110
or chemically dispersed, 23% evaporated or dissolved, and the remaining 23% was
left in the environment sequestered in both deep benthic and shallow coastal sediments (McNutt et al. 2012). Within the water column and seafloor sediments, dissolved and dispersed hydrocarbons induced rapid changes in microbial communities
(Kleindienst et al. 2015a; Joye et al. 2016). While the microbial response to DWH
oil in planktonic ecosystems has been extensively studied, less information is
available on the microbial response in sediments (Kimes et al. 2014; King et al.
2015; Joye et al. 2016).
A large body of literature, including laboratory and field studies, is devoted to
hydrocarbon biodegradation in the marine environment (Hazen and Prince 2015).
However, despite tremendous progress inspired by the DWH spill, the fate and
transport of oil are underexplored in deep ocean ecosystems in comparison to their
shallow-water counterparts. Historically, the majority of hydrocarbon biodegradation studies have been performed in the laboratory, with pure cultures or enrichment
cultures under conditions that resemble the surface ocean, and relatively few studies
have been conducted under high-pressure and low-temperature conditions that
mimic deepwater conditions. This fundamental gap in the understanding of microbial hydrocarbon degradation is in contrast to the petroleum industry’s trend of
increasing oil and gas production from ultradeep (>1500 m) wells and the risk of
another deep sea oil well blowout. Application of chemical dispersants and their
influence on biodegradation or weathering has yet to be interrogated across the full
range of oceanographic conditions observed in areas of oil exploration/production.
In addition, more information is available on the environmental controls of hydrocarbon degradation under conditions relevant to marine water columns in comparison to the seafloor or sediments. This lack of knowledge of the impacts of
oceanographic controls, especially in the deep sea, acts as a critical obstacle to the
effective parameterization of oil plume models.
7.2 Biodegradation in the Water Column
7.2.1 Rate of Liquid and Gaseous Hydrocarbon
Biodegradation in the Water Column
Hydrocarbon degradation in the water column is limited by a complex and interacting suite of factors (Fig. 7.1). Hydrocarbon solubility exerts a strong regulatory
force on hydrocarbon degradation rates because hydrocarbons are not soluble in
the aqueous phase (Joye et al. 2018). In the presence of ample hydrocarbons,
genomic potential, electron acceptor (i.e., oxygen) availability, and nutrient and
metal availability regulate microbial abundance and, hence, activity (Joye et al.
2016, 2018). During the DWH spill, oil and low molecular weight alkanes, like
methane, were concentrated in the deepwater plume (Joye 2015), and additional oil
was present in surface oil slicks. No direct rates of oil degradation in the
J. E. Kostka et al.
or chemically dispersed, 23% evaporated or dissolved, and the remaining 23% was
left in the environment sequestered in both deep benthic and shallow coastal sediments (McNutt et al. 2012). Within the water column and seafloor sediments, dissolved and dispersed hydrocarbons induced rapid changes in microbial communities
(Kleindienst et al. 2015a; Joye et al. 2016). While the microbial response to DWH
oil in planktonic ecosystems has been extensively studied, less information is
available on the microbial response in sediments (Kimes et al. 2014; King et al.
2015; Joye et al. 2016).
A large body of literature, including laboratory and field studies, is devoted to
hydrocarbon biodegradation in the marine environment (Hazen and Prince 2015).
However, despite tremendous progress inspired by the DWH spill, the fate and
transport of oil are underexplored in deep ocean ecosystems in comparison to their
shallow-water counterparts. Historically, the majority of hydrocarbon biodegradation studies have been performed in the laboratory, with pure cultures or enrichment
cultures under conditions that resemble the surface ocean, and relatively few studies
have been conducted under high-pressure and low-temperature conditions that
mimic deepwater conditions. This fundamental gap in the understanding of microbial hydrocarbon degradation is in contrast to the petroleum industry’s trend of
increasing oil and gas production from ultradeep (>1500 m) wells and the risk of
another deep sea oil well blowout. Application of chemical dispersants and their
influence on biodegradation or weathering has yet to be interrogated across the full
range of oceanographic conditions observed in areas of oil exploration/production.
In addition, more information is available on the environmental controls of hydrocarbon degradation under conditions relevant to marine water columns in comparison to the seafloor or sediments. This lack of knowledge of the impacts of
oceanographic controls, especially in the deep sea, acts as a critical obstacle to the
effective parameterization of oil plume models.
7.2 Biodegradation in the Water Column
7.2.1 Rate of Liquid and Gaseous Hydrocarbon
Biodegradation in the Water Column
Hydrocarbon degradation in the water column is limited by a complex and interacting suite of factors (Fig. 7.1). Hydrocarbon solubility exerts a strong regulatory
force on hydrocarbon degradation rates because hydrocarbons are not soluble in
the aqueous phase (Joye et al. 2018). In the presence of ample hydrocarbons,
genomic potential, electron acceptor (i.e., oxygen) availability, and nutrient and
metal availability regulate microbial abundance and, hence, activity (Joye et al.
2016, 2018). During the DWH spill, oil and low molecular weight alkanes, like
methane, were concentrated in the deepwater plume (Joye 2015), and additional oil
was present in surface oil slicks. No direct rates of oil degradation in the
J. E. Kostka et al.