Geochemistry of Antarctic periglacial soils from Harmony Point, Nelson Island

Abstract

Little is known about the geochemical baseline of Antarctic soils in different environments. We investigated the soil geochemistry of the two main landscape units of Harmony Point (Nelson Island, Maritime Antarctica): the coastal domain and the upper platform. Fourteen soil samples (seven in each landscape unit) were divided according to depth (hA for surface and hC for subsurface horizons) and characterized by their major, trace elements and REE concentrations. The concentration of major elements (SiO 2 , TiO 2 , Al 2 O3, Fe 2 O 3 , MgO, CaO, MnO, and K 2 O) were determined by X-ray fluorescence, whereas trace elements were quantified by inductively coupled plasma-optical emission spectrometry (Co, Ni, As, Cd, Pb, Ba, Cr, Cu, V, Zn, and Zr) and REE by inductively coupled plasma mass spectrometry. The results showed geochemical variation with depth, either related to pedological processes (phosphatization, humification, podzolization, and cryoturbation), and parent material constitution (andesitic basalt in upper platform and mixed volcanic sediments in coastal domain). The main chemical aspects distinguishing Harmony Point soils from other Maritime Antarctic soils from the vicinity are: (i) higher CIA index; (ii) P 2 O 5 enrichment due to bird guano and enhanced pedogenesis; (iii) REE retention; (iv) enrichment in Fe 2 O 3 and S concentrations. The REE concentration was influenced by weathering processes combined with allochthonous inputs, such as volcanic ashes and iceberg-transported granitic boulders at the coastal domain. The Harmony Point soils are little subjected to anthropic impacts, so they can be used as a basis for environmental monitoring programs in the Maritime Antarctica region.