Roberto F.M. Michel

Lead adsorption in the clay fraction of two soil profiles from Fildes Peninsula, King George Island

Abstract Antarctica is considered the most isolated continent, but it is not free of pollution, which arrives at specific localities mainly as a result of tourism and research activities. Among environmentally harmful substances, heavy metals are especially important because of their high toxicity to organisms. The aim of this study was to estimate the maximum adsorption of lead (Pb) onto the clay fraction of samples from two soil profiles from the Fildes Peninsula, King George Island, South Shetland Islands. Experimental data were fitted to the Langmuir isotherm, and the adsorption parameters were correlated to mineralogical attributes of this soil fraction characterized by chemical extractions and X-ray diffraction. Values of maximum adsorption of Pb in the clay fraction were extremely high (maximum value: 322 581 mg kg-1) when compared to those of soil samples from other regions of the world. Adsorption occurred in two stages: first stage in which a high percentage of Pb was adsorbed, and second stage in which adsorption was lower. From an environmental point of view, soils with high contents of clay and amorphous minerals, ones usually associated with ornithogenic activity in Antarctica, should have greater efficiency in filtering Pb, thus reducing risks of leaching and groundwater contamination.

Soils of the South Orkney and South Shetland Islands, Antarctica

The present Chapter presents an overview on soils from Maritime Antarctica, comprising ice-free areas distributed along the South Orkney (SOI) and South Shetland Islands (SSI). Published and novel data were compiled, with focus on pedogenesis and soils geography, in a total of 365 pedons, of which 71 % are from King George Island. Seven soil-forming processes occur, including cryoturbation, gleization, melanization, podzolization, paludization, and phosphatization. Six soil orders have been reported in the SOI and SSI, including Gelisols, Entisols, Inceptisols, Histosols, Mollisols, and Spodosols, which represent half of the orders in ST. Gelisols are predominant at altitudes above 30 m.a.s.l. to 100 m.a.s.l., where discontinuous permafrost exists. The most abundant great group is the Haploturbels, illustrating the importance of cryoturbation. We conclude with a summary of the current knowledge on soil formation and distribution in the SOI and SSI, and a prospect of future research needs and questions.

Hg distribution and speciation in Antarctic soils of the Fildes and Ardley peninsulas, King George Island

Abstract Data on the content and speciation of mercury (Hg) in the soils of Antarctica are scarce and vary greatly between the regions studied, but overall Hg concentrations found were generally very low. We investigated the Hg quantity and speciation by solid-phase Hg pyrolysis and chemical fractionation in selected maritime Antarctic soils, comparing ornithogenic and non-ornithogenic areas of the Fildes and Ardley peninsulas of King George Island. The total Hg contents ranged from 4.3–256 ng g-1, and values for ornithogenic soils were the highest recorded for Antarctic soils. A close correlation between Hg and organic matter was observed in the ornithogenic soils, with levels decreasing with depth. In the non-ornithogenic soils, a correlation between Hg content and soil depth was also observed, but the values were found to increase with depth. Thermograms showed that all Hg was in the 2+ oxidation state and was predominantly linked to organic matter, corroborating the chemical fractionation results for the ornithogenic soils. These results show the need for further refined studies about the interactions of Hg with organic matter in order to better understand the biogeochemistry of this metal in the Antarctic environment.

Cosmo-SkyMed X-band SAR data for classification of ice-free areas and glacier facies on Potter Peninsula, King George Island Antarctica

The climate change phenomena have been influencing terrestrial and glacial ecosystems around the planet. Maritime Antarctica is especially sensitive to these climate variations and over the last 50 years increasing global air temperatures have caused extensive glacial retreat. The objective of this study is to evaluate the potential use of the SAR technology in monitoring the surface dynamics of the Potter Peninsula, King George Island, maritime Antarctica. An image generated by the SAR satellite COSMO-SkyMed, obtained on 2 February 2011, was used to extract the backscattering values of targets on the surface for further processing and classification, using a supervised statistic classifier of maximum likelihood for the determination of the surface classes. The average backscattering of water bodies presented high similarity, which made its separation unattainable. On the other hand, the surface classes’ bare ice and wet snow over the glacier presented distinct average backscattering values, which allowed an efficient and precise classification using only this parameter. The classification process showed satisfactory results for periglacial environments, presenting high fidelity to the field data.

Chemometric tools in chemical fractionation data of soil samples from five antarctic research stations

Este estudo foi centrado na avaliacao quimica de amostras de solos provenientes de diversas estacoes de pesquisa na Antartica. Amostras de solos de referencia foram coletadas em locais com minimo impacto antropico, distantes das estacoes de pesquisa. Locais selecionados nas vizinhancas das estacoes Frei Montalva e Escudero (Chile), Grande Muralha (China), Bellingshausen (Russia) e Artigas (Uruguai) foram os pontos a priori supostamente antropizados deste estudo. O procedimento de extracao sequencial (SEP) baseado no protocolo proposto pelo BCR (Community Bureau of Reference) foi aplicado para a determinacao de Cu, Mn e Zn. Com o auxilio dos metodos PCA (analise de componentes principais) e PARAFAC (analise de fatores paralelos) foram extraidas informacoes significativas a partir dos dados brutos obtidos com SEP. As amostras de solos afetadas pelas estacoes de pesquisa estao associadas com elevadas concentracoes de metais pesados (especialmente Cu e Zn, dentre os elementos investigados, nas fracoes mais labeis de SEP aplicado). Este indicio de contaminacao esta relacionado com o uso de oleo diesel para geracao de energia pelas estacoes antarticas. The aim of this study was to carry out a broad chemical investigation of selected soil samples from Antarctica, near different Antarctic scientific stations. Soil samples collected in background reference sites, with minimal human impact, far away from the stations were used as control samples. Anthropogenic places at the vicinity of the following stations Frei Montalva and Escudero (Chile), Great Wall (China), Bellingshausen (Russia) and Artigas (Uruguay) were studied as a priori human impacted sites. The sequential extraction procedure (SEP) based on the BCR (Community Bureau of Reference) protocol was applied for Cu, Mn and Zn determination. With the help of PCA (principal component analysis) and PARAFAC (parallel factor analysis) methods, meaningful information was extracted from the raw data obtained from SEP procedure. Soil samples affected by the scientific stations are associated with higher heavy metal contents (especially Cu and Zn, between the investigated metals, in the most labile fractions of the SEP applied). This pollution signal is associated with diesel use for the energy generation by the Antarctic stations.

Relationship between solar radiation and surface distribution of vegetation in Fildes Peninsula and Ardley Island, Maritime Antarctica

ABSTRACT The aim of this work is to produce a simplified vegetation map of ice-free areas of the Fildes Peninsula (FP) and Ardley Island (AI) thought object-oriented classification using a QuickBird satellite image and to evaluate the influence of the global solar radiation (GSR) over the vegetation distribution. The vegetation data were generated from multiresolution segmentation using the panchromatic and infrared layers, and for the classification we calculated the normalized vegetative difference index (NVDI) and the green NVDI. Two classes were created – Lichen and Moss Cushion SubFormation and Moss Subformation – with 48 vegetation samples collected on surveys during the austral summers of 2008 and 2009. We used a kappa index to evaluate the classification efficiency using 100 sampled points obtained in austral summer of 2013. The GSR was estimated, and in order to evaluate the effect of meteorological phenomena and cloudless, we measured the GSR using a net radiometer model CNR4 installed in FP between 2014 and 2016. The estimate of GSR was done for seasons of 2015, in order to estimate the light compensation point and the saturation point for the plant communities in FP and AI. The kappa index was 0.73 and the global accuracy was 0.78, showing consistency between the classification and ground truth. The area was covered by vegetation in FP was 16.7% and in AI is 59.1%. The vegetation cover is distributed differently at FP and AI, and our results suggest GSR plays an important role in vegetation distribution and these tendencies could be related to greater GSR demand by mosses when compared to lichens.