Characteristics of minke whale (Balaenoptera acutorostrata) habitat at the head of the Laurentian Channel in the St. Lawrence Estuary, Canada were identified by quantifying environmental and temporal habitat variables and comparing them to the presence or absence of minke whales during the summer of 1996. Identification photographs of minke whales taken during the summers of 1995 and 1996 were used to examine intra-annual and year to year habitat use by individual minke whales. Minke whales were primarily distributed between the 50 m and 100 m bathymetric contours which corresponds to the ridge of the Laurentian Channel. This region is characterized by a steep slope in bottom topography which causes predictable accumulations of euphausiids and capelin (Mal lotus villosus), the principal prey species of minke whales. Tide phase, lunar phase and time of season, all of which cause slight fluctuations in prey abundance did not appear to have a significant influence on minke whale presence or movements. Individual minke whales exhibited site tenacity in returning to a localized area both within a season and in consecutive years. / Graduation date: 1999

Benthic uptake of mercury (Hg) governs bioavailability to fish yet there are still large gaps in our knowledge of what mediates this process. Without this information it is difficult to ascertain where Hg accumulation in the foodweb will be greatest. In the St. Lawrence River Area of Concern (AOC) at Cornwall, one contaminated zone (Zone 1) shows elevated Hg in yellow perch (Perca flavescens) and their prey items compared to those from other zones in the AOC. Greater availability of Hg to benthos due to unique physical features (large deposition of woodfibre deposits) of Zone 1 is hypothesized to account for this observation. In this study, amphipods (Gammarus fasciatus) and (Echinogammarus ischnus) were collected in Zone 1 using artificial substrates between June-September 2007, and Hg concentrations compared to those obtained in sediments and porewaters of surficial sediments, as well as methane gas evasion rates. Methylmercury (MeHg) concentrations in amphipods were significantly related to porewater total Hg (THg) and MeHg concentrations. No parallel relationship was found for sediment Hg concentrations or methane bubbling rates from sediments. Spatial and temporal trends in Hg bioavailability were evident from significant relationships with water column depth and temperature. Water column depth was associated with higher MeHg concentrations in amphipods and porewaters. Concentrations of porewater MeHg were above the detection limit in all of the June samples, the month which also coincided with highest amphipod MeHg concentrations. Finally, sediment organic matter may be influencing patterns of MeHg availability in Zone 1, and displayed a negative relationship to amphipod MeHg. Although bubbling from contaminated sediments did not directly correlate with amphipod Hg uptake, future studies should look at the influence of bubbling on the redistribution of contaminated sediment particles within the zone. / Thesis (Master, Biology) -- Queen's University, 2008-12-30 23:34:20.287

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 163-170).

The Pine Hill collection was discovered in the archaeology lab at State University of New York College at Potsdam after remaining unstudied for over 30 years since its initial excavation in the 1960s and 1970s. Pine Hill has been identified as a fifteenth century St. Lawrence Iroquois village site, located in St. Lawrence County, New York. The faunal remains and bone tools from the site indicate food procurement strategies, seasonal activities, the presence of discrete activity areas at the site, and the production and use of a wide range of bone tools. Replication experiments conducted on several bone tool types provide insight about how these tools were made, used, and how quickly they might be discarded. As one of the first reports on a St. Lawrence Iroquois site in the region, this study presents important information about this group.

We have developed a regional mass balance model for the St. Lawrence River near Cornwall, Ontario that describes the fate and transport of mercury in three forms, elemental mercury (Hg0), divalent mercury (Hg2+), and methyl mercury (MeHg), in a five compartment environment (air, water, sediments, periphyton, and benthos). Our first objective was to construct a steady-state mass balance model to determine the dominant sources and sinks of mercury in this environment. Our second objective was to construct a dynamic mass balance model to predict and hindcast mercury concentrations in this environment. We compiled mercury concentrations, fluxes, and transformation rates from previous studies completed in this section of the river to develop the model in STELLA®. The inflow of mercury was the major source to this system, accounting for 0.42 mol month-1, or 95.5% of all mercury inputs, whereas outflow was 0.28 mol month-1, or 63.6% of all losses, and sediment deposition was 0.12 mol month-1, or 27.3% of all losses. The dynamic mass balance model provides estimated results that are consistent with measured data and predicts historical local industrial emissions to be approximately 400 kg year-1. Uncertainty estimates were greatest for advective fluxes in surface water, porewater, periphyton, and benthic invertebrates. This model is useful for predicting and hindcasting mercury concentrations in other aquatic environments because it contains the three main environmental compartments, all forms of mercury, and compartments (e.g. periphyton) not included in previous mercury multi-media models.

We have developed a regional mass balance model for the St. Lawrence River near Cornwall, Ontario that describes the fate and transport of mercury in three forms, elemental mercury (Hg0), divalent mercury (Hg2+), and methyl mercury (MeHg), in a five compartment environment (air, water, sediments, periphyton, and benthos). Our first objective was to construct a steady-state mass balance model to determine the dominant sources and sinks of mercury in this environment. Our second objective was to construct a dynamic mass balance model to predict and hindcast mercury concentrations in this environment. We compiled mercury concentrations, fluxes, and transformation rates from previous studies completed in this section of the river to develop the model in STELLA®. The inflow of mercury was the major source to this system, accounting for 0.42 mol month-1, or 95.5% of all mercury inputs, whereas outflow was 0.28 mol month-1, or 63.6% of all losses, and sediment deposition was 0.12 mol month-1, or 27.3% of all losses. The dynamic mass balance model provides estimated results that are consistent with measured data and predicts historical local industrial emissions to be approximately 400 kg year-1. Uncertainty estimates were greatest for advective fluxes in surface water, porewater, periphyton, and benthic invertebrates. This model is useful for predicting and hindcasting mercury concentrations in other aquatic environments because it contains the three main environmental compartments, all forms of mercury, and compartments (e.g. periphyton) not included in previous mercury multi-media models.

We have developed a regional mass balance model for the St. Lawrence River near Cornwall, Ontario that describes the fate and transport of mercury in three forms, elemental mercury (Hg0), divalent mercury (Hg2+), and methyl mercury (MeHg), in a five compartment environment (air, water, sediments, periphyton, and benthos). Our first objective was to construct a steady-state mass balance model to determine the dominant sources and sinks of mercury in this environment. Our second objective was to construct a dynamic mass balance model to predict and hindcast mercury concentrations in this environment. We compiled mercury concentrations, fluxes, and transformation rates from previous studies completed in this section of the river to develop the model in STELLA®. The inflow of mercury was the major source to this system, accounting for 0.42 mol month-1, or 95.5% of all mercury inputs, whereas outflow was 0.28 mol month-1, or 63.6% of all losses, and sediment deposition was 0.12 mol month-1, or 27.3% of all losses. The dynamic mass balance model provides estimated results that are consistent with measured data and predicts historical local industrial emissions to be approximately 400 kg year-1. Uncertainty estimates were greatest for advective fluxes in surface water, porewater, periphyton, and benthic invertebrates. This model is useful for predicting and hindcasting mercury concentrations in other aquatic environments because it contains the three main environmental compartments, all forms of mercury, and compartments (e.g. periphyton) not included in previous mercury multi-media models.

The St. Lawrence Platform (SLP) and Humber Zone (HZ) of the southern Quebec Appalachians has historically been explored as a potential hydrocarbon reservoir. Extensive vitrinite reflectance studies on the basin resolved the degree of thermal maturation yet the timing of the thermal maximum is not well undertood. Determining the timing of such low temperature events can allow for a better understanding of the shallow crustal processes that may have allowed for the generation and entrapment of oil and gas. We have employed apatite (AHe) and zircon (ZHe) (U-Th)/He thermochronmetry across a network of late Cambrian to late Ordovician siliciclastic and Grenvillian basement samples in order to resolve the history within the ~210-35°C window. Single crustal dates from individual samples show age dispersion by as much as 300 m.y. with a strong positive to negative correlation with increasing eU concentration. A similar positive correlation can be observed when significant intra-sample grain size variation is present. AHe and ZHe data in the southwestern portion of the basin, near Montreal, allow for thermal maxima of up to 200°C to occur either during the late Ordovician, as a result of the Taconic orogeny, or from the continued sedimentation into the Devonian as a result of the Acadian orogeny. Regional burial trends deduced from these thermal maxima along with local paleo-geothermal gradients indicate that if sedimentation continued after the late Ordovician there was no significant increase in burial in southwestern portion of the SLP as previously suggested. Maximum heating is followed by a protracted cooling through the ZHe partial retention zone (PRZ) into the late Jurassic and early Cretaceous where the cooling rate increases by an order of magnitude through the AHe PRZ until ca. 100 Ma. The timing of this accelerated cooling is coeval with the passage of the Great Meteor Hot Spot across the area; the cooling may be a result of increased erosion from thermal uplift. Within the HZ, both the external and internal sections experienced rapid cooling through the Silurian after the Taconic thermal maximum. The timing of relatively rapid cooling coincides with documented normal faulting and back-thrusting in the orogen, which is the likely cause of exhumation. The HZ witnessed protracted cooling through the late Jurassic, when there is a one order of magnitude increase in cooling rate until surface conditions are attained. Increased recognition of these low temperature events has augmented our understanding of the evolution of accretionary orogens and consequently reduces the risks associated with oil and gas exploration.

Neoproterozoic-Early Cambrian continental rifting related to the breakup of the supercontinent Rodinia framed the continental margin of eastern Laurentia and the departing cratons around the opening Iapetus Ocean. The result of continental extension was the production of a zig-zag set of promontories and embayments on the eastern Laurentian margin defined by northeast-trending rift segments offset by northwesttrending transform faults. The St. Lawrence promontory defines the Laurentian margin in western Newfoundland. There, Neoproterozoic-Carboniferous clastic, volcanic, and carbonate successions record protracted continental rifting and passive-margin thermal subsidence followed by destruction of the margin during the early, middle, and late Paleozoic Appalachian orogenic cycles. Palinspastic restoration of deformed Paleozoic strata by a set of balanced cross sections resolves the structure, stratigraphy, and timing of Paleozoic tectonic events on the St. Lawrence promontory. Synrift and post-rift subsidence profiles, as well as abrupt along-strike variations in the age, thickness, facies, and the palinspastically restored extent of synrift and post-rift stratigraphy, indicate the St. Lawrence promontory was founded upon a low-angle detachment rift system. Upperplate margins, lower-plate margins, and transform faults that bound zones of oppositely dipping low-angle detachments are recognized along specific segments of the promontory. A detailed U-Pb and Lu-Hf isotopic detrital zircon study elucidates the identity of specific cratons conjugate to the St. Lawrence promontory in the pre-rift configuration of Rodinia. Approximately 510 zircons from 9 samples collected from basement and overlying Early Cambrian synrift rocks in Newfoundland were analyzed by LA-ICP-MS for U-Pb ages and Hf isotopic ratios. Synrift samples yielded ages ranging from 3605 Ma to 544 Ma with maximum age frequencies of 1000-1200 Ma (Grenville), 1350-1450 Ma (Pinware), and 2650-2800 Ma (Superior), while two basement samples yielded U-Pb ages of 1044 Ma and 1495 Ma. 177Hf/176Hf isotopic ratios of ca.1000 Ma, 1200 Ma, and 1400- 1600 Ma zircons from Newfoundland basement and synrift rocks are a close match to reported 177Hf/176Hf ratios for Baltican zircons of the same vintage, suggesting that Baltica was conjugate to the St. Lawrence promontory.

As a result of the legacy of industrial contamination over the last century, areas of sediment deposition in the St. Lawrence River at Cornwall, ON, contain high concentrations of mercury (Hg). The popular sport-fish species, yellow perch (Perca flavescens) and walleye (Sander vitreus) have been found to contain mercury concentrations exceeding Ontario Ministry of Environment consumption guidelines. Interestingly, a paradox exists between two contaminated sites – despite elevated sediment Hg concentrations at Zone 2, fish from Zone 1 contain higher Hg concentrations. Further research has indicated that these patterns of Hg were not attributed to growth rate, condition factor, diet composition, or trophic position of yellow perch. Rather, Hg concentrations in yellow perch may be described by the heterogeneity of prey contamination and fish bioenergetics. As a result of the paradox between total Hg (THg) concentrations in sediments and biota between two contaminated sites, it was necessary to examine the benthic invertebrate community and how it may transfer Hg from sediments to yellow perch. This apparent paradox now extends to all prey items, since prey items from the stomach contents of yellow perch caught in Zone 1 were significantly more contaminated than those of Zone 2. Use of δ15N and δ13C, measures of trophic position and energy source, respectively, indicated that prey selection, but not food chain length, may also be an important factor in explaining the variation in Hg burdens in yellow perch. Small-scale patterns of biomagnification, as shown by a comparison of δ15N and logTHg, indicated that the rates of biomagnification were similar among zones, but the amount of THg present at the base of the food web was twice as high at Zone 1 as at other contaminated sites. Overall, the relative importance of vertical and horizontal food web structure changed spatially and temporally, highly influencing THg concentrations of prey items and yellow perch. / Thesis (Master, Biology) -- Queen's University, 2007-08-02 08:02:40.26