This study aims to assess the potential environmental risks posed by sediments in five lakes affected by present or historical metallurgy. Special attention is paid to the lakes Dammsjön and Värlingen in mid Sweden, where the sediments were contaminated after a breach in a nearby tailings dam used for storing residue from a metal processing plant. The sediments were examined for their metal content by X-ray fluorescence spectroscopy (XRF) analysis of loose powder samples. A subset of the samples from Dammsjön and Värlingen was also used for a simple pH-analysis and an experimental XRF analysis of evaporated leachate. To obtain a larger variety of samples for the XRF analysis of evaporated leachate, loose powder sediment and leachate from three additional lakes affected by extractive metallurgy, Tisken, Gruvsjön and Storjuktan, were likewise examined with XRF. The sediments from all lakes contained high levels of metals, and environmental standards for Pb (in all lakes) and Cd (in Storjuktan) were exceeded. The leachate tests showed that metals can be extracted using this method, including Cu and Ni in lake Tisken. This might indicatehigher bioavailability, but further studies are needed to confirm this interpretation. Dammsjön andVärlingen are contaminated by several metals, including Hg and As. The pH-analysis indicated that the deposited sediment is not the source of the prolonged low pH in Dammsjön, and that another source, possibly continued leaks from the tailings dam, needs to be found. The results call for close environmental monitoring, to minimise further contamination and damage to the environment.

No description available.

This study is designed to (a) demonstrate the highly productive nature of the littoral area as compared to the pelagic region, (b) the possible importance of phyco-periphyton in the diets of fish, (c) the effects of meteorological conditions on distribution of phytoplankton, and (d) a demonstration of the invalidity of using artificial substrates as a universal means of measuring productivity.

<p>Lakes and wetlands cover a large portion of the earth’s surface and play a crucial role in hydrology. They provide permanent and temporary storage for water within the landscape allowing for greater infiltration and evaporation along with a reduction in peak flooding events. Lakes and wetlands also provide many other non-hydrological benefits such as their ability to improve water quality and provide wildlife and fisheries habitat. Despite their known benefits, wetland destruction has been a prominent issue for many years. This study quantifies the hydrologic effects of lakes and wetlands by introducing a parametrization method for hydrologic model simulations in the North American Land Data Assimilation System (NLDAS) domain. Lake profiles were created based on the geospatial lake depth-area relationship through interpolation of known lake depths and areas throughout the domain. Wetlands were parametrized based on topographic wetness index (TWI) calculated using high-resolution DEM imagery. Wetland profiles were created using a binning technique along with the DEM and land use classifications. The Variable Infiltration Capacity (VIC) macroscale hydrologic grid-based model and its associated lake and wetland algorithm were used to quantify the effects of lakes and wetlands on streamflow. Profiles were generated for every corresponding VIC grid cell in the NLDAS domain, but for this study two watersheds, the Buttahatchee River in Mississippi and the Black River in North Carolina, were selected to test the parametrization and quantify the impact of lakes and wetlands on watershed hydrology. The Buttahatchee River watershed contains 6.6% lakes and wetlands, which were predominantly clustered near the stream channel, and the Black River watershed contained 19.2% lakes and wetlands which were spread out across the entirety of the watershed. Simulated daily streamflow with and without the lake and wetland algorithm activated was used to evaluate impacts on flood frequency as well as components of the water balance. Flood magnitude decreased due to the presence of lakes and wetlands. This decrease was 5.8% and 29.6% for a 10-year return period flood for the Buttahatchee River and the Black River sites, respectively. Mean annual flowrate decreased significantly as a result of lakes and wetlands indicating storage of water in the lakes and wetlands allowed for a greater degree of evapotranspiration. There were 1.6% and 10.9% decreases in average streamflow rates as well as corresponding 0.3% and 4.1% increases in annual evapotranspiration in the Buttahatchee River and Black River watersheds, respectively. While lakes and wetlands reduce peak flood events and decrease average streamflow rates through increased storage and evapotranspiration, the magnitude of these impacts varies based on the quantity and distribution of lakes and wetlands in the watershed as well as the climate and vegetation present. </p>

Based on case studies in Lao PDR, this research investigates the importance of small waterbody fisheries to rural households, the impact of enhancement initiatives on resources and resource users, and the opportunities and constraints of communityled enhancement. Detailed biological, socio-economic, and institutional data on small water body fisheries were collected and analysed in an integrated framework. Small waterbody fisheries contributed substantially to rural livelihoods, with average household catches of 66 kg/year, equivalent in value to approximately half the household rice production (the major crop grown in the region). Poorer households caught and sold more fish than other socio-economic groups. Active management of small waterbody fisheries by stocking and the regulation of fishing had significant impacts on fish stocks, yields, and the type, magnitude and distribution of benefits to villagers. Stocked fisheries managed by and for the village showed higher standing stocks and returns to fishing effort, and thus generated substantial efficiency benefits even though yields were not significantly higher than in unmanaged fisheries. Benefits were in the form of income to the community, partially passed on to households, (equally between socio-economic groups), through reduced financial contributions to the village. Institutional analysis suggests that locally adapted rules, ownership rights, low cost monitoring and enforcement, and information about benefits are key factors in promoting and sustaining community enhancement efforts, as well as the presence of individuals with substantial leadership skills. Results suggest that communities can and do successfully set up and maintain enhancement initiatives and that enhancement of small water body fisheries can generate substantial benefits. However these will only be sustained if it corresponds to villager's objectives and coincides with conducive institutional arrangements and, crucially, an enabling external policy environment. To achieve the full potential of enhancements, research should be aimed at furthering villager's understanding of the status and potential of their resource in terms of these objectives.

Bibliography: leaves 231-240 / vi, 240 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1986

Thesis (Ph.D.) in Physics--University of Maine, 2006. / Includes vita. Includes bibliographical references (leaves 94-99).

Thesis (Ph.D.)--York University, 2005. Graduate Programme in History. / Typescript. Includes bibliographical references (leaves 519-553). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNR11619

Chlorophyll-a (chl-a) concentration is an indicator of the trophic status and is extensively used as a measurement of the algal biomass which affects the level of eutrophication in aquatic systems. High concentration of chl-a may indicate high biomass of phytoplankton which can decrease the quality of water or eliminate important functional groups in the ecosystem. Predicting chl-a concentrations is desirable to understand how great impact chl-a may have in aquatic systems for different scenarios during long-time periods and seasonal variation. Several models of predicting annual or summer chl-a concentration have been designed using total phosphorus, total nitrogen or both in combination as in-parameters. These models have high predictive power but are not constructed for evaluating the long-term change or predicting the seasonal variation in a system since the input parameters often are annual values or values from other specific periods. The models are in other words limited to the range where they were constructed. The aim with this thesis was to complement these models with other methods and models which gives a more appropriate image of how the chl-a concentration in an aquatic system acts, both in a short as well as a long-time perspective. The results showed that with a new method called Statistically meaningful trend the Baltic Proper have not had any change in chl-a concentrations for the period 1975 to 2007 which contradicts the old result observing the p-value from the trend line of the raw data. It is possible to predict seasonal variation of median chl-a concentration in lakes from a wide geographically range using summer total phosphorus and latitude as an in-parameter. It is also possible to predict the probability of reaching different monthly median chl-a concentrations using Markov chains or a direct relationship between two months. These results give a proper image of how the chl-a concentration in aquatic systems vary and can be used to validate how different actions may or may not reduce the problem of potentially harmful algal blooms. / Koncentrationen av klorofyll-a (chl-a) är en indikator på vilken trofinivå ett akvatiskt system har och används som ett mått på algbiomassa som påverkar övergödningen i akvatiska system. Höga koncentrationer av chl-a i sjöar kan indikera hög biomassa av fytoplankton och försämra kvalitén i vattnet eller eliminera viktiga funktionella grupper i ett ekosystem. Det är önskvärt att kunna prediktera chl-a koncentrationer för att förstå hur stor påverkan chl-a kan ha för olika scenarier i akvatiska system under längre perioder samt under säsongsvariationer. Flera modeller har tagits fram som predikterar årsvärden eller sommarvärden av chl-a koncentrationer och i dessa ingår totalfosfor, totalkväve eller en kombination av båda som inparametrar. Dessa modeller har hög prediktiv kraft men är inte utvecklade för att kunna utvärdera förändringar över längre perioder eller prediktera säsongsvariationer i ett system eftersom inparametrarna ofta är årsmedelvärden eller värden från andra specifika perioder. Modellerna är med andra ord begränsade till den domän som de togs fram för. Målet med denna avhandling var att komplettera dessa modeller med andra metoder och modeller vilket ger en bättre förståelse för hur chl-a koncentrationer i akvatiska system varierar, både i ett kortsiktigt och ett längre perspektiv. Resultaten visade att med en ny metod som kallas för Statistiskt meningsfull trend så har egentliga Östersjön inte haft någon förändring av chl-a koncentrationer under perioden 1975 till 2007 vilket motsäger tidigare resultat då p-värdet tas fram från en trendlinje av rådata. Det är möjligt att prediktera säsongsvariationer av median chl-a koncentrationer i sjöar från en bred geografisk domän med totalfosfor från sommar och latitud som inparametrar. Det är även möjligt att beräkna sannolikhetenav ett predikterat värde för olika månadsmedianer av chl-a koncentrationer med Markovkedjor eller ett direkt samband mellan två månader. Dessa resultat ger en reell förståelse för hur chl-a koncentrationer i akvatiska system varierar och kan användas till att validera hur olika åtgärder kan eller inte kan reducera problemet av de potentiellt skadliga algblomningarna.

Des del 2002, s'han desenvolupat una sèrie de proxies climàtiques basades en biomarcadors derivats d'arquees i bacteris. Aquests biomarcadors són els glicerol dialquil glicerol tetraèters o GDGTs. D'entre aquestes proxies, l'índex TEX86 s'aplica en sediments per tal de reconstruir les temperatures superficials del mar i dels llacs; els índexs MBT i CBT són utilitzats conjuntament per a reconstruir la temperatura superficial de l'aire i l'índex BIT permet avaluar la contribució relativa de material provinent del sòl i material pelàgic en els sediments. A causa del recent desenvolupament d'aquestes proxies, hi ha encara un gran nombre d'aspectes metodològics i d'aplicació que han estat poc estudiats. Per això, l'objectiu d'aquesta tesi ha estat la comparació i optimització de diversos procediments analítics implicats en la determinació dels GDGTs, així com l'estudi d'aquests biomarcadors en nous ambients, amb especial atenció en els llacs.En la part analítica d'aquesta tesi, s'ha comparat el mètode estàndard de clean-up de les mostres basat en el fraccionament de lípids en alúmina amb la hidròlisi alcalina; a més, s'han comparat diversos adsorbents i graus d'activació per al fraccionament dels lípids. Els resultats demostren que el TEX86 és robust respecte a aquestes tècniques, mentres que l'índex BIT depèn del grau d'activació de l'adsorbent. En la cromatografia, s'han dut a terme una reducció del flux i un augment de la velocitat dels anàlisis sense pèrdua de resolució cromatogràfica. Finalment, s'han utilitzat dos espectròmetres de masses de disseny diferent per a mesurar els índexs TEX86 i BIT i se n'ha confirmat la comparabilitat. Per altra banda, s'ha observat una sensibilitat extrema del BIT respecte a les condicions d'optimització dels espectròmetres.S'ha estudiat les concentracions dels GDGTs en els sediments superficials d'un conjunt de 38 llacs de la Península Ibèrica per tal d'identificar els factors que en determinen la distribució relativa. L'anàlisi de components principals indica que la major part de la variança pot explicar-se amb l'origen dels GDGTs (del sòl o lacustre), el grau de ciclització interna i el grau de metilació dels GDGTs. Els resultats demostren que les proxies MBT/CBT i el TEX86 tenen una utilitat limitada en la predicció de les temperatures d'aquests llacs, possiblement perquè la distribució de GDGTs és determinada per una mescla complexa de factors. Utilitzant l'anàlisi de clusters s'ha identificat un subconjunt de llacs on els índexs TEX86 i MBT/CBT mantenen una relació linial forta amb les temperatures instrumentals de l'aire.L'estudi dut a terme al llac Baikal (Sibèria) combina els resultats de trampes de sediment, sediments superficials i dos testimonis sedimentaris que corresponen a l'últim cicle glacial-interglacial. Els valors per a l'índex BIT al sediment suggereixen una contribució minsa de material provinent del sòl i les temperatures superficials del llac derivades de l'índex TEX86 es troben dins el rang anual de les mesures de temperatures superficials. En els testimonis sedimentaris, les variacions en profunditat del TEX86 i l'MBT/CBT revelen un senyal climàtic que es concreta en el registre de la transició de condicions glacials a interglacials i l'acord parcial amb les reconstruccions climàtiques existents per a la regió del llac Baikal derivades d'altres proxies.En darrer lloc, l'estudi exploratori dut a terme al cràter del Bosumtwi (Àfrica) revela la presència de GDGTs en les roques impactades i es discuteixen tres hipòtesis en referència a l'origen dels GDGTs trobats.El treball presentat amplia el rang de tècniques analítiques que poden utilitzar-se de forma fiable per a la mesura dels índexs basats en GDGTs i profunditza en l'aplicació i validació dels GDGTs com a proxies climàtiques en sediments lacustres, particularment de la Península Ibèrica i Sibèria. / Since 2002, several climate proxies based on biomarkers of Archaea and Bacteria, the GDGTs, have been developed and applied in sedimentary archives worldwide. Among the proposed proxies, the TEX86 index is applied in sediments to reconstruct sea surface temperatures (SST) and lake surface temperatures (LST); The MBT and CBT indices are together applied as a proxy for past surface air temperature and the BIT index is measured in sediments to assess qualitatively relative inputs of pelagic-originated material versus soil material. Given the novelty of these proxies, there is plenty of scope to improve upon a range of issues regarding their measurement and application. Consequently, the aim of this thesis has been to tackle analytical methodological issues to gain in analytical reliability and sample throughput, and expand the range of environments where GDGT proxies have been appraised, particularly in lake environments.In the analytical section of the thesis, two sample clean-up methods, i.e. alumina fractionation and alkaline hydrolysis are compared. Additional tests compare alumina and silica in their activated and deactivated states as adsorbents onto which GDGTs are fractionated. Results show that TEX86 values are robust using these methodologies, while BIT values are dependant on adsorbent activation state. Regarding the chromatographic analysis, an increase in the analysis velocity and a reduction of flow are effectively implemented without loss of chromatographic peak resolution. Additionally, two mass spectrometer designs, i.e. an ion-trap system and a quadrupole system, are used for the measurement of a wide range of values of TEX86 and BIT indices, and results confirm the comparability of both systems. However, BIT values are found to be extremely sensitive to the MS tuning conditions. In order to find out the main factors influencing the GDGTs distribution in lacustrine environments, a suite of surface sediments from 38 Iberian lakes are surveyed. Principal component analysis of the relative concentrations of GDGTs indicates that terrestrial versus lacustrine origin, combined with degree of cyclization and degree of methylation of the lipids are the principal factors accounting for the GDGT distribution in the sediments. The measurement of the MBT/CBT proxy represents a pioneer application of these indices in lake sediments. TEX86 and MBT/CBT are shown to have a limited applicability in predicting the lake temperature, likely due to a complex combination of factors influencing the GDGT abundances. Using cluster analysis a subset of lakes is selected with a rather linear relationship of TEX86 and CBT/MBT with instrumental air temperatures. In the study conducted in lake Baikal in Siberia, sediment traps, surface sediments and two cores spanning the last glacial-interglacial cycle are analysed in the north and south basins of the lake. BIT values both for the particulate material collected and the surface sediments suggest low influence of soil-derived material. TEX86 derived LST from the water column particulate material and sediments are in the range of measured annual LST. The down-core variations of the TEX86 and MBT/CBT proxies reveal a climatic signal, inferred both from the reconstructed transition from glacial to interglacial conditions and the partial agreement with reconstructed changes in Lake Baikal region derived from other proxies applied in the sediments. The work presented extends the range of analytical techniques that can be reliably used for the measurement of the GDGT indices and provides deeper knowledge on the application and validation of GDGTs as climate proxies in lacustrine sediments, in particular from the Iberian and Siberian regions.