Made available in DSpace on 2016-08-19T12:56:48Z (GMT). No. of bitstreams: 1 Dissertacao LISANDRA MARIA DA SILVA CARVALHO.pdf: 1316969 bytes, checksum: 74b629e185747db756cae70ea00cf5db (MD5) Previous issue date: 2014-07-31 / FUNDAÇÃO DE AMPARO À PESQUISA E AO DESENVOLVIMENTO CIENTIFICO E TECNOLÓGICO DO MARANHÃO / Mangrove estuaries are subject to amendments provoked by anthropogenic activities. The contamination by metals in estuarine environments is of paramount importance, since these cannot be degraded and, therefore, accumulate in sediments promoting certain toxicity to benthic organisms and humans. This risk is directly linked to the availability and mobility of metals in sediments. Although Cd, Cr, Cu, Pb, Ni and Zn are found at trace levels in the environment, several studies have been made on the basis of their toxic potential. The aim of this study is to determine the distribution and fractionation of trace metals in sediments of mangrove Paciência river, both on the surface and in the depth profile and to estimate the risk of these elements to aquatic life. Metal Fractionation in mangrove sediment (surface and depth profile) of Paciência river in Maranhão Island was conducted using the method of sequential extraction protocol by the European Commission. The metal concentrations were determined using inductively coupled plasma optical emission spectrometry technique (ICPOES). The mobility of metals (sum of the three most mobile fractions F1, F2 and F3) had values approximately 80 %, suggesting that the impact of human activities. The results showed that the total concentration levels of metals were below TEL (Threshold effect level), with the exception of Pb, whose values provide risk to aquatic life. The redox potential (Eh) decreased with depth (-110 mV at the surface to -360 mV at the bottom), and showed high correlation with Fe in fraction F2 (r² = 0,89). Other parameters studied showed no increasing or decreasing along the depth behavior, indicating that other variables may be affecting the distribution and dynamics of metals in sediment. / Os estuários de manguezais estão sujeitos às transformações decorrentes de diversas atividades antrópicas e a sua contaminação por metais é de suma importância, uma vez que estes não podem ser degradados e se acumulam nos sedimentos promovendo certa toxicidade aos organismos bênticos e aos seres humanos. Este risco está diretamente ligado à disponibilidade e mobilidade dos metais em sedimentos. Embora os metais Cd, Cr, Cu, Pb, Ni e Zn sejam encontrados em níveis traço no ambiente, vários estudos têm sido realizado em função do seu potencial tóxico. O objetivo desse trabalho é determinar a distribuição e o fracionamento dos metais traço nos sedimentos de manguezal do rio Paciência, tanto na superfície quanto no perfil de profundidade, bem como estimar o risco desses elementos para vida aquática. O fracionamento de metais no sedimento de mangue (superfície e perfil de profundidade) do rio Paciência, na ilha do Maranhão foi realizado utilizando o método da extração sequencial pelo o protocolo da Comissão Europeia. As concentrações dos metais foram determinadas usando a técnica por espectrometria de emissão ótica de plasma indutivamente acoplado (ICP-OES). A mobilidade dos metais (soma das três frações de maior mobilidade F1, F2 e F3) apresentou valores cerca de 80 %, o que sugere impacto das atividades antropogênicas. Os resultados da concentração total demonstraram que os níveis de metais estavam abaixo do TEL (Threshold effect level), com exceção do Pb, cujos valores oferecem risco para a vida aquática. O potencial redox (Eh) diminuiu com a profundidade (-110 mV na superfície até -360 mV na parte inferior), e mostrou alta correlação com Fe na fração F2 (r² = 0,89). Outros parâmetros estudados não apresentaram um comportamento crescente ou decrescente ao longo da profundidade, indicando que outras variáveis podem estar afetando a distribuição e a dinâmica dos metais em sedimento.

In this Dissertation, systematic work has been carried out to study the road-deposited sediment and its adsorbed pollutants from a stormwater pollution perspective. Solid-phase concentration, surface load, source apportionment, risk assessment, and desorption dynamics of polycyclic aromatic hydrocarbons and/or heavy metals in road-deposited sediments (RDS) were investigated. In order to provide data to assist potential strategies of stormwater pollution mitigation and integrated catchment management to minimise the adverse impacts of RDS adsorbed pollutants on stormwawter quality, the following specific topics were addressed. ⑴ The influences of traffic load and antecedent dry-weather period on pollution level and ecological risk of heavy metals in RDS were analyzed. ⑵ The build-up dynamics and chemical fractionation of metals were determined. ⑶ The potential source contributions and risk assessment of polycyclic aromatic hydrocarbons in size-fractionated RDS were firstly determined by a Principal component analysis - Multiple linear regression receptor model. ⑷ The qualitative and quantitative source apportionments of polycyclic aromatic hydrocarbons were subsequently investigated through a combined qualitative Molecular Diagnostic Ratio and quantitative Positive Matrix Factorization source apportionment with an extended data set. ⑸ The exposure risk of polycyclic aromatic hydrocarbons were evaluated and calculated by incremental lifetime cancer risk models. ⑹ Then, a novel ecological risk assessment approach to the RDS adsorbed toxic substances was developed, which was explored exclusively for the study of RDS for a water pollution aspect. ⑺ Finally, the effects of rainwater, major wastewater constituents of dissolved organic matter and surfactant on the leaching of heavy metals from RDS were carried out.