Isotope-based partitioning of streamflow in the oil sands region, northern Alberta: Towards a monitoring strategy for assessing flow sources and water quality controls

AbstractStudy regionThis study is based on the rapidly developing Athabasca Oil Sands region, northeastern Alberta.Study focusHydrograph separation using stable isotopes of water is applied to partition streamflow sources in the Athabasca River and its tributaries. Distinct isotopic labelling of snow, rain, groundwater and surface water are applied to estimate the contribution of these sources to streamflow from analysis of multi-year records of isotopes in streamflow.New hydrological insights for the regionThe results provide new insight into runoff generation mechanisms operating in six tributaries and at four stations along the Athabasca River. Groundwater, found to be an important flow source at all stations, is the dominant component of the hydrograph in three tributaries (Steepbank R., Muskeg R., Firebag R.), accounting for 39–50% of annual streamflow. Surface water, mainly drainage from peatlands, is also found to be widely important, and dominant in three tributaries (Clearwater R., Mackay R., Ells R.), accounting for 45–81% of annual streamflow. Fairly limited contributions from direct precipitation illustrate that most snow and rain events result in indirect displacement of pre-event water by fill and spill mechanisms. Systematic shifts in regional groundwater to surface-water ratios are expected to be an important control on spatial and temporal distribution of water quality parameters and useful for evaluating the susceptibility of rivers to climate and development impacts

Looking forward through the past: identification of 50 priority research questions in palaeoecology

1. Priority question exercises are becoming an increasingly common tool to frame future agendas in conservation and ecological science. They are an effective way to identify research foci that advance the field and that also have high policy and conservation relevance. 2. To date, there has been no coherent synthesis of key questions and priority research areas for palaeoecology, which combines biological, geochemical and molecular techniques in order to reconstruct past ecological and environmental systems on time-scales from decades to millions of years. 3. We adapted a well-established methodology to identify 50 priority research questions in palaeoecology. Using a set of criteria designed to identify realistic and achievable research goals, we selected questions from a pool submitted by the international palaeoecology research community and relevant policy practitioners. 4. The integration of online participation, both before and during the workshop, increased international engagement in question selection. 5. The questions selected are structured around six themes: human–environment interactions in the Anthropocene; biodiversity, conservation and novel ecosystems; biodiversity over long time-scales; ecosystem processes and biogeochemical cycling; comparing, combining and synthesizing information from multiple records; and new developments in palaeoecology. 6. Future opportunities in palaeoecology are related to improved incorporation of uncertainty into reconstructions, an enhanced understanding of ecological and evolutionary dynamics and processes and the continued application of long-term data for better-informed landscape management

Ketone metabolism in the purple non-sulphur bacterium Rhodobacter capsulatus

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN015272 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Mapping water yield distribution across the South Athabasca Oil Sands (SAOS) area: Baseline surveys applying isotope mass balance of lakes

Study region: Surveys of stable isotopes of water in 121 lakes were conducted between 2007 and 2009 to assist in characterizing baseline hydrology of the South Athabasca Oil Sands area, Alberta, a 35,000 km2 boreal forest region with subdued relief, about 70% wetland cover, and a mosaic of lakes, rivers and buried channel networks. The region, currently under rapid development for in-situ oil sands, was close to baseline conditions at the time of survey. Study focus: Using an isotope mass balance approach, isotope data were applied to estimate water yield to lakes across the region. High-resolution maps were created to illustrate the spatial distribution of water yield and to compare observed patterns to geologic and physiographic features. New hydrological insights for the region: Site-specific differences in water yield were found in relation to geologic and physiographic features. Notably, high water yields were found in lakes underlain by Colorado shale, lower runoff was found in proximity to incised and buried channels. Consistent patterns from year-to-year reveal zones of low runoff which may be more susceptible to development-related impacts including changes in surface/groundwater interaction and pressurization or depressurization of aquifers or formations. The approach may be helpful for informing design of new monitoring programs to ensure runoff variability is considered. Periodic reassessments are recommended to capture potential development and/or climatic change impacts on the water cycle. Keywords: Isotopes, Lakes, Water balance, Evaporation, Runoff, Boreal, Oil sand

Stable isotope mass balance of fifty lakes in central Alberta: Assessing the role of water balance parameters in determining trophic status and lake level

Study region: This study spans the Prairie/parkland/boreal transition in central Alberta, including lakes in the Athabasca, North Saskatchewan, Battle River and Red Deer Basins. Study focus: Stable isotopes of water, oxygen-18 and deuterium, were measured in a network of 50 lakes during 2008 and 2009. The lakes are the subject of recent concern due to widespread lake level decline and development of eutrophic conditions that have been attributed to climate and land-use impacts. An isotope mass balance method was applied to estimate evaporation/inflow, water yield, and water residence times to assess relationships between water balance and lake status. New hydrological insights: Water yield was found to range from near 0 to 235 mm, evaporation/inflow was found to range from 18 to 136 %, and water residence time ranged from 2.3 to 58 years. The healthiest lakes in terms of trophic status are deep lakes with smaller catchments with long residence times. These lakes may have stable or variable water levels. Distressed lakes are often shallow prairie lakes with limited inflow and shorter residence times, and situated in areas with higher evaporation rates. High conductivity and high sulfate in some eutrophic lakes, attributed to saline groundwater inflow, may inhibit algae and cyanobacterial growth, thereby promoting healthier conditions. Extended drought under climate warming is expected to cause eventual decline of water levels in a greater number of lakes

Isotopic and geochemical surveys of lakes in coastal B.C.: Insights into regional water balance and water quality controls

Study region: This study was conducted within a 100,000 km2 area of British Columbia, (B.C.) Canada including Vancouver Island, the Georgia Basin, and the Pacific and Kitimat mountain ranges rising from the Pacific Ocean. Study focus: A stable isotope mass balance method is applied to estimate evaporation loss and water yield from a remote network of 560 lakes on Vancouver Island and coastal B.C., based on helicopter sampling surveys conducted between 2008 and 2015. Spatial patterns in derived hydrological parameters are compared to water quality indicators and watershed characteristics to provide insight into water quantity and water quality relationships in the region, to be incorporated within a future critical loads assessment. New hydrological insights for the region: Regional trends in lake water balance, underlying physical drivers, and geochemical processes potentially influencing critical loads of acidity are described. Dominant non-anthropogenic regional drivers of geochemistry include sea spray, lithology, weathering and elevation. Significant contrast is noted in alkalinity between the sedimentary and volcanic substrates on Vancouver Island and igneous intrusive substrates of the Pacific and Kitimat ranges. A positive correlation is found between elevation and water yield to lakes, while the opposite is observed for rivers, which is interpreted to reflect disconnection of low elevation lakes from regional drainage networks. This may invalidate use of river gauge data for critical loads assessment in this or similar regions

A multiproxy palaeolimnological investigation of Holocene environmental change, between c. 10 700 and 7200 years BP, at Holebudalen, southern Norway

Geochemical analyses (x-ray fluorescence, 13C and C/N ratios) were used to reconstruct early Holocene environments (between 10685 and 7260 cal. yr BP) at a small lake near Holebudalen, southern Norway. Results show a period of increasing stability, with reduced catchment inwash (shown by titanium and potassium minerals), vegetation stabilization and increasing aquatic productivity (C/N ratios). However, periods of instability (loss on ignition (LOI) decrease) are also seen (most notably at c. 9060 cal. yr BP). Chironomid-inferred July temperature (CI-T) reconstructions show a cooling of c. 2°C (RMSEP = 1.0°C) between c. 8400 and 8000 cal. yr BP and so high-resolution (5 mm; c. 20 yr) diatom analyses were conducted between 8675 and 7830 cal. yr BP in order to further investigate this change. Between c. 8270 and 8000 cal. yr BP there were large reductions (> 50%) in the abundance of tychoplanktonic diatoms (eg, Aulacoseira species) and absolute increases in periphytic diatom communities (eg, Navicula pupula, Pinnularia mesolepta). The multiproxy analyses suggest a period of increased lake ice cover with associated reductions in turbulence during this time. Diatom flora changes are concomitant with a fall in percent LOI and increased catchment erosion at the site and other evidence of regional climatic perturbations in the early Holocene. Therefore, superimposed upon an early Holocene warming trend at Holebudalen, there are climatic perturbations, for example reflected between c. 8200 and 8000 cal. yr BP by diatom communities

The distribution and abundance of chironomids in high-latitude Eurasian lakes with respect to temperature and continentality: development and application of new chironomid-based climate-inference models in northern Russia

The large landmass of northern Russia has the potential to influence global climate through amplification of climate change. Reconstructing the climate in this region over millennial timescales is crucial for understanding the processes that affect the climate system. Chironomids, preserved in lake sediments, have the potential to produce high resolution, low error, quantitative summer air temperature reconstructions. Canonical correspondence analysis (CCA) of modern surface sediments from 100 high-latitude lakes, located in northern European Russia to central Siberia, showed chironomid distribution was primarily driven by July air temperatures. The strong relationship enabled the development of chironomid-inference model based on 81 lake and 89 taxa to reconstruct July air temperature. Analysis of a range of chironomid-inferred temperature model suggest the best to be a two component weighted averaging and partial least squares (WA-PLS model) with r2jack = 0.92 and RMSEP = 0.89°C. Comparison of species responses to July temperature with the Norwegian training set showed the temperature optima of individual species was 1-3°C in the Russian data regardless of modelling technique. This suggests that chironomid-based inference models should only be applied to sediment cores collected within the geographic source area of the training set. The differing responses between the Norwegian and Russian faunas led to the development of a 149 lake, 120 taxa chironomid-continentality inference model. The 2-component WA-PLS model was the minimal adequate model with r2jack = 0.73 and RMSEP = 9.9. Recent warming in the Arctic has been spatial and seasonal heterogeneous; in many areas warming is more pronounced in the spring and autumn leading to a lengthening of the summer, while summer temperatures have remained relatively stable. A continentality model has the potential to detect these seasonal changes in climate. The Russian inference model also improves the representation of a number of taxa, such as Corynocera oliveri-type, Constempellina and Paracladius, which frequently occur in subfossil assemblages from arctic Russian lakes, but are poorly represented in European training sets. These are cold-adapted taxa and their absence from the training sets could lead to overestimations of July temperatures in fossil samples where these taxa form a major component (for example see Andreev et al. 2005). Comparison of reconstructed July air temperatures and continentality indices from a tundra lake in north-east European Russia showed close agreement with local instrumental records over the past 70 years and suggests the models may produce reliable estimates of past climate