The levels and distribution of trace metals (Cr, Mn, Co, Ni, Cu, Zn, Cd and Pb) at eleven water and sediment stations on the Little Akaki River (LAR) in Addis Ababa, Ethiopia, were determined. The binding forms of the metals in various geochemical fractions of the sediments were also quantified. The molar ratio of the sum of the simultaneously extractable metals (∑SEM) and acid-volatile sulphide (AVS)-as a measure for predicting metal-induced toxicity-was estimated. LAR trace levels in water for Cu, Zn, and, particularly Mn were, in most instances, higher than the recommended guidelines for healthy aquatic ecosystems. Total trace metal (TTM) contents in the LAR sediments at certain stations exceeded "threshold effect concentrations" and even "probable effect concentrations", especially in the cases of Zn, Cu, Ni, Pb, and at all stations for Mn. This became more apparent after applying "normalizations" to the relatively lower TTM adsorption capacities of coarse-grained, organic-poor sediments. Sequential extraction of the sediments showed that trace metals generally have a higher affinity for Fe-Mn oxide and organic matter/sulphidic fractions, followed by the residual fraction. Mn was relatively strongly bound to the exchangeable, carbonate bound fractions, whereas a large proportion of Cr was found in the residual fraction. The Σ[SEM]/[AVS] ratio pointed to potential metal-induced toxicity of sediments collected from seven out of the eleven stations. The results indicate that trace metal pollution pose risks to the health of ecosystems, and to human communities that use the river for a range of different purposes.
The Oldman River flows 440 km from its headwaters in south-western Alberta, through mountains, foothills and plains into the South Saskatchewan River. Peak flows occur in May and June. Three major reservoirs, together with more than a dozen other structures, supply water to nine irrigation districts and other water users in the Oldman basin. Human activity in the basin includes forestry, recreation, oil and gas development, and agriculture, including a large number of confined livestock feeding operations. Based on the perception of basin residents that water quality was declining and of human health concern, the Oldman River Basin Water Quality Initiative was formed in 1997 to address the concerns. There was limited factual information, and at the time there was a desire for finger pointing. Results (1998-2002) show that mainstem water quality remains good whereas tributary water quality is more of a challenge. Key variables of concern are nutrients, bacteria and pesticides. Point source discharges are better understood and better regulated, whereas non-point source runoff requires more attention. Recent data on Cryptosporidium and Giardia species are providing benefit for focusing watershed management activities. The water quality data collected is providing a foundation to implement community-supported urban and rural better management practices to improve water quality.
To investigate the potential for fish tainting from exposure to oil sands extraction wastewaters, rainbow trout were exposed to four different tailings pond wastewaters for a period of 24 hours. Subsequently, the fish were sacrificed, filleted and bile drawn from the gall bladder. Sensory analysis, performed by 10 pre-screened panelists, revealed that each of the four wastewater streams tainted the exposed fish to a detectable degree. Chemical analyses of the fish fillet, wastewater and fish bile revealed the presence of alkylated benzenes and phenols. The total level of phenols detected in the fish tissue was well above reported odour threshold levels. The additional presence of organic sulphur compounds identified in the wastewater suggests that they may also have contributed to the detected level of fish taint.
The Watershed Restoration Program (WRP) in British Columbia was initiated under the ausoices of Forest Renewal B.C. to restore, protect and maintain fisheries, aquatic and forest resources adversely impacted by past forest-harvesting practices, by carrying out community-based remedial work on hillslopes and streams. Specific restoration components focus on impacted hillslopes, gullies, riparian areas, stream channels and fish habitat. Fish habitat restoration is typically carried out after an assessment of upslope risks (followed by rehabilitation) and instream conditions. Restoration techniques include restoring fish access, streambank stabilization, rehabilitating channellized reaches to provide fish holding pools and riffles, re-establishing instream cover and structure by addition of boulder clusters and large woody debris (LWD), restoring and creating off-channel habitat, and resupply of nutrients. After the restoration work is completed, research evaluation and operational monitoring are conducted to determine the overall success and ultimate benefit of the work. Fesearch evaluation is not project-specific, but may involve evaluation of a specific technique (e.g., LWD placements), and synoptic studies and 'paired assessments'of experimental control and treatment streams. Routine and project effectiveness monitoring is project-specific and is carried out after the instream work is completed and has passed post-construction inspection. Routine monitoring is a low intensity activity to determine functionality and condition of the restoration works. lt is mainly a visual activity, and may include simple measurements or indicators (e.9., for structural stability), and can be undertaken on an annual basis or after each major storm. Project effectiveness monitoring is of higher intensity, and is conducted on a selected subset of projects where there are uncertainties of outcome or adaptive management benefits. This monitoring typically includes fish sampling and physical measurements: pool widths and depths, stream gradient, channel form, and channel substrate characteristics. Engineering level surveys (to tie bed and water surface elevations and cross sections to a specific benchmark) are frequently required for quantitative comparisons of restoration works (before, as-constructed and post-restoration). Where possible, project effectiveness monitoring should be related to published estimates of increases in fish abundance due to habitat improvements (biostandards) established during the planning and prescriptive phase. Evaluation and monitoring of fish habitat restoration projects, both in the shorter and longer term, are essential to improve biological, technical and cost effectiveness of projects, and to identify and incorporate innovations. Evaluation techniques described in the paper were developed to evaluate activities to restore streams impacted by past logging
The Province of Alberta, Canada recently introduced a Water Management Policy for the South Saskatchewan River Basin that called for determination of the maximum amount of water that can be allocated for irrigation and other uses in the various sub-basins of the South Saskatchewan River. Part of this process required determining the environmental flows (also called instream flow needs) according to the stated objective which was for the full protection of the aquatic environment. Environmental flow determinations were developed to reflect the seasonal pattern and general changes in magnitude, frequency, timing and duration of the natural flow hydrograph both within a year and between years. The intent was to provide flow values based on the ecological need for natural flow variation. To meet these expectations, four ecosystem components were chosen to represent the full extent of the aquatic ecosystem: water quality, fish habitat, riparian vegetation, and channel maintenance. The environmental flow values for each of the individual components were integrated to produce an ecosystem based value. The final flow values were generated for 27 reaches in the SSRB using a weekly time-step in a flow duration curve format (in total, 1404 discreet flow determinations).
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