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Polycyclic aromatic hydrocarbons (PAHs) and aliphatic hydrocarbons (AHs), including petroleum biomarkers, were studied in four sediment cores collected around Deception and Penguin Islands, Antarctica. Total PAHs in Deception Island (DCP) samples ranged from 2.0 to 26.8 ng g−1, and in Penguin Island (PGI) varied between 13.2 and 60.3 ng g−1. Multiple sources of PAHs were verified in DCP, with petrogenic-derived compounds being predominant over the last 10 years. In PGI, PAHs related to natural contributions from the erosion of coal deposits were reported. Total AHs in DCP ranged from 4.5 to 19 μg g−1 and in PGI varied between 5.3 and 21.9 μg g−1. In DCP, the n -alkanes distribution pattern showed the presence of petroleum residues in the top sections and both terpanes and hopanes were detected, related to the use of fossil fuels for power generation and in different types of vessels. In PGI, the main source of n -alkanes was marine inputs and only terpanes were detected. The slight increase in hydrocarbon levels observed from 1980 onward in DCP was assumed to be due to the development of tourism in the region and to the scientific station activities. In PGI, anthropogenic-related hydrocarbons were detected in the recent sections and were linked to the development of tourism near the island, scientific activities and the increase in vessel traffic. In general, the concentrations of hydrocarbons found around both islands were comparable to those found in uncontaminated Antarctic regions. Image 1 • Low concentrations of hydrocarbons were found in both island. • Levels were compared to those found in pristine regions of Antarctica. • Coal seam erosion has been a natural source of PAHs and terpanes in Penguin Island. • Increase in anthropogenic compounds reported in recent sections of the cores. Evidences of hydrocarbons related to anthropogenic sources were reported in two Antarctica islands with an increase tendency in recent years. [ABSTRACT FROM AUTHOR]

In this study, the polycyclic aromatic hydrocarbons (PAHs) from the sediment cores M2 in the Pryza Bay of the Antarctica were quantitatively measured using GC-MS analysis, and it is found that the PAHs mainly included bicyclic naphthalene compounds, tricyclic phenanthrene and fluorine series (dibenzofuran and dibenzothiophene), and tetracyclic fluoranthene, pyrene and chrysene series. The results showed that the phenanthrene series with low molecular weight (tricyclic compounds) had a relatively higher content than the series with high molecular weight (tetracyclic compounds). The fluoranthene/(fluoranthene and pyrene) ratio of M2 varied from 0.46 to 0.54. Integrated with the content of 1,7-dimethyl-phenanthrene and terrigenous chrysene, it is inferred that PAHs in the sediments from the Pryzd Bay were originated from a mixed source of the products of petroleum, refined products and coal combustion, natural source and terrigenous higher plants. Complete methyl dibenzothiophene and dimethyldibenzothiophene series compounds were detected in the sediment cores, which are closely associated with a reducing environment. The ratio of dibenzothiophene to dibenzofuran was between 0. 46 and 3. 21, mostly greater than 0. 7. Combined with the oxidation/reduction index (Pr/Ph) ranging from 0.45 to 0.61 for the sediment cores, it is indicated that these compounds were formed in a normal reducing environment. Ge-ochemical parameters of PAHs such as TNR-1 (0.53-1.57), MPI (0.24-1.21), MDR (1.83-5.57), and MDBI (0.41-0.93), and maturity parameters such as C29/C29 ( +), C3122S/C31 (22S +22R), C3222S/C32 (22S +22R) and Ts/(Tm +Ts) were all indicative of high maturity. However, all the above parameters were significantly deviated from those of modern sediments and modern organisms, which undoubtedly shows the input of exogenous mature organic matter. [ABSTRACT FROM AUTHOR]

A sediment core (L2) from Larsemann Hills, Antarctica was analyzed for Biogenic Silica (BSi), Sand (%) and Total Organic Carbon (TOC). The 78 cm core length represents the time span of ∼8.3 cal ka BP. The values of BSi from the core show prominent high productivity from ∼8.3 to ∼6 cal ka BP in comparison to less productivity in mid-late Holocene (∼6 cal ka BP to recent). Moreover, high sand (%) infers the glacio-fluvial deposition from ∼8.3 to ∼5 cal ka BP TOC shows little variation through out the core, except in the upper ∼10 cm (∼4 cal ka BP) part wherein it is comparatively high. The increased TOC in the upper part of the core possibly indicates presence of algal mat due to exposure of the lake to the ice free (glacier free) conditions. [ABSTRACT FROM AUTHOR]

Antarctic climate changes influence environmental changes at both regional and local scales. Here we report Holocene paleolimnological changes in lake sediment core Sk4C-02 (length 378.0 cm) from Lake Skallen Oike in the Soya Kaigan region of East Antarctica inferred from analyses of sedimentary facies, a range of organic components, isotope ratios of organic carbon and nitrogen, and carbon-14 dating by Tandetron accelerator mass spectrometry. The sediment core was composed of clayish mud (378.0–152.5 cm) overlain by organic sediments (152.5 cm-surface). The age of the surface and the core bottom were 150 (AD1950-1640) and ca. 7,030 ± 73 calibrated years before present (cal BP), respectively, and the mean sedimentation rate was estimated to be 0.55 mm/year. Multi-proxy analyses revealed that the principal environmental change in the core is a transition from marine to lacustrine environments which occurred at a depth of 152.5 cm (ca. 3,590 cal BP). This was caused by relative sea level change brought about by ongoing retreat of glaciers during the mid-Holocene warming of Antarctica, and ongoing isostatic uplift which outpaced changes in global (eustatic) sea level. The mean isostatic uplift rate was calculated to be 2.8 mm/year. The coastal marine period (378.0–152.5 cm, ca. 7,030–3,590 cal BP) was characterized by low biological production with the predominance of diatoms. During the transition period from marine to freshwater conditions (152.5-approximately 135 cm, ca. 3,590–3,290 cal BP) the lake was stratified with marine water overlain by freshwater, with a chemocline and an anoxic (sulfidic) layer in the bottom of the photic zone. Green sulfur bacteria and Cryptophyta were the major photosynthetic organisms. The Cryptophyta appeared to be tolerant of the moderate salinity and stratified water conditions. The lacustrine period (approximately 135 cm-surface, ca. 3,290 cal BP-present) was characterized by high biological production by green algae (e.g. Comarium clepsydra and Oedegonium spp.) with some contributions from cyanobacteria and diatoms. Biological production during this period was 8.7 times higher than during the coastal marine period. [ABSTRACT FROM AUTHOR]