Composition and Biodegradation of a Synthetic Oil Spilled on the Perennial Ice Cover of Lake Fryxell, Antarctica

Abstract

A helicopter crashed in January 2003 on the 5 m-thick perennial ice cover of Lake Fryxell, spilling synthetic turbine oil Aeroshell 500. Molecular compositions of the oils were analyzed by gas chromatography-mass spectrometry and compared to the composition of contaminants in ice, meltwater, and sediments collected a year after the accident. Aeroshell 500 is based on C20-C33 Pentaerythritol triesters (PET) with C5-C10 fatty acids susbstituents and contain a number of antioxidant additives, such as tricresyl phosphates. Biodegradation of this oil in the ice cover occurs when sediments are present PETs with short fatty acids substituents are preferentially degraded, whereas long chain fatty acids seem to hinder esters from hydrolysis by esterase derived from the microbial assemblage. It remains to be seen if the microbial ecosystem can degrade tricresyl phosphates. These more recalcitrant PET species and tricresyl phosphates are likely to persist and comprise the contaminants that may eventually cross the ice cover to reach the pristine lake water.

Aircraft Recirculation Filter for Air-Quality and Incident Assessment

“…Their mass spectra pattern typically had a base peak at 85 amu and strong ion fragments at 113 and/or 91 amu, plus additional ions at 127, 156, and/or 184 amu. These ion fragments are consistent with the mass spectra of a homologous series of pentaerythritol triesters and tetraesters reported to be synthetic turbine oil [15,16]. Presence of these ion fragments in a GC peak with the absence of ion fragments at 71, 99, and 141 amu, common ion fragments in long-chain hydrocarbons also commonly found on the filter extracts, were used to confirm if a peak in the chromatograph of the filter extract was a synthetic pentaerythritol trimesters rather than a saturated, long chain-petroleum hydrocarbon, which elute at similar retention times.…”

Density Functional Theory Rate Calculation of Hydrogen Abstraction Reactions of N-Phenyl-α-naphthylamine Antioxidants

“…The first solvent used was heptane, as a representative of nonpolar hydrocarbon mixtures (i.e., mineral oils). Moreover, aromatic amines are often used in synthetic oils, such as those with a polyol ester base stock composed primarily of a mixture of fatty acid esters of pentaerythritol and dipentaerythritol . The presence of multiple esters functional groups raises the dielectric constant and increases the interaction with the reacting molecules .…”

“…Moreover, aromatic amines are often used in synthetic oils, such as those with a polyol ester base stock composed primarily of a mixture of fatty acid esters of pentaerythritol and dipentaerythritol. 23 The presence of multiple esters functional groups raises the dielectric constant and increases the interaction with the reacting molecules. 24 As such, it is important to look at the effect of more polar solvents on the computed reaction rate constants.…”

Laser-induced fluorescence emission (LIFE) from Lake Fryxell (Antarctica) cryoconites

“…Average annual ice-cover thickness is controlled by the rate of freezing of lake water at the bottom of the ice (∼30 cm a −1 ) and the ablation loss at the ice/air interface via sublimation (∼15–60 cm a −1 ). On average, the balance of these processes produces ∼30 cm a −1 of net upward movement of the ice (Jaraula and others, 2009). The lake ice cover is almost crystal clear (Fig.…”