Controls on the contemporary distribution of lake thecamoebians (testate amoebae) in the Greater Toronto Area and their potential as water quality indicators.

Thecamoebians were examined from 71 surface sediment samples collected from 21 lakes and ponds in the Greater Toronto Area to (1) elucidate the controls on faunal distribution in modern lake environments; and (2) to consider the utility of thecamoebians in quantitative studies of water quality change. This area was chosen because it includes a high density of kettle and other lakes which are threatened by urban development and where water quality has deteriorated locally as a result of contaminant inputs, particularly nutrients. Fifty-eight samples yielded statistically significant thecamoebian populations. The most diverse faunas (highest Shannon Diversity Index values) were recorded in lakes beyond the limits of urban development, although the faunas of all lakes showed signs of sub-optimal conditions. The assemblages were divided into five clusters using Q-mode cluster analysis, supported by Detrended Correspondence Analysis. Canonical Correspondence Analysis (CCA) was used to examine species-environment relationships and to explain the observed clusterings. Twenty-four measured environmental variables were considered, including water property attributes (e.g., pH, conductivity, dissolved oxygen), substrate characteristics, sediment-based phosphorus (Olsen P) and 11 environmentally available metals. The thecamoebian assemblages showed a strong association with phosphorus, reflecting the eutrophic status of many of the lakes, and locally to elevated conductivity measurements, which appear to reflect road salt inputs associated with winter de-icing operations. Substrate characteristics, total organic carbon and metal contaminants (particularly Cu and Mg) also influenced the faunas of some samples. A series of partial CCAs show that of the measured variables, sedimentary phosphorus has the largest influence on assemblage distribution, explaining 6.98% (P < 0.002) of the total variance. A transfer function was developed for sedimentary phosphorus (Olsen P) using 58 samples from 15 of the studied lakes. The best performing model was based on weighted averaging with inverse deshrinking (WA Inv, r jack 2= 0.33, RMSEP = 102.65 ppm). This model was applied to a small modern thecamoebian dataset from a eutrophic lake in northern Ontario to predict phosphorus and performed satisfactorily. This preliminary study confirms that thecamoebians have considerable potential as quantitative water quality indicators in urbanising regions, particularly in areas influenced by nutrient inputs and road salts.

Testate amoebae as indicators of hydroseral change: an 8,500 year record from Mer Bleue Bog, eastern Ontario, Canada.

Testate amoebae have been used widely as a proxy of hydrological change in ombrotrophic peatlands, although their response to abiotic controls in other types of mire and fenland palaeo-environments is less well understood. This paper examines the response of testate amoebae to hydroseral and other environmental changes at Mer Bleue Bog, Ontario, Canada, a large ombrotrophic peatland, which evolved from a brackish-water embayment in the early Holocene. Sediments, plant macrofossils and diatoms examined from a 5.99 m core collected from the dome of the bog record six stages of development: i) a quiet, brackish-water riverine phase (prior to ca. 8500 cal BP); ii) a shallow lake (ca. 8500–8200 cal BP); iii) fen (8200–7600 cal BP); iv) transitional mire (7600–6900 cal BP); v) pioneer raised mire (6900–4450 cal BP); and vi) ombrotrophic bog (4450 cal BP-present).

Testate amoebae, notably small (<25 µm diameter) specimens of Centropyxis aculeata type, first appear in low abundances in sediments ascribed to the lacustrine phase. Diatoms from the same horizons record a shallowing in water depth, a decline in salinity and the development of emergent macrophytic vegetation, which may have provided favourable conditions for testate amoeba colonization. The testate amoeba communities of the inferred fen phase are more diverse and include centropyxids, cyclopyxids, Arcellidae and Hyalospheniidae, although the assemblages show some differences to those recently reported in modern European fen environments. The Fen–Bog Transition (FBT) is also dominated by C. aculeata type. The change in testate amoeba communities around this key transition is apparent in the results of Detrended Correspondence Analysis (DCA), and appears to reflect a latent nutrient gradient and a secondary moisture gradient. DCA analyses of plant macrofossil remains around the FBT show a similar trend, although the sensitivity of the two proxies to the inferred environmental changes differs. Comparisons with other regional mid-Holocene peatland records confirm the important influence of reduced effective precipitation on the testate amoeba communities during the initiation and development of Sphagnum-dominated, raised bog communities.

Drift dispersal in central Southern Ontario /

Two tills are readily identi-f i able in central Southern Ontario, a very stony, loose deposit o-f variable matrix (Dummer till) and a moderately stony, fissile and compact deposit that is more homogeneous (drumlinized till). The quantity o-f Precambr i an, Paleozoic and Shadow Lake Formation (Paleozoic) rock types were determined and corresponding isopleth maps drawn. The changes in lithology content occurred in the direction o-f transport, there-fore, compositional isopleths o-f till may be considered equipotential lines for the reconstruction of glacier flow paths. Areal gradations of drift lithology indicated that the prime agents of dispersal were ice and glacial meltwaters. The down-ice abundance trend of till components indicated a dispersal pattern showing the concentration of a given lithology type peaking within a few kilometres of the source followed by a rapid decline and thereafter, a more gradual decrease with increasing distance. Within the esker deposits, igneous rocks may form the major component and can extend further onto the limestone plain than in the adjacent till. Evidence is presented that indicates the "style" of dispersal was one in which glacial ice may have been strongly influenced by local bedrock topography and the regional structural trends. The ice tended to follow pre-existing valleys and lows, depositing till composed mainly of local bedrock. Gradations in Paleozoic clast content showed that the local bedrock lithology became the primary till component within 3 km of down-ice transport. Evidence is presented that indicated the last glaciation may have occurred as a relatively thin ice mass, followed by stagnation and recession. No evidence of a lateglacial re-advance was found within the study area. Because of the lack of a contact between the Dummer and drumlinized till, and because of results showing gradation of the Dummer till into the drumlinized till (as indicated by lithology content and grain size), it is suggested that no re-advance occurred.

The surficial geology, sedimentology and geochemistry of the late glacial sediments and Paleozoic bedrock in the Campbellford area, Ontario, with special reference to the Dummer Complex /

The Dummer Complex extends 180 km along the Precambrian - Paleozoic contact from Tamworth to Lake Simcoe. It is composed of coarse, angular Paleozoic clasts in discontinuous, pitted, hummocky deposits. Deposits are usually separated by bare or boulder strewn bedrock, but have been found in the southern drumlinized till sheet. Dummer Complex deposits show rough alignment with ice-flow. Eskers cross-cut many of the deposits. Dummer sediment subfacies are defined on the basis of dominant coarse grain size and lithology, which relate directly to the underlying Paleozoic formation. Three subglacial tills are identified based on the degree of comminution and distance of transport; the immature facies of the Dummer Complex; the mature facies of the drumlinized till sheet and; the submature facies which is transitional. Carbonate geochemistry was used for till-bedrock correlation in various grain sizes. Of the 3 Paleozoic formations underlying the Dummer Complex, the Gull River Fm. is geochemically distinctive from the Bobcaygeon and Verulam Formations using Ca, Mg, Sr, Cu, Mn, Fe and Na. The Bobcaygeon Fm. and Verulam Fm. can be differentiated using Ca and the Sr/Ca ratio. The immature facies from 1.0 phi and finer is dominated by the non-carbonate, long distance transported component which decreases slightly downice. The submature till facies contains more long distance material than the immature facies. Sr and Mn can be used to correlate the Gull River immature till facies to the underlying bedrock the other subfacies could not be distinguished from each other or their respective source formation. This method proved to be ineffective for sediments with greater than 35% non-carbonate component, due to leaching of elements by the dissolving acid.The Dummer Complex is produced subglacially , as the compressional ice encounters the permeable Paleozoic carbonates. The increased shear strength of the ice and pore pressures in the carbonates results in the basal ice zones becoming debris ladden. Cleaner ice overrides the basal debris . laden dead ice which then acts as the glacier bed. During retreat, the Simcoe lobe stagnates as flow is cut-off by the Algonquin Highlands.

Structural studies in the Southern Province, South of Sudbury, Ontario

Rocks correlated with the Hough Lake and Quirke Lake Groups of the Huronian Supergroup form part of a northeasterly trending corridor that separates 1750 Ma granitic intrusive rocks of the Chief Lake batholith from the 1850 Ma mafic intrusive rocks of the Sudbury Igneous Complex. This corridor is dissected by two major structural features; the Murray Fault Zone (MFZ) and the Long Lake Fault (LLF). Detailed structural mapping and microstructural analysis indicates that the LLF, which has juxtaposed Huronian rocks of different deformation style and metamorphism grade, was a more significant plane of dislocation than the MFZ. The sense of displacement along the LLF is high angle reverse in which rocks to the southeast have been raised relative to those in the northwest. South of the LLF Huronian rocks underwent ductile defonnation at amphibolite facies conditions. The strain was constrictional, defined by a triaxial strain ellipsoid in which X > Y > z. Calculations of a regional k value were approximately 1.3. Penetrative ductile defonnation resulted in the development of a preferred crystallographic orientation in quartz as well as the elongation of quartz grains to fonn a regional southeast-northwest trending, subvertical lineation. Similar lithologies north of the LLF underwent dominantly brittle deformation under greenschist facies conditions. Deformation north of the LLF is characterized by the thrusting of structural blocks to form angular discordances in bedding orientation which were previously interpreted as folds. Ductile deformation occurred between 1750 and 1238 Ma and is correlated with a regional period of south over north reverse faulting that effected much of the southern Sudbury region. Post dating the reverse faulting event was a period of sedimentation as a conglomerate unit was deposited on vertically bedded Huronian rocks. Rocks in the study area were intruded by both mafic and felsic dykes. The 1238 Ma mafic dykes appear to have been offset during a period of dextral strike slip displacement along the major fault'). Indirect evidence indicates that this event occurred after the thrusting at 950 to 1100 Ma associated with the Grenvillian Orogeny.

A comparative study of the change in diatom inferred ph of a staircase of lakes in the Algoma District, Northern Ontario /

Four staircase lakes occupying a single watershed located in the Algoma District, north of Lake Superior were chosen for this study. I examined the subfossil diatom assemblage in the top twenty centimeters of the surface sediments in each of these four lakes in an attempt to reconstruct their respective past pH history. From these analyses it was possible to test the hypothesis that the rate of change of diatom inferred pH was not significantly different in lakes located one below the other in a single "staircase" within a single watershed system. My results indicated that the four Z lakes had been acid for at least the last century. The water color of the three upper Z lakes (Z1, Z2 and Z3) was brown (>30 Pt Co units). The bottom lake (Z4) was the only clear water lake in the system «5 Pt Co units). This bottom staircase lake had no muskeg development around its shoreline. The alkaliphilous diatoms in the Z watershed system were important in determining the diatom inferred pH of the four Z lakes. The centric diatoms were extremely rare in the clearwater bottom lake (Z4). The ecology of the Eupodiscales is perhaps important in the interpretation of sediment in the more acid environment. Lake Z4 was the only one that had a progressive as well as a significant decrease in its downcore diatom inferred pH since the early 1960's. This lead me to speculate that the humic substances present in the upper three brown water lakes (Z1, Z2 and Z3) were perhaps Important in buffering them against a further decrease in water pH even though they were located within an area which was sensitive to acid precipitation.

Palynology of late-glacial and postglacial sediments in Georgian Bay, Ontario, Canada, as related to the Great Lakes history /

This investigation comprises three parts: (1) the source, mechanism of transport, and distribution of pollen, spores and other palynomorphs in Georgian Bay bottom sediments and a comparison of these data with the contemporary vegetation, (2) the relative significance of fluvial transportation of pollen and spores, and (3) the late- and postglacial history of vegetational and climatic changes in the Georgicin Bay region. Modem pollen and spore assemblages in Georgian Bay do reflect the surrovinding vegetation when preservation and pollen production by the different species are considered and accounted for. Relative pollen percentage and concentration isopoll patterns indicate that rivers contribute large quantities of pollen and spores to Georgian Bay. This is further substantiated by large amounts of pollen and spores which were caught in traps in the Moon, Muskoka, and Nottawasaga Rivers which flow into Georgian Bay. The majority of pollen and spores caught in these traps were washed into the rivers by surface water runoff and so reflect the vegetation of the watershed in a regional sense. In a 12.9 metre long sediment core from northeastern Georgian Bay the relative percentage and absolute pollen concentrations allow correlation of Georgian Bay Lake phases with climatic and forest history. Four distinct pollen zones are distinguished: zone GB IV which is the oldest, reflects the succession from open spruce woodland to boreal forest; zone GB III represents a period of pine-mixed hardwoods forests from about 10,000 to 7,500 years ago. A pine-maplehemlock association dominated in zone GB II, although during the culmination of postglacial warming about 4,000 to 5,000 years ago the Georgian Bay forests had a more deciduous character. Zone GB I clearly shows European man's disturbance of the forest by logging activities.

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.

Environmental assessment and biomonitoring of the Twelve Mile Creek watershed, Niagara Peninsula, Ontario

In light of the heavy reliance of the people of the Niagara Peninsula on the T\\'elve Mile Creek (TMC) watershed for recreational activities and for municipal and industrial uses ( e.g., drinking water, shipping and discharge of effluents), it was deemed prudent to assess the envirol1tnental health of the system by analysing the sediments total and exchangeable metal, and TPH contents. The MOEE has set guidelines with limits for the protection and management of aquatic sediments, and the sediments from the headwaters of the TMC have total metal and TPH (subset of O&G) contents well below the lower provincial limits. Areas of environmental concern where total metal contents in sediments, either individually or collectively, exceed the guideline, are the south side of Lake Gibson, the Old WeIland Canal, a segment of TMC just south of the QEW and Martindale Pond. The total metal content of sediments does not in all instances identify areas of biological concern. Instead, it has been found that the exchangeable metal fraction of sediments is a better indicator of metal availability and thus potential accumulation in organisms. In some instances, the exchangeable metal fraction agrees with the total metal fraction defining areas of environmental concern, but it does vary from site to site reflecting the natural variability of the ambient environment. Overall, the exchangeable metal fraction of sediments appears to be a better indicator of anthropogenic pollution and ecosystem impact. A histochemical study of Anodon.ta sp., Elliptio sp. and zebra mussels (Dreissena polyn'101pha) was done in conjunction with passive biomonitoring of zebra and quagga mussels (Dreissena bugensis) from the Twelve Mile Creek watershed and Lake 51. Clair (Jeanette's Creek, Chatham, Ontario). The highest concentrations of divalent metals such as Cu, Ni, Cd, and Zn, and trivalent Al appear to accumulate in gill and kidney tissues. Metal contents of organ tissues in Anodonta sp. vary with size class. Organ metal content varies among size classes, thus requiring consideration of size in biomonitoring studies. Shucked zebra and quagga mussel tissues, exhibited similar size class to Al content trends. In addition they reflected the Al content trends of top (approximately 10 cm) most sediments in the Twelve Mile Creek watershed. Quagga mussels appear to have higher Al concentrations than zebra mussels, thus suggesting that quagga mussels may be better passive biomonitors of AI. Cd content in zebra mussel tissues, seemed to increase with size class trends. This was not demonstrated in the quagga mussel tissues. This suggests that Cd may be regulated by quagga mussels and not by zebra mussels, and that zebra mussels may be better passivebiomonitors of Cd than are quagga mussels. Zebra mussel, quagga mussel, Anodonta sp., and Elliptio sp. were used in a two part, active (translocated) biomonitoring study of the Twelve Mile Creek watershed. There was no statistical difference in death rates between zebra and quagga mussels after 65 days of biomonitoring. However there does appear to be a difference of death rates between sites. Unfortunately the data base did not permit us to differentiate between sites. Relative to Port Colborne Harbour (Port Colborne, Ontario), the Twelve Mile Creek watershed appears to be elevated in bioavailable AI. An area near the terminus of the Twelve Mile Creek appears to be an area of environmental concern since mussels seemed to have accumulated relatively large concentrations of Cd, Zn, and Pb. In addition to possible metal loading from a nearby outfalls, or possible upstream outfalls, road salt runoff from storm sewers may have contributed to metal accumulation through cation exchanges processes. Similar trends in cumulative quagga mussel metal concentrations during the two time periods (65 and 159 days), suggest that quagga mussels may reach equilibrium within 65 days of translocation. Differences in bioaccumulated metal concentrations of the two dreissenid species demonstrate that active biomonitoring studies must use a variety of organisms to adequately assess the environmental situation of specific waterways and/or bodies.

Environmental assessment of Lake Gibson sediments, water quality, and soils of the Niagara Region

In light of the fact that literature on toxicity of heavy metals in non-acidified freshwater systems is sparse, this project was initiated to conduct an environmental assessment of Lake Gibson. Chemistry of soils from adjacent areas and vineyards in the region provide a comparative background database. Water quality determinations were used to identify and highlight areas of environmental concern within the Lake Gibson watershed. A Shelby Corer was used to obtain 66 sediment cores from Lake Gibson. These were sectioned according to lithology and color to yield 298 samples. A suite of 122 soil samples was collected in the region and vicinity of Lake Gibson. All were tested for metals and some for Total Petroleum Hydrocarbons (TPH). Evaluation of the results leads to the following conclusions: 1. Metal concentrations ofAI, Cd, Cu, Cr, Pb, Ni, Fe and Zn in soils from the Niagara Region are well below background limits set by the Ministry of the Environment and Energy (MOEE) for provincial soils. 2. There is a spatial and depth difference for some of the metals within the various soils. The Cr, Ni and Pb contents of soils vary throughout the region (pLake Gibson fall below the LEL (Lower Effect Level) guideline specified by the MOEE for aquatic ecosystems. 4. All other metal contents exceed the LEL, and in some instances they also exceed the SEL (Severe Effect Level) guideline. In this instance acute toxicity testing of 11 the sediments is required to assess impact on the aquatic biota. 5. Specifically, effluents and discharges from outfalls, roadways, railways and industrial activities are all degrading the local ecosystem. 6. Mineral oil and greases are a major environmental concern in the sediments of Lake Gibson. Ofthe 240 samples tested for TPH, 200 samples exceed the MOEE Open Water Disposal Guideline of 1,500 mg/kg. 7. Four areas within Lake Gibson are especially degraded with respect to TPH. One area is just downstream from the Old WeIland Canal divergence point and waterfall. Other areas of concern are located just south of Beaverdams Road and just west ofthe Ontario Hydro control pipes; south ofthe Village ofBeaverdams. The fourth area of environmental concern and TPH impact is located between Highway 406 and Merrittville Highway.

Palaeopigment accumulation and implcations for paleolimnology over the lost century for two Ontario lakes

Crawford Lake is a meromictic lake, which is 24 m deep and has an area of 2.5 ha, and has never been reported to have mixed below 16 m. Lady Evelyn Lake, which became a reservoir when a dam was built in 1916, is dimictic with a maximum depth of about 35 m. 1 My research proved that both native chlorophylls and the ratio of chlorophyll derivatives to total carotenoids were better preserved in the shallower lake (Crawford Lake) because it was meromictic. Thus the anaerobic conditions in Crawford Lake below 16 m (monimolimnion) provide excellent conditions for pigment preservation. Under such conditions, the preservation of both chlorophylls and carotenoids, including oscillaxanthin and myxoxanthophyll, are extremely good compared with those of Lady Evelyn Reservoir, in which anaerobic conditions are rarely encountered at the mud-water interface. During the period from 1500 to 1900 A. D. in Crawford Lake, the accumulation rates of oscillaxanthin and myxoxanthophyll were extremely high, but those of chlorophyll derivatives and total carotenoids were relatively low. This was correlated with the presence of a dense benthic mat of cyanobacteria near the lake's chemocline. Competition for light between the deep dwelling cyanobacteria and overlying phytoplankton in this meromictic lake would have been intensified as the lake became more and more eutrophic (1955-1991 A. D.). During the period from 1955 to 1991 A. D., the accumulation rates of chlorophyll derivatives and total carotenoids in the sediment core from Crawford Lake (0-7.5 cm, 1955-present) increased. During this same period, the accumulation rates of cyanobacterial pigments (Le. oscillaxanthin and myxoxanthophyll) declined as the lake became more eutrophic. Because the major cyanobacteria in Crawford Lake are benthic mat forming Lyngbya and Oscillatoria and not phytoplankton, eutrophication resulted in a decline of the mat forming algal pigments. This is important because in previous palaeolimnological studies the concentrations of oscillaxanthin and myxoxanthophyll have been used as correlates with lake trophic levels. The results of organic carbon a13c analysis on the Crawford Lake sediment core supported the conclusions from the pigment study as noted above. High values of a13c at the depth of 34-48 cm (1500-1760 A. D.) were related to a dense population of benthic Oscillatoria and Lyngbya living on the bottom of the lake during that period. The Oscillatoria and Lyngbya utilized the bicarbonate, which had a high a 13C value. Very low values were found at 0-7 cm in the Crawford sediment core. At this time phytoplankton was the main primary producer, which enriched 12C by photosynthetic assimilation.

Petrography, geochemistry and structure of the Timmins area, Ontario

Regional structural analysis of the Timmins area indicates four major periods of tectonic deformation. The DI deformation is characterized by a series of isoclinal FI folds which are outlined in the study area by bedding, pillow tops and variolitic flows. The D2 deformation developed the Porcupine Syncline and refolded the Fl folds about a NE. axis. A pervasive S2 foliation developed during low grade (greenschist) regional metamorphism associated with the D2 deformation. The S2 foliation developed south of the Destor-Porcupine Break. The third phase of tectonic D3 deformation is recognized by the development of a S3 sub-horizontal crenulation cleavage which developed on the plane of the S2 foliation. No meso scopic folds are associated with this deformation. The 8 3 crenulation cleavage is observed south of the Destor-Porcupine Break. The D4 tectonic deformation is recorded as a subvertical S4 crenulation cleavage which developed on the plane of the S2 foliation and also offsets the S3 crenulation cleavage. Macroscopic F4 folds have refolded the F2 axial plane. No metamorphic recrystallization is associated with this deformation. The S4 crenulation cleavage is observed south of the Destor-Porcupine Break. Petrographic evidence indicates that the Timmins area has been subjected to pervasive regional low grade (greenschist) metamorphism which has recrystallized the original mineralogy. South of the study are~ the Donut Lake ultramafic lavas have been subjected to contact medium grade (amphibolite facies) metamorphism associated with the intrusion of the Peterlong Lake Complex. The Archean volcanic rocks of the Timmins area have been subdivided into komatiitic, tholeiitic and calcalkaline suites based on Zr, Ti0 2 and Ni. The three elements were used because of their r e lative immobility during subsequent metamorphic events. Geochemical observations in the Timmins area indicates that the composition of the Goose Lake and Donut Lake Formations are a series of peridotitic, pyroxenitic and basaltic komatiites. The Lower Schumacher Formation is a sequence of basaltic komatiites while the upper part of the Lower Schumacher Formation is an intercalated sequence of basaltic komatiites and low Ti0 2 tholeiites. The variolitic flows are felsic tholeiites in composition and geochemical evidenc e sugg ests that they developed as a n immiscible splitting of a tholeiitic magma. The Upper Schumacher Formation is a sequence of tholeiitic rocks dis p laying a mild iron enrichment. The Krist and Boomerang Formations are the felsic calc-alkaline rocks of the study area which are characteristically pyroclastic. The Redstone Fo rmation is dominantly a calc-alkali ne sequence of volcani c rocks whose minor mafic end me mbers exposed in 1t.he study hav e basaltic komatiitic compositions. Geochemical evidence sugges ts that the Keewatin-type se dimentary rocks have a composition similar to a quartz diorite or a granodiorite. Fi e l d obs ervations and petrographic evidence suggests that they were derived fr om a distal source and now repr esent i n part a turbidite sequence. The Timiskaming-type sedimentary rocks approach the c omp osi t ion of the felsic calc-alkaline rocks of the study area . The basal conglomerate in the study are a sugge s ts that th e uni t was derived fr om a proximal source. Petrographic and ge ochemical evidence suggests that the peridotitic and pyroxenitic komatiites originated as a 35-55% partial melt within the mantle, in excess of 100 Km. depth. The melt ros e as a diapir with the subsequent effusion of the ultramafic lavas, The basaltic komatiites and tholeiitic rocks originated in the mantle from lesser degrees of partial melting and fractionated in low pressure chambers. Geochemical evidence suggests a "genetic link" between the basaltic komatiites and tholeiites, The calc-alkaline rocks developed as a result of the increa.se In PO in the magma chamber. The felsic calcalkaline rocks are a late stage effusion possibly the last major volcanic eruptions in the area.

The sedimentology of the Bloomington fan complex: an element of the Oak Ridges Moraine, Southern Ontario

The Oak Ridges Moraine is a major physiographic feature of south-central Ontario, extending from Rice Lake westward to the Niagara Escarpment. While much previous work has largely postulated a relatively simple the origin of the moraine, recent investigations have concentrated on delineating the discernible glacigenic deposits (or landform architectural elements) which comprise the complex mosaic of the Oak Ridges Moraine. This study investigates the sedimentology of the Bloomington fan complex, one of the oldest elements of the Oak Ridges Moraine. The main sediment body of the Bloomington fan complex was deposited during early stages of the formation of the Oak Ridges Moraine, when the ice subdivided, and formed a confined, interlobate lake basin between the northern and southern lobes. Deposition from several conduits produced a fan complex characterized by multiple, laterally overlapping, fan bodies. It appears that the fans were active sequentially in an eastward direction, until the formation of the Bloomington fan complex was dominated by the largest fan fed by a conduit near the northeastern margin of the deposit. Following deposition of the fan complex, the northern and southern ice margins continued to retreat, opening drainage outlets to the west and causing water levels to drop in the lake basin. Glaciofluvial sediment was deposited at this time, cutting into the underlying fan complex. Re-advancing northern ice then closed westerly outlets, and caused water levels to increase, initiating the re-advance of the southern ice. As the southern ice approached the Bloomington fan, it deposited an ice-marginal sediment complex consisting of glacigenic sediment gravity flows, and glaciolacustrine and glaciofluvial sediments exhibiting north and northwesterly paleocurrents. Continued advance of the southern ice, overriding the fan complex, ii produced large-scale glaciotectonic deformation structures, and deposited the Halton Till. The subaqueous fan depositional model that is postulated for the Bloomington fan complex differs from published models due to the complex facies associations produced by the multiple conduit sources of sediment feeding the fans. The fluctuating northern and southern ice margins, which moved across the study area in opposite directions, controlled the water level in the interlobate basin and caused major changes in depositional environments. The influence of these two lobes also caused deposition from two distinct source directions. Finally, erosion, deposition, and deformation of the deposit with the readvance of the southern ice contributed further to the complexity of the Bloomington fan complex.

The utility of sedimentary diatoms as a measure of historical lake ph

As a result of increased acid precipitation, the pH of a large number of Canadian Shield lakes has been falling. Prior to this study there was no documentation available to explain the history of lake acidification for the Algoma area lakes. In order to obtain this information the diatom inferred pH technique was developed in this study. During two field seasons, July 1981 and July 1982, short sediment cores (circa 25-30 cm) were collected from 28 study lakes located north of Lake Superior, District Algoma, Ontario. The surface sediment diatoms (0-1 cm) from each of these lakes were carefully identified, enumerated, and classified in terms of their pH indicator status. The surface sediment diatom analysis indicated that lake pH is one of the most important factors affecting the species composition and relative abundance of diatom populations. Thus diatom assemblages can be sensitive indicators of lake acidification. When Nygaard's index alpha was plotted against observed lake pH, a statistically significant relationship resulted (r=-0.89; p=lakes (lakes X4, CS, U3, and WI). The repeatability of this technique was confirmed by comparing two downcore paleo-pH profiles of Lake WI. These two paleo-pH profiles represented almost identical paleo-pH patterns for Lake WI. The paleo-pH study of Lake X4 revealed that the lake has been rather acidic (pH <5.6) for the last 200 years. It appears that the recent increase in acid precipitation 3 over the last 30 years has not altered the water pH compared to the lake's pH history. However, the paleo-pH study of another acidic lake (Lake CS) indicated that its pH has significantl}* dropped over the last 30 years . During this time the Lake CS pH has dropped almost 2 pH units (7.1 to 5.2). The other two lakes studied for downcore pH were circumneutral in nature . One of these lakes (Lake U3) displayed a relatively stable pH history while the other lake (Lake WI) displayed significant pH fluctuations over post-Ambrosia time. The variable pH history of Lake WI was probably associated with the Algoma sintering plant plume and forest fires. A significant relationship between surface sediment diatoms and observed lake pH and secondly a statistically significant relationship between index alpha and observed pH suggested that diatoms are one of the best indicators of lake pH. Thus diatom inferred pH technique has great potential in explaining the rate of lake acidification.