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1
Chubb, P. T., D. C. Vogel, D. C. Peck, R. S. James, and R. R. Keays. "Occurrences of pseudotachylyte at the East Bull Lake and Shakespeare–Dunlop intrusions, Ontario, Canada." Canadian Journal of Earth Sciences 31, no. 12 (December 1, 1994): 1744–48. http://dx.doi.org/10.1139/e94-155.
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Pseudotachylyte bodies were recently identified within and adjacent to the Early Proterozoic East Bull Lake and Shakespeare–Dunlop intrusions, located approximately 25–40 km west-southwest of the western margin of the Sudbury Igneous Complex. These breccia-like bodies locally form extensive vein networks and are preferentially developed along the contact between the intrusions and older Archean granitoid rocks. The pseudotachylyte veins comprise variable proportions of locally derived rock fragments and an aphanitic to fine-grained crystalline matrix that commonly displays flow textures. The veins appear to have formed by intense cataclasis and (or) frictional melting. These occurrences are very similar in appearance to Sudbury Breccia dykes that are observed at a radial distance of up to 80 km from the Sudbury Igneous Complex. Sudbury Breccia is widely believed to have formed as a result of the Sudbury event—a cataclysmic explosion that occurred at 1.85 Ga. The location of the pseudotachylyte veins described herein may coincide with one of the concentric bands of relatively intense Sudbury Breccia development observed to the north of the Sudbury Igneous Complex.
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Braverman, Doreen. "Greater Sudbury / Grand Sudbury, Ontario." Raven: A Journal of Vexillology 18 (2011): 59–61. http://dx.doi.org/10.5840/raven20111834.
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Parmenter, Andrew C., Christopher B. Lee, and Mario Coniglio. ""Sudbury Breccia" at Whitefish Falls, Ontario: evidence for an impact origin." Canadian Journal of Earth Sciences 39, no. 6 (June 1, 2002): 971–82. http://dx.doi.org/10.1139/e02-006.
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Sudbury breccias are unusual clastmatrix rock bodies formed in abundance around the Sudbury Igneous Complex, the most obvious manifestation of a major impact event at Sudbury. At Whitefish Falls, ~70 km southwest of Sudbury, similar breccias consisting of clasts of argillite and amphibolite dyke enclosed in a fine-grained matrix of host rock are developed in metamorphosed argillites of the Huronian Supergroup. Pre-brecciation brittle textures in the host argillite and breccia clasts, such as layer-parallel foliation offset by cataclastic fractures, suggest that the host rock was entirely competent prior to brecciation. One composite penetrative foliation and its associated ductile folding were also formed in the argillite host prior to brecciation. Post-brecciation ductile deformation produced a regionally dominant eastwest-trending foliation, and two late-stage folding events, and indicate a syn-Penokean age of brecciation. The breccias at Whitefish Falls are enriched in ferromagnesian minerals compared to adjacent, embayed and partially digested, host rock. Flow-foliated breccia matrices surround a highly rounded clast phase. These features are characteristic of impact-related pseudotachylyte, formed during extreme cataclasis and friction melting of the impacted host rock. We propose that these breccias formed by injection of a high-strain, pseudotachylytic melt, triggered by the Sudbury impact event, and focused along a blind superfault, coincident with a post-Penokean high-strain zone.
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Kellett, R. L., and B. Rivard. "Characterization of the Benny deformation zone, Sudbury, Ontario." Canadian Journal of Earth Sciences 33, no. 9 (September 1, 1996): 1256–67. http://dx.doi.org/10.1139/e96-095.
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Remote sensing imagery and geophysical data are well known as valuable tools for reconnaissance mapping in unknown areas, but they can also be used to reinterpret existing regional geological maps. A combination of airborne magnetic data and synthetic aperture radar images, at both a regional and a detailed scale, have been used to identify a wrench-fault system on the Canadian Shield north of the Sudbury structure. The 3–4 km wide deformation zone comprises a set of subparallel vertical faults bounding blocks of Archean granites, Archean metavolcanics of the Benny greenstone belt, and Paleoproterozoic metasediments of the Huronian supergroup. Using high-resolution airborne radar and magnetic data, the fault zone is found to extend for 40 km along the southern margin of the Benny greenstone belt. The wrench-fault system may have been tectonically active during several episodes throughout the Proterozoic. An interpretation of these data, supported by additional field mapping, indicates that the 1240 Ma Sudbury dyke swarm has been intruded through the deformation zone after its most active period of movement. Overprinting of Sudbary impact breccia at the southern edge of the deformation zone suggests that some movement occurred on the faults postdating the 1850 Ma meteorite impact. Lineaments that correlate spatially with the wrench-fault system can be traced across the southern Superior Province and the Cobalt Embayment on the regional images. However, more high-resolution studies are required to establish the same overprinting relationships along the length of the lineaments.
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Gurov, E. P., V. V. Permiakov, and B. M. French. "REMAINS OF PALEOFLORA IN THE BRECCIAS OF THE ONAPING FORMATION, SUDBURY IMPACT STRUCTURE, ONTARIO, CANADA." Geological Journal, no. 1 (April 16, 2021): 17–31. http://dx.doi.org/10.30836/igs.1025-6814.2021.1.222790.
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Electron microscopic investigations of four breccia samples of the Onaping Formation, Sudbury impact structure, Canada, have been carried out for the search of possible remains of paleoflora and identification of the nature of organic matter and their composition. Two forms of plant remains were discovered in the breccias. The first form is represented by single plant particles scattered in the matrix of breccias and included in gas vesicles in devitrified glasses. These particles are leaf-shaped, stem-shaped, tubular, and spherical objects, ranging from 5-10 to 200-300 µm in size. It is supposed that algal flora inhabiting the sea basin before the Sudbury impact was the source of this form of plant residues in breccias. The second form of plant remains in breccias is represented by plant detritus in carbon-bearing fragments of mudstones included in the breccia matrix. These fragments, reaching a size to 1000-1200 µm, have irregular shapes and complicated rugged contacts with the host breccia. Plant residues in mudstones are mainly ribbon-like scraps from 3-5 to 200-300 µm long, some while rare particles have a more complex shape. The matrix of the mudstones is a heterogeneous fine-grained clay-like substance with a network of micron-wide open joint fissures. The carbon content in mudstone matrix ranges from 7-10 to 20-25 wt%. Muddy bottom sediments of the pre-impact sea basin are supposed to be a source of mudstone fragments in breccias, while the algal flora inhabited the sea during their sedimentation served as a source of plant detritus in mudstones. Fragments of mudstones and floral residues are an important source of organic carbon in breccias of the Onaping Formation. The discovery of paleofloral remains in the breccias indicates the existence of a previously unknown complex algal flora that inhabited the pre-impact sea before the impact event 1.85 billion years ago at the very end of the Paleoproterozoic. The Sudbury impact structure is comparable in size to the Chicxulub impact structure, the formation of which caused the Cretaceous-Paleogene mass extinction. We assume that the formation of the Sudbury structure had a catastrophic impact on the paleoflora of the late Paleoproterozoic, the remnants of which were preserved in the breccias of the Onaping Formation.
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O’Callaghan, J. W., G. R. Osinski, P. C. Lightfoot, and R. L. Linnen. "Reconstructing the geochemical signature of Sudbury Breccia, Ontario, Canada: implications for exploration models." Applied Earth Science 125, no. 2 (April 2, 2016): 92–93. http://dx.doi.org/10.1080/03717453.2016.1166658.
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Fullagar, Peter K., Dean W. Livelybrooks, Ping Zhang, Andrew J. Calvert, and Yiren Wu. "Radio tomography and borehole radar delineation of the McConnell nickel sulfide deposit, Sudbury, Ontario, Canada." GEOPHYSICS 65, no. 6 (November 2000): 1920–30. http://dx.doi.org/10.1190/1.1444876.
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In an effort to reduce costs and increase revenues at mines, there is a strong incentive to develop high‐resolution techniques both for near‐mine exploration and for delineation of known orebodies. To investigate the potential of high‐frequency EM techniques for exploration and delineation of massive sulfide orebodies, radio frequency electromagnetic (RFEM) and ground‐penetrating radar (GPR) surveys were conducted in boreholes through the McConnell massive nickel‐copper sulfide body near Sudbury, Ontario, from 1993–1996. Crosshole RFEM data were acquired with a JW-4 electric dipole system between two boreholes on section 2720W. Ten frequencies between 0.5 and 5.0 MHz were recorded. Radio signals propagated through the Sudbury Breccia over ranges of at least 150 m at all frequencies. The resulting radio absorption tomogram clearly imaged the McConnell deposit over 110 m downdip. Signal was extinguished when either antenna entered the sulfide body. However, the expected radio shadow did not eventuate when transmitter and receiver were on opposite sides of the deposit. Two‐dimensional modeling suggested that diffraction around the edges of the sulfide body could not account for the observed field amplitudes. It was concluded at the time that the sulfide body is discontinuous; according to modeling, a gap as small as 5 m could have explained the observations. Subsequent investigations by INCO established that pick‐up in the metal‐cored downhole cables was actually responsible for the elevated signal levels. Both single‐hole reflection profiles and crosshole measurements were acquired using RAMAC borehole radar systems, operating at 60 MHz. Detection of radar reflections from the sulfide contact was problematic. One coherent reflection was observed from the hanging‐wall contact in single‐hole reflection mode. This reflection could be traced about 25 m uphole from the contact. In addition to unfavorable survey geometry, factors which may have suppressed reflections included host rock heterogeneity, disseminated sulfides, and contact irregularity. Velocity and absorption tomograms were generated in the Sudbury Breccia host rock from the crosshole radar. Radar velocity was variable, averaging 125 m/μs, while absorption was typically 0.8 dB/m at 60 MHz. Kirchhoff‐style 2-D migration of later arrivals in the crosshole radargrams defined reflective zones that roughly parallel the inferred edge of the sulfide body. The McConnell high‐frequency EM surveys established that radio tomography and simple radio shadowing are potentially valuable for near‐ and in‐mine exploration and orebody delineation in the Sudbury Breccia. The effectiveness of borehole radar in this particular environment is less certain.
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Shaw, CSJ, G. M. Young, and C. M. Fedo. "Sudbury-type breccias in the Huronian Gowganda Formation near Whitefish Falls, Ontario: products of diabase intrusion into incompletely consolidated sediments?" Canadian Journal of Earth Sciences 36, no. 9 (September 1, 1999): 1435–48. http://dx.doi.org/10.1139/e99-057.
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Sudbury breccias are commonly attributed to meteoritic impact at about 1.85 Ga in the vicinity of the Sudbury Igneous Complex. In the Whitefish Falls area, about 75 km southwest of Sudbury, similar breccias are widely developed in argillites of the ~2.3 Ga Gowganda Formation. There is abundant evidence of "soft sediment" deformation of the Huronian sediments in the form of complex "fault" contacts, clastic dyke intrusions, and chaotic folding. These movements appear to have been penecontemporaneous with intrusion of highly irregular diabase bodies, which are interpreted as being older than the ~2.2 Ga Nipissing diabase. Complex shapes of diabase bodies and highly irregular contact relationships between diabase and argillites, including intrusions of sediment veins into diabase, support intrusion of the diabase into incompletely consolidated sediments. These data, together with chemical evidence of mixing of diabase, argillite, and other materials in the breccia bodies, suggest that the breccias at Whitefish Falls may have formed as a result of interaction between hot mafic magma and semiconsolidated, water-rich mud, more than 350 Ma prior to formation of the Sudbury Igneous Complex and attendant phenomena that are presumed to be impact related.
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Archambault, Daniel J., and Keith Winterhalder. "Metal tolerance in Agrostis scabra from the Sudbury, Ontario, area." Canadian Journal of Botany 73, no. 5 (May 1, 1995): 766–75. http://dx.doi.org/10.1139/b95-084.
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Acid, metal-contaminated soils are frequently colonized by plant species that have evolved tolerance to metals. Agrostis scabra (tickle grass) grows at several such sites in the Sudbury area. To test whether these populations were tolerant to metals, three experiments were performed. A hydroponic root growth experiment, in which clonal ramets from contaminated and uncontaminated sites were grown in metal-amended nutrient solutions, showed that plants from the Sudbury area had greater tolerance indices than those from outside Sudbury. A seed-based hydroponic experiment, where seeds were germinated in metal solutions, showed that metal-tolerance indices calculated from root growth were mostly greater for populations from Sudbury but that leaf growth was not a good indicator of metal tolerance. A seed-based soil-bioassay experiment, in which seeds were germinated on soils covered with filter paper, showed that seeds from contaminated sites performed better on contaminated soil and a 50:50 soil mixture (contaminated–uncontaminated) than those from uncontaminated sites. Populations of A. scabra growing on contaminated soils in the Sudbury area therefore appear to have been selected for metal tolerance. Ecological aspects of metal tolerance and the possible role of A. scabra in the revegetation of the Sudbury area are discussed. Key words: Agrostis scabra, tolerance, metals, acid soil, contamination.
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Hanley, J. J., and J. E. Mungall. "CHLORINE ENRICHMENT AND HYDROUS ALTERATION OF THE SUDBURY BRECCIA HOSTING FOOTWALL Cu Ni PGE MINERALIZATION AT THE FRASER MINE, SUDBURY, ONTARIO, CANADA." Canadian Mineralogist 41, no. 4 (August 1, 2003): 857–81. http://dx.doi.org/10.2113/gscanmin.41.4.857.
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O’Callaghan, J. W., G. R. Osinski, P. C. Lightfoot, R. L. Linnen, and J. R. Weirich. "Reconstructing the Geochemical Signature of Sudbury Breccia, Ontario, Canada: Implications for Its Formation and Trace Metal Content." Economic Geology 111, no. 7 (October 7, 2016): 1705–29. http://dx.doi.org/10.2113/econgeo.111.7.1705.
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McClenaghan, M. B., D. E. Ames, and L. J. Cabri. "Indicator mineral and till geochemical signatures of the Broken Hammer Cu–Ni–PGE–Au deposit, North Range, Sudbury Structure, Ontario, Canada." Geochemistry: Exploration, Environment, Analysis 20, no. 3 (November 7, 2019): 337–56. http://dx.doi.org/10.1144/geochem2019-058.
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The Broken Hammer Cu–Ni–PGE–Au footwall deposit in the North Range of the Sudbury Structure in Canada consists of a shallow surface zone of vein-hosted and vein stockwork-hosted mineralization within Sudbury breccia developed in the quartz monzonite Levack Gneiss Complex. The surface of the deposit consists of a 2–120 cm wide chalcopyrite vein and numerous smaller veins dominated by chalcopyrite–magnetite–millerite with trace gold, platinum group minerals, tellurides, bismuthides and selenides. The Laurentide Ice Sheet flowed southward across the region depositing a sandy till that contains abundant sperrylite (hundreds of grains), chalcopyrite, pyrite and gold in the heavy mineral fraction down-ice of mineralization. Mineral liberation analysis of the <0.25 mm heavy mineral fraction of metal-rich till identified a broader suite of PGM and sulfides than visual identification methods. The <0.063 mm fraction of till displays a strong geochemical signature of the mineralization for Pd, Pt, Au, Cu and Ag and, to a lesser extent, Bi, Te and Sn; however, geochemical signatures are not detectable as far down-ice as indicator minerals. Till sampling has not been used for exploration in the Sudbury region because of the abundant outcrop and the use of geophysical and prospecting techniques. This study demonstrates that indicator mineral and till geochemical methods are useful exploration tools for the region. The presence of sperrylite and chalcopyrite in oxidized till indicates that even thin (<1 m) highly weathered till is an effective sample medium here.
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Hanley, J. J., J. E. Mungall, C. J. Bray, and M. P. Gorton. "THE ORIGIN OF BULK AND WATER-SOLUBLE Cl AND Br ENRICHMENTS IN ORE-HOSTING SUDBURY BRECCIA IN THE FRASER COPPER ZONE, STRATHCONA EMBAYMENT, SUDBURY, ONTARIO, CANADA." Canadian Mineralogist 42, no. 6 (December 1, 2004): 1777–98. http://dx.doi.org/10.2113/gscanmin.42.6.1777.
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Wayland, Mark, and Donald K. McNicol. "Movements and survival of Common Goldeneye broods near Sudbury, Ontario, Canada." Canadian Journal of Zoology 72, no. 7 (July 1, 1994): 1252–59. http://dx.doi.org/10.1139/z94-167.
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We examined movements and survival of Common Goldeneye (Bucephala clangula) broods in a highly acidified area on the Canadian Precambrian Shield near Sudbury, Ontario, during 1989 and 1990. When data from the 2 years were combined, a total of 16 females had led their broods from nesting to rearing lakes, while only 4 had raised their broods on the nesting lake. Initial brood-rearing lakes contained a greater biomass of invertebrate prey and were closer to neighbouring lakes than corresponding nesting lakes. Eight broods undertook 17 secondary movements between rearing lakes. These movements were not related to differences between lakes in prey biomass or distance to neighbouring lakes. Daily survival rates of age-class I and age-class II ducklings did not differ between years. When data from the 2 years were combined, it was found that duckling survival was not related to brood movements or prey biomass. Duckling survival was higher on clustered lakes than on isolated lakes. The availability of alternate brood-rearing lakes with sufficient invertebrate prey, in addition to the primary brood-rearing lake, may be an important factor influencing Common Goldeneye brood movements and survival in our study area.
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McCormick, K. A. "Chlorine and Alkali Geochemical Halos in the Footwall Breccia and Sublayer Norite at the Margin of the Strathcona Embayment, Sudbury Structure, Ontario." Economic Geology 97, no. 7 (November 1, 2002): 1509–19. http://dx.doi.org/10.2113/97.7.1509.
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Hall, Heather. "Exploring Innovation in Northern Canada with Insights from the Mining Innovation System in Greater Sudbury, Ontario." Northern Review, no. 45 (June 29, 2017): 33–56. http://dx.doi.org/10.22584/nr45.2017.003.
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Griffiths, Ronald W., and W. Keller. "Benthic Macroinvertebrate Changes in Lakes near Sudbury, Ontario, following a Reduction in Acid Emissions." Canadian Journal of Fisheries and Aquatic Sciences 49, S1 (December 19, 1992): 63–75. http://dx.doi.org/10.1139/f92-301.
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Benthic macroinvertebrates were sampled from three lake basins before and after a reduction in acidity, a result of reduced acid emissions from the smelting industry in Sudbury, Ontario. The number of taxa and macroinvertebrate density were greater in the later surveys of the lakes than expected by chance alone. Species richness and macroinvertebrate density were higher in all littoral habitats and in profundal habitats of two lake basins. Species richness showed little change and macroinvertebrate density was lower in the profundal habitat of the third lake basin. Increased survival, probably as a result of reduced chemical toxicity, best accounted for the higher species richness and benthic density. Trout predation, through a numerical response, probably masked these responses in the profundal habitat of the third lake basin because the refuge area from predation (i.e. region of the hypolimnion low in dissolved oxygen) was small. These data indicate that biological recovery of industrially acidified lakes is possible solely by reducing emissions, provided that recolonizing species are not locally extinct.
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Schaefer, Stephen J., and Penelope Morton. "Two komatiitic pyroclastic units, Superior Province, northwestern Ontario: their geology, petrography, and correlation." Canadian Journal of Earth Sciences 28, no. 9 (September 1, 1991): 1455–70. http://dx.doi.org/10.1139/e91-128.
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Two Archean komatiitic pyroclastic rock units occur on opposite sides of the Quetico Fault in northwestern Ontario. The eastern unit, the Dismal Ashrock, is located 3 km north of Atikokan, Ontario, on the north side of the Quetico Fault within the Wabigoon Subprovince of the Superior Province. It is part of a suprascrustal sequence, the Steep Rock Group. The Grassy Portage Bay ultramafic pyroclastic rock unit (GUP) is located 100 km to the west, on the south side of the Quetico Fault, and is part of an overturned succession comprising mafic metavolcanic rocks, GUP, and metasedimentary rocks. The Dismal Ashrock dips steeply, is little deformed, has undergone greenschist metamorphism, and is divided into komatiitic lapilli tuff, komatiitic volcanic breccia, komatiitic volcaniclastic rocks, and a mafic pillowed flow. GUP outcrops form an arcuate fold interference pattern, are strongly deformed, and have undergone amphibolite metamorphism. GUP is divided into komatiitic lapilli tuff and komatiitic volcanic breccia. Both pyroclastic units contain cored and composite lapilli, evidence for explosive volcanism. Locally, some of the lapilli fragments are highly vesicular (up to 30% by volume), greater than reported for any other komatiites. Other fragments show no vesicularity. The low vesicularity of some of the pyroclasts and, in the case of the Dismal Ashrock, their association with pinowed lava flows may indicate explosive hydrovolcanic activity. The Dismal Ashrock and GUP are high in MgO, Cr, and Ni and are unusually enriched in Fe, Ti, Zr, Mn, P, Ba, Nb, Rb, and Sr compared with other komatiites. These unique geochemical compositions are not understood at this time.
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Bagatto, Giuseppe, and Joseph D. Shorthouse. "Biotic and abiotic characteristics of ecosystems on acid metalliferous mine tailings near Sudbury, Ontario." Canadian Journal of Botany 77, no. 3 (August 20, 1999): 410–25. http://dx.doi.org/10.1139/b98-233.
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INCO Ltd., a large mining company near Sudbury, Ont., deposits vast amounts of tailings on its property. These tailings contain elevated levels of Cu, Ni, and sulphides, and to curtail dust and acid drainage, INCO has undertaken a long-term project to cover its tailings with vegetation. Yearly amelioration of fresh tailings with limestone and fertilizer, followed by seeding with various grasses and herbs, transplanted conifers, and the later colonization of volunteer species of plants from adjoining forests, has resulted in the formation of ecosystems of varying age and complexity. To assess the long-term effectiveness of INCO's vegetation techniques, we studied floral diversity, attributes of developing soils, and the accumulation of Cu and Ni in various plant species growing on tailings at different stages of development. Habitat disturbance by tailings deposition, and its subsequent floral recolonizaton, is an example of "anthropogenic succession." Tailings that do not receive amelioration in the form of lime, fertilizer, and seeding remain free of vegetation, other than sparce clumps of the metal-tolerant grass Deschampsia caespitosa (L.) Beauv. Once amelioration begins, various species of grasses and herbs are able to subsist and within 8 years volunteer species begin to colonize. Substrate pH of dried tailings is less than 4 while the pH in upper horizons ranges from 5 to 6, increasing as the sites become more florally diverse; however, pH at lower depths remains less than 4. Substrate organic content in upper horizons at restored sites ranges from 4.5 to 5.0%. Water-soluble concentrations of Cu and Ni in upper horizons ranges from 1 to 5 µg/g dry mass, and 0.5 to 6 µg/g dry mass, respectively, and both metals decrease with increasing floral diversity. Levels of Ni increase at lower depths indicating greater substrate mobility. Levels of Cu and Ni are higher in plants from tailings than in those from control sites; however, concentrations do not decrease in plants from older and more florally diverse tailings sites. Root tissues contain significantly higher concentrations of Cu and Ni than aerial tissues. Monitoring air with moss plates indicates that dispersal of airborne metallic dust remains a problem.Key words: mine tailings, Sudbury, anthropogenic succession, copper, nickel, acid, monitoring.
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Toline, C. Anna, and Allan J. Baker. "Genetic Differentiation among Populations of the Northern Redbelly Dace (Phoxinus eos) in Ontario." Canadian Journal of Fisheries and Aquatic Sciences 51, no. 6 (June 1, 1994): 1218–28. http://dx.doi.org/10.1139/f94-122.
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Eighteen populations of northern redbelly dace (Phoxinus eos) from three regions in Ontario were examined genetically using protein electrophoresis. Differentiation among regions was greater (FST = 0.100) than within them (FST = 0.045–0.064), suggesting that levels of gene flow are high enough to prevent differentiation through drift only within regions. Levels of heterozygosity, percent polymorphic loci, and number of alleles per locus are high relative to other fish species, which suggests that populations of dace in this study have not been subject to severe bottlenecks. Thus, population divergence has apparently occurred gradually over the last 10 000 yr. Average heterozygosity was not correlated with pond area. Thus, populations in Algonquin Park are not more prone to the effects of drift than those in the other two regions. Populations from the Sudbury region were genetically differentiated from those in Algonquin Park and from near Kingston, a result consistent with the historical biogeography of Ontario. Despite relatively high levels of heterozygosity, observed levels in this study deviated significantly from those expected from Hardy–Weinberg equilibrium. The breeding biology of P. eos and other fish suggests that our results may be explained by the presence of population substructuring in the localities sampled.
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Krantzberg, G., and P. M. Stokes. "Benthic Macroinvertebrates Modify Copper and Zinc Partitioning in Freshwater–Sediment Microcosms." Canadian Journal of Fisheries and Aquatic Sciences 42, no. 9 (September 1, 1985): 1465–73. http://dx.doi.org/10.1139/f85-184.
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The effects of bioturbation on metal dynamics in freshwater–sediment systems were examined. In general, benthic macroinvertebrates caused significant changes in Cu and Zn partitioning among physicochemical forms in the sediment. The proportion of cation-exchangeable and specifically adsorbed Cu observed in Chub Lake (Muskoka–Haliburton) microcosms colonized by chironomids and chaoborids was greater than that for uncolonized sediment. The same relationship held for Cu in Lohi Lake (Sudbury) microcosms supporting a similar benthic community and for Cu and Zn in Port Credit (Lake Ontario) sediments inhabited by tubificids. The ability of tubificid worms to increase sediment Eh was recorded and related to Cu and Zn dynamics. We conclude that macroinvertebrate communities have the potential to increase metal concentrations in the water column, particularly during short episodes of high burrowing activity, and that in situ studies are warranted to verify this potentiality.
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Blancher, Peter J., and Donald K. McNicol. "Tree swallow diet in relation to wetland acidity." Canadian Journal of Zoology 69, no. 10 (October 1, 1991): 2629–37. http://dx.doi.org/10.1139/z91-370.
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We examined 12 825 prey of tree swallows (Tachycineta bicolor) northeast of Sudbury, Ontario, to observe the importance of aquatic food and the influence of wetland pH on swallow diet during the breeding season. Items of aquatic origin constituted most of the biomass in diets of both nestlings and adults. Molluscs and Ephemeroptera (mayflies), whose distributions in the study wetlands were strongly influenced by pH, were eaten by swallows, particularly nestlings. The major change in nestling diet in relation to wetland acidity was a decrease in mayflies and a corresponding increase in aquatic Diptera at wetlands of lower pH. The number of aquatic taxa eaten by nestlings was lowest at acidic wetlands. The total biomass of emerging insects captured at acidic wetlands was not lower than at wetlands of higher pH, and in fact tended to be greater. The rate at which swallows fed their young and the amount of food fed to nestlings were not related to wetland pH or other wetland characteristics. Nevertheless, the reduced availability of calcium-rich foods at acidic wetlands and the change in types of food available may play a role in the reduced reproductive success of swallows at acidic wetlands.
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Niyogi, S., P. Couture, G. Pyle, D. G. McDonald, and C. M. Wood. "Acute cadmium biotic ligand model characteristics of laboratory-reared and wild yellow perch (Perca flavescens) relative to rainbow trout (Oncorhynchus mykiss)." Canadian Journal of Fisheries and Aquatic Sciences 61, no. 6 (June 1, 2004): 942–53. http://dx.doi.org/10.1139/f04-044.
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This study evaluated the >400-fold tolerance to acute waterborne Cd of a metal-tolerant fish, yellow perch (YP, Perca flavescens), relative to a sensitive model fish, rainbow trout (RBT, Oncorhynchus mykiss), from the perspective of the acute Cd biotic ligand model (BLM). Three-hour gill binding characteristics for Cd and its competitor, Ca, in both species exhibited only small quantitative differences, but gill Cd accumulations at 3 h and 24 h, which were associated with 50% lethality at 96 h (3- and 24-h LA50s), were 52- to 60-fold higher in YP relative to RBT. However, the acute Cd BLM cannot be extended from RBT to YP by simple adjustments of LA50 values because unlike RBT, in YP, LA50s (3 and 24 h) were 26- to 47-fold greater than the capacity of the characterized set of Cd-binding sites. Moreover, 3-h gill Ca and Cd binding characteristics in wild YP, collected from one clean (Geneva) and two metal-contaminated softwater lakes (Hannah and Whitson) around Sudbury region, northern Ontario, revealed that chronic waterborne factors like hardness and Cd preexposure can influence both Cd and Ca binding in fish gills and could have major implications for the future refinement of the acute Cd BLM approach.
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Casselman, John M., and John M. Gunn. "Dynamics in Year-Class Strength, Growth, and Calcified-Structure Size of Native Lake Trout (Salvelinus namaycush) Exposed to Moderate Acidification and Whole-Lake Neutralization." Canadian Journal of Fisheries and Aquatic Sciences 49, S1 (December 19, 1992): 102–13. http://dx.doi.org/10.1139/f92-305.
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Accurate age-interpretation techniques were developed, using scales and otoliths, to examine the role of whole-lake neutralization in the resurgence of a lake trout (Salvelinus namaycush) fishery in Nelson Lake (pH 5.7) near Sudbury, Ontario. Calcified structures and data from 860 lake trout were collected from 1972 to 1987. The population was characterized by the regular cyclic occurrence of strong year classes, which were probably an effect of pulse angling, cyclic food abundance, and possibly intraspecific interaction. The majority (65.8%) of the lake trout caught in the exceptional winter fishery of 1980 (3.3 kg∙ha−1) were in the lake prior to liming in 1975–76. Young lake trout (up to age 4) of the 1975 and 1976 year classes grew bigger and had larger scales than other year classes from 1973 to 1977, coinciding with an increase in hypolimnetic zooplankton, probably related to improved water quality. Otoliths grew significantly larger and more translucent and exceeded relative growth of scales and body for all ages in 1976 (18% greater) and for the 1976 year class, confirming that otolith accretion can come from the ambient water because liming increased the calcium content by 33% that year, the only observed direct effect of the treatment.
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Popp, Jesse N., and Victoria M. Donovan. "Fine-scale tertiary-road features influence wildlife use: a case study of two major North American predators." Animal Biology 66, no. 3-4 (2016): 229–38. http://dx.doi.org/10.1163/15707563-00002500.
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Roads have become a major concern for wildlife managers. Determining if fine-scale features influence wildlife road use is crucial information when developing management strategies to protect species at risk or to assist in preventing negative trophic interactions. We investigated the effects of fine-scale habitat and road-related features on the tertiary-road use of two major predator groups, the American black bear (Ursus americanus) and wolves (Canis lupus,C. lycaon, and hybrids). Scat occurrence, used as a measure of a species’ intensity of use, along with several road-related features and surrounding fine-scale habitat variables, were recorded within tertiary-road segments near Sudbury, Ontario, Canada. An information theoretic approach was used to determine which of several different candidate models best predicted tertiary-road use by our major predator groups. Road width and distance to primary roads were found to be the strongest predictors of occurrence on tertiary roads for both predators, with smaller road width and greater distances to primary roads leading to higher levels of occurrence. Habitat cover and cover type, expected to influence foraging opportunities, were not found to be strong predictors of tertiary-road use. Our findings highlight the importance of fine-scale studies for understanding road use.
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McCradden, Melissa D., Tasmie Sarker, and P. Alison Paprica. "Conditionally positive: a qualitative study of public perceptions about using health data for artificial intelligence research." BMJ Open 10, no. 10 (October 2020): e039798. http://dx.doi.org/10.1136/bmjopen-2020-039798.
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ObjectivesGiven widespread interest in applying artificial intelligence (AI) to health data to improve patient care and health system efficiency, there is a need to understand the perspectives of the general public regarding the use of health data in AI research.DesignA qualitative study involving six focus groups with members of the public. Participants discussed their views about AI in general, then were asked to share their thoughts about three realistic health AI research scenarios. Data were analysed using qualitative description thematic analysis.SettingsTwo cities in Ontario, Canada: Sudbury (400 km north of Toronto) and Mississauga (part of the Greater Toronto Area).ParticipantsForty-one purposively sampled members of the public (21M:20F, 25–65 years, median age 40).ResultsParticipants had low levels of prior knowledge of AI and mixed, mostly negative, perceptions of AI in general. Most endorsed using data for health AI research when there is strong potential for public benefit, providing that concerns about privacy, commercial motives and other risks were addressed. Inductive thematic analysis identified AI-specific hopes (eg, potential for faster and more accurate analyses, ability to use more data), fears (eg, loss of human touch, skill depreciation from over-reliance on machines) and conditions (eg, human verification of computer-aided decisions, transparency). There were mixed views about whether data subject consent is required for health AI research, with most participants wanting to know if, how and by whom their data were used. Though it was not an objective of the study, realistic health AI scenarios were found to have an educational effect.ConclusionsNotwithstanding concerns and limited knowledge about AI in general, most members of the general public in six focus groups in Ontario, Canada perceived benefits from health AI and conditionally supported the use of health data for AI research.
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Toline, C. Anna, and Allan J. Baker. "Foraging tactic as a potential selection pressure influencing geographic differences in body shape among populations of dace (Phoxinus eos)." Canadian Journal of Zoology 71, no. 11 (November 1, 1993): 2178–84. http://dx.doi.org/10.1139/z93-306.
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Geographic differences in body shape among 18 populations of northern redbelly dace in three regions of Ontario (Sudbury, Algonquin Provincial Park, and Kingston) were quantified with truss analysis. Principal component analysis of size-adjusted residuals of the trusses revealed that 35.11% of the morphological variation in body shape is explained on principal component I. This axis describes the major trend in body shape variation, ranging from populations in which fish are relatively deep-bodied to those in which fish are more shallow-bodied. Shape variation among populations in Algonquin Park spanned the range observed among all three regions in Ontario. Experiments were thus conducted on two Algonquin populations differing considerably in body shape, and it was found that deeper bodied fish from one population were significantly more adept at capturing evasive prey than were relatively shallow-bodied fish from another population. This finding is not only consistent with functional analysis of fish shape but also fits predictions from foraging theory. Fish catching plentiful but evasive prey should rely on ambush predation, and thus have a large body depth, which increases body area relative to mass, in order to optimize acceleration. Conversely, fish catching less evasive food occurring at low density should use a tactic of wide foraging, for which they need a streamlined anterior body suitable for cruising over extended periods of time. Samples from the natural population revealed that deep-bodied fish had a significantly greater number of evasive prey in their guts, and that the more shallow-bodied fish had relatively few. Furthermore, the pond in which the deeper bodied fish occurred had significantly higher prey density than the pond inhabited by the shallow-bodied fish. Because the Algonquin populations experience sufficient gene flow to prevent differentiation due to drift alone, the most likely explanation for population differentiation resides in selection on body shape for foraging tactic.
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Hargreaves, Jennifer, Alan Lock, Peter Beckett, Graeme Spiers, Bryan Tisch, Lisa Lanteigne, Tamara Posadowski, and Michael Soenens. "Suitability of an organic residual cover on tailings for bioenergy crop production: A preliminary assessment." Canadian Journal of Soil Science 92, no. 1 (January 2012): 203–11. http://dx.doi.org/10.4141/cjss2010-056.
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Hargreaves, J., Lock, A., Beckett, P., Spiers, G. A., Tisch, B, Lanteigne, L., Posadowski, T. and Soenens, M. 2012. Suitability of an organic residual cover on tailings for bioenergy crop production: A preliminary assessment. Can. J. Soil Sci. 92: 203–211. To test the potential for production of bioenergy crops, such as canola and corn, an organic cover was constructed over acid-producing mine tailings containing nickel and copper, belonging to Vale in Sudbury, Ontario, Canada. The 1 m deep cover was of organic residuals (biosolids) obtained from a regional paper mill. Corn and canola crops were successfully grown using agricultural techniques. Crop yields from each of 2 yr from the tailings site were greater than those obtained at an agricultural site in the region. Root, shoot and grain analyses indicated low potential for bioaccumulation of potentially hazardous metals from the organic residual cover or the underlying tailings. Over the short term, there was no evidence of metal movement into the biosolids cover or uptake by the crops from the underlying tailing deposits. Importantly, canola seeds and corn kernels, the feedstocks for biodiesel and ethanol biofuels production, did not accumulate environmentally sensitive metals. This preliminary study demonstrates that the placement of an organic residuals cover on mine tailings to support growth of bioenergy crops is a potential novel reclamation strategy for the mining and smelting industry, or for industrial brownfields in general.
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Kolaj, Michal, and Richard Smith. "Using spatial derivatives of electromagnetic data to map lateral conductance variations in thin-sheet models: Applications over mine tailings ponds." GEOPHYSICS 78, no. 5 (September 1, 2013): E225—E235. http://dx.doi.org/10.1190/geo2012-0457.1.
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Mine waste, variable overburden, and the saprolite associated with nickel laterites have conductivity thicknesses (conductances) that vary laterally. In order for electromagnetic methods to be used to easily map lateral changes in conductance over thin-sheet-like bodies such as these, a simple conductance estimation method has been developed from Price’s equation. Through forward modeling, we found that assuming a uniform conductance and solving for an apparent conductance was sensitive enough to identify lateral conductance changes. The method was independent of the transmitter location, and each measurement provided a direct estimate of the apparent conductance below that station. The receiver can be moved around quickly allowing for lateral variations in apparent conductance to be determined efficiently. However, one of the required terms in the equation used is the vertical derivative of the secondary vertical magnetic field ([Formula: see text]). The accurate measurement of spatial electromagnetic derivatives requires a good signal-to-noise ratio (S/N), which can be hampered by low derivative signal values. Field studies performed over a dry tailings pond in Sudbury, Ontario, Canada, showed that an S/N greater than three was achievable even with [Formula: see text] values of less than [Formula: see text]. Apparent conductance estimates revealed that the tailings had a large resistive zone associated with surface vegetation, which may be correlated with favorable growing conditions and/or less conductive or thinner tailing material. Larger apparent conductances in other areas may be related to zones of thicker tailings and/or more conductive material (possibly due to increased metal content). Further drilling and sampling work is required to answer these ambiguities. Regardless, mapping the conductance of a thin sheet is an important step toward assessing if there are leftover metals in mine waste. However, the developed method is general and can be used in many other situations involving laterally varying thin bodies.