ABSTRACT
Naphthenic acids are toxic and corrosive substances in oil sands leachates comprising a group of saturated aliphatic and alicyclic carboxylic acids in hydrocarbon deposits (petroleum, oil sands bitumen, and crude oils). In the current study, photolysis was applied to naphthenic acid mixtures and individual compounds to determine the efficacy of a variety of UV/vis radiation sources for reducing both concentration and aryl hydrocarbon (Ah) receptor binding as a measure of toxicity. The results show that the concentrations of neither the compounds nor the mixtures were significantly reduced in Athabasca River water, although compositional changes occurred within the mixtures and Ah receptor binding potential was affected by photolysis. Photolysis at UV254 was the most effective radiation source applied in all instances.
Subject(s)
Carboxylic Acids/chemistry , Water Pollutants, Chemical/analysis , Environmental Monitoring , Photolysis , Rivers , Silicon Dioxide , Ultraviolet RaysABSTRACT
The photodegradation kinetics of atrazine (2-chloro-6-(ethylamino)-4-isopropylamino-1,3,5-triazine) and ametryne (2-methylthio-4-ethylamino-6-isopropylamino-s-triazine), in fresh and coastal salt water from Barbados, were measured under irradiation with artificial solar and UV254-radiation. The first-order rate constants were greater for ametryne than for atrazine, and the rates were reduced in seawater relative to fresh water, and in soil slurries relative to fresh water. However, rates were accelerated in the presence of iron(III) at pH 3 due to photo-Fenton type processes. This rate enhancement was reduced at ambient pH values (pH 7-7.5) representative of surface water in Barbados. These results have important implications for the relative persistence of these contaminants in aquatic environments in tropical areas.
Subject(s)
Atrazine/chemistry , Herbicides/chemistry , Photolysis , Soil Pollutants/metabolism , Triazines , Water Pollutants, Chemical/metabolism , Atrazine/radiation effects , Barbados , Biodegradation, Environmental , Catalysis , Fresh Water/chemistry , Herbicides/radiation effects , Hydrogen-Ion Concentration , Seawater/chemistry , Ultraviolet Rays , Water Pollutants, Chemical/radiation effectsABSTRACT
A liquid chromatography-negative ion electrospray mass spectrometric (LC-ESI-MS) method was evaluated for detection of four prevalent softwood-derived resin acids in natural water. Method detection limits based on a signal-to-noise ratio of 3:1 in river water samples of 0.40, 0.40, 0.30 and 0.25 microg l(-1) for abietic, dehydroabietic, isopimaric and pimaric acids, respectively, are comparable or lower than reported GC methods. Unlike the majority of GC methods, however, the three structural resin acid isomers (abietic, isopimaric and pimaric acids) do not separate sufficiently under the various LC conditions evaluated in this work. Therefore, LC-ESI-MS may not be suitable for instances where measurement of individual isomeric resin acids is required. However, the method is suitable for trace analysis of resin acids in natural waters where isomeric speciation is not required.
