Banca de DEFESA: ELISANGELA COSTA SANTOS
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.DISCENTE : ELISANGELA COSTA SANTOS
DATA : 05/07/2019
HORA: 09:00
LOCAL: Sala de Seminários do Instituto de Química
TÍTULO:
CHEMICAL / GEOCHEMICAL CHARACTERIZATION OF SEDIMENTS OF THE LOW STRAIN OF THE SAN FRANCISCO RIVER TO ASSESS ENVIRONMENTAL IMPACTS
PALAVRAS-CHAVES:
São Francisco River, sediment, trace elements, origin organic matter, ecological risk, stable isotopes
PÁGINAS: 125
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
RESUMO:
The low strain of the São Francisco river covers an area that divides between the States of Alagoas and Sergipe, in the stretch after the Xingó Dam, to its mouth, in the city of Sergipe. The objective of this work was to characterize, through chemical and geochemical parameters, the sediments of the low strain of the São Francisco River, in order to evaluate possible environmental impacts. Samples of surface sediments were collected during three seasons, two in dry season (February 2014 and December 2015) and one in the rainy season (July 2016), in the two margins of four transects, totaling 8 sampling points. Core samples of sediments were collected in 7 localities (Pão de Açúcar-AL, Niterói-SE, Traipu-AL, Gararu-SE, Xinaré-AL, Pindoba-SE, Ilha das Flores-SE) in July 2016 at the depths of 2 to 44 cm, to verify the influence of the dams on sedimentation behavior. The Environmental Protection Agency's analytical procedure, EPA 3051A, was applied to the sediments and trace elements were determined by inductively coupled plasma optical emission spectrometry (ICP OES). The origin and sources of organic matter (OM) were evaluated using elemental ratios by elemental analysis coupled to mass spectrometry. The results obtained after partial decomposition of the sediment samples in microwave oven and determination by ICP OES were evaluated through guideline values established by sediment quality guides. It was possible to infer that the samples collected in the low strain of the São Francisco river presented clayey minerals of the kaolinite and ilite type. Concentrations of As in PA-AL (2014) and IF-SE (2015, 2016) were above the criteria of the values for TEL (Threshold Effect Level) and PEL (Probable Effect Level). The concentrations obtained for Cd in PA-AL, GA-SE, IF-SE (2014 to 2016), NI-SE, XI-AL, PI-SE (2014 and 2016), TA-AL (2016) and PE-AL (2015 and 2016) were above the minimum value established by the Canadian and US legislation, TEL and LEL (Lowest Effect Level). In PA-AL (2014) and NI-SE (2016) the values exceeded that established by the Canadian legislation (PEL). In IF-SE (2016) the values are above the limits established by the US legislation, SEL (Severe effect level). The concentration values found for Cr in sediments of SE-SE (2016) presented levels above the lower thresholds established by the American legislation (LEL). The calculated potential ecological risk index reflects great concern in the NI-SE and IF-SE locations, since it was between moderate to high in 2016. By the calculated ecological risk factor for the different locations in the different periods, it can been that the elements As, Cr, Cu, Ni and Pb offer greater ecological risk. In relation to phosphorus, it was observed that a decrease in the flow rate for the NI-SE, TA-AL, GA-SE, XI-AL, PE-AL and IF-SE discharges resulted in an increase in P concentration in the sediment. The results on the origin and source of OM related to the sediments of the Low strain of the São Francisco river revealed different constitutions composed of bacteria, marine algae and C3 plants. The stable isotopes δ13C and δ15N evidenced the presence of sewage, fertilizers, cyanobacteria and OM typical of the estuary. In this way, it is inferred that the work carried out warns about the need for a monitoring in the region of the low strain of the São Francisco river, since the reduction of the flow is more felt by the localities closest to the mouth, due to the decrease of fresh water in relation to the entrance of the sea water, occurring accumulations of OM, fertilizers and trace elements. The work also contributed to the generation of a database on the composition and quality of sediments of the low strain of the São Francisco River
MEMBROS DA BANCA:
Externo ao Programa - 6285989 - ANTONIO FERNANDO DE SOUZA QUEIROZ
Externo ao Programa - 1033477 - JOSE ROBERTO BISPO DE SOUZA
Externo à Instituição - KARINA SANTOS GARCIA
Interno - 1303987 - MARIA ELISABETE MACHADO
Externo à Instituição - RAILDO MOTA DE JESUS - UESC-BA
Presidente - 285528 - VANIA PALMEIRA CAMPOS
Externo ao Programa - 284762 - YVONILDE DANTAS PINTO MEDEIROS