Produção de Hgorganico em sedimentos tropicais a partir do Hg0 : experimentos em microcosmos

Orientador : Wilson de Figueiredo JardimDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de QuimicaMestrad

Aquatic biogeochemistry of organic mercury in the Rio Negro Basin, Amazon

Orientador: Wilson de Figueiredo JardimTese (doutorado) - Universidade Estadual de Campinas, Instituto de QuimicaDoutoradoQuimica AnaliticaDoutor em Ciência

Simultaneous Determination of Phenanthrene and Benzo(a)pyrene in Water Samples by Synchronous Fluorescence Spectroscopy

A simple and sensitive method was developed to simultaneously determine phenanthrene and benzo(a) pyrene in water samples using synchronous fluorescence spectroscopy with a 56-nm Delta lambda. The method was used to simultaneously determine both compounds in samples of spiked surface water. Analytical recoveries were 96.9-101.1% for phenanthrene and 95.8-103.5% for benzo(a) pyrene. Analytical results were checked for precision with 15 measurements for each compound. Relative standard deviations were 1.9% for phenanthrene and 2.9% for benzo(a) pyrene, which shows that the proposed method is quite precise.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Metal fluxes at the sediment-water interface in rivers in the Turvo/Grande drainage basin, So Paulo State, Brazil

Purpose The Turvo/Grande drainage basin (TGDB), located in the northwestern region of So Paulo state, covers an area of 15,983 km(2). The region is typically regarded as agricultural by the So Paulo State Environmental Agency, but the industrial area is expanding, and some studies have shown that metal concentrations in water can be higher than the values regulated by Brazilian law. Therefore, the aim of this study was to assess the role of sediments as a source or a sink of metals for drainage basin management.Materials and methods Interstitial water from different sediment depths (0-42 cm) and the sediment-water interface and sediment core samples were collected in February and July 2010 from the Preto, Turvo, and Grande rivers. Quantification of Cr, Cu, Fe, Mn, Ni, and Pb in these samples was performed by graphite furnace or flame atomic absorption spectrometry. Metal diffusive flux estimation from sediment into the overlying water was calculated by Fick's First Law of Diffusion.Results and discussion The fluxes of all metals for the three rivers were positive, indicating diffusion into the overlying water. Ni and Pb showed the lowest diffusive fluxes, which ranged from 2.4 to 3,978 mu g m(-2) day(-1) for Ni and from -0.1 to 1,597 mu g m(-2) day(-1) for Pb. In turn, Cu and Cr were subject to the largest transfer to water, especially in the dry season (Cr, 4.5-7,673 mu g m(-2) day(-1); Cu, 1.3-14,145 mu g m(-2) day(-1)). The Preto River (urban area) showed smaller fluxes than the Grande River (agricultural area), and the values of the latter were higher than those found in other impacted areas of the world.Conclusions The diffusive fluxes indicate that sediments from the TGDB act as a source of metals for the water column, with increased export of metals, particularly Cr and Ni, from the sediment into the overlying water during the dry season.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Mercury Redox Chemistry in the Negro River Basin, Amazon: The Role of Organic Matter and Solar Light

Pristine water bodies in the Negro River basin, Brazilian Amazon, show relatively high concentrations of mercury. These waters are characterized by acidic pH, low concentrations of suspended solids, and high amounts of dissolved organic matter and are exposed to intense solar radiation throughout the year. This unique environment creates a very dynamic redox chemistry affecting the mobility of mercury due to the formation of the dissolved elemental species (Hg-0). It has been shown that in this so-called black water, labile organic matter from flooded forest is the major scavenger of photogenerated H2O2. In the absence of hydrogen peroxide, these black waters lose their ability to oxidize Hg-0 to Hg2+, thus increasing Hg-0 evasion across the water/atmosphere interface, with average night time values of 3.80 pmol m(-2) h(-1). When the dry period starts, labile organic matter inputs gradually diminish, allowing the increasing concentration of H2O2 to re-establish oxidative water conditions, inhibiting the metal flux across the water/atmosphere interface and contributing to mercury accumulation in the water column.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Water quality index as a simple indicator of aquaculture effects on aquatic bodies

This paper proposes a water quality index (WQI) to subsidize management actions in the Medio Paranapanema Watershed in São Paulo State, Brazil, as a simple pollution indicator for aquaculture activity. Water quality of the Macuco and Queixada rivers was investigated for 2 years (from May 2003 to May 2005). The index proposed in this work is composed of three measurable environmental parameters-turbidity, total phosphorus and dissolved oxygen. Concentrations of these three variables were normalized on a scale from 0 to 100 and translated into statements of water quality (excellent, good, regular, fair and poor). The index was applied to seventeen monitoring points in the aquatic bodies described above and compared to others, one being that used by the Environmental Protection Agency of United States and proposed for the National Sanitation Foundation, other employing minimal index and the last one considering the minimum operator concept. The results show that the degradation in this watershed from aquaculture activity can be easily inferred with this index, which is more restricted than the others routinely used to infer water quality. (C) 2007 Elsevier Ltd. All rights reserved

Hydrochar obtained with by-products from the sugarcane industry: Molecular features and effects of extracts on maize seed germination

Sugarcane bagasse, vinasse and a mixture of sugarcane bagasse and vinasse were hydrothermally carbonized (HTC), with and without the addition of phosphoric acid, in order to propose new applications of sucroenergetic industry by-products on soil. Detailed information on the composition and properties of hydrochars has been obtained through elemental composition, thermogravimetric analysis, nuclear magnetic resonance and, ther- mochemolysis GC-MS. The soluble acidic fraction from the hydrochar samples were applied to maize seeds to evaluate the agronomic potential as biostimulants and relate the molecular features with maize seed germina- tion. The HTC treatment converted polysaccharide-based biomasses into hydrochars with hydrophobic charac- teristics (C-Aryl and C-Akyl). Furthermore, the addition of phosphoric acid further increased the overall hydrophobicity and shifted the thermal degradation of the hydrochars to higher temperatures. Biomass influ - enced the hydrochars that formed, in which the molecular features of sugarcane bagasse determined the for- mation of more polar hydrochar, due to the preservation of lignin and phenolic components. Meanwhile, the HTC of vinasse resulted in a more hydrophobic product with an enrichment of condensed and recalcitrant organic fractions. The germination assay showed that polar structures of bagasse may play a role in improving the maize seeds germination rate (increase of ~11%), while the hydrophobic domains showed negative effects. The re- sponses obtained in germination seems to be related to the molecular characteristics that organic extracts can present in solution