into the North Sea. More than two decades, the annual total number of oil leakage in
the sea have denied from all sources. In this region, in 1999, the ratio of reported
slicks by flight hours was 22 Â 10
À2 and it decreased to 4 Â 10
À2 in 2010. This study
indicates that international cooperation is required to reduce the marine contamination and lead to a cleaner environment.
Case 2: Northern Gulf of Mexico
Liu et al. (2017) studied the environmental factors that have effect on the
oil-degrading bacterial populations in the Northern Gulf of Mexico in both the
deep and surface waters. Their purpose was investigation of the roles of nutrients,
temperature and initial bacterial community to select the oil degraders via a series of
incubation experiments in the Gulf of Mexico. Pyrosequencing and gas
chromatography-mass spectrometry have applied to analyze the bacterial community and residual oil, respectively. The results indicated that temperature has a key
role to select the oil-degrading bacteria. Nutrients and the initial community also
have the important effects on the enhancement of hydrocarbon-degrading bacterial
communities. Additional analysis revealed that temperature, initial community, oil
and water chemistry explained 57%, 19%, 14%, and 10% of the variation observed,
respectively.
Case 3: Arctic Seawater
McFarlin et al. (2014) studied the biodegradation of dispersed oil in Arctic seawater
at À1
C. Biodegradation in cold regions is a slow process and the degree of its
success depends on the properties and fate of oil spilled, and major microbial and
environmental limitations. Understanding the impact of oil in Arctic seawater is an
important factor to consider since offshore gas and oil exploration expands in the
Arctic. The purpose of the article was to study the chemical loss due to bioremediation of crude oil at Alaska North Slope that happens in the water column after
successful dispersion of a surface oil slick. They measured mineralization and
biodegradation in mesocosms containing Arctic seawater collected from the Chukchi Sea, Alaska and incubated at À1
C. Indigenous microorganisms treated the
weathered as well as fresh oil over 60 days, with oil losses ranging from 46% to 61%,
up to 11% mineralization. Their study indicated that the indigenous microorganisms
to Arctic seawater have ability to perform extensive biodegradation of physically
and chemically dispersed oil at an environmentally relevant temperature (À1
C) in
the absence of additional nutrients. They concluded that the biodegradation of oil in
Arctic seawater is extensive at À1
C.
482
M. Fatehi et al.
the sea have denied from all sources. In this region, in 1999, the ratio of reported
slicks by flight hours was 22 Â 10
À2 and it decreased to 4 Â 10
À2 in 2010. This study
indicates that international cooperation is required to reduce the marine contamination and lead to a cleaner environment.
Case 2: Northern Gulf of Mexico
Liu et al. (2017) studied the environmental factors that have effect on the
oil-degrading bacterial populations in the Northern Gulf of Mexico in both the
deep and surface waters. Their purpose was investigation of the roles of nutrients,
temperature and initial bacterial community to select the oil degraders via a series of
incubation experiments in the Gulf of Mexico. Pyrosequencing and gas
chromatography-mass spectrometry have applied to analyze the bacterial community and residual oil, respectively. The results indicated that temperature has a key
role to select the oil-degrading bacteria. Nutrients and the initial community also
have the important effects on the enhancement of hydrocarbon-degrading bacterial
communities. Additional analysis revealed that temperature, initial community, oil
and water chemistry explained 57%, 19%, 14%, and 10% of the variation observed,
respectively.
Case 3: Arctic Seawater
McFarlin et al. (2014) studied the biodegradation of dispersed oil in Arctic seawater
at À1
C. Biodegradation in cold regions is a slow process and the degree of its
success depends on the properties and fate of oil spilled, and major microbial and
environmental limitations. Understanding the impact of oil in Arctic seawater is an
important factor to consider since offshore gas and oil exploration expands in the
Arctic. The purpose of the article was to study the chemical loss due to bioremediation of crude oil at Alaska North Slope that happens in the water column after
successful dispersion of a surface oil slick. They measured mineralization and
biodegradation in mesocosms containing Arctic seawater collected from the Chukchi Sea, Alaska and incubated at À1
C. Indigenous microorganisms treated the
weathered as well as fresh oil over 60 days, with oil losses ranging from 46% to 61%,
up to 11% mineralization. Their study indicated that the indigenous microorganisms
to Arctic seawater have ability to perform extensive biodegradation of physically
and chemically dispersed oil at an environmentally relevant temperature (À1
C) in
the absence of additional nutrients. They concluded that the biodegradation of oil in
Arctic seawater is extensive at À1
C.
482
M. Fatehi et al.