While predictions based on linear sorption isotherms agree well with solution concentrations, for the conditions evaluated this approach overestimates the percentage of contaminant biodegraded by as much as 50%.
Lighter crudes, such as the oil released from the BP Deepwater Horizon spill, contain a higher proportion of simpler lower molecular weight hydrocarbons that are more readily biodegraded than heavy crudes, such as the oil released from the Exxon Valdez.
The lacustrine saline sediments of the Lagoa Feia Formation (source rock) were interpreted as the source for the typical "Campos oils", including the samples P1 (Coquinas reservoir in Lagoa Feia Formation, classified as not biodegraded) and P2 (Calcarenites reservoir in Macaé formation, classified as biodegraded) (Mello et al. 1988; Mohriak et al. 1989), see Figure 2.
The original and biodegraded polymers were characterized using chemical techniques as well as nuclear magnetic resonance, Fourier transform infra-red spectroscopy, gel permeation chromatography, solution viscosity and X-ray diffraction.
Ether is not hydrolyzed or biodegraded in environmental media, so is persistent if released to soil or water.
The consortia showed preferences for metabolizing hydrocarbons > hopanes > steranes > tricyclic terpanes during a 90-day period, after which this trend changed and steranes were more biodegraded than hopanes.
The increase in capillary fringe enhanced the percentage of the contaminant biodegraded in the unsaturated zone, up to 40%, which is comparable to that in the saturated zone.
However, most chemically synthesized surfactants are only partially and slowly biodegraded by the environmental microbes, some of which are known to be toxic to animals, ecosystems, and humans, contributing to secondary pollutants (Henkel et al. 2012; Murphy et al. 2005).
In addition, possibly due to less steric hindrance of 2,4-DNT than 2,6-DNT, 2,4-DNT seemed to be more easily to be biodegraded than 2,6-DNT (Fortner et al. 2003).
The calculation of biodegradation rates of the spilled oil requires information on the stoichiometric coefficients such as the mass of biodegraded hydrocarbon compounds per oxygen consumed (h) and the microbial biomass produced per mass of hydrocarbon compound biodegraded (Yoil) for individual or group of hydrocarbon.
