Recent Temporal Patterns in the Chemistry of Small,Acid-sensitive Lakes in Central Ontario,Canada

We monitored the chemistry of 603 small water bodies in three acid-sensitive regions of central Ontario, Canada (Algoma n=235, Muskoka n=216, Sudbury n=152) between 1988^-1996 to determine whether they have responded to recent SO2 emission reductions, and whether any chemical changes were related to lake characteristics. During the study, 27-56% of lakes declined in SO₄ ^2- concentrations, 41-57% declined in base cation concentrations, but only 26-28% increased in pH or ANC (acidity status). Increases in pH were greatest in lakes with low ANC, but had weak relationships to lake color or volume. No consistent trends were observed for DOC, NO₃ ^- or TP concentrations. Clearly, the long-term biological recovery of these sensitive aquatic ecosystems will depend on interactions among several environmental stressors, including acidification.     

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.     

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.     

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.     

Water quality improvements in the Sudbury,Ontario, Canada area related to reduced smelter emissions

Data from water quality studies conducted in the Sudbury, Ontario, Canada area indicate that substantial decreases in the acidity of surface waters have accompanied reductions in SO₂ emissions from the Sudbury smelting industry since 1977. On average, acidic lakes in the Sudbury area showed a decrease in H⁺ of ～ 50% between 1974–76 and 1981–83, and the severity of springtime pH depressions in streams decreased. Although many Sudbury area surface waters remain highly acidic, general decreases in acidity appear to be continuing. The results demonstrate that reductions in emissions of acids and acid precursors result in concomitant improvements in water quality.     

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.     

Ecosystem recovery after emission reductions: Sudbury,Canada

A case history is presented describing the ecosystem changes that accompanied the nearly 90% reduction of SO₂ and metal particulate emissions from Sudbury smelters during the past 25 years. The instances of severe ground-level fumigations that caused acute damage to vegetation in an area of approximately 1,000 km² have been nearly completely eliminated. Significant improvements in water quality have also occurred in many of the estimated 7,000 acid-damaged lakes. Several species of acid-sensitive phytoplankton, Zooplankton and insects have invaded lakes where improvements have occurred. Epiphytic lichens have reinvaded the former lichen desert that once extended out 7 km from the smelters. Sensitive species such as Evernia mesomorpha and Usnea hirta now exist throughout the area. The vascular plant communities have been relatively slow to recover in the most severely damaged terrestrial areas. Metal-tolerant grasses (e.g. Agrostis scabra. Deschampsia caespitosa) were the first species to invade the barrens. Acid- and metal-contamination of soil, severe microclimate conditions, and the damaging effects of insect pests appear to delay recovery of terrestrial ecosystems. Recovery rates of aquatic ecosystems are also affected by a suite of physical, chemical and biotic interactions and many lakes remain severely damaged.     

Origin and Transport of Aeolian Sediment from New Clearcuts into Boreal Lakes,Northwestern Ontario,Canada

Movement of aeolian (wind-blown) inorganic sediment was indexed in and around new riparian and upland clearcuts in northwestern Ontario, Canada with bucket-style terrestrial litterfall traps. Aeolian sediment originated primarily from clearcuts, roads, and skid trails, where soil disturbance was high and forest hitterfall was low. Relatively small amounts of aeolian sediment were recovered from riparian buffer strips and upland forest. Aeolian sediment was observed to reach lakes adjacent to the clearcuts and may be responsible for elevated levels of littoral sedimentation measured in one study lake. However, the amounts of sediment deposition observed are not likely to cause important changes in water quality or benthic habitat for algae, invertebrates, or fish in these lakes.     

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.     

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.     

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.     

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.     

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.     

Legacy Arsenic Pollution of Lakes Near Cobalt,Ontario, Canada: Arsenic in Lake Water and Sediment Remains Elevated Nearly a Century After Mining Activity Has Ceased

Century old mine tailings in the Cobalt and Silver Center areas are widely dispersed throughout the terrestrial and aquatic environments and contain high concentrations of arsenic. Arsenic concentrations were found to be as high as 972 μg/L in surface waters and 10,800 mg/kg in lake sediment. The mean values for arsenic in surface waters and sediment from 9 lakes directly influenced by mining activity were 431 μg/L and 1704 mg/kg, respectively, whereas in the 12 control lakes with no mining activity in their catchment had mean values of 2.2 μg/L and 11 mg/kg in their water and sediment, respectively. Lakes impacted by downstream tailing migration (n?=?4) were also assessed and had intermediate concentrations of arsenic. Principal component analysis identified contaminated lakes as having different geochemical signatures than control lakes but lake sediment that was sampled below tailings in contaminated lakes, deposited pre-mining, can resemble the geochemistry of those found in control lakes. Arsenic concentrations in these samples ranged from 4.4 to 185 mg/kg, which can be considered reasonable background as these areas contained abundant mineral deposits that could naturally elevate background concentrations. Even though background concentrations are naturally elevated, the presence of arsenic-rich tailings in these lakes has prevented any natural recovery from occurring. Fe-Mn oxides at the water-sediment interface perpetually scavenge arsenic from buried tailings below and from contaminated surface waters that cause arsenic concentrations to remain enriched in the upper sediments even after tailings have been buried by lake sediment. This process has prevented recovery of the lake ecosystems even after nearly a century without mining.     

Phytoplankton community of an acidified,heavy metal—Contaminated lake near Sudbury,Ontario: 1973–1977

Phytoplankton data for 1973 to 1977 from Clearwater Lake, an acid- and heavy metal—contaminated lake near Sudbury, Ontario are presented.Peridinium inconspicuum (Lemmermann) comprised between 30 and 55% of the average, ice-free period biomass of 0.33 to 0.73 mg l^?1 and is considered indicative of acidic lakes if it forms a substantial portion of the total biomass. The data were compared with those from three other contaminated and ten uncontaminated lakes in Ontario. The phytoplankton communities of all contaminated lakes were dominated byP. inconspicuum while chrysophytes dominated the uncontaminated lakes. Community biomass was better correlated with phosphorus concentration than with hydrogen ion concentration. There was some evidence of reductions of biomass in lakes with the highest heavy metal concentrations. Limitations of phytoplankton data collected in synoptic surveys are discussed.     

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.     

Adoption of soil conservation practices: An empirical analysis in Ontario,Canada

Soil degradation threatens environmental quality and sustainable food production. As a result of efforts to promote soil conservation, farmers in Canada are thought to be reasonably aware of both the importance of conservation and the existence of remedial and preventive practices. Despite this, the adoption of conservation practices has been less than overwhelming. Forces other than awareness and positive attitude seem to be constraining many land managers from employing available conservation methods. This paper presents the findings from an empirical investigation of the use of soil conservation practices and barriers to their adoption in the southwestern region of Ontario, Canada. The analysis is set in the context of literature on technology adoption. A scheme for measuring farm-level conservation effort is developed, and barriers to adoption are derived from an analysis of a range of independent physical, personal, and economic factors, and from the obstacles or constraints identified by producers themselves. Key barriers relate to economic pressures, the complexity and compatibility of practices, and perceptions regarding the actual need for practices. The findings have relevance for the design of public policies and programs, notably the importance of supplying information on farm-level implications of conservation methods and the need for a stable economic environment for agriculture to allow longer-term planning.     

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.     

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.