DEVELOPMENT AND VALIDATION OF VOLTAMMETRIC METHOD FOR DETERMINATION OF IRON AND ITS CHEMICAL SPECIATION IN PORE WATER TO SEDIMENT OF THE PATOS LAGOON-RS / DESENVOLVIMENTO E VALIDAÇÃO DE MÉTODO VOLTAMÉTRICO PARA DETERMINAÇÃO DE FERRO E SUA ESPECIAÇÃO QUÍMICA EM ÁGUA INTERSTICIAL NO SEDIMENTO DA LAGOA DOS PATOS-RS

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

Sediments can act as accumulators as well as sources of pollutants. Depending on the port activities are in local growth rate by expanding the port of Rio Grande (RS), studies that show the location of the site investigation is important to predict the intake of iron in this environment. In this work, the chemical speciation of iron and measuring the concentration of total dissolved metal in samples of sediment interstitial waters of the Saco Mendanha (RS) were evaluated, using the Adsorptive Stripping Voltammetry Cathode with ligand 2,3-dihydroxynaphthalene. The main objective of this study was to validate the analytical methodology to perform the chemical speciation of iron in pore waters, which involved the Linear range, limits of detection and quantification, accuracy and precision. The limit of detection was found to be 0.11 nmol L-1. The concentration of iron, total dissolved and labile fractions of three distinct interface water/sediment between 0 and -5 cm and -15 to -20 cm deep in the sedimentary column. In any samples, the concentration of labile iron was found between 4.64 to 135.37 μmol L-1, the concentration of dissolved metal was 6.25 to 322.70 μmol L-1 and total iron of 83.36 390.30 μmol L-1. The low concentration of labile metal in comparison to the total dissolved fraction and indicates the presence of stable complexes between metal and natural organic matter present in the pore water, thus making the metal less bioavailable to the local biota. During the months of sampling the sediment was observed variations in the concentration of the metal, which in April was the largest contribution of the metal in the water column to the sediment. This transfer of metal to the sediment may be related to the strong change in salinity at the sampling site, from 16 in february to 33 in april and close to zero in the months of august and november 2009.

ASSUNTO(S)

speciation diluição iron voltammetry especiação ferro sedimento voltametria quimica analitica dilution sediment água intersticial porewater

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