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Neville Lake


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Location

Barrhead County No. 11 AB
Canada

Neville Lake


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Location

Division No. 18 SK
Canada

Climate cycles drive aquatic ecologic changes in the Fort McMurray region of northern Alberta, Canada


Year: 2015

Abstract:
Understanding ecologic response to climate cycles will aid in defining current and future ecological changes associated with climate change and allow for a differentiation between climate-driven versus anthropogenic driven environmental stresses. The paleoecological record from a northern Canadian lake located 40 km east of the Athabasca Oil Sands operation records a benthic stress-induced ecological response to climate cycles such as the El Niño Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO). Arcellacea (testate lobose amoebae) preserved in a freeze core obtained from “ALE”, an upland lake in Northeastern Alberta, Canada, were used to reconstruct climate and associated benthic response since 1875 A.D. ALE is situated in a boreal wetland environment where inorganic sediment delivery is overwhelmingly dominated by surface overland flow transport during spring melt. Arcellacea are benthic protists that are excellent indicators of aquatic ecology. Relationships between arcellacean family groupings which represent either healthy or stressed environmental conditions were compared to instrumental climate indices. Modeling using wavelet analysis identified strong ENSO cycles in all arcellacean proxies and weaker PDO cycles in only the healthy ecosystem indicator. The ENSO phenomenon in the tropical Pacific Ocean drives the largest interannual variation in climate across western Canada, and in the study region has been associated with fluctuations in winter precipitation and temperature. The healthy ecosystem indicators decreased in response to positive El Niño and PDO conditions, which are characteristic of decreased precipitation and therefore nutrient input to boreal lakes. The relationship between arcellaceans and climate anomalies shows that climate driven variations in nutrient input influence boreal aquatic ecology. The link between aquatic ecology and climate has significant implications on oil sands risk assessment and the determination of reclamation endpoints.

High resolution paleolimnology of lakes in the Athabasca oil sands mining region Alberta Canada


Author(s): Neville, L. A.

Year: 2014

Abstract:
The Athabasca oil sands (AOS) represent one of Canada’s most economically important natural resources. Understanding the origin, fate and long-term impact of these industrial operations requires geoscientific knowledge of the potential environmental impacts. To quantify current impact an understanding of long-term environmental drivers is required. Here we utilize arcellaceans (testate lobose amoebae) to identify the long-term peleoecologic history of the area, against which ecological stress associated with anthropogenic activities may be defined. Surface sediment samples were collected from 63 lakes forming a 75 km radius encompassing potential airborne and waterborne contaminate pathways. Total mercury (THg) in lakes close to the AOS were similar to values recorded in lakes farthest away and to values recorded in lakes surrounding coal fire plants in central Alberta. All lakes except one had THg concentrations lower than current CCME guidelines. The spatial extent of arcellacean ecosystem stress did not correlate with THg concentrations. To understand the long-term history of the AOS area a freeze core (ALE) spanning 1,870 cal yr BP - present was used to assess how climate anomalies influence lake hydrology and ecology. Deconvolution of the grain size spectra indicates that populations are likely responding to overarching environmental controls. The coarser bedload material was interpreted to reflect high discharge events that occur during spring melts. A proxy ratio of the coarse:fine fractions demonstrates abrupt oscillations of both high and low frequency and indicates that variation in spring melt volume and velocity was likely forced by climate change. Further ii investigation of the grain size data showed that the hydrologic character of ALE has responded to known ocean-atmosphere cycles, particularly the El Niño Southern Oscillation (ENSO) and that these cycles are underwent abrupt expression shifts every ca. 270-370 years. We attribute the expression shift to movement of the jet stream, which controls air mass distribution at this locality. An investigation of the ecological character of ALE from 1875 AD - present reveals that the arcellacean community was also influenced by climate anomalies and that decreased nutrient input, which is a function of precipitation during the El Niño phase of ENSO, applied stress to benthic ecology in these boreal lakes.

Relationship between ecological indicators (Arcellacea) total mercury concentrations and grain size in lakes within the Athabasca oil sands region, Alberta


Year: 2014

Abstract:
Industrial mercury (Hg) sources associated with the processing of Athabasca oil sands (AOS), Alberta, Canada, may pose an environmental risk to nearby water bodies via either waterborne or airborne transport. Using a dataset derived from 63 lakes in the area, this study investigates the relationships between total-Hg (THg), organic matter, grain size, and lake ecology as measured by environmentally sensitive arcellacean (testate lobose amoebae) communities. The lakes studied include 59 lakes within a 75 km radius of the operations, plus four distal lakes ~150 km from the main industrial operations. Hg transport to the lakes is primarily through airborne pathways. The four distal lakes in the Peace–Athabasca Delta (~150 km downstream of the AOS operations) were examined to determine if the operation is emitting potential waterborne inputs, in addition to airborne inputs, and to identify any associated impact to those ecosystems. Total mercury in lakes close to the AOS were similar to values recorded in lakes farthest away. THg was most closely linked to the silt fraction, suggesting much of the Hg in these lakes is minerogenic in origin, either adsorbed and/or lattice-bound. THg is not statistically related to organic matter as has been observed in other Canadian lakes. The ecologic response to THg levels was investigated via the distribution of key indicator species and, or species diversity (Shannon diversity index). The spatial extent of arcellacean ecosystem stress in the study lakes did not correlate with THg concentrations. This is perhaps due to the generally low THg levels found in these lakes, all except one had THg concentrations lower than current CCME guidelines. While these findings may rule out any direct link between THg concentrations in the lakes and observed Arcellacea faunas, ecosystem stress unrelated to THg was observed northeast of the AOS, which warrants further examination. The results of this research suggest that the natural lake arcellacean faunas in the region are not being significantly impacted by current THg concentrations.

Relationship between ecological indicators (Arcellacea), total mercury concentrations and grain size in lakes within the Athabasca oil sands region, Alberta


Year: 2014

Abstract:
Industrial mercury (Hg) sources associated with the processing of Athabasca oil sands (AOS), Alberta, Canada, may pose an environmental risk to nearby water bodies via either waterborne or airborne transport. Using a dataset derived from 63 lakes in the area, this study investigates the relationships between total-Hg (THg), organic matter, grain size, and lake ecology as measured by environmentally sensitive arcellacean (testate lobose amoebae) communities. The lakes studied include 59 lakes within a 75 km radius of the operations, plus four distal lakes ~150 km from the main industrial operations. Hg transport to the lakes is primarily through airborne pathways. The four distal lakes in the Peace–Athabasca Delta (~150 km downstream of the AOS operations) were examined to determine if the operation is emitting potential waterborne inputs, in addition to airborne inputs, and to identify any associated impact to those ecosystems. Total mercury in lakes close to the AOS were similar to values recorded in lakes farthest away. THg was most closely linked to the silt fraction, suggesting much of the Hg in these lakes is minerogenic in origin, either adsorbed and/or lattice-bound. THg is not statistically related to organic matter as has been observed in other Canadian lakes. The ecologic response to THg levels was investigated via the distribution of key indicator species and, or species diversity (Shannon diversity index). The spatial extent of arcellacean ecosystem stress in the study lakes did not correlate with THg concentrations. This is perhaps due to the generally low THg levels found in these lakes, all except one had THg concentrations lower than current CCME guidelines. While these findings may rule out any direct link between THg concentrations in the lakes and observed Arcellacea faunas, ecosystem stress unrelated to THg was observed northeast of the AOS, which warrants further examination. The results of this research suggest that the natural lake arcellacean faunas in the region are not being significantly impacted by current THg concentrations.