Distributions of aliphatic hydrocarbons and polycyclic aromatic hydrocarbons in sediments from a subtropical estuary to the adjacent Western Taiwan Strait: Implications of possible sources and potential transport

To study the distribution patterns, possible sources and potential transport of organic matters in the marginal sea, surface sediments were collected from a subtropical estuary (Jiulong River Estuary, JRE) and the inner shelf... [ view full abstract ]

To study the distribution patterns, possible sources and potential transport of organic matters in the marginal sea, surface sediments were collected from a subtropical estuary (Jiulong River Estuary, JRE) and the inner shelf of adjacent Western Taiwan Strait (WTS), n-alkanes, polycyclic aromatic hydrocarbons (PAHs) have been investigated. Odd C25-C31 n-alkanes were predominant in the JRE, while C14-C17 n-alkanes had high abundance reserves in the coastal area. The terrigenous/marine ratios of n-alkane reflected biogenic terrestrial inputs reduced, while marine inputs increased from the JRE to WTS, reflects the transport changes of relative contributions from allochthonous and autochthonous hydrocarbons to the sediments. The concentrations of anthropogenic PAHs and perylene, retene from the natural diagenetic formation of terrestrial organic matters (soil-derived materials) decreased with the descending distance from the JRE to WTS, the correlations between anthropogenic PAHs and perylene or retene were significant, reflected they were likely to share the same fluvial input and transport pathways, the compositions and isomer ratios of PAHs indicated that the estuarine materials tended to transport to the southern coast. The proportion of perylene relative to the total 5-ring PAHs increased from the JRE to WTS, implied the early diagenesis of terrestrial organic matters enhanced gradually. The presence of the unresolved complex mixture (UCM), hopanes and steranes indicated petrogenic contribution, PAH isomeric ratios reflected a pattern of mainly pyrogenic input in the estuary while petrogenic sources in the coast. Therefore, organic matters accumulated in the WTS adjacent to the JER were derived from both terrestrial and marine sources.