25th International Meeting on Organic Geochemistry IMOG 2011

P-142
Geochemical parameters assessment in sediments of Lake
Coari (Amazon)
Tatiana Santos da Cunha 1 , Francisco Fernando Lamego Simões Filho 1 , Celso Marcelo
Franklin Lapal 2 , Maria de Lourdes Moreira 1 , Luis Landau 3 , Celeste Yara dos Santos
Ciqueira 3
1 Instituto de Engenharia Nuclear - Comissão Nacional de Energia Nuclear, Rua Hélio de Almeida, 75,Zip
Code 21941-906, Rio de Janeiro, Brazil, 2 Instituto Nacional de C&T de Reatores Nucleares Inovadores, Rio
de Janeiro, Brazil, 3 Centro de Tecnologia - Bloco I sala 214, Av. Athios da Silveira Ramos, 149, Rio de
Janeiro, Brazil (corresponding author:tatianadantasrj@yahoo.com.br)
This study aims to understand Lake Coari function
through the geochemical analysis of sediments,
assessing the contaminants input into the lake and
also their behavior in case of environmental accident
in the region.
To achieve this proposal, we collected samples an
surface sediments located downstream (Tesol 1) and
upstream (Tesol 2) of Petrobras Terminal; a core at
the entrance of Lake Coari and another in front of the
Coari city.
The objective was to compare the concentrations of
metals, organic matter with possible factors
controlling the deposition process in these different
points. The deposition of 210 Pb was also evaluated in
order to correlate the geochemical parameters with
their respective sources.
The sediment profile at the entrance of Lake Coari
(P4) showed higher values of TOC (0.72%) and C/N
(27.4%), whereas in the sediment profile P5, situated
into the lake Coari, the TOC values (0 44%) and C/N
(18.3%) were lower. It suggested higher affinity of P4
with the material carried by the Solimões river.
The predominance of odd n-alkanes of higher
molecular weight and higher intensities for n-C29 in
surface samples of the P4 sediment profile and Tesol
corroborate the terrestrial debris as the main source
of those materials. Records of perylene in some of
those samples reinforce this origin.
Highest concentrations of metals with anthropogenic
origin corresponded to excess
210 Pb, ie, the
sediments brings the latest sign of anthropogenic
disturbance within the lake Coari. Thus, the effects of
the material transported by the Solimões river
reaches the entrance of the lake while the sediments
within the lake portray a system without the influence
of the main river. At this site the sediment deposition
reflects the input of material from the kale‘s drainage
basin and lake primary productivity.
The analysis also confirmed the absence of
petrogenic material in the region, proving that it was
not yet impacted by oil activities.
Figure 1: Study area
References:
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Princípios básicos e técnicas afins. Rio de Janeiro,
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[3] Barrocas, P.S.R. 1998. Estudos da concentração
de metais pesados nos igarapés Matrinxã, Acará,
Bolívia, Tarumã (Manaus-AM). Dissertação de
Mestrado em Ciências Ambientais. Centro de
Ciências Ambientais. Universidade Federal do
Amazonas.
[4] Bouloubassi, I. 1990. Aspects de la biogéochimie
des hydrocarbures non aramatiques dans La colonne
d‘eau et lês sediments du milieu côtier: cas du delta
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[5] Bouloubassi, I.; Saliot, A., 1993. Dissolved,
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