295
(i.e., abundance of each GDGT species relative to total GDGT abundance) in the
collected sediment cores follow the distribution typically observed in warmer water
environments such as GoM (i.e., GDGT-5 > GDGT-0 > > GDGT-1 ∼ GDGT-2
> > GDGT-3; Pearson and Ingalls 2013; Schouten et al. 2002), demonstrating a
basic comparability of results obtained using FTICR-MS and traditional HPLC-MS
methods for GDGTs. Despite generally similar trends of GDGT species in the analyzed northern GoM sediment cores, the variability of their ratios (i.e., proxy indices) records subtle changes related to the perturbations of the marine system at a
given location. A recent study has observed an excursion of GDGT-derived BIT
proxy and stable carbon isotope signature of benthic foraminifera in a sediment core
collected in the DeSoto Canyon in 2014 (Fig. 17.4). Excursion of BIT to lower values (0.11) at 9 mm downcore, is due to the higher abundance of the iGDGT-5 peak
(crenarchaeol and its isomers). Similar BIT changes in the northern GoM driven by
crenarchaeol concentrations have been observed previously and attributed to seasonably variable delivery of marine planktonic OM to sediments (Smith et al. 2012).
A geochronological model sets this horizon within the DWH timeframe, putatively
suggesting that this observation might be reflecting MOSSFA-driven deposition of
planktonic archaeal biomass. This is corroborated by the depletion of foraminiferal
%,7
& &D&2
Fig. 17.4 Branched and isoprenoid tetraether (BIT) index and stable carbon isotope signature of
benthic foraminifera in a sediment core collected at the DSH08 site in 2014. Note the negative
excursions of the two proxies, a putative record of coeval deposition of planktonic biomass and
petrocarbon via MOSSFA. For each sediment interval, the average reconstructed year is shown,
based on the short-lived radioisotope geochronology model. Associated error of the model is
approx. ±1 year. (Data are publicly available through the Gulf of Mexico Research Initiative
Information and Data Cooperative (GRIIDC) at https://data.gulfresearchinitiative.org (DOI:
https://doi.org/10.7266/N71R6NGQ, https://doi.org/10.7266/N7S180HN))
17 Long-Term Preservation of Oil Spill Events in Sediments: The Case…
(i.e., abundance of each GDGT species relative to total GDGT abundance) in the
collected sediment cores follow the distribution typically observed in warmer water
environments such as GoM (i.e., GDGT-5 > GDGT-0 > > GDGT-1 ∼ GDGT-2
> > GDGT-3; Pearson and Ingalls 2013; Schouten et al. 2002), demonstrating a
basic comparability of results obtained using FTICR-MS and traditional HPLC-MS
methods for GDGTs. Despite generally similar trends of GDGT species in the analyzed northern GoM sediment cores, the variability of their ratios (i.e., proxy indices) records subtle changes related to the perturbations of the marine system at a
given location. A recent study has observed an excursion of GDGT-derived BIT
proxy and stable carbon isotope signature of benthic foraminifera in a sediment core
collected in the DeSoto Canyon in 2014 (Fig. 17.4). Excursion of BIT to lower values (0.11) at 9 mm downcore, is due to the higher abundance of the iGDGT-5 peak
(crenarchaeol and its isomers). Similar BIT changes in the northern GoM driven by
crenarchaeol concentrations have been observed previously and attributed to seasonably variable delivery of marine planktonic OM to sediments (Smith et al. 2012).
A geochronological model sets this horizon within the DWH timeframe, putatively
suggesting that this observation might be reflecting MOSSFA-driven deposition of
planktonic archaeal biomass. This is corroborated by the depletion of foraminiferal
%,7
& &D&2
Fig. 17.4 Branched and isoprenoid tetraether (BIT) index and stable carbon isotope signature of
benthic foraminifera in a sediment core collected at the DSH08 site in 2014. Note the negative
excursions of the two proxies, a putative record of coeval deposition of planktonic biomass and
petrocarbon via MOSSFA. For each sediment interval, the average reconstructed year is shown,
based on the short-lived radioisotope geochronology model. Associated error of the model is
approx. ±1 year. (Data are publicly available through the Gulf of Mexico Research Initiative
Information and Data Cooperative (GRIIDC) at https://data.gulfresearchinitiative.org (DOI:
https://doi.org/10.7266/N71R6NGQ, https://doi.org/10.7266/N7S180HN))
17 Long-Term Preservation of Oil Spill Events in Sediments: The Case…