Depositional history of sedimentary sterols around Penguin Island, Antarctica

Abstract

Lipid biomarkers are potential tools for identifying the sources, diagenesis and reactivity of organic matter (OM) in marine systems, including in Antarctica where the particular environmental characteristics have motivated several studies of organic markers. Sedimentary sterol distributions were determined in two sediment cores (PGI-1 and PGI-2) collected from the marine environment around Penguin Island, Antarctica, during the 2007–08 summer. The cores were sectioned at 1 cm intervals and the sterols were analysed using gas chromatography with flame ionization detection. The results indicate that the sterols were subjected to decades of degradation and transformation with depth in both cores. However, an expected progressive conversion of stenols to stanols (evaluated by 5α-stanols/Δ5-stenols ratio) within the deepest sediment layers was not clear, suggesting low degradation rates. In PGI-1, the deposition of large quantities of penguin guano affected the distribution of sterols and, consequently, primary production was favoured by the ornithogenic soil input. The results contribute to the understanding of the current processes associated with primary sources and transformation of OM in this important region of the Antarctic environment.

Photosynthetic Production Determines Bottom Water Oxygen Variations in the Upwelling Coastal South China Sea Over Recent Decades

“…Similarly, the 5αstanol/Δ 5 -sterol ratios are found higher in surface sediments with comparatively lower bottom water DO levels in the Yangtze River estuary (Zhu et al, 2012) and the PRE (Guo, 2015), implying that the ratio records in downcore sediments may reflect bottom water (surface sediment) redox conditions in the past. This is followed by a recent study on short cores around Penguin Island, demonstrating that sedimentary variations of the 5α-stanol/Δ 5sterol ratios may be attributed to changes in bottom water conditions at the study sites at the time of deposition (Ceschim et al, 2016). Accordingly, in this study, sedimentary C 28 Δ 22 /Δ 5,22 ratios are likely also predominantly determined by bottom water DO conditions that modulate the extent of anaerobic conversion of C 28 Δ 5,22 at its initial deposition as a component of surface sediments.…”

Angiographic result of index PCI determines the presence of right ventricular infarction in patients with acute inferior myocardial infarction

“…Multi-proxy paleolimnological approaches that include independent tracers add confidence to historical records. Lipid biomarkers have shown potential for tracking seabird and human enrichment to lake/pond sediments (Ceschim et al, 2016).. In addition, previous research showed that pond sediments adjacent to bird colonies were greatly enriched in cholesterol relative to the plant-derived sitosterol (Cheng et al, 2016).…”