Banca de DEFESA: LAÍS DE JESUS SOUZA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : LAÍS DE JESUS SOUZA
DATA : 14/12/2020
HORA: 09:00
LOCAL: defesa remota
TÍTULO:

SOURCES OF ORGANIC MATTER FOR THE SURFACE SEDIMENTS OF AN ANTHROPIZED TROPICAL BAY (BAY OF ALL SANTOS, BAHIA, BRAZIL)

PALAVRAS-CHAVES:

Stable isotopes, n-alkanes, coastal systems, carbon cycle, contamination.

PÁGINAS: 72
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
SUBÁREA: Geologia
ESPECIALIDADE: Geoquímica
RESUMO:

Coastal systems are essential in the global carbon cycle, acting as sources of organic
matter (O.M.) for the oceans or as carbon sinks through the accumulation of this
element in sediments. The characterization of the main sources (natural or
anthropogenic) of O.M. is an important indicator of productivity and anthropic impacts
on the environment. It can be made by the analysis of carbon and nitrogen stable
isotopes or the analysis of organic molecular markers, as n-alkanes. Todos os Santos
Bay (TBS), the second largest bay in Brazil, has important ecosystems such as
mangroves, Atlantic forest, apicuns and coral reefs. Although the bay is important,
different anthropogenic activities are developed in its area and surroundings, that
increase the input of effluents (domestic, agricultural, or industrial) and contamination
by petroleum. The purpose of this study is to evaluate the main natural and
anthropogenic sources of O.M. for a large tropical that present anthropogenic impacts.
For this, 61 samples of surface sediments were collected at TBS, granulometric
fractions were analyzed; and total organic carbon (TOC), total nitrogen (TN), δ 13 C and
δ 15 N; and concentrations of n-alkanes (n-C 10 - n-C 35 ) in sediment. The concentrations of
TOC, TN and n-alkanes ranged from 0.10 to 2.18%, 0.04 to 0.22% and 1.65 to 11.4 μg
g -1 (dry weight), respectively. There are marine, terrestrial sources and the anthropic
influence for O.M. deposited. The predominance of high molecular weight n-alkanes
(C 29 and C 31 ) indicates the main source of these compounds for TBS is higher plants.
The planktonic sources were observed in central areas and entrance of the bay, and
degradation processes of the O.M. by bacteria occurred mainly in the regions of sand
granulometry.

MEMBROS DA BANCA:
Interno - 2134515 - ANA CECILIA RIZZATTI DE ALBERGARIA BARBOSA
Externo à Instituição - MARCELO DA ROSA ALEXANDRE - UFSC
Externo ao Programa - 2349838 - MARIA DO ROSARIO ZUCCHI
Presidente - 3055474 - TATIANE COMBI