Landscape changes on Deception Island’s coast after subglacial volcanic eruptions

M.C. Muniz1, R.M Anjos1, *, R.P. Cardoso1, L. H. Rosa2, R. Vieira1, H. Marotta1, K. Macario1, A. Ayres Neto1, C.D.N. Barboza1, A.S. Cid1, L.F. Rodrigues1

1LARA – Laboratório de Radioecologia, Instituto de Física, Universidade Federal Fluminense, Av. Gal Milton Tavares de Souza, s/no, Gragoatá, 24210-340, Niterói, RJ, Brazil.

We have examined the radiocarbon ages, carbon and nitrogen isotopic compositions, and particle-size distributions in an ornithogenic soil profile from the Whalers Bay, Deception Island in Antarctica. In general, the textural characteristics of the sediment samples can be classified as muddy sand (very coarse silty very fine sand, poorly sorted). The δ13C values range from −24.8‰ to −23.0‰, showing that the predominant carbon source in Antarctic sediments is from terrestrial origin, such as mosses and lichens. The C/N ratio of the organic matter range of 5.2–8.6, consistent with the presence of penguin guano. The δ15N values range from 1.3‰ to 6.6‰, such that higher values (> 6) are observed in the topsoil and the layer of 27.5 ± 2.5 cm. However, the layers below them show a gradual decrease of δ15N. The chronology from bulk sediment samples indicate that the initial development of the organic matter began between 12500 and 11800 yr cal. BP. Additionally, the upper ground layers (between 2.5 ± 2.5 and 22.5 ± 2.5 cm depth) do not exhibit the age values monotonically increasing with depth. This behavior is only observed for layers below 27.5 ± 2.5cm depth, suggesting that the soil around this area can only be considered undisturbed below this sediment layer. Layers above this value are subjected to intense water erosion. Environment changes from the subglacial volcanic eruptions can be considered as an important factor not only for the understanding of its destruction power, but also about of the meltwater discharge effects on the autochthonous production imbalance and the erosion input from highest areas to the Antarctic coastal areas.