations indicated that the model had a good performance rating with a Nash-Sutcliffe model efficiency coefficient (NS) of 0.66 and coefficient of determination (R2) of 0.66 for the calibration period; and an NS of 0.76 and R2 of 0.78 for the validation period. Three LULC change scenarios and three precipitation scenarios were developed to be used in a scenario analysis with the calibrated SWAT model. Each LULC change scenario represents a different amount of developed land (3.4, 3.7, and 4.7% of watershed area). Precipitation data was analyzed to select weather data for each precipitation scenario that each had different amounts of annual precipitation (763, 907, and 996 mm). A scenario analysis was conducted that analyzed how stream/channel flows and loads of sediment, total nitrogen, and total phosphorus were impacted under scenario conditions. A general increase in all output variables was exhibited as the amount of precipitation and developed land increased; with impacts from precipitation variability outweighing impacts from varying amounts of developed land. Furthermore, sediment loads were the variable most impacted by differing amounts of developed land. This study provides information on how LULC and precipitation can influence watershed hydrology that can be used in watershed management for the M-A region.

No description available.

Forest clearance can affect the levels of dissolved organic carbon (DOC), nutrient concentrations and algal biomass in streams, but the possible effect of these inputs on downstream lakes is usually surmised rather than demonstrated. To evaluate the effect of forest clearance on DOC and nutrient cycling in lakes, DOC, total phosphorus (TP), total nitrogen (TN) and chlorophyll (chl a) concentrations were measured in 47 Canadian Shield lakes in Quebec. Of these lakes, 25 were located in drainage basins that were partially clear-cut one to four years previously. In the disturbed sites, an uncut 20-m bufferstrip was left around the lakes and permanent water courses. / To account for differences among the watersheds that are not related to forest harvesting, I also collected a series of catchment and morphometric variables (watershed area, lake area, drainage ratio, forest, wetland, and upstream lake area, watershed slope, water residence time and lake depth). Lake characteristics in undisturbed and disturbed watersheds were compared to determine if forest clearance has a detectable effect on the water quality of downstream lakes. Although comparisons of seasonal and monthly means of the water quality variables between disturbed and reference sites were inconclusive, likely because of high natural variability, the size of the clear-cut was significantly related to means of the water quality characteristics. DOC, TP, TN and chl a increased in lake water with the area of the clear-cuts when large portions of the watershed ($>$50%) were cleared. The results of this study suggest that logging has an effect on water quality and even though a bufferstrip of twenty meters reduces this effect largely, it may not be enough to provide complete protection against the effects of logging activities.

The Indus Basin Irrigation System (IBIS) irrigates 16 million ha of land in Pakistan. The irrigation water is also used for domestic consumption in rural areas and where the ground water is brackish. Many major cities and towns dispose their untreated wastewater directly into the irrigation canal network, which ultimately has adverse impacts on the downstream water quality. In order to better understand the water quality variations, several parameters were measured along a 45 km long irrigation canal (Hakra-6R) in Punjab, Pakistan during the year 2000. The parameters measured were: biochemical oxygen demand (BOD), nitrate (NO3), ammonia (NH3), Escherichia coli (E.coli), dissolved oxygen (DO), pH, and water temperature. The PC-QUASAR model was used as predictive tool to simulate the water quality concentrations along the downstream locations of Hakra-6R canal. The measured data were used to validate the PC-QUASAR model. The model efficiencies ranged from 0.40 to 0.96 for selected parameters. A sensitivity analysis showed that the nitrification, denitrification, BOD sedimentation, and BOD algae rate were the most sensitive parameters of model performance. The BOD decay and sediment oxygen rates have negligible influence on model output. Water quality analysis showed that irrigation water was highly contaminated regarding microbiological aspects (E.coli &sim; 4000 N/100ml).

<p>This study forms part of a broader project co-funded by the Water Research Commission (WRC), and CSIR Parliamentary Grant (PG) and Strategic Research Panel (SRP) research grants, aimed at surveying selected water resources within the 19 Water Management Areas in South Africa. Furthermore, it aims at determining the concentrations of Hg and MeHg in various environmental compartments collected from priority water resources, to identify the potential Hg hotspots, and to assess the degree of compliance with national and international guidelines. Mercury concentrations in the environment have increased globally and this has caused much anxiety in terms of the adverse effects it has on aquatic ecosystems, their organisms, and the communities they sustain. Human health risks associated with the consumption of fish elevated containing Hg concentrations have received minimal attention particularly in South Africa. It is imperative that any potential adverse impacts of Hg on aquatic ecosystems, and the subsequent impacts on human health, be investigated.</p>

<p>The aim of the study was to quantify the extent of inorganic chemical pollution of the Franschhoek River and draw relationships between contaminants in water, sediment and plants. The invasive Acacia mearnsii and Salix babylonica and indigenous Brabejum stellatifolium species were chosen as biomonitors due to their wide spread distribution along the river and their apparent ability to accumulate heavy metals. The sites chosen allowed for comparison of the river quality upstream with that of the river further down stream as it meandered through residential, agricultural and recreational areas, until it joined with the Berg River further downstream. The general aim of the study was to assess the degree of inorganic pollution in the Franschhoek River to evaluate its contribution to pollution of the Berg River, of which it is an important tributary. Also understanding the sources of the pollution would contribute to the ability to reduce pollution.</p>