Banca de DEFESA: LUCAS MEDEIROS GUIMARAES

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : LUCAS MEDEIROS GUIMARAES
DATA : 19/07/2018
HORA: 09:00
LOCAL: Instituto de Geociências
TÍTULO:

Temporal changes in the quality of the organic matter deposited in the Itapicuru estuary, Bahia, Brazil

PALAVRAS-CHAVES:

Atlantic Forest, contamination, n-Alkanes, Polycyclic Aromatic Hydrocarbons, EPA/LN

PÁGINAS: 51
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
SUBÁREA: Geologia
ESPECIALIDADE: Geoquímica
RESUMO:

The estuary of Itapicuru’s river is located at Environmental Protected Area (EPA) of North Coast of Bahia. Although this system presents pristine conditions, some environmental impacts are observed, such as changes in vegetal coverage for commercial plantations and some caused by the presence of small fisheries communities. The main objective of this study is to evaluate the importance of these impacts in temporal changes in the amount and in the type of organic matter (O.M.) deposited in the estuary of Itapicuru’s river. For that, were analyzed the vertical distribution of n-Alkanes and polycyclic aromatic hydrocarbons (PAHs) in sub-samples of a sedimentary core collected at the estuary margin. Were also evaluated: the distribution of the granulometric fraction; the content of total organic carbon (TOC) and of total nitrogen (TN); and the isotopic ratio of TOC (δ¹³C) and of TN (δ¹³C). For the dating, was calculated the sedimentation rate from the radioactive decay of ²¹⁰Pb (0,54 ± 0,05 cm year^-1). The reporting period of the core is from 1907 (base) to 2017 (top). The concentrations of TOC, TN and of total n-Alkanes ranged, respectively, from 0,65% to 2,51%, from 0,07% to 0,13% and from 1.331 ng g^-1 to 7.301 ng g^-1 in dry weight (dw). Temporal changes occured together with the changes in the mud’s content. This, in it’s turn, is influenced by anthropic intervetnions (i.e., highway constructions) and for the disorderly use of the soil for all the hydrographic basin of Itapicuru’s river. Were applied diagnostic reasons that showed that the main source of n-Alkanes to the region is the one provided by vascular plants. Changes in the importance of this contribution occured due to natural processes (climatic) and anthropic (changes in vegetal coverage due to plantations of pinus, eucalyptus and coconuts). The concentrations of total PAHs ranged from 1,98 ng g^-1 to 43,1 ng g^-1 dw, showing a low contamination rate in the study area. The sources of PAHs are local, such as the use of fishing vessels with diesel engine, the advance of urbanization and space valorization. Although these anthropic contributions, the estuary of Itapicuru’s river can be considered a tropical estuary relatively preserved.

MEMBROS DA BANCA:
Presidente - 2134515 - ANA CECILIA RIZZATTI DE ALBERGARIA BARBOSA
Externo ao Programa - 1522396 - VANESSA HATJE
Externo à Instituição - RAFAEL ANDRÉ LOURENÇO - USP