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In ice-covered rivers, dissolved oxygen (DO) might fall below critical levels for aquatic biota in the absence of surface aeration, combined with low winter flow conditions and reduced photosynthesis rates. Open-water zones, however, can be created downstream of a diffuser by warm effluent discharges, resulting in an increase in surface aeration. In this study, we modeled the behavior of the effluent plume and the resulting open-water lead development in the Athabasca River, Alberta, Canada downstream of a pulp mill diffuser. The DO was found to increase by 0.26 mg/L due to surface aeration of an open-water lead of 6.07 km. We also evaluated oxygen injection into the effluent pipeline to increase the DO in the river. At an injection rate of 3,500 and 5,000 lb/day of liquid oxygen, the DO was increased by 0.16 and 0.21 mg/L, which corresponded to an absorption efficiency of about 50%. The artificial aeration technique evaluated here appears to be an effective alternative to increase DO levels in ice-covered rivers. The results of this study are important in developing accurate DO models for ice-covered rivers and in evaluating oxygen injection systems. DOI: 10.1061/(ASCE)0733-9372(2007)133:11(1051) CE Database subject headings: Dissolved oxygen; Effluents; Diffusion; Ice; Rivers; Reaeration.

Quantification of naphthenic acids in water has been traditionally performed after extraction with organic solvents followed by analytic methods that are complex and costly for preliminary research or for continuous monitoring purposes. This study examines the application of fluorescence in organic solvents as an effective alternative, and the role of organic solvents on quantification results. Nine organic solvents were used: three polar protic alcohols (methanol, ethanol, and propanol), three polar aprotic (dichloromethane, acetone, and acetonitrile) and three non-polar (hexane, toluene, and diethyl ether). The calibration curves of the polar protic solvents performed the best; they had lower light scattering and higher method sensitivity than polar aprotic and non-polar. Methanol was selected for further experiments having a strong linearity for concentrations lower than 250 mg/L (R2> 0.99), and a low relative standard deviation (< 10%). The method sensitivity was improved by 70% using a methanol-deionized water mixture (50:50) as a solvent. The synchronous fluorescence mode with a reduced offset value of Δλ = 10 nm demonstrated potential for fingerprinting. The fluorescence technique for quantifying total naphthenic acids directly in organic solvents is a cost-effective analytical method compatible with the solid phase extraction of the sample. [ABSTRACT FROM AUTHOR]

Abstract: The Community Multiscale Air Quality (CMAQ) and the Sparse Matrix Operator Kernel Emissions (SMOKE) modeling systems were used to simulate emissions and air quality in North Eastern Alberta where a rapid rise in oil sands development has caused air quality concerns over the last decade. The models were run on a 36/12/4 km domain for the four month period of May through August 2002. A model performance evaluation was conducted by comparing the CMAQ model estimates against ambient air quality measurements. In the Alberta oil sands region, the model tended to achieve or nearly achieve ozone model performance goals, albeit with an underestimation bias. The magnitudes of the observed PM2.5 concentrations were matched by the modeling system, except when the observed PM2.5 concentrations were influenced by emissions from forest fires in which case the model underestimated the observed PM2.5 concentrations. The CMAQ-estimated 4th highest daily maximum 8-hour ozone concentrations in the oil sands region were below the 65 ppb Canada Wide Standard (CWS) as well as the 58 ppb Alberta Management Plan Trigger Level. The highest estimated ozone concentrations occurred near the oil sands development area just north of Fort McMurray with values approaching, but below, the 58 ppb Management Plan Trigger Level; estimated ozone concentrations are much lower in the farther northern portions of the oil sands region. The acute (i.e., maximum 3-day value) SUM60 vegetative ozone exposure metric was mostly less than 100 ppb h, which is below the threshold of concern for crops. However, just north of Fort McMurray there were small areas where the acute SUM60 metric exceeded the 500–700 ppb h threshold of concern for crops with maximum values in plumes from sources in the oil sands mine area of ∼900 ppb h. The maximum chronic (three-month average) SUM60 ozone exposure metric was below the thresholds of concern. The CMAQ-estimated maximum 98th percentile 24-hour average PM2.5 concentration occurs in the mine area north of Fort McMurray and was below the CWS threshold (30 μg m−3), however it was above the Alberta Management Plan Trigger Level (20 μg m−3). The estimated 98th percentile 24- hour average PM2.5 concentrations were mostly in the 2–6 μg m−3 range with regions of higher PM2.5 concentrations predicted just north of Fort McMurray in the oil sands development region. [Copyright &y& Elsevier]

Abstract: We conducted four source apportionment simulations using the Community Multiscale Air Quality (CMAQ) photochemical grid modelling system in order to investigate and assess the relative importance of specific emissions sources and/or geographic regions on ambient ozone and PM air quality in the Alberta Oil Sands Region (AOSR). Local point and area sources, medium range transport of mobile sources and biogenic emissions were examined. The elimination of emissions from local stationary point sources reduced 8-h ozone concentrations and greatly reduces the PM2.5 concentrations in AOSR; similar results are seen in the local area source zero-out simulations but with less ozone and PM2.5 reductions than seen in the local point source zero-out run. Although the mobile source medium-range transport reduced 8-h ozone concentrations in the urban plume from Edmonton that results in some ozone and PM2.5 concentration reductions in the southern part of the AOSR, it has little effect on the elevated ozone and PM2.5 concentrations in the oil sands development area of the AOSR where the highest ozone and PM2.5 concentrations are estimated. The elimination of all anthropogenic emissions in Alberta so that only biogenic emissions remained resulted in large reductions in 8-h ozone concentrations in the AOSR, with the highest remaining ozone in the 50–52ppb range occurring south of Fort McMurray; very low PM2.5 concentrations are also estimated across Alberta, including the AOSR, when anthropogenic emissions are eliminated in Alberta. [Copyright &y& Elsevier]