MSc., Faculty of Science, University of Witwatersrand, 2011 / A multifactor ecological integrity index, focusing on freshwater ecosystems on a quaternary catchment scale, can be of great benefit to conservation planning. No ecological integrity index has previously been developed for South African quaternary catchments. In this study an index was developed based on three environmental surrogates: land cover, river integrity and fish species conservation status, with the intention of identifying quaternary catchments of highest conservation concern. By developing such an index, the aim was to provide a general indication of the degree to which catchments have been transformed from a natural environment to a human altered environment, thereby identifying catchments most in need of conservation. For the three available datasets, indices were developed using a five category point-scoring system. A score of one indicates a completely degraded environment and a score of five indicates a pristine environment. The original land cover data consisted of 49 different land cover types which were reduced to five land cover transformation scores. Available river integrity data already existed in five categories and a numerical score of one to five was applied to each category. Fish species conservation status was scored according to the IUCN red data list classifications on a similar basis. Subsequently, a weighted mean score expressed as a percentage was calculated for the three indices for each quaternary catchment. These indices indicate the degree of change/transformation from a natural system (100%) to a largely degraded system (20%). Ultimately, an ecological integrity index was calculated as a mean value of the three related but independent indices. However, the results of the developed ecological integrity index were not representative of real world conditions. This is largely attributed to the lack of complete data found in two out of the three datasets used in the study. Some of the main limitations encountered were the lack of river segment definitions within each catchment and the incomplete and un-systematic collected fish species data records. The land cover data, on the contrary, was of high definition and high standard. It is recommended that in the interim, the developed land transformation index, based on a detailed analysis of land cover, be used as an indicator index of ecological integrity of catchments

<p> The reactions of methyllithium and phenyllithium with the iminium chloride, [(2R,3S)-2,3-dihydroxy-3-(6,7 -dimethoxy-3,4-dihydroisoquinolin-1-yl)]propionate hydrochloride, 34 as a means of preparing enantiomerically pure compounds are described. These reactions afford a single product in high yield. The nmr spectra of the products, 1-(1 ,2,3-trihydroxy-3,3-dimethylpropyl)-1 ,2,3,4-tetrahydro-6,7 -dimethoxy-1- methylisoquinoline 54 and 1-( 1,2,3-trihydroxy-3,3-diphenylpropyl)-1,2,3,4-tetrahydro-6,7- dimethoxy-1-phenylisoquinoline 62, are discussed and an explanation is given to account for the diastereoselectivity of the reaction. By this method, enantiomerically pure compounds bearing a quaternary centre at C-1 of the tetrahydroisoquinoline system may be prepared. Oxidative degradation of the hydroxylated side chain of compound 62 has led to the preparation of several other new compounds. </p> <p> The usefulness of the t-butoxycarbonyl group as a selective protecting group for nitrogen in the preparation of 2-t-butyloxycarbonyl-1,2,3,4-tetrahydro-1-(1,2,3- trihydroxy-3,3-dimethylpropyl)-6,7-dimethoxy-1-methylisoquinoline 59 is described. It has advantages over the ethoxycarbonyl group in that it not only selectively protects the amino group but also is easy to remove by short treatment with trifluoroacetic acid and water at room temperature. Treatment of 59 with sodium periodate afforded the aldehyde, 1-formyl-2-t-butyloxycarbonyl-1,2,3,4-tetrahydro-6,7-dimethoxy-1-methylisoquinoline, 60. An attempted oxidation of the aldehyde 60 to the acid is also described. </p> <p> A review of recent methods of inducing chirality at C-1 of the tetrahydroisoquinoline system is given in the Introduction. </p> / Thesis / Master of Science (MSc)

No description available.

Groundwater conditions beneath 11 hectares property owned by HydroOne near the southeastern edge of the Oak Ridges Moraine were assessed for contamination susceptibility using groundwater and geological information from HydroOne monitoring on-site and within one kilometre. Geological information was obtained from preexisting well records and a deep cored hole through dense glacial deposits (Newmarket Till) and through two deep regional sand aquifers (Thorncliffe and Scarborough Aquifers) into shale at 130 mbgs. The multiple data types included water levels, Tritium-Helium groundwater dating, oxygen-18 and deuterium, and major and minor ions. The water table is close to surface (<3m) and wells above 22 m depth in the highly active shallow zone show chemicals and Coliform Bacteria from human activities including roads, septics and agriculture. Shallow groundwater flows downward towards the Thorncliffe aquifer; the bottom of this most active zone is unknown due to insufficient data from deeper wells. Two private wells (100 mbgs) thought to be in the Thorncliffe aquifer contain constituents indicative of human influence. Seven of eight homeowner wells show tritium from nuclear power stations, one at detection limit. Three hypotheses are proposed to explain the susceptibility of wells in the Thorncliffe Aquifer to contamination: 1) the Newmarket aquitard is contains preferential pathways due to fractures connected to sand layers allowing deep penetration of contamination, 2) recharge can occur directly into the Thorncliffe aquifer in areas where Newmarket Till is non-existent, and 3) wells have faulty construction allowing short-circuiting to depth of contaminated shallow water down and along well casings. Based on the current data preferential pathways through the Newmarket is the most plausible hypothesis. However, additional work to define groundwater flow paths both on and off-site as well as additional geochemical and isotopic analyses from existing and new deep wells is needed to better determine risk to residential wells. / Thesis / Master of Science (MSc) / A groundwater study was conducted in an eight square kilometre area at the southeast edge of the Oak Ridges Moraine near Oshawa, ON. It included: geology from a 130m hole through overburden (including Newmarket Till) to bedrock, groundwater age determinations and water chemistry obtained by Hydro One from 16 monitoring wells on HydroOne property (11 hectares) and 25 nearby homeowner wells, most less than 22m deep. Wells above 22m show salt and other constituents from roads, septics or agriculture and show young groundwater age. Two deep wells (100m) in the Thorncliffe Aquifer beneath the Newmarket Till also show these chemicals; one of them sampled for tritium-helium showed young age, as do some intermediate -depth wells. The pathways for young water migrating so deep are undetermined.

It is widely believed that Australian Aboriginals utilised fire to manage various landscapes however to what extent this impacted on Australia???s ecosystems remains uncertain. The late Pleistocene/Holocene fire history from three sites within the Sydney Basin, Gooches Swamp, Lake Baraba and Kings Waterhole, were compared with archaeological and palaeoclimatic data using a novel method of quantifying macroscopic charcoal, which is presented in this study. The palynology and other palaeoecological proxies were also investigated at the three sites. The Gooches Swamp fire record appeared to be most influenced by climate and there was an abrupt increase in fire activity from the mid-Holocene perhaps associated with the onset of modern El Ni??o dominated conditions. The Kings Waterhole site also displayed an abrupt increase in charcoal at this time however there was a marked decrease in charcoal from ~3 ka. Lake Baraba similarly had displayed low levels of charcoal in the late Holocene. At both Kings Waterhole and Lake Baraba archaeological evidence suggests intensified human activity in the late Holocene during this period of lower and less variable charcoal. It is hence likely that at these sites Aboriginal people controlled fire activity in the late Holocene perhaps in response to the increased risk of large intense fires under an ENSO-dominated climate. The fire history of the Sydney Basin varies temporally and spatially and therefore it is not possible to make generalisations about pre-historic fire regimes. It is also not possible to use ideas about Aboriginal fire regimes or pre-historic activity as a management objective. The study demonstrates that increased fire activity is related to climatic variation and this is likely to be of significance under various enhanced Greenhouse scenarios. There were no major changes in the composition of the flora at all sites throughout late Pleistocene/Holocene although there were some changes in the relative abundance of different taxa. It is suggested that the Sydney Sandstone flora, which surrounds the sites, is relatively resistant to environmental changes. Casuarinaceae was present at Lake Baraba during the Last Glacial Maximum and therefore the site may have acted as a potential refugium for more mesic communities. There was a notable decline in Casuarinaceae during the Holocene at Lake Baraba and Kings Waterhole, a trend that has been found at a number of sites from southeastern Australia.

<p>The aim of this thesis is to describe present and past coastal dune environments in southern Buenos Aires Province, Argentina. </p><p>The present vegetation of a dune system and its zonation are described on the basis of air photographs, physiognomy of the dune system and floristic composition. The vegetation was characterized by a large number of Poaceae and Asteraceae species. Five vegetation zones, based on floristic composition, were defined by cluster analysis. </p><p>Pollen-vegetation comparison revealed that pollen assemblages differed considerably from the associated vegetation. Some of the major discrepancies were caused by large differences between pollen and vegetation proportion of <i>Hyalis argentea</i> and <i>Discaria americana</i>. However, the local vegetation was well represented in recent soil samples. Pollen traps recorded predominantly extralocal and regional pollen. </p><p>A new species of ostracods was recovered from an interdunal lake. The species, a giant cypridid, was described and illustrated, and its geographical distribution and ecology were discussed. </p><p>Two sediment sequences from the coastal intertidal zone and from a shallow freshwater lake were analysed for loss on ignition, calcareous microfossils (ostracods and foraminifers), macro remains and pollen. The coastal sequence was deposited between 7890 and 7630 cal. BP. Its pollen assemblages were typical for halophytic associations, with some psammophytic taxa also present in recent vegetation. The microfossils were representative of a littoral lagoon. The lake sequence comprised the last 3000 cal. BP. Pollen spectra indicated a relatively stable vegetation composition after the lake had been formed. Pollen assemblages reflected the present regional grassland vegetation with taxa characteristic for the surrounding dune communities. Human settlement was indicated in the pollen spectra by the presence of introduced taxa in the uppermost samples. </p><p>The data presented provide a useful reference for the interpretation of fossil sequences from similar environments.</p>

<p>The Holocene spread of <i>Picea abies</i> in Scandinavia provides an excellent opportunity for detailed study of the dynamics of tree spread and population expansion. Early- and mid-Holocene macrofossil evidence for the presence of <i>Picea abies</i> in Scandinavia has questioned traditional interpretations of the timing and direction of its spread. This study aims to determine the pattern of the spread of <i>Picea abies</i> in Scandinavia from pollen and other data, to evaluate the significance of possible early outpost populations and to deduce possible factors that influenced the spread and population expansion of <i>Picea abies</i> in Scandinavia. </p><p>Palaeoecological investigations were carried out on the sediments of four small lakes in central Sweden to gain detailed insight into the dynamics of the spread. Holocene pollen diagrams with independent dating control were collected from Fennoscandia and adjacent areas to compare the timing of selected features of the <i>Picea abies</i> pollen curve. Computer models were used to test possible scenarios for the spread and <i>Picea abies</i> population expansion. </p><p><i>Picea abies</i> entered the Scandinavian peninsula from the east at different times and by different pathways. Early-Holocene outposts can be discerned in pollen records from northwest Russia, eastern and northeastern Finland for the time before 9000 cal. BP. Pollen records from Sweden and Norway indicate small <i>Picea abies</i> populations after 8000 cal. BP. The mid to late-Holocene spread, which superficially resembles a front-like pattern, may in fact represent a wave of expanding populations. Disturbance through fire and human activity did not significantly influence the pattern of the spread. Changing climate parameters, slow adaptation and gene flow through seeds and pollen have to be considered as possible explanations for the late spread of the tree. Population dynamics and propagule pressure are likely to be important factors that shaped the spread of <i>Picea abies</i>.</p>

The aim of this thesis is to describe present and past coastal dune environments in southern Buenos Aires Province, Argentina. The present vegetation of a dune system and its zonation are described on the basis of air photographs, physiognomy of the dune system and floristic composition. The vegetation was characterized by a large number of Poaceae and Asteraceae species. Five vegetation zones, based on floristic composition, were defined by cluster analysis. Pollen-vegetation comparison revealed that pollen assemblages differed considerably from the associated vegetation. Some of the major discrepancies were caused by large differences between pollen and vegetation proportion of Hyalis argentea and Discaria americana. However, the local vegetation was well represented in recent soil samples. Pollen traps recorded predominantly extralocal and regional pollen. A new species of ostracods was recovered from an interdunal lake. The species, a giant cypridid, was described and illustrated, and its geographical distribution and ecology were discussed. Two sediment sequences from the coastal intertidal zone and from a shallow freshwater lake were analysed for loss on ignition, calcareous microfossils (ostracods and foraminifers), macro remains and pollen. The coastal sequence was deposited between 7890 and 7630 cal. BP. Its pollen assemblages were typical for halophytic associations, with some psammophytic taxa also present in recent vegetation. The microfossils were representative of a littoral lagoon. The lake sequence comprised the last 3000 cal. BP. Pollen spectra indicated a relatively stable vegetation composition after the lake had been formed. Pollen assemblages reflected the present regional grassland vegetation with taxa characteristic for the surrounding dune communities. Human settlement was indicated in the pollen spectra by the presence of introduced taxa in the uppermost samples. The data presented provide a useful reference for the interpretation of fossil sequences from similar environments.

The Holocene spread of Picea abies in Scandinavia provides an excellent opportunity for detailed study of the dynamics of tree spread and population expansion. Early- and mid-Holocene macrofossil evidence for the presence of Picea abies in Scandinavia has questioned traditional interpretations of the timing and direction of its spread. This study aims to determine the pattern of the spread of Picea abies in Scandinavia from pollen and other data, to evaluate the significance of possible early outpost populations and to deduce possible factors that influenced the spread and population expansion of Picea abies in Scandinavia. Palaeoecological investigations were carried out on the sediments of four small lakes in central Sweden to gain detailed insight into the dynamics of the spread. Holocene pollen diagrams with independent dating control were collected from Fennoscandia and adjacent areas to compare the timing of selected features of the Picea abies pollen curve. Computer models were used to test possible scenarios for the spread and Picea abies population expansion. Picea abies entered the Scandinavian peninsula from the east at different times and by different pathways. Early-Holocene outposts can be discerned in pollen records from northwest Russia, eastern and northeastern Finland for the time before 9000 cal. BP. Pollen records from Sweden and Norway indicate small Picea abies populations after 8000 cal. BP. The mid to late-Holocene spread, which superficially resembles a front-like pattern, may in fact represent a wave of expanding populations. Disturbance through fire and human activity did not significantly influence the pattern of the spread. Changing climate parameters, slow adaptation and gene flow through seeds and pollen have to be considered as possible explanations for the late spread of the tree. Population dynamics and propagule pressure are likely to be important factors that shaped the spread of Picea abies.

A Quaternary perspective on the paleoceanographic evolution of the central Arctic Ocean has been obtained in this PhD thesis by studying sediment cores from all of the Arctic’s major submarine ridges and plateaus. The included cores were mainly recovered during the Healy-Oden Trans-Arctic expedition in 2005 and the Lomonosov Ridge off Greenland expedition in 2007. One of the main thesis objectives is to establish whether different sediment depositional regimes prevailed in different parts of the central Arctic Ocean during the Quaternary and, if so, establish general sedimentation rates for these regimes. This was approached by dating key cores using the decay of the cosmogenic isotopes 10Be and 14C, and through stratigraphic core-to-core correlation using sediment physical properties. However, the Arctic Ocean sea ice complicated the use of 10Be for dating because a solid sea ice cover prevents the 10Be isotopes from reaching the seafloor, resulting in too old ages. Dating using 14C is also complicated due to uncertain marine reservoir age corrections in the central Arctic Ocean. The core-to-core correlations show five areas with different depositional regimes; the northern Mendeleev Ridge and Alpha Ridge, southern Mendeleev Ridge, Morris Jesup Rise, Lomonosov Ridge and Yermak Plateau, listed in the order of increasing sedimentation rates from ~0.5cm/ka to ~4.8 cm/ka. A detailed study of the relationship between sediment bulk density and grain sizes suggests a strong link between variations in clay abundance and bulk density. Grain size analysis of a Lomonosov Ridge core show that fine silt and clay dominates the interglacials, possibly due to increased suspension freezing of these size fractions into sea ice and/or nepheloid transport. Sediments younger than the marine isotope stage (MIS) 7 generally contain more coarse silt, attributed to a regime shift during the Quaternary with increased iceberg transport into the central Arctic Ocean from MIS 6 and onwards. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: In progress. Paper 4: In progress. Paper 5: In progress. Paper 6: In progress.