Distribution and origins of n-alkanes, hopanes, and steranes in rivers and marine sediments from Southwest Caspian coast, Iran: implications for identifying petroleum hydrocarbon inputs

Abstract

The occurrence of n-alkanes and biomarkers (hopane and sterane) in surface sediments from Southwestern coasts of Caspian Sea and 28 rivers arriving to this lake, determined with a gas chromatography-mass spectrometry method, was used to assess the impacts of anthropogenic activities in the studied area. The concentrations of total n-alkanes (Σ21 n-alkane) in costal and riverine sediments varied from 249.2 to 3899.5 and 56 to 1622.4 μg g(-1), respectively. An evaluation of the source diagnostic indices indicated that petroleum related sources (petrogenic) were mainly contributed to n-alkanes in costal and most riverine sediments. Only the hydrocarbons in sediment of 3 rivers were found to be mainly of biogenic origin. Principal component analysis using hopane diagnostic ratios in costal and riverine sediments, and Anzali, Turkmenistan, and Azerbaijan oils were used to identify the sources of hydrocarbons in sediments. It was indicated that the anthropogenic contributions in most of the costal sediment samples are dominated with inputs of oil spills from Turkmenistan and Azerbaijan countries.

Determination of biological markers of organic substances in sediment and soil samples by gas chromatography

“…These alicyclic compounds originate dominantly from cell membranes of bacteria, microorganisms and algae, which are ubiquitous in sediments. The group includes several homologous series of tri-, tetra-, and pentacyclic triterpanes (Shirneshan et al, 2016;Paul and Dutta, 2106;Belin et al, 2018). The most commonly used alicyclic biomarkers are hopanes, which provide information on oil-sourcerock correlations (Grigoriadou et al, 2008).…”

“…Hydrocarbons found in soil and sediments reflect both natural and anthropogenic inputs as well as diagenetic processes taking place in the water column and during transport and sedimentation (Shirneshan et al, 2016). Crude oil consists mainly of a complex mixture of hydrocarbon compounds (aliphatic and aromatic) and non-hydrocarbon compounds (resins and asphaltenes).…”

Polycyclic aromatic hydrocarbon source fingerprints in the environmental samples of Anzali—South of Caspian Sea

“…The strong development of urbanization and industrialization of the large cities has produced an increased entrance of the pollutants to the aquatic ecosystems such as the Caspian Sea (Tolosa et al, 2004). About 122,000 tons of petroleum materials are annually entered into the Caspian Sea in various ways, with 75,000 tons of which entering via the rivers (Shirneshan et al, 2016a).…”

Spatiotemporal variability of hydrocarbons in surface sediments from an intensively human-impacted Xiaoqing River-Laizhou Bay system in the eastern China: Occurrence, compositional profile and source apportionment

“…Coastal areas receive tremendous amount of natural and anthropogenic organic matter (OM) from land through river transport (Canuel and Hardison, 2016). Hydrocarbons, as an important component of OM, have received great attention since they adsorb onto particles, settle and accumulate in surface sediments, making surface sediments an important pool of hydrophobic contaminations (e.g., Volkman et al, 1992;Commendatore et al, 2012;Shirneshan et al, 2016). During resuspension and remobilization, hydrocarbons can be released from sediments into the overlying water, resulting in secondary pollution in the coastal environment (Gobas and MacLean, 2003;Dong et al, 2016).…”

“…For example, aliphatic hydrocarbons are widely applied to separate natural (e.g., leaf waxes) from anthropogenic inputs (e.g., petroleum and derivatives) (Eglinton and Hamilton, 1967;Yunker et al, 2002;Commendatore et al, 2012). Hopanes and steranes are commonly used as indicators of petroleum contaminations (Aboul-Kassim and Simoneit, 1996;Shirneshan et al, 2016). Linear alkylbenzenes (LABs), a series of compounds that have been added in the manufacture of commercial detergents since 1960s, can serve as an exclusive indicator of domestic waste inputs through fluvial transport (e.g., Takada and Ishiwatari, 1987;Medeiros et al, 2005).…”