Banca de DEFESA: WAGNER PEREIRA DOS SANTOS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : WAGNER PEREIRA DOS SANTOS
DATE: 23/09/2021
TIME: 08:30
LOCAL: Google Meet
TITLE:

HEAVY METALS SPECIATIONIN AQUATIC SEDIMENTS FROM A COASTAL RESERVOIR IN NORTHEAST BRAZIL

KEY WORDS:

Sequential extraction procedure; Mehlich-1; Extremoz Lake; aquatic sediments; Hyalella Azteca.

PAGES: 74
BIG AREA: Outra
AREA: Ciências Ambientais
SUMMARY:

Metals such as Cd, Cr, Cu, Ni, Pb and Zn have the potential to cause toxic effects and have several human sources such as domestic and industrial sewage, agrochemicals and emissions from vehicles powered by petroleum derivatives. The choice of method for extracting these metals from different matrices (e.g. water, soil, plant) can vary according to the desired objective. Single-step extraction methods can be used in plant metal availability analyzes and are more aimed at extracting the total bioavailable phase. Sequential extraction procedures are among the most commonly used methods to obtain information on the speciation of trace metals in contaminated soils and sediments. Our general objective was to evaluate the relationship between the results of ecotoxicological tests and trace metals removed (leached) from different chemical phases (exchangeable, reducible, oxidizable and residual) in the bottom sediments of Extremoz Lake, in Rio Grande do Norte, Brazil. The two specific objectives were: to evaluate, by different extraction methods (ME – Mehlich-1 and SEP – Sequential Extraction Procedure), the availability of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in aquatic sediments of theExtremoz Lake; to evaluate the influence of heavy metals released from different bioavailable chemical fractions in sediments on the survival of the amphipod Hyalellaazteca. The results showed that the extraction performed by SEP, when compared to ME, showed greater efficiency in removing the metals Cd, Cr, Cu and Zn according to the averages obtained and, among these elements, only Cd did not have significant correlations with the survival of H. azteca. The results of the SEP extraction indicated that the bioavailable chemical fractions may reflect the interactive effect of metals in the mixtures on the survival of the test organism. Even though they do not point to toxic effects in the short term, the bioaccumulation of metals such as Cd, Cr, Cu, Ni, Pb and Zn may have future consequences. Works like this one enable a perception of the constant degradation of aquatic environments due to anthropogenic influence, highlighting the importance of deepening more detailed studies related to the physical and chemical characteristics of water reservoirs in urban environments.

BANKING MEMBERS:
Presidente - 1298966 - RAQUEL FRANCO DE SOUZA
Interna - 1279472 - ELIANE MARINHO SORIANO
Externo à Instituição - ROBERTO RODRIGUES DE SOUZA - UFS