At present, carbon dioxide (CO 2 ) is the largest contributor among greenhouse gases. This article addresses the potential application of photocatalysis to the reduction of CO 2 emissions from industrial flue gas streams. Not only does this process remove CO 2 , but it can also convert CO 2 into other chemical commodities such as methane, methanol, and ethanol. In addition, the photocatalytic process can consume less energy than conventional methods by harnessing solar energy. Given these advantages, photocatalysis is an attractive alternative for CO 2 capture. This article reviews the principle of photocatalysis; existing literature related to photocatalytic CO 2 reduction; and the effects of important parameters on process performance, including light wavelength and intensity, type of reductant, metal-modified surface, temperature, and pressure. Finally, we discuss various system configurations for UV and solar photocatalytic reactors. The advances in photocatalysis technology indicate a promising application potential for significant reductions of CO 2 emissions and a positive impact on climate change effects.

Naphthenic acids are comprised of a large collection of saturated aliphatic and alicyclic carboxylic acids found in hydrocarbon deposits (petroleum, oil sands bitumen, and crude oils). Naphthenic acids enter surface water systems primarily through effluent discharge, but also through groundwater mixing and erosion of riverbank oil deposits. Of the possible environmental receptors (i.e., air, soil, and water), the most significant is water. Ambient levels of naphthenic acids in northern Alberta rivers in the Athabasca Oil Sands are generally below 1 mg L(-1). However, tailings pond waters may contain as high as 110 mg L(-1). The complexity of natural naphthenic acids in petroleum deposits poses an analytical challenge as reflected by the several techniques reported for quantitation of naphthenic acids in the environment. Although naphthenic acids are known to be persistent biomarkers used in identification of oil source maturation, little is established regarding their relative degradation pathways in aquatic environments. Published research related to the potential for microbiological degradation and adsorption to typical Athabasca Oil Sands soils reveal that naphthenic acids are likely to persist in the water column and, with prolonged exposure, accumulate in sediments. However, other than a very general knowledge of environmental persistence, the occurrence and fate of naphthenic acids has been sparsely studied. This article brings together some of those environmental persistence results, as well as detailed information regarding the origin of naphthenic acids in tailings ponds, chemistry and toxicological considerations, current analytical methods for aquatic sampling, and areas of future remediation research.

This article provides a review of the routine methods currently utilized for total naphthenic acid analyses. There is a growing need to develop chemical methods that can selectively distinguish compounds found within industrially derived oil sands process affected waters (OSPW) from those derived from the natural weathering of oil sands deposits. Attention is thus given to the characterization of other OSPW components such as oil sands polar organic compounds, PAHs, and heavy metals along with characterization of chemical additives such as polyacrylamide polymers and trace levels of boron species. Environmental samples discussed cover the following matrices: OSPW containments, on-lease interceptor well systems, on- and off-lease groundwater, and river and lake surface waters. There are diverse ranges of methods available for analyses of total naphthenic acids. However, there is a need for inter-laboratory studies to compare their accuracy and precision for routine analyses. Recent advances in high- and medium-resolution mass spectrometry, concomitant with comprehensive mass spectrometry techniques following multi-dimensional chromatography or ion-mobility separations, have allowed for the speciation of monocarboxylic naphthenic acids along with a wide range of other species including humics. The distributions of oil sands polar organic compounds, particularly the sulphur containing species (i.e., OxS and OxS2) may allow for distinguishing sources of OSPW. The ratios of oxygen- (i.e., Ox) and nitrogen-containing species (i.e., NOx, and N2Ox) are useful for differentiating organic components derived from OSPW from natural components found within receiving waters. Synchronous fluorescence spectroscopy also provides a powerful screening technique capable of quickly detecting the presence of aromatic organic acids contained within oil sands naphthenic acid mixtures. Synchronous fluorescence spectroscopy provides diagnostic profiles for OSPW and potentially impacted groundwater that can be compared against reference groundwater and surface water samples. Novel applications of X-ray absorption near edge spectroscopy (XANES) are emerging for speciation of sulphur-containing species (both organic and inorganic components) as well as industrially derived boron-containing species. There is strong potential for an environmental forensics application of XANES for chemical fingerprinting of weathered sulphur-containing species and industrial additives in OSPW.

Naphthenic acids (NAs) have been implicated as some of the most toxic substances in oil sands leachates and identified as priority substances impacting on aquatic environments. As a group of compounds, NAs are not well characterized and comprise a large group of saturated aliphatic and alicyclic carboxylic acids found in hydrocarbon deposits (petroleum, oil sands bitumen, and crude oils). Described is an analytical method using negative-ion electrospray ionization mass spectrometry (ES/MS) of extracts. Preconcentration was achieved by using a solid-phase extraction procedure utilizing a crosslinked polystyrene-based polymer with acetonitrile elution. Recovery of the Fluka Chemicals NA mixture was highly pH-dependent, with 100% recovery at pH 3.0, but only 66 and 51% recoveries at pHs 7 and 9, respectively. The dissolved phase of the NA was very dependent on sample pH. It is thus critical to measure the pH and determine the appropriate mass profiles to identify NAs in natural waters. The ES/MS analytical procedure proved to be a fast and sensitive method for the recovery and detection of NAs in natural waters, with a detection limit of 0.01 mg/L.

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Cade-Menun, B. J., Bell, G., Baker-Ismail, S., Fouli, Y., Hodder, K., McMartin, D. W., Perez-Valdivia, C. and Wu, K. 2013. Nutrient loss from Saskatchewan cropland and pasture in spring snowmelt runoff. Can. J. Soil Sci. 93: 445–458. To develop appropriate beneficial management practices (BMPs) for a watershed, it is essential to quantify the nutrients lost from agricultural fields and to identify the mechanisms of nutrient transport. To determine appropriate BMPs for a watershed in southeastern Saskatchewan, nutrient concentrations were measured in spring 2010 in snowmelt runoff from fertilized annual cropland (zero till) and perennial tame pastures. The majority of nutrient loss was in dissolved form, rather than as particulates. Significantly more nitrogen (N) was lost from pastures as dissolved ammonium than from cropland, while significantly more dissolved organic N was lost from croplands. Although there were no significant differences in total phosphorus (P) loss, there were significantly higher concentrations of dissolved reactive P in runoff from cropland, and significantly higher particulate P in runoff from pastures. Total carbon (C) in runoff was higher from cropland, due mainly to significantly higher dissolved organic C concentrations. Runoff from cropland contained significantly higher concentrations of dissolved potassium and sulfur, reflecting the fertilization of cropland fields with these nutrients. These preliminary results demonstrate that nutrients may be transported from agricultural lands by different mechanisms (e.g., in dissolved versus particulate forms) as a function of cropping system, requiring the development of specific types of BMPs to best control nutrient losses.

Naphthenic acids (NAs) are concentrated in oil sand process water (OSPW) as a result of caustic oil sands extraction processes. There is considerable interest in methods for treatment of NAs in OSPW. Earlier work has shown that the combination of ultraviolet (UV) and microwave treatments in the laboratory was effective in reducing the concentration of classical NAs. Here we apply Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to further characterize NAs treated with (a) UV (254 nm) in the presence of TiO(2) catalyst; and/or (b) microwave irradiation (2.45 GHz). FT-ICR MS was used to characterize the NA fraction before and after treatment. Acidic oxygen-containing classes were most abundant in all samples whereas other heteroatomic classes were least abundant or not present in some samples. For example, the SO(2)-containing species were absent in UV- or combined UV- and microwave-treated samples. The O(2) class was dominant in all samples, indicative of NAs. However, samples treated with UV and microwave radiation have a lower relative abundance of other heteroatomic classes. We observed O(2), S(1)O(2), O(3), S(1)O(3), O(4), O(5), and O(6) classes, whereas the species with relatively high O(n) content, namely, the O(3), O(5), and O(6) classes, were present only in UV- and microwave-treated samples. The relatively high O(n) content is consistent with oxidation of the parent acids in treated samples. There may thus be potential implications for environmental forensics. For example, the monitoring of the ratio of SO(2):O(2) or tracking the relative abundances of O(2), O(3), O(4), O(5), and O(6) classes may provide insights for distinguishing naturally derived oil sands components from those that are process-related in aquatic environments.

A comparison of the acidic and basic extracts of oil sands process water (OSPW) was performed using positive- and negative-ion electrospray ionization (ESI) and atmospheric pressure photoionization (APPI), coupled with a 12 T solariX Fourier transform ion cyclotron resonance mass spectrometer (FTICR MS). In general, the acid-neutral extracts showed higher oxygen content within the negative-ion profiles (both APPI and ESI). The hydrocarbon class was readily observed in the base-neutral extract. Furthermore, a comparison of O2S (radical ion) and O2S [H] (protonated) classes in positive-ion APPI data showed significant differences in the distribution of double-bond equivalent (DBE) versus carbon number, which are indicative of differences in structures of the two classes. The S-containing species were relatively more abundant in the base-neutral extract, and the radical O2S ions displayed the characteristic profile of thiophenic compounds. ESI profiles for samples extracted at both pH values (2 and 11) investigated were suitable for characterization of the most polar components within the complex OSPW mixture, while APPI was suitable for the ionization of a broader range of heteroatom classes. Because profile comparisons are important for environmental forensics, this study highlights the need for careful attention to extraction pH effects on the measured profiles of OSPW components.