Modeling the impact of dilution on the microbial degradation time of dispersed oil in marine environments

TL;DR

This paper presents a biophysical model showing that rapid dilution in marine environments delays microbial oil degradation by about a week, highlighting microscale interactions crucial for biodegradation.

Contribution

It introduces a mechanistic biophysical model that accounts for microscale bacteria-oil interactions under dilution, providing new insights into biodegradation delays in marine oil spills.

Findings

Dilution causes approximately a one-week delay in biodegradation onset.

Rapid dilution maintains an encounter-limited state, hindering bacteria-oil interactions.

The model offers a baseline for understanding microscale biodegradation in dilute conditions.

Abstract

Dispersants aid the breakup of crude oil masses and increase the available interfacial surface area for bacteria to degrade insoluble hydrocarbons in the marine environment. However, this common view neglects key aspects of the microscale interactions between bacteria and oil droplets, particularly the encounters between these elements that are required for degradation to occur. This chapter discusses a biophysical model for hydrocarbon consumption of suspended oil droplets under conditions of rapid dilution that occur in natural environments. Based on the model, which includes typical biological growth parameters, dilution is found to produce an effective delay in the onset of biodegradation by approximately a week. The steady and rapid reduction in oil concertation, due to dilution, is found to outpace the production of oil-degrading bacteria that result from colonization of degrading oil droplets, maintaining the process in an encounter-limited state. This mechanistic model provides a baseline for better understanding of microscale biodegradation in dilute oil environments and can help inform the design of mitigation strategies in marine systems.