Characteristics of heavy metals and their evaluation in suspended sediments from Piracicaba river basin (São Paulo, Brazil)

Fluxes of the particulate heavy metals like chromium (Cr), copper (Cu), cobalt (Co), nickel (Ni), zinc (Zn) and lead (Pb) were determined along the Piracicaba River basin. Suspended sediments from the main channel and tributaries were sampled during January 2005 (high water period) and analyzed for total concentrations after extraction by alkaline fusion procedure. The average concentrations showed a significant increase pattern from upstream to downstream for Zn, Cr, Ni, Cu and Pb, except for Co, in which only a small variation was noted. The specific fluxes of Zn, Cr and Ni were slightly higher (79.9, 33.3 and 20 kg km-2 yr-1, respectively) in comparison to other industrialized regions in Asia, Europe, North and South America. Significative correlations between organic matter and Cr, Cu and Co, observed in the suspended sediments along the Piracicaba River basin, revealed that heavy metals were adsorbed or complexed by the organic matter, while Ni and Pb were significatively correlated with Fe oxide. The geo-accumulation index (Igeo) used to evaluate the pollution degree of the Piracicaba River sediments, revealed a medium to strong pollution for Zn in the entire basin and moderate pollution for Cr and Ni at downstream direction around an important area covered by sugar cane plantations and urban areas influenced by domestic sewage

Silicate rock weathering and atmospheric/soil CO2 uptake in the Amazon basin estimated from river water geochemistry: seasonal and spatial variations

Using the data of the CAMREX project (1982–1984) on the water geochemistry of the Amazon river and its main tributaries, it was possible to assess the silicate rock weathering processes and the associated consumption of atmospheric/soil CO2, taking into account seasonal and spatial variations. This study confirms the important role of the Andes in the fluvial transport of dissolved and particulate material by the Amazon, and it shows for the first time that the silicate weathering rate and atmospheric/soil CO2 consumption are higher in the Andes than in the rest of the Amazon basin. The seasonal variations exhibit the significant role of runoff as a major factor controlling silicate weathering processes and show that the chemical erosion rates vary greatly from low discharge to high discharge. The average weathering rate estimated for the whole Amazon basin (15 m/My) is comparable to other estimations made for other tropical–equatorial environments. A comparison between physical and chemical weathering rates of silicate rocks for the Amazon basin and for each tributary basin show that in the Andes and in the Amazon trough, the soil thicknesses are decreasing whereas in the Shield the soil profiles are deepening

Piracicaba river basin : mechanical and chemical erosion

It was carried out the characterization of the mechanical and chemical erosive processes in the Piracicaba River basin, for the period 1992-1996, in terms of the fluvial transport of dissolved and particulate materials. The mechanical erosion was calculated from the suspended sediment transport in the basin, considering the surface runoff discharge and the respective concentration calculated taking in account the statistical hydrogram separation method employed. The specific physical degradation calculated for the Piracicaba River basin was 90 t/km2.a, which correspond the velocity of the soil thickness reduction of about 64 m/Ma. The dissolved load of Piracicaba River was corrected due to the influence of the atmospheric inputs, mainly for SO4 2-, Ca2+ and Mg2+ (79.6; 63.8 and 41.8%, respectively). After the input corrections, it was estimated the total atmospheric/soil CO2 consumed during the silicate weathering (229 x 103 moles/km2.a) and the total chemical erosion (16.6 t/km2.a) expressed in terms of the total dissolved solids transported in the basin. The velocity of the silicate rock profile reduction (2.8 m/Ma) was calculated by the fluvial transport of dissolved silica knowing the mean silica concentrations in the parent rock and in the soil profile

Heavy metal distribution in recent sediments along the Tietê River basin (São Pauro, Brazil)

The distribution of heavy metals in recent sediments deposited along the Tietê River, a highly polluted river in southeast region of Brazil was studied. Around the metropolitan area of São Paulo city (25 million people), the pollution is related to municipal wastes and industrial effluents with reinforced downstream by agricultural activities. The observed increase of heavy metal concentrations is particularly important for Zn in the upper basin and Cu, Co and Cr at mouth. Geo-accumulation index calculation, related to the regional background, showed that the sediments along the basin are seriously polluted by heavy metals of anthropogenic origin, mainly Cu, Co, Cr and Zn. Calculated index suggests medium to very strongly pollution

Rainfall, runoff and temperature fluctuations in the Amazon basin and oscillation of global climate over the last century

Over the past century, the world's climate has been changing. The rainfall over the continents, the global stream water discharge, the global air temperature and the CO2 content in the atmosphere have together been increasing. However, in the Amazon basin, examination of data existing and the estimation of missing data reveal that for about the past century, between 1910 and 1990, the air temperature has been decreasing, and the rainfall and the river discharge have been increasing but showing very large fluctuations. It is shown that the evolution of the global climate, over continents becoming warmer and wetter, should not mask the following realities: (1) amplitudes of fluctuations are large; (2) regional and global trends do not necessarily move in the same directions and (3) regional and global fluctuations, even if of similar amplitude and of equal periodicity, are not synchronous

Heavy metal distribution in the bottom sediments along Tietê river basin.

Analysis of heavy metals in fluvial sediments has been used to better understand the potential hazards and critical toxicity of heavy metals mainly related to the anthropogenic influences of urban sewage, industrial effluents and agricultural activity. The present study analyzed the heavy metals, such as Cr,Cu,Ni,Zn and Pb in the bottom sediments along the Tietê river basin, a polluted watershed in the Southeast region of brazil.The distribution of the concentrations of heavy metals in the upper basin decreased in the following order: Zn>Cr>Pb>Ni>Cu, whereas, in the middle part of the basin (wich is under strong urban and industrial influences), high concentrations of Zn, Cu and Cr were abserved measuring 648,200 and 183 µg g-1 respectively. The sequential chemical extraction in relation to the total ocncentration was used to assess the potential bioavailability of heavy metals. In the upper part of the basin, the heavy metals extracted from the bottom sediments were mainly related to the residual fraction, whereas, in the middle part of the basin, the bioavailability of Zn,Cr and Ni was higher than 60%, and these metals was mainly related to the iron oxide phase.The high concentration of heavy metals observed in the middle basin of the Tietê river(after the metropolitan area of São Paulo)when compared with the average concentration found in the geochemical bottom,showed that,in terms of enrichment factor and geoaccumulation index,the degree of pollution by Zn is high and by Ni is high to moderate in the down stream direction

Erosion chimique et mécanique dans le bassin de l'Amazone. Evaluation du ruissellement par la méthode dite des réservoirs à contribution variable mais à composition constante

Une méthode de séparation des écoulements constituant les hydrogrammes de crue: ruissellement et écoulement de base, est proposée et appliquée au bassin de l'Amazone. Les deux écoulements ainsi que les concentrations supposées constantes dans chacun des deux réservoirs dont ils sont issus, sont calculés à partir du débit total et des concentrations en substances dissoutes ou particulaires, organiques ou minérales, mesurées au cours de 7 campagnes de prélèvements effectuées entre 1982 et 198

Relation between rainfall spatial distribution and runoff components in meso scales tropical basin

This paper goal is to verify differences on surface runoff among some selected areas in the Piracicaba river basin, which have different soil types. Spatial distribution of precipitation was studied with geographic information system (GIS) for 2 periods: the 30-year normal (1962-1993) and the study period (1995-1997). In order to separate the stream hydrograph, the numerical filters statistical procedure was used. The results showed that the same surface runoff for all areas studied, independently of its land use or geologic formationO objetivo desse trabalho é verificar a existência de diferenças significativas no escoamento superficial e subterrâneo entre sub-bacias com diferentes tipos de solo na bacia do rio Piracicaba/SP Para isso foi estudada a distribuição espacial da precipitação no período considerado no estudo (1995 -1997) e para um período de 30 anos (1962 - 1993) com a utilização de um Sistema de Informações Geográficas. Para a separação do escoamento total utilizou-se uma técnica estatística de filtros numéricos, que demonstrou que os escoamentos superficial e subterrâneo são semelhantes em todas as sub-bacias estudadas, independente da formação geológica e do uso do sol

TRANSPORTE DE ESPÉCIES QUÍMICAS DISSOLVIDAS EM ÁGUAS FLUVIAIS DE UMA MICROBACIA COM EUCALIPTOS EM ANGATUBA, SÃO PAULO

The fluvial behavior of major chemical dissolved species in a small catchment forested with eucalyptus near Angatuba, São Paulo, Brazil was investigated in terms of specific transport during two rainy events, before and after the wood cutting. The specific transports were calculated according to the stochastic and the partial area integration methods. Although giving similar results, the partial area integration was better adapted for isolated rainy events. Significant specific transports were observed for SiO2 and HCO3 - in both rainy events. After the wood cutting a fluvial increase of K+, Cl- and SO4 2- could be observed mainly related to agricultural practices in the catchment. The low dissolved loads, verified in the Entre Rios stream, confirm the low mineraralization degree of the superficial waters showing to be very dependent of the pluvial recharge process in the catchment. Keywords: transport, small catchment, chemical species, eucalyptus.As concentrações das principais espécies químicas dissolvidas bem como seus transportes fluviais foram quantificadas no córrego Entre Rios, em uma microbacia reflorestada com eucaliptos em Angatuba, SP, durante dois eventos chuvosos, antes e após a colheita da madeira, sendo comparados dois métodos de cálculo, o estocástico e o de integração de áreas. Embora com resultados similares, o método de integração de áreas se mostrou melhor adaptado à situação proposta, evidenciando que SiO2 e HCO3 - apresentaram os transportes específicos mais significativos em ambos os períodos de amostragem. Após a colheita de madeira foi possível verificar um aumento na concentração de K+, Cl- e SO4 2- devido aos tratos culturais e adubação para o próximo ciclo de plantas. Os baixos transportes observados confirmaram a baixa minerabilidade das águas superficiais, se mostrando altamente dependentes do processo de recarga. Palavras-chave: transporte fluvial, microbacia, espécies químicas, eucaliptos

ESTIMATIVA DO ESCOAMENTO SUPERFICIAL RÁPIDO E SUA CARGA EM SUSPENSÃO COM A APLICAÇÃO DO MODELO DE SEPARAÇÃO DE HIDROGRAMAS COM FILTROS NUMÉRICOS: BACIA DO RIO SOROCABA - SP

O escoamento fluvial total de uma bacia de drenagem, considerando um modelo de dois reservatórios, pode ser entendido como a soma do escoamento superficial rápido com o escoamento de base ou subterrâneo, estando o primeiro relacionado diretamente com a recarga pluvial e responsável direto pelo dinamismo da erosão mecânica em bacias de drenagem. Dada a importância do rio Sorocaba como manancial de abastecimento de água para cerca de 1.000.000 habitantes, este trabalho teve por objetivo estimar o escoamento superficial rápido, com ênfase na separação do escoamento total num modelo de dois componentes, com o emprego de filtros numéricos auto-recursivos de 1ª ordem, para o período de 1984 a 2008, em termos de variabilidade temporal e carga de material particulado transportado fluvialmente. O conhecimento do componente escoamento superficial rápido do rio Sorocaba nos últimos 25 anos forneceu subsídios para uma melhor avaliação e entendimento dos processos erosivos predominantes na bacia de drenagem e suas conseqüências aos corpos de água. Esta componente representou 38,04% do escoamento total médio anual e sua variabilidade se mostrou diretamente associada ao regime de precipitação, com uma carga estimada de material particulado transportado no período chuvoso 10 vezes superior à observada no período seco. Palavras-chave: hidrologia, escoamento superficial rápido, bacia de drenagem, material particulado em suspensã