Julie E. Wilson

Scale, assessment components, and reference conditions: Issues for cumulative effects assessment in Canadian watersheds

Recent years have witnessed an increase in the use of watershed-based cumulative effects assessment (WCEA) in Canada; however, several challenges remain regarding its effective implementation and execution. Fundamental to WCEA is the establishment of linkages between environmental stressors and particular and measurable components of the aquatic environment. Dynamic and often synergistic relationships between the multiple physicochemical stressors in the landscape can affect water quantity, quality, and the health of aquatic species. Essential decisions must be made about what to measure to characterize both stressors and aquatic effects, what scale is appropriate for measurement, and to what the measurements should be referenced. This review presents lessons learned from case studies conducted in 6 different watersheds across Canada, each focused on advancing the science behind WCEA, but with varied objectives and approaches. Issues of scale, selection of aquatic environmental components or indicators for assessment, and reference conditions were compared and contrasted to highlight common challenges that can affect the implementation and outcome of a WCEA. The lack of long-term monitoring data and data inconsistencies were identified as frequently limiting factors for the advancement of WCEA science and the application of WCEA. Recommendations were made for developing a comprehensive and integrated methodology for WCEA in Canada.

Accumulated state assessment of the Peace-Athabasca-Slave River system

Effects-based analysis is a fundamental component of watershed cumulative effects assessment. This study conducted an effects-based analysis for the Peace-Athabasca-Slave River System, part of the massive Mackenzie River Basin, encompassing 20% of Canadas total land mass and influenced by cumulative contributions of the W.A.C. Bennett Dam (Peace River) and industrial activities including oil sands mining (Athabasca River). This study assessed seasonal changes in 1) Peace River water quality and quantity before and after dam development, 2) Athabasca River water quality and quantity before and after oil sands developments, 3) tributary inputs from the Peace and Athabasca Rivers to the Slave River, and 4) upstream to downstream differences in water quality in the Slave River. In addition, seasonal benchmarks were calculated for each river based on pre-perturbation post-perturbation data for future cumulative effects assessments. Winter discharge (January-March) from the Peace and Slave Rivers was significantly higher than before dam construction (pre-1967) (p < 0.05), whereas summer peak flows (May-July) were significantly lower than before the dam showing that regulation has significantly altered seasonal flow regimes. During spring freshet and summer high flows, the Peace River strongly influenced the quality of the Slave River, as there were no significant differences in loadings of dissolved N, total P (TP), total organic C (TOC), total As, total Mn, total V, and turbidity and specific conductance between these rivers. In the Athabasca River, TP and specific conductance concentrations increased significantly since before oil sands developments (1967-2010), whereas dissolved N and sulfate have increased after the oil sands developments (1977-2010). Recently, the Athabasca River had significantly higher concentrations of dissolved N, TP, TOC, dissolved sulfate, specific conductance, and total Mn than either the Slave or the Peace Rivers during the winter months. The transboundary nature of the Peace, Athabasca, and Slave River basins has resulted in fragmented monitoring and reporting of the state of these rivers, and a more consistent monitoring framework is recommended.

Processes affecting surface and chemical properties of chrysotile: Implications for reclamation of asbestos in the natural environment

Holmes, E. P., Wilson, J., Schreier, H. and Lavkulich, L. M. 2012. Processes affecting surface and chemical properties of chrysotile: Implications for reclamation of asbestos in the natural environment. Can. J. Soil Sci. 92: 229-242. A landslide at the headwaters of the Sumas River in southwestern British Columbia, is a seasonal and episodic source of chrysotile asbestos to the floodplain soil. Fresh alluvial deposits of fibres have potential for aeolian movement, posing a health risk to the Sumas watershed population. To understand the effects aquatic and pedogenic processes have on the fibres, asbestos materials from the river and floodplain were subjected to organic acid treatments in the laboratory. Changes were monitored by X-ray diffraction, scanning electron microscopy and elemental analysis. Fibre surfaces modified by organic acid treatments were similar to those affected by natural processes in that they showed a high loss of elements from the brucite layer compared with the silica tetrahedral layer, and the surfaces became smoother due to the loss of a rough amorphous coating. To initiate sustainable reclamation practices, changes in fibre surfaces by natural processes need to be considered and enhanced by incorporation of organic amendments that produce complexing soil acids. Reclamation activities should focus on recently deposited sediment along the floodplain. Non-polluting organic material, such as peat, compost and sawdust could be applied to increase reaction potential and kinetics of the reaction of chrysotile with naturally occurring acids.

Effects of natural acids on surface properties of asbestos minerals and kaolinite

Serpentine, and other asbestos minerals, are considered potential hazards to human respiratory health. It has been postulated that the surface characteristics of these substances, such as surface charge and adsorbed metals, notably Fe and other transition metals, may be the major agents responsible for their toxicity. There is a general consensus that the amphibole group of minerals possesses a greater health risk than serpentines dominated by chrysotile. There have been suggestions that natural processes can alter the surfaces of these minerals and reduce their potency. This study examined the effects of carbonic acid, oxalic acid and hydrochloric acid on the surface characteristics of two trioctahedral minerals, actinolite (amphibole) and chrysotile (serpentine), and compared the results to a non-asbestiform, dioctahedral mineral, kaolinite. Results confirm that the treatments alter the mineral surfaces by changing the zeta potential of the asbestiform minerals from positive to negative and by removing considerable amounts on non-crystalline Fe and other metals. X-ray analyses indicated that mineral structure was little affected by the treatments, and TOF-SIMS revealed that treatments did remove surface adsorbed metals and cations in octahedral coordination within the samples.