Sudbury smelter impact on atmospheric deposition of acidic substances in Ontario

During the period from June 1982 to March 1983, there was a prolonged shutdown of the INCO and Falconbridge smelters at Sudbury, Ontario. Taking advantage of this opportunity, the Air Resources Branch of the Ontario Ministry of the Environment undertook a detailed analysis of the impact that the resulting emission reductions had on the atmospheric deposition of acidity and SO_X in Ontario. This paper summarizes the various meteorological analyses and mathematical modeling estimates that were carried out in order to determine the contribution of the Sudbury smelters to atmospheric deposition in Ontario. For sulfates, the Sudbury contribution to the total wet deposition was typically less than 15% at the receptors studied. Furthermore, the smelters were found to contribute on the order of 10 to 20% of the total dry deposition of S compounds in central and northeastern Ontario, and less than 10% elsewhere.     

Natural changes in the planktonic rotifera of a small acid lake near Sudbury,Ontario following water quality improvements

Swan Lake is a small, acidic, metal-contaminated lake located near Sudbury, Ontario. During the past 8 yr, the lake has experienced a substantial increase in pH, together with significant reductions in the concentrations of heavy metals and base cations. These changes were observed only after acid and metal emissions from Sudbury area smelters were reduced. The composition of the planktonic Rotifera in the lake has changed concurrent with improvements in water chemistry. Dominance of the rotifer community by the acidophile Keratella taurocephala has been sharply reduced in recent years, while significant increases in the densities of Polyarthra spp., Chromogaster ovalis, Conochiloides natans and Trichocerca similis have been observed.     

Sulphate in Sudbury, Ontario, Canada, Lakes: Recent Trends and Status

Sulphur emissions from the Sudbury, Ontario, metal smelting industry have affected thousands of lakes in Ontario, Canada. Reductions in these emissions during the 1970's resulted in reduced lakewater SO₄ concentrations and other water quality changes in the 1970's and 1980's. Further declines in lakewater SO₄ concentrations have accompanied additional recent S emission reductions achieved by 1994. Recent (1997) SO₄ concentrations are still related to distance from the Sudbury smelters. A strong inverse relationship with distance is evident to about 45 km, and is most pronounced in lakes within about 20 km. In lakes beyond 45 km, dissolved organic carbon (DOC), which was correlated with hydrological response time and total phosphorus concentrations, was the best correlate with recent SO₄ concentrations, indicating that some slowly-flushing, oligotrophic lakes still exhibit a "Sudbury" effect. Most lakes beyond 45 km, however, showed SO₄ declines and recent SO₄ concentrations comparable to lakes around Dorset, ～200 km from Sudbury, suggesting that these lakes are now most affected by the long-range atmospheric transport of S.     

Pathways of chemical recovery in acidified,metal-contaminated lakes near Sudbury,Ontario, Canada

This paper describes the recovery pathways of two lakes situated near the Coniston nickel-copper smelter. These lakes were exposed to very intense airborne pollution, including SO₂, H₂SO₄, Ni and Cu, during the 60 year operation of the smelter. After the closure of the Coniston smelter in 1972 and the subsequent improvement in air quality, the water quality in both lakes began to improve. Despite their proximity and exposure to similar inputs, the lakes differed both in the rate and magnitude of recovery. This study demonstrates the capacity of lakes to recover from chemical stresses over a very short period. Changes in Cu and Ni concentration could be predicted, while changes in pH, measured as H⁺, could not. The reasons for this discrepancy as well as the processes and lake parameters that control chemical recovery are discussed.     

Biological recovery of two previously acidified,metal-contaminated lakes near Sudbury Ontario,Canada

Studies are reported on two small lakes at Sudbury, Ontario located close to a nickel-copper smelter which closed in 1972. At that stage, Baby Lake had a pH of 4.0–4.2 while the adjacent Alice Lake had a pH 5.9–6.3. Both lakes were almost entirely devoid of algae and had neither Zooplankton nor fish. Soon after the closure of the smelter, with its large airborne volume of sulphur dioxide and of copper and nickel containing particulates, the chemistry of the lakes began to change. By 1985, Baby Lake had changed from pH 4.0 to 6.8 and is now at pH 7.2. The pH of Alice Lake increased from a low of 5.9 in the early 1970s to 6.9–7.4 in the mid 1980s and is now at 7.3. Copper and nickel concentrations also decreased in both lakes during this period. The first biota found in the lakes in the post-smelter stage in the early 1980s were benthic red chironomids, planktonic rotifers, and a limited number of phytoplankton species, of which Rhizosolenia was the most common. By the 1990s, 13 phytoplankton species were present in each lake, with a substantial Zooplankton fauna (14 species) of rotifers, copepods, and cladocerans. There are now numerous insect larvae in the sediment and some small fish in both lakes. The biological recovery, which followed substantial reductions in acidity and in soluble nickel and copper concentrations in the waters, is a slower process than chemical recovery and is initially characterized by the dominance of a few species.     

Distribution of Trace Elements in Soils from the Sudbury Smelting Area (Ontario,Canada)

The sequential extraction procedure proposed by the European Commission Measurement and Testing Programme, combined with Scanning Electron Microscopy and Energy Dispersive X-ray Analysis(SEM/EDS), was applied to identify and quantify the chemical andmineralogical forms of Cu, Ni, Fe, Mn, Zn, Pb, Cr and Cd presentin the topsoil from a mining and smelting area near Sudbury (Ontario, Canada). The possible mobility of the chemical forms was also assessed. The metal fractions: (1) soluble and exchangeable, (2) occluded in manganese oxides and in easily reducible iron oxides, (3) organically bound and in form of sulphides, (4) residual mainly present in the mineral lattice structures were separated. Cu and Ni were the major metallic contaminants, occurring in soils in broad ranges of concentrations: Cu 11–1890 and Ni 23–2150 mg kg^-1. Cu was uniformly distributed among allthe extracted fractions. Ni was found associated mainly withthe residual forms, accounting for 17–92%, with an averageof 64%, of the total Ni present in the soils. Fe, Mn, Zn,Pb, Cr and Cd, while occurring in most analysed samples innormal soil concentrations, were primarily held in theresidual mineral fraction (on average >50%). The solubleand exchangeable forms made a small contribution (≤8.1%)to the total content of metals extracted. At least 14% ofthe total Cd, Mn and Pb was mobilised from the reducibleforms. The oxidizable fraction assumed mean values higher than10% only for Pb and Zn. Statistical treatment of the experimental data showed significant correlations between totalmetal content of the soils, some soil properties such as pH value, clay and organic matter content, and metal concentrationsin the various fractions. SEM/EDS analysis showed Fe in form ofoxides and sulphides in soils and Cu, Ni, Mn, Zn and Cr in association with iron oxides. Numerous black carbonaceous particles and precipitates of aluminium fluoride salts, observedin the solid residue left after `total’ digestion, were found tocontain Fe, Ni and Cr.     

Accumulation of atmospherically deposited metals in Wetland soils of Sudbury,Ontario

Concentrations of Cu, Ni, Fe, and Mg in soil/sediment material from 25 wetlands in the Sudbury, Ontario, region decline logarithmically with increasing distance from several ore smelters. Total Cu and Ni reach concentrations potentially toxic to plant life in soil/sediment material near the smelters. Despite random variation in soil/sediment pH and Eh, NH₄OAc extractable Cu, Ni and Fe, and DTPA extractable Cu Ni and Mg show the same pattern as total Cu, Ni, Fe, and Mg. The failure of DTPA extractable Fe to show the same pattern as total Fe may be due to the inadequacy of the DTPA soil test when testing Fe in acid soils. Soil/sediment organic C content increases with distance from the smelters, but is unrelated to pH or Eh.     

Trends in small lake water chemistry near Sudbury,Canada, 1983–1991

While many studies have documented improvements in chemical conditions of large lakes near Sudbury, Canada in response to reduced smelter emissions, few have examined changes in water chemistry of small lakes. We studied trends in water chemistry of 97 small (<10 ha), shallow (<15 m) lakes northeast of Sudbury that are important habitat for breeding waterfowl. Currently, many small lakes near Sudbury are acidified, with little acid-neutralizing capacity and with relatively high concentrations of Al, Mn, and Ni. We also present evidence of short-term improvements in pH and SO₄ levels, but demonstrate that, over a nine year period, there has been no consistent, long-term trend of chemical recovery. Chemical conditions in these lakes varied considerably between 1983 and 1991, and responded quickly to changes in precipitation levels. However, the present condition of most lakes suggests that further reductions in emissions will be required to improve these habitats for breeding waterfowl.     

Heavy metals in fish from a series of metal-contaminated lakes near Sudbury,Ontario

Elevated levels of Ni, Cu, and Zn are present in surficial sediments of lakes in the Sudbury region of northeastern Ontario. Metal concentrations in sediments were highest in lakes closest to local smelters, and decreased rapidly with distance: equations are presented describing these relationships. Several fish species were collected from a series of these metal-contaminated lakes, and analyzed for metal content of muscle, liver, and kidney tissues. Muscle tissue was a poor indicator of increased metal availability. Liver tissue was a good indicator for Cu, while kidney tissue was best for Ni. Zinc levels in tissues varried little among either fish species or lakes. The presence of elevated levels of Cu in liver, and elevated levels of Ni in liver and kidney tissues of fish from certain lakes supported the hypothesis that some fish populations were being stressed by metal additions to local aquatic habitats. Although the degree of lake contamination (as indicated by Cu concentrations in sediments) was one factor influencing Cu availability, water quality parameters such as alkalinity and DOC also appeared to be very important.     

Least limiting water range indicators of soil quality and corn production, eastern Ontario, Canada

The least limiting water range (LLWR) attempts to incorporate crop-limiting values of soil strength, aeration, and water supply to plant roots into one effective parameter (on the basis of soil water content). The LLWR can be a useful indicator of soil quality and soil physical constraints on crop production. This study focused on assessing dynamic cultivation zone LLWR parameters between different cropping/tillage/trafficked clay loam plots at Winchester, Ont., to identify potential management impact on surficial soil physical conditions for contrasting growing seasons. This study also evaluated dynamic cultivation layer LLWR variables as indicators of corn (Zea mays L.) plant establishment and corn yield. The results suggest that no-till soils had lower average air-filled porosities (AFP) and O₂ concentrations than respectively managed tilled plots for both years of study. Potential trafficking effects on aeration properties were most evident in no-till relative to till; preferentially trafficked no-tilled plots had lower AFP and O₂ concentrations than respective non-preferentially trafficked no-till plots for both years of study. Corn establishment and yield variability were principally explained by cumulative differences between daily AFP and aeration threshold values, and the cumulative number of days daily AFP was below an AFP aeration threshold for specific corn growth stage periods. Lower AFP was linked to lower yields and plant establishments. Soil strength, as measured by cone penetration resistance, was important over certain sites, but not as important globally as AFP in predicting crop properties. Overall, conventional tilled soils that were not preferentially trafficked had most favorable aeration properties, and subsequently, greatest corn populations and yields. No-till soils were at greater risk of aeration limiting conditions, especially those in continuous corn and preferentially trafficked.     

Floristic changes in soil algae and cyanobacteria in reclaimed metal-contaminated land at Sudbury,Canada

Logging, fires and smelting have produced extensive barren areas in Sudbury, Ontario. Soils from these areas have a low pH (3.7 to 4.2), elevated concentrations of Cu and Ni, and are subject to erosion. A successful revegetation program has been in operation since 1978. Manual applications of limestone, fertilizers and seeds have produced extensive grassy swards. Enrichment cultures (Bold Basal and Allen's medium) were used to compare the soil algae and cyanobacteria from barren sites with those treated 6 mo, 2, 4, and 5 yr ago. Cultures of soils from barren sites were characterized by a low diversity of chlorophytes and a few diatoms. Cyanobacteria were absent. In comparison, treated soils yielded an increased diversity of chlorophytes and included a number of cyanobacterial genera. Chlorophyll a analysis indicates a higher biomass of autotrophic organisms on treated sites. Increased diversity and biomass on treated soils may reduce erosion while the presence of N fixing cyanobacteria could contribute to the fertility of these soils. A filamentous picocyanobacterium appeared in enrichment cultures (1/3 strength Allen's medium) of treated soils but not of untreated soils. The techniques of epifluorescence microscopy may be valuable in further investigations of autotrophic soil organisms.     

Correlation between Microcrustaceans and Environmental Variables along an Acidification Gradient in Sudbury, Canada

Multivariate methods were used to relate microcrustacean (pelagic and littoral) richness and composition (presence/absence) to water quality and other environmental variables. All acidification variables (pH, aluminium, ANC) showed significant correlation with both species richness and composition. The variation in microcrustacean richness was best explained by the combination of dissolved organic carbon (DOC), fish species richness and lake area. Of 16 variables tested, pH showed strongest correlation with the main gradient in the crustacean composition explaining between 13 and 16% of the variance in the species data (CCA). pH, elevation, lake area, average depth, DOC, conductivity and fish species richness explained 30–54% of the total variance. Stronger correlation was obtained between species composition and environmental data in analyses which included the between-year differences than analyses based on the cumulative species records. Analyses based on the pelagic species exclusively gave similarly stronger correlation than analyses based on all crustacean species. Small changes in the species composition during the three years of study may be an indication of recovery of microcrustaceans in Killarney lakes.     

Evaluating macroinvertebrate responses to recovery from acidification in small lakes in Ontario,Canada

The biomonitoring program of Environment Canada examines food chains in small Ontario lakes to interpret ecological responses of waterfowl and their foods to changing acid deposition. Macroinvertebrates and fish were sampled in three acid-sensitive regions: Muskoka (1991; N=20), Algoma (1992; N=20), and Sudbury (1994; N=22). Small lakes (<11 ha;=" important=" breeding=" habitat=" for=" waterfowl)=" were=" chosen=" to=" cover=" the=" range=" of=" ph=" in=" each=" region,=" and=" include=" those=" with=" and=" without=" fish.=" in=" all=" regions,=" macroinvertebrate=" taxonomic=" richness=" (particularly=" nekton=" and=" benthos)=" was=" greater=" in=" fishless=" lakes=" compared=" to=" lakes=" with=" fish.=" among=" fishless=" lakes,=" taxonomic=" richness=" (especially=" benthos)=" was=" positively=" correlated=" with=" ph,=" although=" regional=" differences=" were=" evident.=" previous=" studies=" near=" sudbury=" have=" shown=" that=" several=" benthic=" groups=" have=" distribution=" and=" abundance=" patterns=" with=" respect=" to=" ph=" (trichoptera,=" ephemeroptera,=" hirudinea,=" amphipoda,=" and=" gastropoda).=" those=" patterns=" continue=" near=" sudbury,=" and=" were=" also=" strongly=" apparent=" in=" algoma.=" in=" all=" regions,=" the=" number=" of=" acid-sensitive=" taxa=" per=" lake=" is=" related=" to=" ph,=" and=" should=" increase=" as=" lakes=" recover=" from=" acidification.=" however,=" predicting=" macroinvertebrate=" responses=" to=" recovery=" must=" consider=" concurrent=" effects=" of=" fish,=" as=" they=" are=" a=" dominant=" factor=" structuring=" these=">     

Metals in stocked Lake Trout (Salvelinus namaycush) in lakes near Sudbury,Canada

Muscle tissue from stocked lake trout (Salvelinus namaycush) from lakes near the smelters at Sudbury, Canada was analyzed for Al, Cu, Fe, Hg, Mn, Ni, and Zn. Metals in tissue were not abnormally high compared with fish from lakes farther away from the smelters. Tissue concentrations of Al, Fe, Mn, and Zn declined significantly after stocking. Because metal concentrations were lower in hatchery water than the study lakes, this decline in tissue metal suggests that diet plays a prominent role in the uptake of these metals in lake trout. Only Hg showed evidence of accumulation to levels that might be harmful for human consumption, and then only in a few older, larger trout. In contrast, tissue Mn and Zn were inversely correlated with trout weight. Fluctuations, independent of age, body weight or time of year, were observed in tissue concentrations of Al, Cu, and Zn. Annual cycles, independent of pH and alkalinity were observed in tissue concentrations of Fe, Hg, Mn, and Ni. Bioaccumulation of metal proved to be an unfounded concern for the rehabilitation of fish populations in lakes near Sudbury.     

Assessing biological recovery of acid-sensitive lakes in Ontario,Canada

Information on breeding waterfowl, habitat and food chains, gathered from acid-sensitive lakes in Ontario, was used to develop a model of effects of acid deposition on waterfowl and their response to predicted sulphur dioxide (SO₂ emission reductions in eastern North America. The Waterfowl Acidification Response Modelling System (WARMS) is composed of an acidification model linked to fish and waterfowl models. WARMS uses pH, area, dissolved organic carbon, total phosphorus, and presence of fish to calculate estimates of pre-acidification, present and eventual steady-state values for pH, fish presence and waterfowl breeding parameters under proposed SO₂ emission scenarios. We used WARMS to estimate chemical and biotic responses to scenarios simulated in three regions of Ontario where biomonitoring studies are underway. For pH and fish presence, WARMS predicts the greatest improvements in the highly damaged Sudbury region, slight improvements in Algoma, and that the strongest proposed emission reductions will be required to maintain current conditions in Muskoka. For waterfowl, species-specific differences are evident among regions. We discuss implications of these assessments of biological recovery for watersheds in eastern Canada.     

Modelling tillage erosion in the topographically complex landscapes of southwestern Ontario, Canada

A tillage erosion model was developed for southwestern Ontario based on the relationship between tillage translocation and slope gradient and slope curvature. Two studies of tillage translocation and tillage erosion were used to calibrate this model, one a comparison of upslope and downslope tillage translocation on shoulder slopes, the other an examination of tillage translocation throughout topographically complex landscapes. Two field sites were used for validation of the model. For both sites, past tillage practices were known and past soil erosion was determined using ¹³⁷Cs as an indicator of soil redistribution. The model accurately predicted the pattern of soil redistribution that had occurred within the two field sites. Severe soil loss was observed and predicted on convex landscape positions and soil accumulation was observed and predicted on concave landscape positions. The model accounted for almost all of the soil lost from the convex upper slope positions where tillage erosion was expected to be the dominant erosion process. There was considerable soil loss and accumulation elsewhere in the landscapes which could not be accounted for by the model and was presumed to be primarily the result of water erosion. It was concluded that tillage erosion must be incorporated into soil erosion modelling for the purposes of soil conservation.     

Photo interpretive study of recovery of damaged lands near the metal smelters of Sudbury,Canada

Aerial photographs from 1970 and 1989 were used to assess the recovery of approximately 100000 ha of smelter-damaged lands near Sudbury, Canada. Recent improvements in air quality enabled conifers to recolonize about 22% of the semi-barrens, an area that consisted of a near monoculture of coppiced and stunted white birch (Betula papyrifera). The more heavily damaged barren areas, surrounding the three smelter sites, exhibited very little natural recovery during the study period. A municipal land reclamation program was responsible for most of the observed revegetation within the barren area. Between 1978 and 1988 approximately 2000 ha of barrens were reclaimed through soil treatment, grassing and tree planting. An estimated 7400 ha of the most heavily damaged land is still in need of immediate remedial treatment. Increased rates of natural recovery are expected in the future as SO₂ emissions are reduced. Continued municipal and expanded industrial reclamation programs in the 1990s will also greatly reduce the extent of bare land.     

Hypolimnetic Alkalinity Generation in Two Dilute, Oligotrophic Lakes in Ontario, Canada

It has been observed that the alkalinity concentrations in the hypolimnia of many thermally stratified lakes increase over the duration of the summer. We have quantified the processes, both redox and exchange, that contributed to the alkalinity increases measured in two lakes that are situated on the Precambrian Shield of Ontario, Canada by measuring hypolimnetic mass balances for all substances involved in alkalinity-generating or -consuming reactions. These include nitrate, ammonium base cations, iron, manganese, sulphate, organic anions, as well as alkalinity itself. In one lake, iron reduction was the dominant source of alkalinity; since this process is probably reversed at fall overturn when hypolimnetic waters mix with oxygenated surface waters, the alkalinity generated by this mechanism is likely temporary in nature. In the second lake, iron reduction and sulphate reduction were both important the latter should provide more permanent alkalinity.     

Social Media for Enhancing Stakeholders' Innovation Networks in Ontario,Canada

ABSTRACT

This case study assessed local food stakeholders' use of Facebook and Twitter to support interaction and build their networks of innovation in Ontario. Data were collected using Netlytic ? an online data mining tool from the social media platforms ? and key informant interviews. Findings revealed that stakeholders could be more innovative in their use of social media, but they would be unlikely to do so, without tapping into beneficial interactions of weak ties, as well as fostering strong ties. They also need to utilize the high brokerage role of key facilitating organizations and develop a social media strategy by integrating both ‘online’ and ‘offline’ interactions.     

Outcomes of longterm deciduous forest restoration in southwestern Ontario, Canada

At present, forest cover in southwestern Ontario, Canada, remains at less than 5% due to intensive agricultural and urban land use. Although much of the extant forest is increasingly protected by legislation, remnants continue to be degraded by the spread of non-native plant species, overgrazing, and recreational use. Some parks in the region have adopted management programs aimed at mitigating this degradation. Over the last 35 years, cottages and roads at Point Pelée National Park have been removed and sites either passively restored (i.e. road or cottage eliminated and vegetation allowed to regenerate) or actively restored (i.e. road or cottage eliminated, exotic vegetation removed, and native species planted). In 1994 and 1995, we assessed the effectiveness of restoration by comparing the understorey plant communities in 28 restored sites with those in less disturbed reference sites. There was a significant increase (P<0.0001) in the similarity of understorey plant communities between restored and reference sites as time-since-restoration increased. Soil moisture, canopy cover, distance to continuous forest, and site-shape all significantly affected plant species composition. Former road sites recovered significantly (P<0.05) more rapidly than former cottage sites, and the former lawns of passively restored cottage sites were the slowest to recover. Five years following active restoration, non-native ruderal species continued to dominate restored sites. The observed recovery of understorey plant communities in restored sites is attributed to their proximity to natural vegetation, and its function as a seed source. In some sites, recovery is substantial and, assuming present trajectories of change are maintained, we predict that recovery could occur in many mesic sites within the next 20 years. Restoration activity facilitates forest recovery and would appear to have a valuable function in mitigating ongoing conflicts between conservation and human use in this region.