Sources of organic matter and paleo-environmental implications inferred from carbon isotope compositions of lacustrine sediments at Inexpressible Island, Ross Sea, Antarctica

The carbon isotopic composition of organic matter (δ 13 C org ) was determined in two sediment cores (IIL1 and IIL9) recovered from Inexpressible Island, Ross Sea, Antarctica, and analyzed to identify the sources of that organic matter. The δ 13 C org values of sediments of IIL9 were found to vary between −14.6‰ and −11.6‰, with a mean of −13.4‰ (n=48). These values were significantly higher than those of IIL1 sediments which varied between −23.2‰ and −20.4‰, with a mean of −21.8‰ (n=55). The variation in δ 13 C org values in these two sediment cores indicate different sources of organic matter. The relatively high δ 13 C org values in IIL9 are in accordance with a source from algae, while the low δ 13 C org values in IIL1 evince significant influence from penguin guano with algae as the secondary source. Compared with the reference data from other high-latitude lake sediments and plants, the δ 13 C org values in IIL9 were extremely high, a result likely related to intense competition for CO 2 assimilation among algal species during the growing season in this relatively shallow pond. These results indicate that sedimentary δ 13 C org is a reliable proxy for paleo-primary productivity in ponds at Inexpressible Island. Citation: Wei Y Y, Jin J, Nie Y G, et al. Sources of organic matter and paleo-environmental implications inferred from carbon isotope compositions of lacustrine sediments at Inexpressible Island, Ross Sea, Antarctica. Adv Polar Sci, 2016, 27: 233-244, doi: 10.13679/j.advps.2016.4.00233