Chapter 8
Organic compounds in saline marine
and estuarine sediments
8.1 MARINE SEDIMENTS
8.1.1 Hydrocarbons
8.1.1.1 Aliphatic hydrocarbons
Walker et al [1] studied profiles of hydrocarbons in sediment according to depth in
sediment cores collected at Baltimore harbour in Chesapeake Bay, Maryland. Gas liquid chromatography was used to detect hydrocarbons present at different depths in
the sediment, while low resolution mass spectrometry was employed to measure concentrations of paraffins, cycloparaffins, aromatic and polynuclear aromatics. Their
data show that the concentrations of total and saturated hydrocarbons decreased with
increased depth, and it was noted that identification and quantification of hydrocarbons in oil-contaminated sediments is required if the fate of these compounds in dredge
spills is to be determined.
May et al [2] have described a gas chromatographic method for analysing hydrocarbons in marine sediments and sea water which is sensitive at the submicrogram
per kilogram level. Dynamic head space sampling for volatile hydrocarbon components requires minimal sample handling thus reducing the risk of sample component
loss and/or sample contamination. The volatile components are concentrated on a
Tenax gas chromatographic precolumn and determined by gas chromatography or gas
chromatography-mass spectrometry.
Brown et al [3] have described a gas chromatography-mass spectrometry technique
for fingerprinting petrogenic hydrocarbons. The technique identified and quantified
n-alkanes, the isoprenoids pristine and phytane, pentacyclic triterpanes, the unresolved
complex mixture, and total hydrocarbon content. Results obtained using sediments
preserved with chloroform during sediment trap collection were compared with those
for unpreserved anoxic sediments and anoxic bottom surface sediment. Petrogenic
hydrocarbons were detected at all stations, concentrations decreasing with increasing
distance from an urban area. Carbon preference index values increased along the
transect, indicating a greater dominance of biogenic hydrocarbons further out in the
archipelago. The compositions of preserved and unpreserved anoxic samples were very
similar. The results indicated that the sediment trap technique was a useful method of
collecting and preserving material for fingerprinting petrogenic hydrocarbons.
Organic compounds in saline marine
and estuarine sediments
8.1 MARINE SEDIMENTS
8.1.1 Hydrocarbons
8.1.1.1 Aliphatic hydrocarbons
Walker et al [1] studied profiles of hydrocarbons in sediment according to depth in
sediment cores collected at Baltimore harbour in Chesapeake Bay, Maryland. Gas liquid chromatography was used to detect hydrocarbons present at different depths in
the sediment, while low resolution mass spectrometry was employed to measure concentrations of paraffins, cycloparaffins, aromatic and polynuclear aromatics. Their
data show that the concentrations of total and saturated hydrocarbons decreased with
increased depth, and it was noted that identification and quantification of hydrocarbons in oil-contaminated sediments is required if the fate of these compounds in dredge
spills is to be determined.
May et al [2] have described a gas chromatographic method for analysing hydrocarbons in marine sediments and sea water which is sensitive at the submicrogram
per kilogram level. Dynamic head space sampling for volatile hydrocarbon components requires minimal sample handling thus reducing the risk of sample component
loss and/or sample contamination. The volatile components are concentrated on a
Tenax gas chromatographic precolumn and determined by gas chromatography or gas
chromatography-mass spectrometry.
Brown et al [3] have described a gas chromatography-mass spectrometry technique
for fingerprinting petrogenic hydrocarbons. The technique identified and quantified
n-alkanes, the isoprenoids pristine and phytane, pentacyclic triterpanes, the unresolved
complex mixture, and total hydrocarbon content. Results obtained using sediments
preserved with chloroform during sediment trap collection were compared with those
for unpreserved anoxic sediments and anoxic bottom surface sediment. Petrogenic
hydrocarbons were detected at all stations, concentrations decreasing with increasing
distance from an urban area. Carbon preference index values increased along the
transect, indicating a greater dominance of biogenic hydrocarbons further out in the
archipelago. The compositions of preserved and unpreserved anoxic samples were very
similar. The results indicated that the sediment trap technique was a useful method of
collecting and preserving material for fingerprinting petrogenic hydrocarbons.