Estratégias analíticas para a avaliação química de solos e liquens da Antártica marítima

• Main Author: Guerra, Marcelo Braga Bueno
• Other Authors: Pereira Filho, Edenir Rodrigues, PEREIRA FILHO, E. R, http://lattes.cnpq.br/7474474218219859
• Format: Thesis
• Language: Portuguese
• Published: Universidade Federal de São Carlos 2011
• Subjects: Química analítica; Antártica; Solos; Metais; Espectrometria; Quimiometria; CIENCIAS EXATAS E DA TERRA::QUIMICA; Artigas; Escudero; Esperanza; Esperanza Station; Ferraz; Solos’; Antarc*; Antarctica; Usnea antarctica
• Online Access: https://repositorio.ufscar.br/handle/ufscar/6205

The aim of this PhD thesis is the ample study of soil and lichen samples from Antarctica, collected in regions under strong anthropogenic impact. Surface soil samples were collected around several scientific stations: Brazilian (Comandante Ferraz), Argentinian (Esperanza), Chilean (Frei Montalva and Escudero), Chinese (Great Wall), Russian (Bellingshausen) and Uruguaian (Artigas). Control soil samples were also collected, for representing areas with low anthropic influence (far away from the local stations). Lichen samples (Usnea antarctica and Usnea aurantiacoatra) were collected near the Chilean and Russian stations, as well as in a control point far 0.5 km from the nearest station. X-ray Fluorescence was used as an analytical tool for the preliminary evaluation on metal contamination in the soil samples. Several extraction solutions (aqua regia, sequential extraction procedure, DTPA and CaCl2 solutions) were used to assess the amounts of metals in the soil samples. For Cd, Cr, Cu, Mn, Ni, Pb and Zn determination in the soil extracts, some analytical strategies were employed, such as fast sequential determination by FAAS in the conventional mode, as well as by using STAT-FAAS and TS-FF-AAS for evaluating Cd and Pb determination in DTPA soil extracts. The chemometric tools: HCA, PCA and PARAFAC were used for soil data treatment. Enrichment factors were calculated in order to infer about the degree of soil contamination. Soil samples collected around the stations diesel tanks were enriched with Cr and Pb. Soil samples from Esperanza station are the most contaminated ones, reaching 46, 18993 and 4823 mg kg-1 for Cd, Pb and Zn, respectively, for the strongest contaminated sites. The use of Flame-AAS and STAT-FAAS in the fast sequential mode appears as a good way that combines higher analytical throughput and better sensitivity (STAT-FAAS). Besides that, minimization of toxic wastes generation and xv economy of reagents are analytical advantages of this approach. The employment of chemometric tools are also an ...