It has been suggested that the dominant controls on alpine sediment transfers during the Holocene Epoch relate to climate change, specifically paraglacial sedimentation and Neoglacial activity. Alpine lakes with appropriate geometry and hydraulic conditions trap a high proportion of sediments inflowing from their surrounding drainage basins. Thus alpine lake sediments have the potential to yield a comprehensive, integrated signal of drainage-basin geomorphic activity through time, which may be interpreted as a proxy record of Neoglacial activity. This study is concerned with the interpretation of alpine lake sediments in glacierized drainage basins as records of Neoglacial activity. It adopts an explicitly geomorphological approach that integrates an understanding of the drainage basin sedimentary system, specifically sediment sources and transfers, with the interpretation of lake sediment deposits and extends existing models of alpine sedimentary response down-valley, away from the immediate proglacial environment. A down-valley sequence of four valley bottom lakes, Kha, Klept, Kokwaskey and Kwoiek, within the Kwoiek Creek watershed, southeastern Coast Mountains of British Columbia, were studied. Sub-bottom sounding and multiple cores from each lake allowed identification of lake-wide changes in sediment input through time; in addition terrain mapping and characterisation of sediment sources provided a framework within which to identify the sources of the lake sediments and their fluctuations through time. Preliminary characterization of the sediments broadly separated organic and clastic components. Detailed laboratory analyses revealed organic matter content to be a good inverse indicator of sedimentation rates. Grain size analyses revealed three distinct textural populations. Graphical partitioning of the cumulative grain size distributions identified each fraction for further analysis. The provenance of the coarsest and intermediate fraction was determined through SEM surface texture analysis of a statistically representative number of grains. The coarsest fraction was derived from localized colluvial sources. The intermediate fraction was derived from glacial sources and strongly filtered downsystem. The finest fraction was characterised as glacial in origin because of consistent trends in its variability at the drainage basin scale through time. Fluctuations in the total influx of the intermediate and finest fractions are interpreted as a proxy record of Neoglacial activity in the watershed. Analysis of persistence in the sedimentation data indicates history of the order 100 yrs, which is interpreted as an index of the relaxation time of sedimentary stores. Basal dates on the sediments provide the earliest dates for deglaciation in the southern Coast Mountains, suggesting that extensive areas of southwestern British Columbia were ice free prior to 11 500 B.P. Three phases of Neoglacial activity centred 6000 to 5000 B.P., 3500 to 2900 B.P. and post 750 B.P are suggested by increased sedimentation rates for glacially-derived material. When compared with reconstructions from a pollen study conducted within the watershed and regional chronologies reported in the literature, there is remarkable consistency. The major advantage of the lake sediment approach as developed in this study is the continuity and apparent sensitivity of the derived proxy records. These records permit a consideration of both the magnitude and frequency of palaeoenvironmental change, specifically Neoglacial activity, at one site. Such a record has not been found elsewhere in British Columbia, where discontinuous terrestrial records have been used. / Arts, Faculty of / Geography, Department of / Graduate

As our global community grapples with the ongoing challenges of climate change mitigation and adaptation, records of past climate changes provide important benchmarks for climate models and insights into the interactions between climate changes, human societies, and the landscape. In this dissertation, I reconstruct past changes in climate and redefine the human settlement history of the North Atlantic region. Understanding the human and climate history of the North Atlantic is particularly important because the region is especially sensitive to changes in climate, and climate and oceanographic changes in the region have global ramifications. I focus on the Faroe Islands and Iceland. These islands are close to oceanographic and atmospheric fronts and are sensitive to small changes in the climate system. Furthermore, the Faroes and Iceland were not settled by humans until the the first millennium CE, and as such, provide climate records that are unaltered by human land use activities for most of the Holocene, and are important test cases for understanding human-climate-landscape interactions after human settlement. In this work, I use lake sediment cores to reconstruct continuous climate records for the Holocene period, and in some cases, snapshots of previous interglacials. Lipid biomarkers are a group of molecules that accumulate in lake sediment and can be traced back to organisms in the lake or its watershed. I use these molecules and their isotopic compositions to quantify past changes in temperature and precipitation isotopes, which provide constraints on past climate and atmospheric circulation. I use fecal biomarkers, which are produced by the gut bacteria of humans and livestock, to determine when humans first settled in a lake’s watershed, and the impact they had on the environment. Ancient DNA stored in lake sediment can also be used to trace past changes in vegetation and to determine if livestock were present in the watershed, enhancing our understanding of agricultural impacts on the landscape. By combining these molecular tools, in Chapter 2, I reconstruct the Holocene and Last Interglacial climate in the Faroe Islands using the hydrogen and carbon isotopes of leaf waxes. In this case, I found that the Faroe Islands slowly transitioned over the Holocene from a climate that was warmer and wetter than present conditions, to a climate that is cooler and drier. In the Faroes, the Last Interglacial climate was similar to the early Holocene. In Chapter 3, I use fecal biomarkers and sedimentary ancient DNA to determine that humans arrived 300 years prior than previously thought. Human settlement caused erosion in the catchment and a shift in the vegetation community. In Chapter 4, I use the hydrogen isotopic composition of leaf waxes in conjunction with a biomarker-based temperature reconstruction from a lake in Iceland to determine past shifts in regional atmospheric circulation. I found that a shift towards more northerly-sourced precipitation, consistent with conditions similar to a positive NAO, occurred at the same time as regional neoglaciation and expansion of sea ice. All together, these records advance our understanding of Holocene and Last Interglacial climate change, the human settlement history

No description available.

The purpose of this investigation was to study the sediment in the upper reaches of Claytor Lake. The lake is a manmade impoundment on the New River near Radford, Virginia. Eleven core samples, varying in length from 66 cm. to 141 cm, were taken from the lake. The concentration of various water quality parameters were determined for segments of the entire length of each core. An in vitro assay was performed in the laboratory to determine the productivity potential of the nutrients contained in the sediments. Results of this investigation showed that sufficient nutrients are contained in the sediments to sustain algae growth. These nutrients, when released under controlled conditions, were found to sustain abundant growth of three algal genera: <u>S. capricornutum, A. flosaguae, and M. aeruginosa</u>. Several nutrients were found to exhibit trends with sediment depth and also to correlate with each other. Particle size distributions were also determined on several of the sediment samples. Several nutrients were found to correlate with particle size of the sediment. / Master of Science

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

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Abstract There are many methods for the restorating a eutrophicated lake. This study has concentrated on chemical treatment of the sediment and the restoration measurements. This study is divided into three parts: studies of the chemical restoration of study lakes, the optimization of the sediment chemical restoration method, and the evaluation of the method effectiveness of the lake restoration. According to the results, it is possible to adsorb phosphorus to the sediment and keep it adsorbed, but chemical treatment will not improve the long term phosphorus adsorption capacity of the sediments. Therefore, the internal phosphorus load from sediments is only temporarily decreased. Contrary to the claims of earlier studies, the chemical treatment should be executed with small doses successively over many years. In this case, the phosphorus from the hypolimnion and the interstitial water is engaged and stored in the sediment. The phosphorus will remain stored unless the acidity of the sediment changes so that the phosphorus-aluminum bond is broke. The most important factors in the sediment chemical restoration are the pH-reaction of the chemical and sediment-water mixture. Also, available phosphorus that can be engaged is important. In addition, the natural variety of the pH-value of the lake must be considered. A laboratory test was made that compared the suitability of five different chemicals for the restoration of lakes. The tested chemicals were chemicals that are commonly used in the production of drinking water and in waste water treatment. The most suitable chemical for lake restoration was Kemira’s CFH0818 which had the best ability to engage phosphorus and the best pH-reaction. The successfulness of the lake restoration can be determined from the phosphate in the interstitial water of the sediment as a primary source of internal phosphorus load. This diffusion calculation can be made in every restoration object before and after the restoration measures. Also, oxygen conditions, pH-value and the process environment of the breakdown of the organic material are determined as tools for the restoration measures. The use of the evaluation methods is mostly limited by the dynamic nature of the process environment over different seasons of the year. So for reliable restoration measurement one must know why, when and where the measurements are made. / Tiivistelmä Rehevän järven kunnostamiseksi on useita menetelmiä: joista tässä tutkimuksessa on keskitytty sedimentin kemikaalikäsittelyyn sekä sen tuloksellisuuden mittaamiseen. Tutkimus jakautuu kolmeen osaan: kemikaalikunnostusten järvikohtaiseen tarkasteluun, sedimentin kemikaalikunnostuksen mitoituksen optimointiin sekä järvikunnostuksen tuloksellisuuden arvioimiseen. Tutkimustulosten mukaan sedimentin kemikaloinnilla voidaan sitoa järvessä kiertävää fosforia sedimenttiin, mutta pysyvää sedimentin fosforinsidontakykyä kertaluontoisella kemikaloinnilla ei saavuteta. Järven sisäinen kuormitus siis hetkellisesti hidastuu, mutta ei lopu sedimentin kemikalointiin. Kemikalointi tulee tehdä pienin kerta-annoksin useana vuonna peräkkäin ja sedimentin pH:n tulisi säilyä välillä 6–8 läpi vuoden. Tällöin kemikaali varastoi sitomansa fosforin sedimenttiin. Kemikaalikunnostuksen tärkeimmät mitoitustekijät ovat kemikaalin pH-vaste vesimassaan ja sedimenttiin sekä sidottavissa oleva fosforimäärä kunnostettavassa järvessä. Tutkimuksen mukaan PAX-18-kemikaali ja vastaavat liuosmaiset alumiini- ja rautakemikaalit eivät ole ensisijaisia järvikunnostuskemikaaleja. Ne on kehitetty juoma- ja jäteveden puhdistamiseen, eli sitomaan nopeasti fosforia ja orgaanista ainetta. Sitä vastoin laboratoriokokeen tulosten perusteella rakeiset adsorptio-kemikaalit, kuten Kemiran CFH0818 sitovat sedimentin fosforia itseensä ilman merkittäviä happamoitumisvaikutuksia. Järvikunnostuksen tuloksellisuutta voidaan arvioida mittaamalla sedimentissä vapaana oleva fosfaattimäärä ja sedimentin hapetustila, happamuus sekä määrittämällä sedimentin fosforinsidontakyky. Mittaukset on tehtävä ennen ja jälkeen kunnostustoimia. Näiden mittausten perusteella voidaan kunnostustoimien tuloksellisuutta arvioida varsin luotettavasti. Tulosten käyttöä rajoittavat lähinnä muuttuvat prosessiolosuhteet eri vuodenaikoina ja toistaiseksi riittävän vertailuaineiston puute. Järvikunnostuksen tuloksellisuuden arvioimiseksi on tiedettävä kohdekohtaisesti miksi, milloin ja mistä mitataan, jotta arvio on luotettava.

No description available.

Sediments from 21 Oregon lakes were analyzed for seven metals (Fe, Mn, Zn, Cu, Co, Ni, V) in three forms (exchangeable, organic+sulfides, and oxyhydroxides+ oxides+ carbonates) using a sequential fractionation procedure. The summer epilimnetic filterable concentration of an eighth (Mo) was also determined. Sedimentary diatom remains and summer phytoplankton populations of the lakes were correlated with the 22 metal parameters and with conservative water chemistry parameters, estimators of lake productivity, and watershed geology. Both the sedimentary metals and the two populations of primary producers correlated best with the ecoregions of Omernik and Gallant (1986). A number of species possessed correlations with specific trace metal extractions or ratios of those extractions. Bloom-forming Anabaenas strongly correlated with sedimentary organic and filterable epilimnetic nickel. Possible Ni limitation of this group was observed in one Cascade lake (Lava). The ratio of organic nickel to cobalt appeared to control the abundance of several sedimentary diatoms. Organic vanadium strongly correlated with a number of diatoms, particularly in the genera, Cyclotella and Fragilaria. Possible V pollution was observed in one lake (Woahink), and frustule remains of C. stelligera significantly increased with increasing total sedimentary V concentrations there. Zinc was the trace metal most frequently found to apparently limit diatom growth. Diatoms may have developed three different responses to Zn limitation; the three groups have been labelled affinity-, velocity-, and (possibly) storage- specialists following Sommer (1985). Possible Zn pollution was observed in two lakes (Oswego and Clear). Phytoplankton and sedimentary diatoms weakly correlated with sedimentary iron by comparison to Ni, V, or Zn. Few strong relationships were observed with manganese, copper, or cobalt. No statistically significant correlations were found with molybdenum, and few correlations between a conservative chemical parameter and a species of phytoplankton were found. There was poor correlation between trace metal concentrations and lake productivity, despite frequently observed correlations between individual species and particular trace metal fractions. These findings suggest that variations in absolute trace metal concentrations, and/or ratios, may be important factors for controlling species distribution, but have relatively little influence upon lake primary productivity or standing stocks.

Lake Burragorang, the focus of this thesis, is the main water supply source for the large population of Sydney and is a major source for the Blue Mountains residents. This study was aimed to evaluate the distribution of heavy metals and their speciation in sediments of Lake Burragorang. The principal focus is on the study of heavy metal pollution and their bioavailability to the aquatic system. Five-step sequential extraction procedure was employed to assess different geochemical forms of certain metals in sediment grabs of Lake Burragorang. This is the first study to report metal speciation data for Lake Burragorang sediments. No significant spatial variations were observed in the speciation trends. The variation in metals and nutrients in the sediments with age was established and has been compared with published historical record, rainfall records and bushfire data. / Master of Engineering (Hons)