Banca de QUALIFICAÇÃO: WAGNER PEREIRA DOS SANTOS

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : WAGNER PEREIRA DOS SANTOS
DATE: 25/09/2020
TIME: 08:30
LOCAL: Google Meet
TITLE:

Speciation of Heavy Metals in Sediments from an Urban Coastal Reservoir in Northeast Brazil

KEY WORDS:

Extremoz lake, sequential extraction, ecotoxicological tests.

PAGES: 29
BIG AREA: Outra
AREA: Ciências Ambientais
SUMMARY:

The Extremoz lake, inserted in the Rio Doce hydrographic basin, Rio Grande do Norte, fits into a degradation scenario due to the rapid and disordered industrial, urban and agricultural expansion. Potentially toxic heavy metals are possibly responsible for the contamination of this water system. Although the occurrence of these metals may have a natural origin due to geological characteristics in different geological terrains, the excessive inputof certain chemical elements due to anthropogenic activities can unbalance ecosystems. In order to verify a relationship between these metals and ecotoxicological test results, samples of aquatic sediments collected at different points in the Extremoz lake, from March to November 2014, were subjected to the selective sequential extraction procedure, which is among the methodologies most used to determine speciation of trace metals in contaminated soils and sediments. This extraction method is commonly employedto determine the speciation of metals in contaminated soils and sediments. The procedure requires the use of a series of proposed reagents that, in theory, will dissolve the specific metals per solution for the solution of certain fractions (exchangeable, reducible, oxidizable and residual). To assess the effectiveness of the applied methodology, certified reference material (BCR-701) was used. Applying the extraction to the samples of aquatic sediments, the results obtained will be correlated with survival data from the test organism H. azteca and granulometry. At point T2, the heavy metals that have a significant negative correlation with the results of ecotoxicological tests are Zn, Cu and Cr linked to the oxidizable fraction (organic matter and sulfides) and to the reducible fraction (Fe oxides and hydroxides), in addition to Zn which is associated to the exchangeable fraction. The presence in a greater proportion of the granulometric fractions coarse sand and silty clay also demonstrated to be associated with the low survival of the test organisms in the studied sediment samples. The data from the T1 point samples must now be worked on and related to their corresponding results of sample toxicity and granulometry, in addition to other variables that are relevant during the analysis. The T1 and T2 points can then be compared by month of sampling (from March to November 2014).

BANKING MEMBERS:
Externo ao Programa - 2149478 - JOSE BRAZ DINIZ FILHO
Interno - 707.819.324-59 - JULIO ALEJANDRO NAVONI - UFRN
Presidente - 1298966 - RAQUEL FRANCO DE SOUZA