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Southern Ontario (southern + ontario)

Distribution by Scientific Domains

Life Sciences	41%
Engineering	35%

Selected Abstracts

Effects of Rock Climbing on the Land Snail Community of the Niagara Escarpment in Southern Ontario, Canada

CONSERVATION BIOLOGY, Issue 2 2003
Michele A. McMillan
We examined the effects of rock climbing on the density, richness, diversity, and community composition of snails on the Niagara Escarpment in southern Ontario, Canada. We sampled from randomly selected climbed and unclimbed sections of cliffs on the plateau ( cliff edge ), cliff face, and talus ( cliff base ). Snail density, richness, and diversity were lower along climbing routes than in unclimbed areas, and community composition differed between climbed and unclimbed samples. These results suggest that rock climbing has significant negative effects on all aspects of the snail community on cliffs; therefore, we recommend the inclusion of gastropods in conservation plans for protected areas containing cliffs. Resumen: Las barrancas del acantilado del Niagara proveen hábitat para comunidades extremadamente diversas de caracoles terrestres que pueden estar en riesgo debido al alpinismo recreativo. Examinamos los efectos del alpinismo en la densidad, riqueza, diversidad y composición de comunidades de caracoles del acantilado del Niagara en Ontario Meridional, Canadá. Tomamos muestras de las mesetas ( bordes de acantilados ), la cara del acantilado y el talud ( base del acantilado ) de secciones de barrancas usadas y no usadas para el alpinismo y seleccionadas al azar. La densidad, la riqueza y la diversidad de caracoles fueron más bajas en las rutas escaladas que en aquellas áreas no escaladas y la composición de la comunidad difirió entre muestras escaladas y no escaladas. Estos resultados sugieren que el alpinismo tiene impactos negativos significativos en todos los aspectos de la comunidad de caracoles en acantilados; por lo tanto, recomendamos la inclusión de gasterópodos en los planes de conservación para áreas protegidas que contengan acantilados. [source]

Development of a SWAT extension module to simulate riparian wetland hydrologic processes at a watershed scale

HYDROLOGICAL PROCESSES, Issue 16 2008
Yongbo Liu
Abstract Using a mass balance algorithm, this study develops an extension module that can be embedded in the commonly used Soil and Water Assessment Tool (SWAT). This module makes it possible to assess effects of riparian wetlands on runoff and sediment yields at a watershed scale, which is very important for aquatic ecosystem management but rarely documented in the literature. In addition to delineating boundaries of a watershed and its subwatersheds, the module groups riparian wetlands within a subwatershed into an equivalent wetland for modelling purposes. Further, the module has functions to compute upland drainage area and other parameters (e.g. maximum volume) for the equivalent wetland based on digital elevation model, stream network, land use, soil and wetland distribution GIS datasets. SWAT is used to estimate and route runoff and sediment generated from upland drainage area. The lateral exchange processes between riparian wetlands and their hydraulically connected streams are simulated by the extension module. The developed module is empirically applied to the 53 km2 Upper Canagagigue Creek watershed located in Southern Ontario of Canada. The simulation results indicate that the module can make SWAT more reasonably predict flow and sediment loads at the outlet of the watershed and better represent the hydrologic processes within it. The simulation is sensitive to errors of wetland parameters and channel geometry. The approach of embedding the module into SWAT enables simulation of hydrologic processes in riparian wetlands, evaluation of wetland effects on regulating stream flow and sediment loading and assessment of various wetland restoration scenarios. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Direct and indirect bully-victims: differential psychosocial risk factors associated with adolescents involved in bullying and victimization

AGGRESSIVE BEHAVIOR, Issue 6 2006
Zopito A. Marini
Abstract The present study examined psychosocial risk factors that differentiated direct and indirect bully-victims from bullies, victims and uninvolved adolescents. A total of 7,290 (3,756 girls) students (ages 13,18,yr) from a region of Southern Ontario, Canada, completed a number of self-report measures to determine the relation between direct and indirect bullying and victimization and several psychosocial risk factors, including normative beliefs about antisocial acts, angry-externalizing coping, social anxiety, depression, self-esteem, temperament, attachment, parental monitoring and peer relational problems. ANCOVA and logistic regression analyses indicated that indirect bully-victims and victims were similar in demonstrating greater internalizing problems and peer relational problems than indirect bullies and uninvolved participants. Furthermore, adolescents involved in indirect bullying (bullies, bully-victims) reported a higher level of normative beliefs legitimizing antisocial behaviour and less parental monitoring (males only) than indirect victims and uninvolved participants. Only normative beliefs legitimizing antisocial behaviour distinguished direct bully-victims and bullies from victims and uninvolved adolescents. Results illuminate the distinct characteristics of direct and indirect bully-victims; theoretical and clinical implications are discussed. Aggr. Behav. 32:551,569. 2006. © 2006 Wiley-Liss, Inc. [source]

Language Nuances and Socioeconomic Outcomes

AMERICAN JOURNAL OF ECONOMICS AND SOCIOLOGY, Issue 2 2010
Alberto Chong
While language enables communication, it also provides a reassuring quality more closely related with issues linked with trust, social capital, and cultural identification. Research on the role of language as a learning process is widespread but there is little evidence on its role as a signal for cultural affinity. We pursue this latter avenue of research and show that subtle language affinity is positively linked with change in socioeconomic outcome variables when using English-speaking data for cities in the Golden Horseshoe area in Southern Ontario during the period 1991 to 2001. [source]

Effects of Rock Climbing on the Land Snail Community of the Niagara Escarpment in Southern Ontario, Canada

Relationships between spatial environmental heterogeneity and plant species diversity on a limestone pavement

ECOGRAPHY, Issue 6 2003
Jeremy T. Lundholm
No empirical studies have examined the relationship between diversity and spatial heterogeneity across unimodal species richness gradients. We determined the relationships between diversity and environmental factors for 144 0.18 m2 plots in a limestone pavement alvar in southern Ontario, Canada, including within-plot spatial heterogeneity in soil depth, microtopography and microsite composition. Species richness was unimodally related to mean soil depth and relative elevation. Microsite heterogeneity and soil depth heterogeneity were positively correlated with species richness, and the richness peaks of the unimodal gradients correspond to the maximally spatially heterogeneous plots. The best predictive models of species richness and evenness, however, showed that other factors, such as ramet density and flooding, are the major determinants of diversity in this system. The findings that soil depth heterogeneity had effects on diversity when the effects of mean soil depth were factored out, and that unimodal richness peaks were associated with high spatial heterogeneity in environmental factors represent significant contributions to our understanding of how spatial heterogeneity might contribute to diversity maintenance in plant communities. [source]

Antidepressants and their metabolites in municipal wastewater, and downstream exposure in an urban watershed

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2010
Chris D. Metcalfe
Abstract Antidepressants are a widely prescribed group of pharmaceuticals that can be biotransformed in humans to biologically active metabolites. In the present study, the distribution of six antidepressants (venlafaxine, bupropion, fluoxetine, sertraline, citalopram, and paroxetine) and five of their metabolites was determined in a municipal wastewater treatment plant (WWTP) and at sites downstream of two WWTPs in the Grand River watershed in southern Ontario, Canada. Fathead minnows (Pimephales promelas) caged in the Grand River downstream of a WWTP were also evaluated for accumulated antidepressants. Finally, drinking water was analyzed from a treatment plant that takes its water from the Grand River 17 km downstream of a WWTP. In municipal wastewater, the antidepressant compounds present in the highest concentrations (i.e., >0.5 µg/L) were venlafaxine and its two demethylation products, O - and N -desmethyl venlafaxine. Removal rates of the target analytes in a WWTP were approximately 40%. These compounds persisted in river water samples collected at sites up to several kilometers downstream of discharges from WWTPs. Venlafaxine, citalopram, and sertraline, and demethylated metabolites were detected in fathead minnows caged 10 m below the discharge from a WWTP, but concentrations were all <7 µg/kg wet weight. Venlafaxine and bupropion were detected at very low (<0.005 µg/L) concentrations in untreated drinking water, but these compounds were not detected in treated drinking water. The present study illustrates that data are needed on the distribution in the aquatic environment of both the parent compound and the biologically active metabolites of pharmaceuticals. Environ. Toxicol. Chem. 2010;29:79,89. © 2009 SETAC [source]

Will climate change be beneficial or detrimental to the invasive swede midge in North America?

GLOBAL CHANGE BIOLOGY, Issue 8 2008
Contrasting predictions using climate projections from different general circulation models
Abstract Climate change may dramatically affect the distribution and abundance of organisms. With the world's population size expected to increase significantly during the next 100 years, we need to know how climate change might impact our food production systems. In particular, we need estimates of how future climate might alter the distribution of agricultural pests. We used the climate projections from two general circulation models (GCMs) of global climate, the Canadian Centre for Climate Modelling and Analysis GCM (CGCM2) and the Hadley Centre model (HadCM3), for the A2 and B2 scenarios from the Special Report on Emissions Scenarios in conjunction with a previously published bioclimatic envelope model (BEM) to predict the potential changes in distribution and abundance of the swede midge, Contarinia nasturtii, in North America. The BEM in conjunction with either GCM predicted that C. nasturtii would spread from its current initial invasion in southern Ontario and northwestern New York State into the Canadian prairies, northern Canada, and midwestern United States, but the magnitude of risk depended strongly on the GCM and the scenario used. When the CGCM2 projections were used, the BEM predicted an extensive shift in the location of the midges' climatic envelope through most of Ontario, Quebec, and the maritime and prairie provinces by the 2080s. In the United States, C. nasturtii was predicted to spread to all the Great Lake states, into midwestern states as far south as Colorado, and west into Washington State. When the HadCM3 was applied, southern Ontario, Saskatchewan, and Washington State were not as favourable for C. nasturtii by the 2080s. Indeed, when used with the HadCM3 climate projections, the BEM predicted the virtual disappearance of ,very favourable' regions for C. nasturtii. The CGCM2 projections generally caused the BEM to predict a small increase in the mean number of midge generations throughout the course of the century, whereas, the HadCM3 projections resulted in roughly the same mean number of generations but decreased variance. Predictions of the likely potential of C. nasturtii spatial spread are thus strongly dependent on the source of climate projections. This study illustrates the importance of using multiple GCMs in combination with multiple scenarios when studying the potential for spatial spread of an organism in response to climate change. [source]

Recharge Through a Regional Till Aquitard: Three-Dimensional Flow Model Water Balance Approach

GROUND WATER, Issue 3 2000
Richard E. Gerber
In southern Ontario, vertical leakage through a regionally extensive till is the primary source of recharge to underlying aquifers used for domestic and municipal water supply. Since leakage is largely controlled by the bulk hydraulic conductivity (K) of the aquitard, accurate estimates of K are necessary to quantify the resource. Considerable controversy exists regarding estimates of K for this aquitard, which vary according to the scale of the test method. For the till matrix, estimates from core samples and slug tests consistently range from 10,11 to 10,10 m/s. Isotopic evidence (3H), on the other hand, indicates that nonmatrix structures such as sand lenses, erosional surfaces, joints, and fractures significantly enhance till permeability. This is confirmed by slug test, pump test, recharge, and water balance studies, which show that K varies over seven orders of magnitude (10,12 to 10,5 m/s). To provide a regional estimate of bulk K and a reliable estimate of vertical recharge through the Northern Till, a numerical ground water flow model was constructed for the Duffins and Petticoat Creek drainage hasin. The model was calibrated to measurements of hydraulic head and estimates and measurements of base flow throughout the basin. This model demonstrates that the vertical hydraulic conductivity (Kv) for the Northern Till ranges from 5 × 10,10 to 5 × 10,9 m/s, values that are up to 2.5 orders of magnitude greater than matrix K estimates. Regional recharge through the Northern Till is estimated to range from 30 to 35 mm/a. [source]

Nitrate Removal Rates in a 15-Year-Old Permeable Reactive Barrier Treating Septic System Nitrate

GROUND WATER MONITORING & REMEDIATION, Issue 3 2008
W.D. Robertson
Permeable reactive barriers (PRBs) have gained popularity in recent years as a low-cost method for ground water remediation. However, their cost advantage usually requires that these barriers remain maintenance free for a number of years after installation. In this study, sediment cores were retrieved from a pilot-scale PRB consisting of a sand and wood particle (sawdust) mixture that has been in continuous operation for 15 years treating nitrate from a septic system plume in southern Ontario (Long Point site). Reaction rates for the 15-year-old media were measured in dynamic flow column tests and were compared to rates measured in year 1 using the same reactive mixture. Nitrate removal rates in the 15-year-old media varied, as expected, with temperature in the range of 0.22 to 1.1 mg N/L/d at 6 °C to 10 °C to 3.5 to 6.0 mg N/L/d at 20 °C to 22 °C. The latter rates remained within about 50% of the year 1 rates (10.2 ± 2.7 mg N/L/d at 22 °C). Near the end of the year 15 column test, media particles >0.5 mm in diameter, containing most of the wood particles, were removed from the reactive media by sieving. Nitrate removal subsequently declined by about 80%, indicating that the wood particles were the principal energy source for denitrification. This example shows that some denitrifying PRBs can remain maintenance free and be adequately reactive for decades. [source]

Hyporheic exchange flows induced by constructed riffles and steps in lowland streams in southern Ontario, Canada

HYDROLOGICAL PROCESSES, Issue 20 2006
Tamao Kasahara
Abstract Stream,subsurface water interaction induced by natural riffles and constructed riffles/steps was examined in lowland streams in southern Ontario, Canada. The penetration of stream water into the subsurface was analysed using hydrometric data, and the zone of > 10% stream water was calculated from a chemical mixing equation using tracer injection of bromide and background chloride concentrations. The constructed riffles studied induced more extensive hyporheic exchange than the natural riffles because of their steeper longitudinal hydraulic head gradients and coarser streambed sediments. The depth of > 10% stream water zone in a small and a large constructed riffle extended to > 0·2 m and > 1·4 m depths respectively. Flux and residence time distribution of hyporheic exchange were simulated in constructed riffles using MODFLOW, a finite-difference groundwater flow model. Hyporheic flux and residence time distribution varied along the riffles, and the exchange occurring upstream from the riffle crest was small in flux and had a long residence time. In contrast, hyporheic exchange occurring downstream from the riffle crest had a relatively short residence time and accounted for 83% and 70% of total hyporheic exchange flow in a small and large riffle respectively. Although stream restoration projects have not considered the hyporheic zone, our data indicate that constructed riffles and steps can promote vertical hydrologic exchange and increase the groundwater,surface water linkage in degraded lowland streams. Copyright © 2006 John Wiley & Sons, Ltd. [source]

The effect of drawdown on suspended solids and phosphorus export from Columbia Lake, Waterloo, Canada

HYDROLOGICAL PROCESSES, Issue 5 2004
Mike Shantz
Abstract This study examines the effect of drawdown on the timing and magnitude of suspended solids and associated phosphorus export from a 12 ha reservoir located in an urbanized watershed in southern Ontario, Canada. Water level in Columbia Lake was lowered by 1·15 m over a 2-week period in November 2001. The total phosphorus (TP) concentrations ranged from 63 to 486 µg L,1 in Columbia Lake and 71 to 373 µg L,1 at its outflow. All samples exceeded the Provincial Water Quality Objective of 30 µg TP L,1. Outflow concentrations of suspended solids and TP increased significantly with decreasing lake level and were attributed to the resuspension of cohesive bottom sediments that occurred at a critical threshold lake level (0·65 m below summer level). Suspended solids at the outflow consisted of flocculated cohesive materials with a median diameter (D50) of c. 5 µm. Particulate organic carbon accounted for 8·5% of the suspended solids export by mass. A total mass of 18·5 t of suspended solids and 62·6 kg TP was exported from Columbia Lake, which represents a significant pulse of sediment-associated P to downstream environments each autumn during drawdown. The downstream impacts of this release can be minimized if the water level in Columbia Lake is lowered no more than 0·5 m below summer levels. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Do the ABCS 135 short cognitive screen and its subtests discriminate between normal cognition, mild cognitive impairment and dementia?

INTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 3 2007
Timothy I. M. Standish
Abstract Background Cognitive screening instruments are either too long for routine clinical use or not sensitive to distinguish mild cognitive impairment (MCI) from normal cognition (NC) or dementia. Objective To evaluate the sensitivity and specificity of the AB Cognitive Screen (ABCS) and its subtests with a view to improving its ability to differentiate between dementia, MCI and NC. The influence of age and education on sensitivity and specificity is also examined. Design Cross-sectional study. Methods Participants with dementia and MCI were recruited from those presenting to four specialty geriatric clinics in southern Ontario. Participants with NC were recruited from the family and friends of patients. A comprehensive geriatric assessment was done including ABCS, SMMSE and 15 point Geriatric Depression Scale. Analysis of variance and receiver operating characteristic (ROC) curves compared test scores. SMMSE scores were also analysed for comparison purposes. Results Three hundred and two participants had dementia, 166 had MCI and 174 had NC. ABCS total scores were significantly different between NC and MCI (mean difference 7.1, 1.8,12.5 CI, p,=,0.000) while SMMSE scores were not (mean difference 0.5, ,0.7,1.7, p,<,0.628). Of individual ABCS subtests, verbal fluency and delayed recall were most sensitive to differences between NC and MCI. ROC curve analysis, which presents sensitivity and specificity, showed verbal fluency was better than delayed recall in distinguishing between NC and MCI, among participants 75 years of age or older. Conclusion The AB Cognitive Screen (ABCS) can be administered in 3,5,min. The SMMSE and ABCS total and subtests significantly distinguished between dementia and MCI or NC. Verbal fluency and delayed recall were best at distinguishing between MCI and NC. The analysis illustrates how each subtest contributes to the sensitivity of the ABCS and suggests ways that sensitivity might be improved. Copyright © 2006 John Wiley & Sons, Ltd. [source]

The occurrence of Campylobacter in river water and waterfowl within a watershed in southern Ontario, Canada

JOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2010
M.I. Van Dyke
Abstract Aims:, Quantitative PCR and a culture method were used to investigate Campylobacter occurrence over 3 years in a watershed located in southern Ontario, Canada that is used as a source of drinking water. Methods and Results:, Direct DNA extraction from river water followed by quantitative PCR analysis detected thermophilic campylobacters at low concentrations (<130 cells 100 ml,1) in 57,79% of samples taken from five locations. By comparison, a culture-based method detected Campylobacter in 0,23% of samples. Water quality parameters such as total Escherichia coli were not highly correlated with Campylobacter levels, although higher pathogen concentrations were observed at colder water temperatures (<10°C). Strains isolated from river water were primarily nalidixic acid-susceptible Campylobacter lari, and selected isolates were identified as Campylobacter lari ssp. concheus. Campylobacter from wild birds (seagulls, ducks and geese) were detected at a similar rate using PCR (32%) and culture-based (29%) methods, and although Campylobacter jejuni was isolated most frequently, C. lari ssp. concheus was also detected. Conclusions:,Campylobacter were frequently detected at low concentrations in the watershed. Higher prevalence rates using quantitative PCR was likely because of the formation of viable but nonculturable cells and low recovery of the culture method. In addition to animal and human waste, waterfowl can be an important contributor of Campylobacter in the environment. Significance and Impact of the Study:, Results of this study show that Campylobacter in surface water can be an important vector for human disease transmission and that method selection is important in determining pathogen occurrence in a water environment. [source]

Calcite,graphite isotope thermometry in amphibolite facies marble, Bancroft, Ontario

JOURNAL OF METAMORPHIC GEOLOGY, Issue 9 2005
S. R. DUNN
Abstract This study presents calcite,graphite carbon isotope fractionations for 32 samples from marble in the northern Elzevir terrane of the Central Metasedimentary Belt, Grenville Province, southern Ontario, Canada. These results are compared with temperatures calculated by calcite,dolomite thermometry (15 samples), garnet,biotite thermometry (four samples) and garnet,hornblende thermometry (three samples). ,cal-gr values vary regularly across the area from >6.5, in the south to 4.0, in the north, which corresponds to temperatures of 525 °C in the south to 650 °C in the north. Previous empirical calibration of the calcite,graphite thermometer agrees very well with calcite,dolomite, garnet,biotite and garnet,hornblende thermometry, whereas, theoretical calibrations compare less well with the independent thermometry. Isograds in marble based on the reactions rutile + calcite + quartz =titanite and tremolite + calcite + quartz = diopside, span temperatures of 525,600 °C and are consistent with calculated temperature,X(CO2) relations. Results of this study compare favourably with large-scale regional isotherms, however, local variation is greater than that revealed by large-scale sampling strategies. It remains unclear whether the temperature,,cal-gr relationship observed in natural materials below 650 °C represents equilibrium fractionations or not, but the regularity and consistency apparent in this study demonstrate its utility for thermometry in amphibolite facies marble. [source]