272
without disturbing the sediment-water interface and carefully extruded at very high
resolution: 2 mm resolution in the top 20 mm and 5 mm resolution below 20 mm
(Schwing et al. 2016).
Several sediment cores were used as a pre-event control, including a box core
beneath a long-term sediment trap mooring in the NGoM collected in January 2009
(PE09–04 MC1;1132 m; 27° 31.508 N, 90° 10.126 W).
Subsamples were freeze dried and microwave digested in closed Teflon® digestion vessels with concentrated trace metal grade HNO 3 at high temperature (165 °C)
and high pressure (~25 bar) for 15 minutes according to standard methods (US EPA
method 3051a) (EPA 1994). The digest was diluted, filtered, and spiked with an
internal standard to correct for instrumental drift. Since hydrofluoric acid was not
used in the digestion method, the digest did not include refractory components such
as aluminosilicates, but did include authigenic phases, crude oil, organic phases,
FeMn oxides, and carbonates. Digested samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS).
16.3 Results and Discussion
16.3.1 Pre-impact Geochemistry
It is well established that the downward flux of organic carbon to the sediments
from overlying surface waters, and the subsequent oxidation of that carbon, is the
driving force for early diagenesis – transformation of organic carbon – in marine
'6+
'6+
3&%
'Z+ ZHOOKHDG
$UHDRIVXUIDFHRLOVOLFNVWXG\
7LPH6HULHV6LWHV
3(
Fig. 16.1 Map of sites. (Modified from Brooks et al. 2015)
D. W. Hastings et al.
without disturbing the sediment-water interface and carefully extruded at very high
resolution: 2 mm resolution in the top 20 mm and 5 mm resolution below 20 mm
(Schwing et al. 2016).
Several sediment cores were used as a pre-event control, including a box core
beneath a long-term sediment trap mooring in the NGoM collected in January 2009
(PE09–04 MC1;1132 m; 27° 31.508 N, 90° 10.126 W).
Subsamples were freeze dried and microwave digested in closed Teflon® digestion vessels with concentrated trace metal grade HNO 3 at high temperature (165 °C)
and high pressure (~25 bar) for 15 minutes according to standard methods (US EPA
method 3051a) (EPA 1994). The digest was diluted, filtered, and spiked with an
internal standard to correct for instrumental drift. Since hydrofluoric acid was not
used in the digestion method, the digest did not include refractory components such
as aluminosilicates, but did include authigenic phases, crude oil, organic phases,
FeMn oxides, and carbonates. Digested samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS).
16.3 Results and Discussion
16.3.1 Pre-impact Geochemistry
It is well established that the downward flux of organic carbon to the sediments
from overlying surface waters, and the subsequent oxidation of that carbon, is the
driving force for early diagenesis – transformation of organic carbon – in marine
'6+
'6+
3&%
'Z+ ZHOOKHDG
$UHDRIVXUIDFHRLOVOLFNVWXG\
7LPH6HULHV6LWHV
3(
Fig. 16.1 Map of sites. (Modified from Brooks et al. 2015)
D. W. Hastings et al.