Acidification and metal contamination in Whitepine Lake (Sudbury,Canada): a paleolimnological perspective

Diatom and chrysophyte assemblages from a sediment core from Whitepine Lake were examined to infer changes in lakewater pH, nickel and aluminum concentrations since pre-industrial times, and to help determine the cause of the virtual extirpation of the lake trout population from the lake during the 1960s and 1970s. Our study indicates that acidification started in the 1920s, and that the maximum inferred pH decline (from 6.2 to 5.8) occurred between 1960 and 1970, coincident with the peak in metal mining and smelting activity in the Sudbury basin. Lakewater [Al] and [Ni], as inferred from our diatom transfer functions, increased. It appears that in addition to the pH decline, elevated [Al] may have played an important role in the decline of lake trout from Whitepine Lake in the 1960s and 1970s. Diatom-inferred lakewater pH and [Ni] have recovered slightly in the recent sediments, which coincides with reductions in emissions that have occurred since the mid-1970s.     

Paleoindication of acidification in Kleiner Arbersee (Federal Republic of Germany,Bavarian Forest) by chydorids,chrysophytes, and diatoms

In a sediment core of Lake Kleiner Arbersee, located in the Bavarian Forest on gneiss bedrock and with spodosolic soils in the catchment, acidification was reconstructed using assemblages of chydorids, scaled chrysophytes, and diatoms as paleoindicators. All paleoindicators demonstrated acidification of Kleiner Arbersee. There were marked differences, however, in the extent of the indicated acidification: In lower layers, where scaled chrysophytes and chydorids clearly indicate beginning acidification, pH-decline inferred by diatoms lies within the standard deviation, and is statistically not significant until the 7 cm layer. We conclude that mallomonadaceans reflect the acidification of the water body and strongly respond to the lowest seasonal pH, as their indicated rate of acidification is higher than that of diatoms, which appear to more closely indicate the pH of the sediment/water interface, especially when the pH of the water column has dropped below ca. 5.5. Chydorids may additionally be influenced by proton release of dense Sphagnum-stands, which cover the littoral of Kleiner Arbersee completely.We dedicate this paper to Prof. Dipl.-Ing. L. Strobel, who encouraged new perspectives in limnological water management, on the occasion of his 65^th anniversary.     

Variability in diatom and chrysophyte assemblages and inferred pH: paleolimnological studies of Big Moose Lake,New York,USA

We measured variability in the composition of diatom and chrysophyte assemblages, and the pH inferred from these assemblages, in sediment samples from Big Moose Lake, in the Adirondack Mountains of New York. Replicate samples were analyzed from (1) a single sediment core interval, (2) 12 different intervals from each of 3 separate cores, and (3) 10 widely spaced surface sediment samples (0–1 cm). The variability associated with sample preparation (subsampling, processing, and counting) was relatively small compared to between-core and within-lake variability. The relative abundances of the dominant diatom taxa varied to a greater extent than those of the chrysophyte scale assemblages. Standard deviations of pH inferences for multiple counts from the same sediment interval from diatom, chrysophyte, and diatom plus chrysophyte inference equations were 0.04 (n=8), 0.06 (n=32), and 0.06 (n=8) of a pH unit, respectively. Stratigraphic analysis of diatoms and chrysophytes from three widely spaced pelagic sediment cores provided a similar record of lake acidification trends, although with slight differences in temporal rates of change. Average standard deviations of pH inferences from diatom, chrysophyte and diatom plus chrysophyte inference equations for eight sediment intervals representing similar time periods but in different cores were 0.10, 0.20, and 0.09 pH unit, respectively. Our data support the assumption that a single sediment core can provide an accurate representation of historical change in a lake. The major sources of diatom variability in the surface sediments (i.e., top 1.0 cm) were (1) differences in diatom assemblage contributions from benthic and littoral sources, and (2) the rapid change in assemblage composition with sediment depth, which is characteristic of recently acidified lakes. Because scaled chrysophytes are exclusively planktonic, their spatial distribution in lake sediments is less variable than the diatom assemblages. Standard deviations of pH inferences for 10 widely spaced surface sediment samples from diatom, chrysophyte and diatom plus chrysophyte inference equations were 0.21, 0.09, and 0.16 of a pH unit, respectively.     

A palaeoecological test of the land-use hypothesis for recent lake acidification in South-West Norway using hill-top lakes

Lakes perched on hill-tops have very small catchments. Their water chemistry is largely influenced by the chemical composition of precipitation and by the underlying bedrock geology. They are ideal sites for testing the hypothesis that land-use and associated soil changes are a major cause of recent lake acidification. On this hypothesis, hill-top lakes in SW Norway are predicted not to show any recent lake acidification because, by their very nature, the chemistry of such lakes is little influenced by land-use or soil changes.Palaeolimnological analyses of diatoms and chrysophytes show that prior to ca. 1914 the two hill-top lakes investigated were naturally acid with reconstructed lake-pH values of at least 4.8–5.1. Since ca. 1914 lake pH values declined to ca. 4.5–4.7. These results contradict the land-use hypothesis. All the available palaeolimnological evidence (diatoms, chrysophytes, pollen, sediment geochemistry, carbonaceous particles) is consistent with the acid-deposition hypothesis.In the absence of any evidence to support the land-use hypothesis as a primary cause of recent lake acidification and in the light of several independent refutations, it is perhaps time to put the land-use hypothesis for recent lake acidification to rest.     

A paleolimnological assessment of lake acidification in five Connecticut lakes

New England has received significant amounts of precipitation with a pH between 4.2 and 4.6. Paleolimnological studies based on siliceous microalgal remains support the hypothesis that some lakes in northern New England have acidified as a result of the acidic deposition. However, paleolimnological analyses from five software lakes in southern New England suggest that these lakes have not acidified in recent years. In all of the study lakes the inferred pH has remained relatively stable, and in two lakes the pH has actually increased slightly in recent years. Despite the relatively stable inferred pH reconstructions, significant shifts in species assemblages were observed in each lake, many of which are believed to correlate with land use changes. It is possible that effects of land use changes (e.g. increased urbanization) have masked potential effects of acid deposition.     

Patterns of pH change inferred from chrysophyte microfossils in Adirondack and northern New England lakes

The silica-scaled chrysophytes are being used increasingly in paleolimnological studies of lake acidification. This study compares the distribution of scaled chrysophytes in the surface sediment of a calibration set of lakes from the Adirondack Park and from northern New England. With the exception of two taxa, species distributions with respect to pH are similar in the two regions. The stratigraphic distribution of chrysophytes is then compared in five Adirondack and three New England lakes. All the presently acid lakes indicate recent lake acidification, with more acid tolerant chrysophytes increasing in relative frequency in the recent sediments. Because the timing of these species changes is unrelated to any watershed disturbances that may have occurred in the lakes' catchments, atmospheric deposition of acids is believed responsible for these recent pH changes.This is the seventh of a series of papers to be published by this journal which is a contribution of the Paleoecological Investigation of Recent Lake Acidification (PIRLA) project. Drs. D. F. Charles and D. R. Whitehead are guest editors for this series.     

The relationship between sedimentary diatom assemblages and lakewater pH in 35 Quebec lakes,Canada

Surface sediment diatoms from 35 soft-water lakes in southern Quebec were studied to examine the relationship with lakewater pH. The lakes ranged in pH from 5.25 to 7.66. The species composition and the relative abundance of diatoms in the study lakes was found to be closely related to pH and/or factors closely associated with pH. Predictive models were developed to infer lakewater pH using simple linear regression equations of index alpha, index B, and multiple regressions using pH preference categories. Among the predictive models examined here, the multiple regression technique provided the highest correlation coefficient (r²=0.88) and the lowest standard error (±0.26 of a pH unit) in computing diatom-inferred pH. This model appears to be the most appropriate to reconstruct lake pH histories in Quebec region.     

Diatom preservation in the recent sediment record of Spanish saline lakes: implications for palaeoclimate study

In palaeoclimate research, fossil diatoms from saline lakes can be excellent indicators of past salinity, a proxy for climate change, although they are sometimes poorly preserved in sediment cores. Spain has numerous salt lakes but the potential of diatoms for studies of climate change has never been investigated. A comprehensive survey of diatom preservation is described based on modern and fossil diatoms from short cores (<50 cm depth) in a representative data-set of 59 sites, and the main factors affecting preservation are investigated using principal components analysis (PCA). Most lakes do not preserve a diatom record; four sites in southern Spain are identified which both contain diatoms and have suitable limnological characteristics for a climate study. Many lakes are ephemeral and the physical effects of desiccation, coupled with other factors such as turbidity and high salinity, are the main factors enhancing diatom dissolution or their failure to be incorporated into the sediment record.     

Paleolimnological investigation of recent acidity changes in Sawanoike Pond, Kyoto, Japan

Sawanoike Pond, an artificial reservoir constructed ca. 150 yrs. ago, lies in an area geologically sensitive to acidification and contains water that is presently weakly acidic (pH 5.5; alkalinity 15 eq 1^-1). Sediments from a core obtained from the northern part and a core from the central part of the pond were analyzed for organic matter, total organic carbon, total nitrogen, natural and artificial radionuclides, pollen, diatoms, metals and spheroidal carbonaceous particles. A peaty silt layer at the bottom of the central core was replaced by a silt layer initially rich in humic substances, but became more mineral-rich near the surface. Although most of the dominant diatoms throughout the cores were acidophilous taxa, some acidobiontic species increased moderately in abundance after the middle 1960's. Diatom-inferred pH values for the northern core are relatively low before about 1930, then increase, reaching a maximum level between the 1930's and the late 1940's. They then decrease to the surface and reach minimum level during the middle 1980's. Diatom-inferred pH declined by 0.4-0.5 units in the northern core and 0.2-0.3 units in the central core since ca. 1910, when vegetation around the shore changed to a community similar to that of recent years. An increase in labile Pb, Zn, Cd and spheroidal carbonaceous particles, indicative of atmospheric deposition of fossil fuel combustion by-products, preceded the decline in inferred pH. The inferred pH decline of the pond could be an acidification due to acidic precipitation caused by fossil fuel combustion.     

The detection of Rhizosolenia (Bacillariophyceae) in sediment of Ontario lakes and implications for paleoecology

The detection of the freshwater genus Rhizosolenia (Bacillariophyceae) remains in sediments is affected by the oxidants used in the digestion procedures. The Rhizosolenia counts decrease from 30% H₂O₂>50% HNO₃>50% chromic acid>100% HNO₃>100% H₂SO₄. Rhizosolenia is mostly found in Ontario lakes with summer average pH ranging from 5.6 to 8.3, Gran alkalinity from 0.2 to 120 mg L^–1 as CaCO₃ and water colour from 4 to 105 Hazen units. Large Rhizosolenia populations are generally found in clear lakes, neutral pH and low alkalinity.     

Paleolimnological reconstruction of recent changes in assemblages of Cladocera from acidified lakes in the Adirondack Mountains (New York)

Remains of Cladocera were examined in short sediment cores from three Adirondack lakes with mean pHs below 5 and a fourth with a mean pH of 6.5. These cores were collected as part of the Paleoecological Investigation of Recent Lake Acidification (PIRLA I) project. Historical and paleolimnological evidence suggests that pH has decreased in each of the acid lakes in recent decades. In all of the study cores, the greatest changes in net accumulation rates, assemblage composition, and species richness occurred in recently deposited sediments. The similar timing of events in all lakes suggests that a regional disturbance was responsible. In the three acid lakes, there was a strong association of changes in cladoceran assemblages and diatom, chrysophyte, and geochemical evidence of acidification. The occurrence of recent changes in non-acid Windfall Pond indicates that other factors may also have affected Cladocera in the study lakes.This is the fifteenth of a series of papers to be published by this journal which is a contribution of the Paleoecological Investigation of Recent Lake Acidification (PIRLA) project. Drs. D. F. Charles and D. R. Whitehead are guest editors for this series.     

Diatom-salinity relationships in 111 lakes from the Interior Plateau of British Columbia,Canada: the development of diatom-based models for paleosalinity reconstructions

Diatoms were identified and enumerated from the surface sediments of 111 lakes, 45 from the Kamloops region and 66 from the Cariboo/Chilcotin region, located on the southern Interior Plateau of British Columbia, Canada. This paper is an extension of another study which investigated the relationship of diatoms to salinity and ionic composition in 65 lakes from the Cariboo/Chilcotin region. The 111 lakes spanned a large gradient in salinity, ranging from fresh through hypersaline (late-summer salinity values ranged from 0.04 to 369 g l^–1), and included both carbonate- and sulphate-dominated lakes with sodium and magnesium as the dominant cations. The Kamloops region had more sulphate-dominated, hypersaline lakes and fewer carbonate-rich lakes than the Cariboo/Chilcotin region. Most lakes had higher salinities in the late-summer compared to the spring.Both salinity and brine-type were important variables that could explain the different diatom assemblages present in the lakes. The majority of diatom taxa had salinity optima in the freshwater to subsaline range (<3 g l^–1), and the taxa displayed a range of both narrow and broad tolerances along the salinity gradient. Weighted-averaging regression and calibration, and maximum likelihood techniques were used to develop salinity inference models from the diatom assemblages based on their relationship to the spring, late-summer and average lakewater salinity measurements. Simple weighted-averaging (WA) models generally produced the same or lower bootstrapped RMSEs of prediction than weighted-averaging with tolerance downweighting (WA(tol)) in the two regional and the combined datasets. Weighted averaging partial least squares (WA-PLS) showed little or no improvement in the predictive abilities of the datasets, as judged by the jackknifed RMSE of prediction. In all cases, the combined dataset of 102 lakes performed better than either of the smaller regional datasets, with relatively little difference between spring, average and late-summer salinity models. The maximum likelihood models gave lower apparent RMSEs of prediction in comparison to other methods; however, independent validation of this technique using methods such as bootstrapping were not undertaken because of the computer intensive nature of such analyses. These diatom-based salinity models are now available for reconstructing salinity and climatic trends from appropriately chosen closed-basin lakes in the Interior region of British Columbia.This is the second in a series of papers published in this issue on the paleolimnology of arid regions. These papers were presented at the Sixth International Palaeolimnology Symposium held 19–21 April, 1993 at the Australian National University, Canberra, Australia. Dr A. R. Chivas served as guest editor for these papers.     

An assessment of recent trophic changes in Windermere South Basin (England) based on diatom remains and fossil pigments

Cyanobacterial carotenoids and diatom remains have been analyzed in recent sediments from the Windermere South Basin (WSB) to study the trophic evolution experienced by the lake. Dates in the top 30 cm were specifically established through radionuclide (²¹⁰Pb and¹³⁷Cs) analyses. Diatom stratigraphy shows dominance of the centric diatomsCyclotella comensis andC. radiosa and several benthic taxa in the early postglacial. This indicates oligotrophy in the WSB during that period. This assemblage was replaced by another dominated by the diatomAsterionella formosa in the 1870's, as has been established from the²¹⁰Pb dating. From that date onwards, the lake underwent a progression towards eutrophy, indicated by the progressive increase inAulacoseira subarctica (c. 1930's),Fragilaria crotonensis (c. 1943), and more recently, of the centricsStephanodiscus parvus (c. 1971) andCyclotella meneghiniana (1988).Carotenoid stratigraphy reveals the differences between different sections of the core. Oscillaxanthin and myxoxanthophyll had very low records in the early and medium parts of the core, but increased fromc. 1950's, showing peaks atc. 1967, 1979 and 1987. Some of these peaks indicated a differential abundance ofOscillatoria, and are matched to those observed directly during the ongoing monitoring of the phytoplankton of the lake.The coincidence between the historic appearance of diatoms associated with nutrient-rich waters and the enhanced carotenoid occurrence suggest a common response to phosphorus enrichment, and that the progressive change towards eutrophy has been accentuated during the last twenty-five years.     

Development of a diatom-based specific conductivity model for the glacio-isostatic lakes of Truelove Lowland: implications for paleoconductivity and paleoenvironmental reconstructions in Devon Island lakes, N.W.T., Canada

Diatoms are identified and enumerated from the surface sediments of 100 lakes of Truelove Lowland, Devon Island, N.W.T., Canada. These lakes range from large oligotrophic lakes, to small tundra ponds, to coastal marine lagoons which are diverse in terms of ionic concentration and composition. The relationship between diatoms and 15 limnological variables is examined using Canonical Correspondence Analysis (CCA). Specific conductivity is identified as the most important variable influencing the distribution of diatoms in the Truelove lakes. A Weighted Averaging (WA) calibration model is developed to predict diatom-inferred specific conductivity. The reliability of the model is tested by evaluating the correlation between observed and diatom-inferred values and determining the error of prediction by bootstrapping. The applicability of the predictive conductivity equation is demonstrated by reconstructing the paleoconductivity history of Fish Lake.     

Diatom assemblages from Adirondack lakes (New York,USA) and the development of inference models for retrospective environmental assessment

Detrended canonical coreespondence analysis (DCCA) was used to examine the relationships between diatom species distributions and environmental variables from 62 drainage lakes in the Adirondack region, New York (USA). The contribution of lakewater pH, Al_m (monomeric Al), NH₄, maximum depth, Mg, and DOC (dissolved organic carbon) were statistically significant in explaining the patterns of variation in the diatom species composition. Twenty-three and sixteen diatom taxa were identified as potential indicator species for pH and Al_m, respectively (i.e. a taxon with a strong statistical relationship to the environmental variable of interest, a well defined optimum, and a narrow tolerance to the variable of interest). Using weighted-averaging regression and calibration, predictive models were developed to infer lakewater pH (r ²=0.91), Al_m (r ²=0.83), DOC (dissolved organic carbon) (r ²=0.64), and ANC (acid neutralizing capacity; r ²=0.90). These variables are of key importance in understanding watershed acidification processes. These predictive models have been used in the PIRLA-II (Paleoecological Investigation of Recent Lake Acidification-II) project to answer policy-related questions concerning acidification, recovery, and fisheries loss.     

Regional assessment of long-term hypolimnetic oxygen changes in Ontario (Canada) shield lakes using subfossil chironomids

Subfossil chironomid assemblages were used to infer long-term water quality changes in south-central Ontario shield lakes, which are currently being impacted by anthropogenic eutrophication, acid rain, and recent climate change. Using a transfer function developed to infer average end-of-summer volume-weighted hypolimnetic oxygen (avg VWHO), a top-bottom paleolimnological approach was used to reconstruct pre-industrial (pre-1850) deepwater oxygen conditions. Comparison with present-day (top surface sediments) chironomid-based inferences of avgVWHO results suggest that hypolimnetic oxygen levels are presently similar to natural, pre-industrial (bottom sediments) levels in most lakes. Approximately half of the study lakes recorded an increase in hypolimnetic oxygen since the 19th century. Inferred changes in avgVWHO correlate well with our results from another chironomid-based oxygen model which reconstructs the Anoxic Factor (AF). When study lakes are separated according to their hydrological status (i.e., natural versus managed), lakes with a dam at their outlet and seasonally managed lake levels had significantly different changes in avgVWHO compared to lakes with natural hydrology. Lakes with a dam at their outlet generally recorded increases in avgVWHO, while natural hydrology lakes mostly recorded declines. There was no relationship between inferred changes in avgVWHO and the density of cottage and resort development along the shorelines of lakes. Changes in dissolved organic carbon (DOC) possibly related to recent climate changes may also be affecting deepwater oxygen, however patterns of change are very subtle.     

Diatom taxonomic and morphological changes as indicators of metal pollution and recovery in Lac Dufault (Québec, Canada)

We studied diatom taxonomic composition and the presence of morphological alterations (size and deformations) along a sediment core collected in Lac Dufault, Abitibi, whose watershed has a long history of mining pollution presently undergoing mitigation. According to sediment dating with ²¹⁰Pb and metal profiles along the core, we could identify four periods in the contamination history of the lake, which were characterized by different diatoms. Tabellaria flocculosa was dominant in the pre-mining period but was drastically reduced at the onset of pollution when Fragilaria cf. tenera became important. This diatom, together with other Fragilaria species and cysts of Chaetoceros muelleri, typified the transition period in which Cu reached its maximum value and other metals started to increase. During the period of maximum contamination with Zn, Cd, and Fe accompanied by acid mine drainage, Achnanthes minutissima and Brachysira vitrea were dominant. These taxa started to wane in the most recent sediments representing a partial chemical recovery. Asterionella formosa, which almost vanished at mining onset, reappeared with high abundance in these superficial sections. Beside these taxonomical shifts, we observed during the contamination period significant reduction in valve length together with increased percentages of valve deformations. Because available data on water chemistry and a diatom-based pH reconstruction suggest that Lac Dufault escaped severe acidification, diatom patterns observed in the core can be mostly ascribed to metal contamination. Individual diatom abundance and valve length had strong statistical relationships with the different metals identified in the core. Diatom changes both taxonomic and morphological can be excellent specific indicator of metal contamination and early recovery.     

Diatom-based transfer functions for western Quebec lakes (Abitibiand Haute Mauricie): the possible role of epilimnetic CO2 concentration in influencing diatom assemblages

Surficial sediments from 76 lakes from two western Quebec regions(Abitibi and Haute Mauricie) were sampled to identify the relationships betweendiatoms and environmental variables. Because the two regions containedradically different diatom communities, we then investigated which factors maybe responsible for the large community discrepancies in the two nearbygeographical areas. Standard lake chemistry variables showed little differencesbetween the regions, although epilimnetic light regimes were slightly lower inAbitibi. Nevertheless, lakes of the two regions with similar light regimes andchemistry still showed a clear separation in their diatoms, implying that otherimportant factors are influencing assemblages. We found that the calculatedconcentration of CO₂ in the open water can explain some of thediscrepancy in diatom assemblages. A pCCA constrained to the concentration ofCO₂ with alkalinity and pH as covariables explained 12.5% of speciesvariance and was significant. Given the lack of a relationship between DOC andCO₂, and because the lakes are heavily supersaturated withCO₂ in the calibration set, lake-to-lake variations inCO₂ concentrations are likely due to groundwater inputs; thepossibility that this environmental variable may be influencing diatomcommunities might allow, in some cases, the reconstruction of historicalchanges in groundwater inputs to lakes. Finally, new calibration models werebuilt in Quebec by using weighted averaging partial least square(WA-PLS) techniques in order to infer pH, CO₂, TP, TN, and, DOC fromdiatom assemblages preserved in the surface sediments.     

Lithological and geochemical record of anthropogenic changes in recent sediments of a small and shallow lake (Lake Pusty Staw,northern Poland)

The article presents the results of lithological and geochemical investigations of recent sediments of Lake Pusty Staw. The analysed sediments document about 300 years of the history of this lake. Historical materials indicate that significant changes in the catchment of the lake took place from the beginning of the 18th century (deforestation and afforestation) followed by 19th century tourist development, and 20th century industrialisation. The sediments were dated using the ²¹⁰Pb and ¹³⁷Cs method and core lithology. These made it possible to establish a reliable chronology to the year 1730. The calculated sedimentation rates ranged between 0.17 and 0.83 cm year^–1. There was a period of intensified erosion caused by land clearance between 1734 and 1810, which resulted in an acceleration in sedimentation rate (0.36 cm year^–1) and a change of lithological type of sediment from detritus gyttja to clayey gyttja. On the basis of Cu, Zn, Cd and Pb content in the sediments, it was determined that the beginning of pollution of the lake dates back to the 19th century and was caused probably by the existence of a health resort. A systematic increase in pollution occurred in the 20th century as a result of industrial plants. Normalised with respect to Al, the content of heavy metals in polluted sediments was from several to twenty times higher than in sediments of the preindustrial period, and a comparison of historical materials with changes of sediments in most cases made it possible to identify the direct causes of the increase in pollution.     

Impacts of Coal-Fired Power Plants on Trace Metals and Polycyclic Aromatic Hydrocarbons (PAHs) in Lake Sediments in Central Alberta, Canada

Trace metals and polycyclic aromatic hydrocarbons (PAH) were analyzed in sediment cores from three central Alberta lakes to determine the contributions of local coal-fired power plants to contaminant loadings. In Wabamun Lake, with four power plants built since 1950 within a 35-km radius, sediment concentrations of mercury, copper, lead, arsenic and selenium have increased by 1.2- to 4-fold. Trace metal enrichments were less pronounced in Lac Ste. Anne and Pigeon Lake, situated 20 km north and 70 km south of Wabamun Lake, respectively. Total Hg flux to Wabamun Lake sediments (21–32μg m⁻² yr⁻¹) has increased 6-fold since 1950, compared to 2- and 1.5-fold increases in Lac Ste. Anne and Pigeon Lake, respectively, since circa 1900. Total PAH flux to surface sediments was 730–1100μg m⁻² yr⁻¹ in Wabamun Lake, 290–420μg m⁻² yr⁻¹ in Lac Ste. Anne, and 140–240μg m⁻² yr⁻¹ in Pigeon Lake. Without adoption of pollution-abatement technology that compensates for increases in generating capacity, continued expansion of coal-burning industry in Alberta will result in increased contaminant deposition, primarily from local sources.