Policyclyc aromatic hidrocarbons study at São Vicente and Santos Estuaries SP using diatomite as adsorbent material / Estudo de hidrocarbonetos policíclicos aromáticos nos estuários de Santos e São Vicente/SP utilizando diatomito como material adsorvente

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Diatomite spheres were used as an adsorbent material for policyclyc aromatic hidrocarbons (PAH) adsorption at water column for the identification of the main contamination sources at two estuaries of Baixada Santista. The samples were held at Santos Estuary (site 1) and São Vicente Estuary (site 2) during the year 2006, at two sites, and in 2007, only at site 2. Together with PAH analyses, some parameters of water quality were measured. This methodology is unique with unprecedented published study, and some tests were conducted focus on the development of PAH extraction from diatomite and the recovery testes. Between the tested methodologies, the PAH extraction was more efficient using mechanic shaking and ultrasonic process. The recovery testes indicate better results for PAH with high molecular weight and the adsorption efficiency occurs in a period of 15 to 30 days. A high influence of the environmental factors was observed at PAH adsorption and the results shows different magnitude when conducted at laboratory and at the natural environment. The water quality result shows the site 2 as more influenced by a river system in comparison with site 1, located at estuary mouth, with higher salinity values. The dissolved oxygen was lower at site 2 indicating higher organic matter contribution. The turbidity analyses also show higher values at site 2 probably due to the diffuse pollution release and the reduced natural water flow in this place. The powder diatomite characterization shows the main composition of well preserved diatoms frustules. In the other hand, the diatomite characterization made after the diatomite going through the process to be used at samples sites, shows the frustules with unpreserved structure, condensed and with high loss of integrity. The PAH concentrations were higher at site 1 than in site 2, probably due to biggest environmental contamination from the harbor (Porto de Santos). Both of the samples sites show the pyrolytic as the main PAH sources probably resulting of the combustion process and atmospheric deposition in water column. These sources can be associated with the atmospheric emissions from Cubatão Complex and refineries. The lower PAH concentrations with low molecular weigh at site 2 indicate light contamination from petrogenic source, like those related with harbor activities. The results obtained for PAH analysis with the diatomite spheres placed in different depth on water column indicate higher concentrations near the surface, probably due the atmospheric deposition. The measurements performed at water column were kept almost constant and near the sediment the concentration start to increase again, as an indication of the presence of sediment movement and re-suspe

ASSUNTO(S)

estuários diatomito baixa santista hpa estuários hpa diatomito baixada santista

ACESSO AO ARTIGO

Documentos Relacionados