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The endorheic basins of the Northern Chilean Altiplano contain saline lakes and salt flats. Two of the salt flats, Gorbea and Ignorado, have high acidic brines. The causes of the local acidity have been attributed to the occurrence of volcanic native sulfur, the release of sulfuric acid by oxidation, and the low buffering capacity of the rocks in the area. Understanding the microbial community composition and available energy in this pristine ecosystem is relevant in determining the origin of the acidity and in supporting the rationale of conservation policies. Besides, a comparison between similar systems in Australia highlights key microbial components and specific ones associated with geological settings and environmental conditions. Sediment and water samples from the Salar de Gorbea were collected, physicochemical parameters measured and geochemical and molecular biological analyses performed. A low diversity microbial community was observed in brines and sediments dominated by Actinobacteria, Algae, Firmicutes and Proteobacteria. Most of the constituent genera have been reported to be either sulfur oxidizing microorganisms or ones having the potential for sulfur oxidation given available genomic data and information drawn from the literature on cultured relatives. In addition, a link between sulfur oxidation and carbon fixation was observed. In contrast, to acid mine drainage communities, Gorbea microbial diversity is mainly supported by chemolithoheterotrophic, facultative chemolithoautotrophic and oligotrophic sulfur oxidizing populations indicating that microbial activity should also be considered as a causative agent of local acidity.

In this work, the changes caused by a chemical modification of the properties and chemical structures of lignin are studied. Lignin from a mixture of Eucalyptus globulus and Eucalyptus nitens obtained through the kraft pulping process was used. The lignin was isolated by acid precipitation and modified by a reaction with maleic anhydride. Maleated lignin (ML) was incorporated to recycled polystyrene (rPS) at 2, 5, and 10 wt-% by a melt-blending process. Fourier transformed infrared spectroscopy (FT-IR) was used to determine the ML structure, and the morphology of rPS/ ML composites was studied by scanning electron microscopy (SEM).Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to study the glass-transition temperature (T g ) and the thermal stability of rPS and rPS/ ML composites and were compared with virgin PS. The T g values of rPS and their composites were higher than those of the virgin PS. TGA revealed that the thermal stability of rPS with 2 and 5% of ML was slightly greater than that of the virgin PS. These results suggest that postconsumer PS can be used to obtain composite materials with good thermal properties.

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