Navegando por Palavras-chave "Geochemistry - water quality"

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    Avaliação ambiental sobre a presença de fósforo nos ambientes aquáticos do Rio Pinheiros e da Represa Billings/SP
    (Universidade Federal de São Paulo, 2013-04-10) Santos, Juliana de Cassia Costa dos [UNIFESP]; Silva, Ivone Silveira da [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    This research had as main objective to perform an environmental assessment of the concentration levels of phosphorus (P) in sediment and water matrices, correlating them with the concentrations of aluminum (Al), calcium (Ca), iron (Fe) and suspended solids in aquatic environments of the Pinheiros River and Billings Dam, SP. The waters and sediments were sampled in depth, resulting in testimonies in five short points in the stretch of the Upper Channel of the Pinheiros River and at one point in Billings Reservoir near the Elevatoria Plant. The waters were filtered through cellulose acetate membrane 0.45 µm and sediment samples were sieved and dried at 80° for 48 hours, being subjected to a complete digestion procedure with H2O2, HNO3 e HCl. The metals and P concentrations were determined for digested extracts as well as water samples filtered by ICP-AES. Were also performed field measurements of the characteristics of surface waters, such as pH, Eh, temperature, conductivity, dissolved oxygen and turbidity. The results indicated that lower concentrations of Al, Ca and Fe in the waters were diagnosed during the dry season, while in the rainy season these concentrations were higher, whereas the concentrations of P showed an opposite behavior. The sediments of the Pinheiros River showed a heterogeneous spatial variation, on the levels of total P along the longitudinal axis and at depth, while the Billings Dam showed higher concentrations of total P in samples collected during the rainy season. The determination of iron, aluminum and calcium revealed that these elements are at elevated concentrations in the studied environments, iron is the most concentrated in all the sampling points, followed by aluminum and calcium. The distribution of metals (Al, Fe and Ca) in the sediments showed similar behavior to phosphorus concentrations, where the values of metals concentrations were almost constant throughout the sampled profiles. Results showed that the waters of the Pinheiros River and Billings Dam are extremely compromised due to constant input from sewers and may be even more influenced by internal loads of phosphorus and metals that can be released from the sediment to the water column. The significant correlations observed between the analyzed elements have indicated some similarity in their source of origin for the Pinheiros River, and consequently for Billings Dam. This can have a negative impact especially regarding to the need to disposal of dredged sediments in these environments, as well as on the internal load of accumulated phosphorus, that can refuel fertilization of the waters, as well as potentiate the accumulation of organic matter and the consequent reduction in levels of dissolved oxygen from the water.