Contamination by oil spills in coastal ecosystems, especially in mangrove zones, has been common in countries with oil industry. The aim of this study was, therefore, to evaluate the efficiency of application of the two models developed for pilot-scale remediation, intrinsic bioremediation (indigenous microorganisms), and phytoremediation (Avicennia schaueriana). The degradation of hydrocarbons was determined by gas chromatography (GS) with flame ionization detector. The metals Al, Fe, Pb, Cr, Cu, Zn, and Ni were determined by flame atomic absorption spectrometry in the mangrove simulated with sediment of Todos os Santos Bay, Brazil. These models also monitor other biogeochemical parameters (nitrogen, phosphorus, total organic carbon, pH, redox potentioal, dissolved oxygen, salinity, temperature, bacterial density). The integrated assessment of data showed that both techniques were effective in degrading organic compounds from oil but that phytoremediation is the most efficient (89% removal). The intrinsic bioremediation model has no direct correlation with metal concentrations, but a positive correlation with Al and Ni was found in the hydrocarbon removal by phytoremediation. Avicennia schaueriana represents efficiency in phytoextraction and phytostimulation. The results suggest that the phytoremediation model, through its various mechanisms, may become a technique for the removal of petroleum hydrocarbons in the presence of metals in mangrove ecosystems near industrial areas.
IMPACTS OF LOCAL VEGETATION CHANGES IN THE ORGANIC MATTERS INPUT FOR A PRESERVED TROPICAL ESTUARY (ITAPICURU-BA RIVER ESTUARY). Estuaries are major areas of organic matter (OM) deposition, playing an important role in the global carbon cycle. The Itapicuru's river estuary (IRE) is in the North Coast of Bahia (Brazil), in an Environmental Protected Area. Although it presents preserved conditions, some environmental changes caused by human activities can be observed. This study evaluated the anthropogenic impacts importance in concentrations/sources of OM deposited in IRE. n-Alkanes and stable isotopes (δ 13 C and δ 15 N) were analyzed in a sediment core collected in the studied region. Total n-alkanes (n-C 15 to n-C 35), TOC and TN concentrations varied from 1,333 to 7,384 ng g-1 , 0.65% to 2.51% and 0.07% to 0.13%, respectively. Values of δ 13 C and δ 15 N ranged from-28.8‰ to-24.3‰,-6.23‰ to 1.87‰, respectively. By the means of the isotopic composition and the selected n-alkanes diagnostic ratios values (Productivity aquatic index; Carbon Preference Index; Average Chain Length and Alkane index), the main OM sources for IRE were determined as C 3 terrestrial plants. This area is covered by mangrove/riparian vegetation, which mainly species have this photosynthetic pathway. Temporal changes in deposited OM occurred due natural and anthropogenic processes, such urban growth in the IRE upstream region.
Several regions in Brazil and the world suffer from the presence of collapsible soils. The development of theories for understanding the phenomenon is significant because the increase of water content is associated with several reasons (e.g., precipitation, rupture of sewage, and water systems). Although some theories explain the behavior of various types of soils, they fail to explain collapsible and structured soils. In this research, an alternative interpretation of the consolidation theory is verified and calibrated for collapsible soil. The alternative model was applied to experimental data from a latosol from southeastern Brazil, and comparisons with the classical theory showed a difference in the saturated hydraulic conductivity of around 100 times. The observation showed promising results compared with the saturated hydraulic conductivity of the field (Guelph Permeameter). Furthermore, consolidation tests verified the collapse potential, the variation of consolidation coefficient and saturated hydraulic conductivity, and the total settlement prevision due to the presence of bleach and washing powder.
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