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The concentrations of polar organic compounds including n-alkanoic acids, n-alkanols, steroids and triterpenoids were determined in extracts of shallow sediments from the Mesopotamian marshlands of Iraq. The sediments were collected by a stainless steel sediment corer, extracted with a dichloromethane and methanol mixture (3:1 v:v) by ultrasonic agitation and then analyzed by gas chromatography–mass spectrometric (GC–MS). The analysis results showed that the n-alkanoic acids ranged from C8 to C20 with concentrations of 7.8 ± 1.2 μg/g sample, whereas the concentrations of n-alkanols, which ranged from C12 to C39 were from 28.6 ± 4.3 to 121.7 ± 18.3 μg/g sample. The steroids and triterpenoids included stenols, stanols, stenones, stanones, tetrahymanol, tetrahymanone and extended ββ-hopanes. The total concentrations of steroids and triterpenoids ranged from 26.8 ± 4.1 to 174.6 ± 26.2 μg/g and from 0.74 ± 0.11 to 11.2 ± 1.7 μg/g sample, respectively. The major sources of these lipids were from natural vegetation, microbial (plankton) residues and bacteria in the sediments, with some contribution from anthropogenic sources (livestock, sewage and petroleum). Further studies of these wetlands are needed to characterize the input rate, transformation and diagenesis of the organic matter and to assess its various sources. [ABSTRACT FROM AUTHOR]

Shallow surface sediment samples from the Mesopotamian marshlands of Iraq were collected and analyzed to determine the distribution, concentrations and sources of aliphatic lipid compounds ( n-alkanes, n-alkanols, n-alkanoic acids, and methyl n-alkanoates) and molecular markers of petroleum in these wetlands. The sediments were collected using a stainless steel sediment corer, dried, extracted with a dichloromethane/methanol mixture and then analyzed by gas chromatography-mass spectrometry (GC–MS). The aliphatic lipid compounds included n-alkanes, n-alkanoic acids, n-alkanols and methyl n-alkanoates with concentrations ranged from 6.8 to 31.1 μg/g, 4.1 to 5.0 μg/g, 5.9 to 7.7 μg/g and from 0.3 to 5.9 μg/g, respectively. The major sources of aliphatic lipids were natural from waxes of higher plants (24–30%) and microbial residues (42–30%), with a significant contribution from anthropogenic sources (27–30%, petroleum), based on the organic geochemical parameters and indices. Further studies are needed to characterize the rate, accumulation and transformation of various organic matter sources before and after re-flooding of these wetlands. [ABSTRACT FROM AUTHOR]

Shallow surface sediment samples from the southern part of the Shatt al-Arab River estuary of Iraq and the northwestern Arabian Gulf were analyzed for polar lipid compounds including n-alkanoic acids, n-alkanols, steroids and triterpenoids. The results showed that the n-alkanoic acids, methyl n-alkanoates and n-alkanols typically ranged from C12 to C32 with total concentrations of 3.2 to 108.2 μg g(-1)dwt sample, from C12 to C30 with totals of 1.1 to 18.9 μg g(-1)dwt sample, and from C14 to C32 at 1.8 to 112.6 μg g(-1)dwt sample, respectively. Steroids and triterpenoids were detected and included stenols, stanols, stenones, stanones, tetrahymanol, tetrahymanone and extended ββ-hopanes. The total steroid concentrations ranged from 2.8 to 78.4 μg g(-1)dwt sample, whereas the triterpenoids varied from 0.05 to 7.6 μg g(-1)dwt sample. The simple regression analysis of the results and the spatial distribution patterns of the identified organic tracers indicated that the inter-compound relationships were related mainly to their major sources. Cluster analysis and principal component analysis (PCA) of data set showed that the sampling sites are similar. These sources were allochthonous (terrestrial vegetation), autochthonous (plankton residues and bacteria in the sediments) and anthropogenic (sewage and petroleum)., (© 2013.)