Sensitivity of yellow passion fruit to ultraviolet-B radiation

The objective of this work was to evaluate the effects of UV-B radiation on the vegetative growth and on the gas exchange characteristics of passion fruit plants (Passiflora edulis) grown in greenhouse. The average unweighted UV-B radiation near the apex of the plants was 8 W m-2 for the UV-B treatment (high UV-B), and 0.8 W m-2 for the control plants (low UV-B). Plants were irradiated with UV-B for 7 hours per day, centered on solar noon, during 16 days. High UV-B radiation resulted in lower shoot dry matter accumulation per plant. The content of UV-B absorbing compounds and anthocyanins was increased in the plants exposed to high UV-B radiation, when compared with the control. UV-B radiation did not affect stomatal conductance or transpiration rate, but reduced photosynthesis and instantaneous water-use efficiency, and increased intercellular CO2 concentration. The accumulation of UV-B-absorbing compounds and anthocyanins did not effectively shield plants from supplementary UV-B radiation, since the growth and photosynthetic processes were significantly reduced.

Palaeotectonic and palaeogeographic evolution of the western Tethys and PeriTethyan domain (IGCP Project 369)

Project No. 369 (''Comparative Evolution of PeriTethyan Rift Basins'') of the International Geological Correlation Program produced a new palaeotectonic-palaeo-geographic atlas of the western PeriTethyan domain. The atlas contains more than two hundred new maps and documents grouped in nine regional sets (Iberia, Polish Trough, Eastern European and Scythian Platforms, Moesian Platform, Levant, Arabian Platform,, Northern Africa, NE Africa-NW Arabia, Libya-Pelagian Shelf plus a set of reconstructions for the whole western Tethys. The area, considered in the atlas stretches. from west to east, from the eastern Atlantic shores to the Urals and, from north to south, from the Baltic shield to equatorial Africa; the time span covered extends from the Late. Carboniferous to the Present. The dataset, resulting from an extensive cooperation between industrial and academic sources, is accessible interactively on a CD-ROM (Stampfli et al., 2001a) and includes legend, timetable, short explanatory notes, full references and additional supporting data. This dataset provides information on the development of the Tethyan realm in space and time. In particular, the relation between the Variscan and Cimmerian cycles in the Mediterranean realm is illustrated by numerous palaeogeographic and palaeotectonic maps.

Novel insulated gamma and lentis retroviral vectors towards safer genetic modification of stem cells

In otherwise successful gene therapy trials insertional mutagenesis has resulted in leukemia. The identification of new short synthetic genetic insulator elements (GIE) which would both prevent such activation effects and shield the transgene from silencing, is a main challenge. Previous attempts with e.g. b-globin HS4, have met with poor efficacy and genetic instability. We have investigated potential improvement with two new candidate synthetic GIEs in SIN-gamma and lentiviral vectors. With each constructs two internal promoters have been tested: either the strong Fr- MuLV-U3 or the housekeeping hPGK.We could identify a specific combination of insulator 2 repeats which translates into best functional activity, high titers and boundary effect in both gammaretro and lentivectors. In target cells a dramatic shift of expression is observed with an homogenous profile the level of which strictly depends on the promoter strength. These data remain stable in both HeLa cells over three months and cord blood HSCs for two months, irrespective of the multiplicity of infection (MOI). In comparison, control native and SIN vectors expression levels show heterogeneous, depend on the MOI and prove unstable. We have undertaken genotoxicity assessment in comparing integration patterns ingenuity in human target cells sampled over three months using high-throughput pyro-sequencing. Data will be presented. Further genotoxicity assessment will include in vivo studies. We have established insulated vectors which harbour both boundary and enhancer-blocking effect and show stable in prolonged in vitro culture conditions. Work performed with support of EC-DG research FP6-NoE, CLINIGENE: LSHB-CT-2006-018933

Ash Particle Erosion on Steam Boiler Convective Section

In this study, equations for the calculation of erosion wear caused by ash particles on convective heat exchanger tubes of steam boilers are presented. Anew, three-dimensional test arrangement was used in the testing of the erosion wear of convective heat exchanger tubes of steam boilers. When using the sleeve-method, three different tube materials and three tube constructions could be tested. New results were obtained from the analyses. The main mechanisms of erosionwear phenomena and erosion wear as a function of collision conditions and material properties have been studied. Properties of fossil fuels have also been presented. When burning solid fuels, such as pulverized coal and peat in steam boilers, most of the ash is entrained by the flue gas in the furnace. In bubbling andcirculating fluidized bed boilers, particle concentration in the flue gas is high because of bed material entrained in the flue gas. Hard particles, such as sharp edged quartz crystals, cause erosion wear when colliding on convective heat exchanger tubes and on the rear wall of the steam boiler. The most important ways to reduce erosion wear in steam boilers is to keep the velocity of the flue gas moderate and prevent channelling of the ash flow in a certain part of the cross section of the flue gas channel, especially near the back wall. One can do this by constructing the boiler with the following components. Screen plates can beused to make the velocity and ash flow distributions more even at the cross-section of the channel. Shield plates and plate type constructions in superheaters can also be used. Erosion testing was conducted with three types of tube constructions: a one tube row, an inline tube bank with six tube rows, and a staggered tube bank with six tube rows. Three flow velocities and two particle concentrations were used in the tests, which were carried out at room temperature. Three particle materials were used: quartz, coal ash and peat ash particles. Mass loss, diameter loss and wall thickness loss measurements of the test sleeves were taken. Erosion wear as a function of flow conditions, tube material and tube construction was analyzed by single-variable linear regression analysis. In developing the erosion wear calculation equations, multi-variable linear regression analysis was used. In the staggered tube bank, erosion wear had a maximum value in a tube row 2 and a local maximum in row 5. In rows 3, 4 and 6, the erosion rate was low. On the other hand, in the in-line tube bank the minimum erosion rate occurred in tube row 2 and in further rows the erosion had an increasing value, so that in a six row tube bank, the maximum value occurred in row 6.

Ruostumattoman teräksen TIG-hitsauksen hitsausnopeuden lisääminen

Diplomityön tavoitteena oli ruostumattoman teräksen koneellisen TIG-hitsauksen hitsausnopeuden lisääminen. Työssä tutkittiin suojakaasun koostumuksen vaikutusta hitsausnopeuteen sekä kahta uudehkoa prosessivariaatiota. Tutkitut prosessit olivat TIG-suurtaajuuspulssihitsaus sekä kaksoiskaasu-TIG-hitsaus. Kirjallisessa osassa perehdyttiin TIG-hitsauksen prosessiparametreihin ja -variaatioihin. Kokeellisessa osassa suoritettiin koehitsauksia hitsausnopeuksien selvittämiseksi. Tavoitteena oli tunkeuman kasvattaminen, mikä mahdollistaa hitsausnopeuden noston läpihitsattaessa. Suojakaasuina käytettiin sekä argonpohjaisia että heliumpohjaisia kaasuja, joihin oli lisätty vetyä. Vedyn avulla hitsausnopeus lisääntyi nykykäytäntöä suuremmillakin pitoisuuksilla. Uutena ilmiönä TIG-hitsauksessa havaittiin keyholen eli lävistysreiän syntyminen korkeita vetypitoisuuksia heliumpohjaisessa suojakaasussa käytettäessä. Keyhole oli kuitenkin erittäin epävakaa, joten jatkotutkimuksien tehtäväksi jää selvittää tarkemmin tämän ilmiön vaikutus. Tutkittuihin prosessivariaatioihin todettiin liittyvän useita laiteteknisiä ongelmia. Hitsausnopeuden suhteen tulokset jäivät vaatimattomiksi. Lähinnä keyholen aukaisemisessa ja aukipitämisessä menetelmistä havaittu hyöty antaa selvän aiheen jatkotutkimuksille.

Sähkömoottorin rakenteen analysointi tärisevässä käytössä

Tämän työn tavoitteena oli suunnitella esimerkkirakenne vaikeisiin olosuhteisiin tarkoitetusta sähkömoottorista. Ensisijaisesti tarkasteltavia osia sähkömoottorin rakenteessa olivat roottoriakseli, laakerointi sekä laakerikilvet. Laakeroinnista tarkasteltiin laakerivaurioiden syntymistä, tarvittavaa esijännitysvoimaa sekä jälkivoitelua. Lisäksi momenttiakselista tarkasteltiin sen vääntövärähtelyominaisuuksia sekä rungosta ja laakerikilvistä niiden jännityksiä B5-kiinnitysasennossa, eli laippakiinnityksessä. Työstä pyrittiin tekemään suunnitteluohje vastaavanlaisiin suunnittelutehtäviin. Tämän työn kirjallisessa osassa tarkasteltiin oikosulkumoottorin rakennetta ja laakerointia, josta perehdyttiin erityisesti erilaisiin kuormitustilanteisiin, voiteluun sekä kestoiänlaskentaan. Lisäksi tarkasteltiin roottoridynamiikkaa ja ominaismuotojen laskentaa. Kokonaisen roottorin, sisältäen roottoriakselin, –levypaketin, laakeroinnin ja ylikuormitussuojan, pienimmäksi ominaistaajuudeksi saatiin 62,1 Hz:ä, joka oli kuitenkin lähes kaksinkertainen verrattaessa roottorin käyntinopeuteen (33,3 Hz:ä). On siis varmaa, että roottorin kestoikä ei heikkene sen ominaistaajuuksien aiheuttamasta resonanssista. Pelkän roottoriakselin pienimmäksi ominaistaajuudeksi saatiin 448,0 Hz:ä. Verrattaessa tätä taajuutta roottorin käyntinopeuteen nähtiin, että roottoriakselin ominaistaajuuksien puolesta rakenne oli selvästi alikriittinen. Tarkasteltaessa roottoriakselin vääntövärähtelyn ominaistaajuutta 12,6 Hz:ä nähtiin, että se oli pienempi kuin moottorin pyörimisnopeus. Tämä ei kuitenkaan ollut moottorin kestoiän kannalta vakavaa. Koska todellisista sähkömoottorin käyttöolosuhteista ei ollut tarkkaa tietoa, tutkittiin laakeroinnin kestoikää kahdessa ääriolosuhteessa, joko moottoriin kohdistuva tärinä oli kokoajan suurin mahdollinen tunnettu tai tärinää ei ollut ollenkaan. Todellinen tilanne on jossakin näiden kahden ääriolosuhteen välissä. Oli kuitenkin varmaa, että tarkasteltava rakenne kestää halutun kestoiän eli 10000 tuntia laakeroinnin puolesta. Laakerikilpien ominaistaajuudet olivat korkeita eikä niillä ollut vaikutusta rakenteen kestoikään. Laakerikilpien korkeat ominaistaajuudet johtuivat niiden jäykästä rakenteesta ja suuresta materiaalipaksuudesta. Tarkasteltaessa momenttiakselin vääntövärähtelyn ominaistaajuutta 7,2 Hz:ä nähtiin, että se oli pienempi kuin moottorin pyörimisnopeus. Tämä ei kuitenkaan ollut moottorin kestoiän kannalta vakavaa, jos ominaistaajuus ja sen kerrannaiset ohitettaisiin sähkömoottorin käytössä hetkellisesti eikä moottoria käytettäisi vääntövärähtelyn taajuudella. Tarkasteltaessa B5-asennon jännityksiä nähdään, että ne kasvoivat rungon ja laakerikilven välisissä kiinnitysruuveissa yllättävän suuriksi. Normaalin ruuvin murtoraja on 640 MPa:a, kun jännitys rungon ja laakerikilven välisissä kiinnitysruuveissa oli suurimmillaan 400 MPa:a. Rakenne oli kuitenkin varmalla puolella kestävyyden suhteen, koska keskimääräinen vetojännitys ruuveissa oli noin 200 MPa:a. Ruuvien jännityksiä voidaan pienentää lisäämällä kiinnitys-ruuvien lukumäärää tai kasvattamalla niiden kokoa. Koko moottorin kiinnitysruuveissa jännitys oli vain 4 MPa:a, koska osan kuormituksesta kantoi laakerikilven olakkeet.

TLR3-Mediated CD8+ Dendritic Cell Activation Is Coupled with Establishment of a Cell-Intrinsic Antiviral State.

Because of their unique capacity to cross-present Ags to CD8(+) T cells, mouse lymphoid tissue-resident CD8(+) dendritic cells (DCs) and their migratory counterparts are critical for priming antiviral T cell responses. High expression of the dsRNA sensor TLR3 is a distinctive feature of these cross-presenting DC subsets. TLR3 engagement in CD8(+) DCs promotes cross-presentation and the acquisition of effector functions required for driving antiviral T cell responses. In this study, we performed a comprehensive analysis of the TLR3-induced antiviral program and cell-autonomous immunity in CD8(+) DC lines and primary CD8(+) DCs. We found that TLR3-ligand polyinosinic-polycytidylic acid and human rhinovirus infection induced a potent antiviral protection against Sendai and vesicular stomatitis virus in a TLR3 and type I IFN receptor-dependent manner. Polyinosinic-polycytidylic acid-induced antiviral genes were identified by mass spectrometry-based proteomics and transcriptomics in the CD8(+) DC line. Nanostring nCounter experiments confirmed that these antiviral genes were induced by TLR3 engagement in primary CD8(+) DCs, and indicated that many are secondary TLR3-response genes requiring autocrine IFN-β stimulation. TLR3-activation thus establishes a type I IFN-dependent antiviral program in a DC subtype playing crucial roles in priming adaptive antiviral immune responses. This mechanism is likely to shield the priming of antiviral responses against inhibition or abrogation by the viral infection. It could be particularly relevant for viruses detected mainly by TLR3, which may not trigger type I IFN production by DCs that lack TLR3, such as plasmacytoid DCs or CD8(-) DCs.

Sisäisten rahoitustoimintojen kehittäminen: case Lumon-yhtiöt

Tutkielman tavoitteena oli analysoida ja kehittää Lumon-yhtiöiden sisäisiä rahoitustoimintoja. Kehitettäviksi toiminnoiksi nousivat Lumon-yhtiöiden pääomarakenne, likviditeetin hallinta ja tilaus-toimitusketjun vertailu vanhan ja uuden toimintatavan välillä. Tarkastelutavaksi valittiin case-tutkimus. Tutkielman kohdeyritys Lumon-yhtiöt on teollisuusyritys, joka on erikoistunut lasi- ja alumiinirakentamiseen. Yrityksen pääomarakennetta tutkittiin haastattelemalla yrityksen johtohenkilöitä. Haastatteluiden perusteella laskettiin pääomarakenteen teorioiden mukaisia merkitseviä tekijöitä. Tuloksista havaittiin, että Lumon-yhtiöt hyötyisivät vieraan pääoman korkojen veroedusta ilman omavaraisuuden vaarantamista. Tätä ei kuitenkaan nähty tarpeelliseksi, koska rahoituksellisen joustavuuden säilyttäminen on merkitsevin pääomarakenteen tekijä. Tutkielmassa muodostettiin likviditeettiä ennustava malli, jonka avulla likviditeettiä voidaan seurata. Mallin pohjaaminen liikevaihtoennusteeseen ei täysin onnistunut, koska ennusteen tarkkuus ei ollut riittävä. Likviditeetin hallinnan osalta tutkittiin myös Lumon-yhtiöiden ulkomaisten tytäryhtiöiden kassavirtojen hallintaan liittyviä haasteita ja esitettiin niihin ratkaisuja. Tutkielmassa analysoitiin likviditeetin näkökulmasta vanhaa toimintatavan ja sitä verrattiin uuteen Lumon Express -toimintatapaan. Mittarina käytettiin käyttöpääomaa. Vertailu osoitti uuden toimintatavan pienentävän käyttöpääoman määrää 30 %.

A study of electromagnetic shielding properties of Ni79Fe16Mo5/copper films

The plane wave electromagnetic interference (EMI) shielding properties of DC sputtered Ni79Fe16Mo5 and copper layers were studied according to ASTM D 4935-89 on frequency range of 50 MHz – 2.5 GHz and RF magnetic shielding effectiveness by shielded magnetic loop probes. Results show that Ni79Fe16Mo5 provides better RF magnetic shielding above the layer thickness of approximately 120 nm. Copper provides better plane wave shielding effectiveness. The effect of shield internal interfaces was studied by depositing thin multilayer structures with and without a dielectric spacer layer.

Imaging polarimetry of the fogbow: polarization characteristics of white rainbows measured in the high Arctic

The knowledge on the optics of fogbows is scarce, and their polarization characteristics have never been measured to our knowledge. To fill this gap we measured the polarization features of 16 fogbows during the Beringia 2005 Arctic polar research expedition by imaging polarimetry in the red, green and blue spectral ranges. We present here the first polarization patterns of the fogbow. In the patterns of the degree of linear polarization p, fogbows and their supernumerary bows are best visible in the red spectral range due to the least dilution of fogbow light by light scattered in air. In the patterns of the angle of polarization α fogbows are practically not discernible because their α-pattern is the same as that of the sky: the direction of polarization is perpendicular to the plane of scattering and is parallel to the arc of the bow, independently of the wavelength. Fogbows and their supernumeraries were best seen in the patterns of the polarized radiance. In these patterns the angular distance δ between the peaks of the primary and the first supernumerary and the angular width σ of the primary bow were determined along different radii from the center of the bow. δ ranged between 6.08° and 13.41° , while σ changed from 5.25° to 19.47° . Certain fogbows were relatively homogeneous, meaning small variations of δ and σ along their bows. Other fogbows were heterogeneous, possessing quite variable δ- and σ-values along their bows. This variability could be a consequence of the characteristics of the high Arctic with open waters within the ice shield resulting in the spatiotemporal change of the droplet size within the fog

Gross anatomical features of the oropharyngeal cavity of the ostrich (Struthio camelus)

Most descriptions of the ostrich oropharynx and oesophagus are superficial and supply little meaningful morphological data. The aim of this investigation is describe the ostrich oropharingeal cavity, in order to supply the deficiency of macroscopic data about this important animal. Five heads of 12 to 14-month-old ostriches of either sex were anatomically dissected to expose the oropharynx. The ostrich oropharynx was "bell-shaped" composed by the maxillary and mandibular ramphoteca. The roof and floor presented two distinct regions different in colour of the mucosa. The rostral region was pale pink contrasting to creamy-pink coloured caudal region. The median longitudinal ridge extended rostrally from the apex of the choana to the tip of the beak in the roof and it is clearly more prominent and rigid than the homolog in the floor that appeared thin and stretched rostrally, continuing caudally surrounding the tongue and the laryngeal mound eventually merging with the oesophageal mucosa. The floor was formed by the interramal region, tongue and laryngeal mound containing shield-shaped glottis. It can be concluded that the present study, in addition to confirming the basic features of the oropharynx previously described for the ostrich, clarified the contradictory information presented in the literature and also provided new, unreported morphological data, some of which may be important when studying nutrition and health in these birds.

Genesis and Evolution of Brittle Structures In Southwestern Finland and Western South Africa. Insights into Fault Reactivation, Fluid Flow and Structural Maturity in Precambrian Cratons

The bedrock of old crystalline cratons is characteristically saturated with brittle structures formed during successive superimposed episodes of deformation and under varying stress regimes. As a result, the crust effectively deforms through the reactivation of pre-existing structures rather than by through the activation, or generation, of new ones, and is said to be in a state of 'structural maturity'. By combining data from Olkiluoto Island, southwestern Finland, which has been investigated as the potential site of a deep geological repository for high-level nuclear waste, with observations from southern Sweden, it can be concluded that the southern part of the Svecofennian shield had already attained structural maturity during the Mesoproterozoic era. This indicates that the phase of activation of the crust, i.e. the time interval during which new fractures were generated, was brief in comparison to the subsequent reactivation phase. Structural maturity of the bedrock was also attained relatively rapidly in Namaqualand, western South Africa, after the formation of first brittle structures during Neoproterozoic time. Subsequent brittle deformation in Namaqualand was controlled by the reactivation of pre-existing strike-slip faults.In such settings, seismic events are likely to occur through reactivation of pre-existing zones that are favourably oriented with respect to prevailing stresses. In Namaqualand, this is shown for present day seismicity by slip tendency analysis, and at Olkiluoto, for a Neoproterozoic earthquake reactivating a Mesoproterozoic fault. By combining detailed field observations with the results of paleostress inversions and relative and absolute time constraints, seven distinctm superimposed paleostress regimes have been recognized in the Olkiluoto region. From oldest to youngest these are: (1) NW-SE to NNW-SSE transpression, which prevailed soon after 1.75 Ga, when the crust had sufficiently cooled down to allow brittle deformation to occur. During this phase conjugate NNW-SSE and NE-SW striking strike-slip faults were active simultaneous with reactivation of SE-dipping low-angle shear zones and foliation planes. This was followed by (2) N-S to NE-SW transpression, which caused partial reactivation of structures formed in the first event; (3) NW-SE extension during the Gothian orogeny and at the time of rapakivi magmatism and intrusion of diabase dikes; (4) NE-SW transtension that occurred between 1.60 and 1.30 Ga and which also formed the NW-SE-trending Satakunta graben located some 20 km north of Olkiluoto. Greisen-type veins also formed during this phase. (5) NE-SW compression that postdates both the formation of the 1.56 Ga rapakivi granites and 1.27 Ga olivine diabases of the region; (6) E-W transpression during the early stages of the Mesoproterozoic Sveconorwegian orogeny and which also predated (7) almost coaxial E-W extension attributed to the collapse of the Sveconorwegian orogeny. The kinematic analysis of fracture systems in crystalline bedrock also provides a robust framework for evaluating fluid-rock interaction in the brittle regime; this is essential in assessment of bedrock integrity for numerous geo-engineering applications, including groundwater management, transient or permanent CO2 storage and site investigations for permanent waste disposal. Investigations at Olkiluoto revealed that fluid flow along fractures is coupled with low normal tractions due to in-situ stresses and thus deviates from the generally accepted critically stressed fracture concept, where fluid flow is concentrated on fractures on the verge of failure. The difference is linked to the shallow conditions of Olkiluoto - due to the low differential stresses inherent at shallow depths, fracture activation and fluid flow is controlled by dilation due to low normal tractions. At deeper settings, however, fluid flow is controlled by fracture criticality caused by large differential stress, which drives shear deformation instead of dilation.

A reconnaissance study of the metamorphic petrology and volcanic geochemistry of a portion of the Island Lake greenstone belt, Manitoba /

The Island Lake greenstone belt is one of the major Archean supracrustal exposures in the northwestern part of the Superior Province of the Canadian Shield. This belt is subdivided into two units: 1) a lower sequence characterised by pillowed to massive, locally pyroclastic, basalt to andesite with a thin central zone of felsic derivatives, all of which are interbedded with and overlain by thick sequences of turbidite facies rock; 2) the upper unit which consists of thick stratified conglomerate overlain by thickly bedded arkose and feldspathic greywacke. Reconnaissance sampling traverses were completed across both the strike of the belt and along its margins with adjacent granitoids. Most of the belt is within the greenschist metamorphic f acies with amphibolite facies occurring in certain areas near t he margins. A post-tectonic, low pressure thermal event may be responsible for the development of a unit of cordierite schi s t which stretches southeastwards from the east end of Cochrane Bay. Volcanism is cyclical in nature changing from tholeiitic to calc-alkaline. There is a general progression in the character of the lavas from mafic t o felsic with stratigraphic height. Chemica l d a ta sugges t that h i gh level fractionation of a mantle- derived ' dry' magma i s t he s ource of the thole i iti c lavas. Contamination of this magma with 'we t' sia l and subsequent fractionation may be r esponsi b l e for the calcalkaline phases .Observations of stratigraphic relationships (in particular the contact between the supracrustals and the granitoids) coupled with the metamorphic and chemical studies, allow the construction of a preliminary model for the evolution of the Island Lake greenstone belt. The following sequential development is suggested: 1) a platform stage characterised by the subaqueous effusion of mafic to intermediate lavas of alternating tholeiitic and calc-alkaline affinities; 2) an edifice stage marked by the eruption of felsic calc-alkaline rocks; 3) an erosional stage characterised by the deposit~on of thick sequences of turbidite facies rocks; 4) the impingement of granitic masses into the margins of the greenstone belt, which was probably related to a downward warping of the supracrustal pilei 5) the erosion of sialic massifs surrounding and within the greenstone belt and of early supracrustal piles, to give the clastic upper unit.

An investigation of geological and geochemical characteristics of late-Quaternay sediments in the Georgian Bay Region, Southern Ontario

Core samples of postglacial sediments and sediment surface samples from Shepherd Lake on the Bruce Peninsula, Harts Lake on the Canadian Shield, and two cores from Georgian Bay (core P-l in the western deep part and core P-7 in the eastern shallow part) have been analyzed for pH, grain size distribution, water content, bulk density, loss on ignition at 4500C and 11000 C, major oxides (Si02 ,A1203,!FeO,MgO,CaO, Na20,K20,Ti02 ,MnO and P205) and trace elements (Ba,Zr,Sr,y,S, Zn,Cu,Ni,Ce and Rb). The sediment in Georgian Bay are generally fine grained (fine silt to very fine silty clay) and the grain size decreases from the Canadian Shield (core p-7) towards the Bruce Peninsula (core P-l) along the assumed direction of sediment transport. This trend coincides with a decrease in sorting coefficient and an increase in roundness. Other physical characteristics, such as water content, bulk density and loss on ignition are positively correlated with the composition of sediments and their compaction, as well as with the energy of the depositional environment. Analyses of sediment surface samples from Shepherd Lake and Harts Lake indicate the influence of bedrock and surficial deposits in the watershed on pH condition that is also influenced by the organic matter content and probably I ! I man's activities. Organic matter content increases significantly in the surface sediment in these small lakes as a result of either natural eutrophication or anthropogenic organic loading. The extremely high organic matter content in Shepherd Lake sediment indicates rapid natural eutrophication in this closed basin and high biological productivity during postglacial time, probably due to high nutrient levels and shallow depth. The chemical composition of the Canadian Shield bedrock is positively correlated with the chemical characteristics of predominantly inorganic lake sediments that were derived from the Shield rocks by glacial abrasion and by postglacial weathering and erosion of both bedrock and surficial deposits. High correlation coefficients were found between organic matter in lake sediments and major oxides (Si02,AI203,.~FeO, MgO,CaO,K20 and MnO) , as well as some trace elements (Ba,Y, S,Zn,Cu,Ni and Rb). The chemical composition of sediments in Harts Lake and core P-7 in Georgian Bay on the Canadian Shield differs from the chemistry of sediments in Shepherd Lake and core P-l in Georgian Bay on the Bruce Peninsula. The difference between cores P-l and P-7 is indicated by values of Si02 , AI203 ,:LFeo,Mgo,CaO,Ba,Zr,Sr,y and S, and also by the organic matter content. This study indicates that the processes of sediment transport, depositional environment, weathering of the rocks and surficial deposits in the watershed, as well as chemical composition of source rocks all affect the chemical characteristics of lake sediments. The stratigraphic changes and variations in lake sediment chemistry with regard to major oxides, trace elements, and organic matter content are probably related to the history of glacial and postglacial lake stages of the Georgian Bay Region and, therefore, the geochemical data can make a useful contribution to a better understanding of the Late-Quaternary history of the Great Lakes.

Diatoms as indicators of lake trophic status

Relationships between surface sediment diatom assemblages and lake trophic status were studied in 50 Canadian Precambrian Shield lakes in the Muskoka-Haliburton and southern Ontario regions. The purpose of this study was to develop mathematical regression models to infer lake trophic status from diatom assemblage data. To achieve this goal, however, additional investigations dealing with the evaluation of lake trophic status and the autecological features of key diatom species were carried out. Because a unifying index and classification for lake trophic status was not available, a new multiple index was developed in this study, by the computation of the physical, chemical and biological data from 85 south Ontario lakes. By using the new trophic parameter, the lake trophic level (TL) was determined: TL = 1.37 In[1 +(TP x Chl-a / SD)], where, TP=total phosphorus, Chl-a=chlorophyll-a and SD=Secchi depth. The boundaries between 7 lake trophic categories (Ultra-oligotrophic lakes: 0-0.24; Oligotrophic lakes: 0.241-1.8; Oligomesotrophic lakes: 1.813.0; Mesotrophic lakes: 3.01-4.20; Mesoeutrophic lakes: 4.21-5.4; Eutrophic lakes: 5.41-10 and Hyper-eutrophic lakes: above 10) were established. The new trophic parameter was more convenient for management of water quality, communication to the public and comparison with other lake trophic status indices than many of the previously published indices because the TL index attempts to Increase understanding of the characteristics of lakes and their comprehensive trophic states. It is more reasonable and clear for a unifying determination of true trophic states of lakes. Diatom specIes autecology analysis was central to this thesis. However, the autecological relationship of diatom species and lake trophic status had not previously been well documented. Based on the investigation of the diatom composition and variety of species abundance in 30 study lakes, the distribution optima of diatom species were determined. These determinations were based on a quantitative method called "weighted average" (Charles 1985). On this basis, the diatom species were classified into five trophic categories (oligotrophic, oligomesotrophic, mesotrophic, mesoeutrophic and eutrophic species groups). The resulting diatom trophic status autecological features were used in the regressIon analysis between diatom assemblages and lake trophic status. When the TL trophic level values of the 30 lakes were regressed against their fi ve corresponding diatom trophic groups, the two mathematical equations for expressing the assumed linear relationship between the diatom assemblages composition were determined by (1) uSIng a single regression technique: Trophic level of lake (TL) = 2.643 - 7.575 log (Index D) (r = 0.88 r2 = 0.77 P = 0.0001; n = 30) Where, Index D = (0% + OM% + M%)/(E% + ME% + M%); 4 (2) uSIng a' multiple regressIon technique: TL=4.285-0.076 0%- 0.055 OM% - 0.026 M% + 0.033 ME% + 0.065 E% (r=0.89, r2=0.792, P=O.OOOl, n=30) There was a significant correlation between measured and diatom inferred trophic levels both by single and multiple regressIon methods (P < 0.0001, n=20), when both models were applied to another 20 test lakes. Their correlation coefficients (r2 ) were also statistically significant (r2 >0.68, n=20). As such, the two transfer function models between diatoms and lake trophic status were validated. The two models obtained as noted above were developed using one group of lakes and then tested using an entirely different group of lakes. This study indicated that diatom assemblages are sensitive to lake trophic status. As indicators of lake trophic status, diatoms are especially useful in situations where no local trophic information is available and in studies of the paleotrophic history of lakes. Diatom autecological information was used to develop a theory assessing water quality and lake trophic status.