title: Effects of environmental conditions on aerobic degradation of a commercial naphthenic acid.
abstract: Naphthenic acids (NAs) are problematic constituents in energy-derived waters, and aerobic degradation may provide a strategy for mitigating risks to aquatic organisms. The overall objective of this study was to determine the influence of concentrations of N (as ammonia) and P (as phosphate), and DO, as well as pH and temperatures on degradation of a commercial NA in bench-scale reactors. Commercial NAs provided replicable compounds necessary to compare influences of environmental conditions on degradation. NAs were quantified using high performance liquid chromatography. Microbial diversity and relative abundance were measured in treatments as explanatory parameters for potential effects of environmental conditions on microbial populations to support analytically measured NA degradation. Environmental conditions that positively influenced degradation rates of Fluka NAs included nutrients (C:N 10:1-500:1, C:P 100:1-5000:1), DO (4.76-8.43 mg L(-1)), pH (6-8), and temperature (5-25 °C). Approximately 50% removal of 61 ± 8 mg L(-1) was achieved in less than 2 d after NA introduction, achieving the method detection limit (5 mg L(-1)) by day 6 of the experiment in treatments with a C:N:P ratio of 100:10:1, DO > 8 mg L(-1), pH ∼8-9, and temperatures >23 °C. Microbial diversity was lowest in lower temperature treatments (6-16 °C), which may have resulted in observed slower NA degradation. Based on results from this study, when macro- and micronutrients were available, DO, pH, and temperature (within environmentally relevant ranges) influenced rates of aerobic degradation of Fluka NAs. This study could serve as a model for systematically evaluating environmental factors that influence NA degradation in field scenarios.
authors.affiliation: Department of Forestry and Environmental Conservation, 261 Lehotsky Hall, Clemson University, Clemson, SC 29634, USA. Electronic address: cierakinley@gmail.com.
authors.forename: Ciera M
authors.initials: CM
authors.lastname: Kinley
authors.affiliation: Department of Environmental Engineering & Earth Sciences, 300 Brackett Hall, Clemson University, Clemson, SC 29634, USA.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Gaspari
authors.affiliation: Department of Forestry and Environmental Conservation, 261 Lehotsky Hall, Clemson University, Clemson, SC 29634, USA.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: McQueen
authors.affiliation: Department of Forestry and Environmental Conservation, 261 Lehotsky Hall, Clemson University, Clemson, SC 29634, USA.
authors.forename: John H
authors.initials: JH
authors.lastname: Rodgers
authors.affiliation: Department of Environmental Engineering & Earth Sciences, 300 Brackett Hall, Clemson University, Clemson, SC 29634, USA.
authors.forename: James W
authors.initials: JW
authors.lastname: Castle
authors.affiliation: Contango Strategies, 410 Downey Road, Saskatoon, SK S7N 4N1, Canada.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Friesen
authors.affiliation: Contango Strategies, 410 Downey Road, Saskatoon, SK S7N 4N1, Canada.
authors.forename: Monique
authors.initials: M
authors.lastname: Haakensen
mesh_terms: D000332:Aerobiosis; D000641:Ammonia / Q000737:chemistry / Q000378:metabolism; D001420:Bacteria, Aerobic / Q000145:classification / Q000378:metabolism; D001673:Biodegradation, Environmental; D002264:Carboxylic Acids / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D006863:Hydrogen-Ion Concentration; D008962:Models, Theoretical; D061329:Oil and Gas Fields; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D010710:Phosphates / Q000737:chemistry / Q000378:metabolism; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D002264:Carboxylic Acids; D010710:Phosphates; D014874:Water Pollutants, Chemical; D000641:Ammonia; D010100:Oxygen; C046170:naphthenic acid
keywords: Aerobic degradation; Commercial naphthenic acid; Environmental conditions; Oil sands process-affected waters; Refinery effluents