260
used FTICR-MS and liquid chromatography with tandem mass spectrometry to identify and quantify the anionic surfactant DOSS (dioctyl sodium sulfosuccinate), a key
component in the dispersant applied during the DWH oil spill. The group was able to
detect the DOSS signature in the oil plume that was formed at 1000–1200 m water
depth near the wellhead, implying that applied dispersant stayed in the plume without appreciably degrading for 64 days after the dispersant application ceased. Further,
the Seidel et al. (2016) group tracked dispersant fate by characterizing the biodegradation markers in the aquatic DOM. The addition of dispersants to the water alters
the metabolic pathways of organic matter biodegradation enabling the tracking of
dispersant using dispersant-derived metabolite markers, such as sulfur-containing
species, likely derivatives of DOSS surfactant (Seidel et al. 2016).
Overall, the advent of ultrahigh-resolution mass spectrometry has revolutionized
the assessment of oil spill signature in the water column.
15.5 FTICR-MS Characterization of Marine Sediments
and Its Relevance for Oil Spill Assessments
Recent sediments are a unique record of present and past biogeochemical processes
and conditions in a given marine system, which reflects source OM inputs, both
biogenic and anthropogenic. Therefore, the knowledge of the composition of sedimentary organic species is essential to understand the “normal,” background state of
a given environment, as well as to identify the impacts of major perturbations, such
as oil spills. Given the complexity and chemical diversity of organic markers which
can be found in sediments, nontargeted, broad-range analytical tools, such as
FTICR-MS, are particularly useful.
For example, very commonly studied microbial markers in sediments are glycerol
dialkyl glycerol tetraethers (GDGTs), lipid membrane constituents of Archaea, and
some bacteria (Schouten et al. 2013). Due to the fact that the distribution of specific
GDGT species changes with environmental conditions such as temperature, nutrients, or pH (Schouten et al. 2013), these species are extensively used as environmental monitoring proxies with wide application in paleoclimate studies. Radović et al.
(2016b) developed a nontargeted APPI-P FTICR-MS method, abbreviated “RADAR”
(Rapid Analyte Detection and Reconnaissance), to explore the compositional complexity of GDGT analogs present in the lipid extracts of the Gulf of Mexico recent
sediments. In this study, the complete series of core GDGT species (0 to 8 alicyclic
rings), including a completely resolved GDGT-4 peak, could be identified. Monoand dihydroxy analogs, as well as glycerol dialkanol diethers, were also reported.
The usefulness of the nontargeted analytical approach provided by FTICR-MS was
clearly evident when the authors offered the putative identification of dihydroxyGDGT species, as well as several other C 83-87 H x O 4–7 previously unknown GDGT
analogs. Furthermore, commonly used sea surface temperature indices, such as
CCaT, TEX
L
86, and the methane index (Schouten et al. 2013), were determined
based on the monoisotopic intensity of appropriate peaks detected in the spectra,
illustrating that FTICR-MS measurements could provide a rapid and reproducible
J. R. Radović et al.
used FTICR-MS and liquid chromatography with tandem mass spectrometry to identify and quantify the anionic surfactant DOSS (dioctyl sodium sulfosuccinate), a key
component in the dispersant applied during the DWH oil spill. The group was able to
detect the DOSS signature in the oil plume that was formed at 1000–1200 m water
depth near the wellhead, implying that applied dispersant stayed in the plume without appreciably degrading for 64 days after the dispersant application ceased. Further,
the Seidel et al. (2016) group tracked dispersant fate by characterizing the biodegradation markers in the aquatic DOM. The addition of dispersants to the water alters
the metabolic pathways of organic matter biodegradation enabling the tracking of
dispersant using dispersant-derived metabolite markers, such as sulfur-containing
species, likely derivatives of DOSS surfactant (Seidel et al. 2016).
Overall, the advent of ultrahigh-resolution mass spectrometry has revolutionized
the assessment of oil spill signature in the water column.
15.5 FTICR-MS Characterization of Marine Sediments
and Its Relevance for Oil Spill Assessments
Recent sediments are a unique record of present and past biogeochemical processes
and conditions in a given marine system, which reflects source OM inputs, both
biogenic and anthropogenic. Therefore, the knowledge of the composition of sedimentary organic species is essential to understand the “normal,” background state of
a given environment, as well as to identify the impacts of major perturbations, such
as oil spills. Given the complexity and chemical diversity of organic markers which
can be found in sediments, nontargeted, broad-range analytical tools, such as
FTICR-MS, are particularly useful.
For example, very commonly studied microbial markers in sediments are glycerol
dialkyl glycerol tetraethers (GDGTs), lipid membrane constituents of Archaea, and
some bacteria (Schouten et al. 2013). Due to the fact that the distribution of specific
GDGT species changes with environmental conditions such as temperature, nutrients, or pH (Schouten et al. 2013), these species are extensively used as environmental monitoring proxies with wide application in paleoclimate studies. Radović et al.
(2016b) developed a nontargeted APPI-P FTICR-MS method, abbreviated “RADAR”
(Rapid Analyte Detection and Reconnaissance), to explore the compositional complexity of GDGT analogs present in the lipid extracts of the Gulf of Mexico recent
sediments. In this study, the complete series of core GDGT species (0 to 8 alicyclic
rings), including a completely resolved GDGT-4 peak, could be identified. Monoand dihydroxy analogs, as well as glycerol dialkanol diethers, were also reported.
The usefulness of the nontargeted analytical approach provided by FTICR-MS was
clearly evident when the authors offered the putative identification of dihydroxyGDGT species, as well as several other C 83-87 H x O 4–7 previously unknown GDGT
analogs. Furthermore, commonly used sea surface temperature indices, such as
CCaT, TEX
L
86, and the methane index (Schouten et al. 2013), were determined
based on the monoisotopic intensity of appropriate peaks detected in the spectra,
illustrating that FTICR-MS measurements could provide a rapid and reproducible
J. R. Radović et al.