Banca de QUALIFICAÇÃO: ARYANNA SANY PINTO NOGUEIRA COSTA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : ARYANNA SANY PINTO NOGUEIRA COSTA
DATE: 08/07/2022
TIME: 13:30
LOCAL: Vídeoconferência via RNP
TITLE:

SIMULATION MODEL OF ARSENIC CONTAMINATION AND ENVIRONMENTAL MONITORING OF MERCURY IN THE AQUATIC ECOSYSTEM OF MUNDAÚ LAGOON (MACEIÓ – AL, BRAZIL)

KEY WORDS:

Contamination; Mechanism of Toxicity; Environmental Monitoring; Arsenic; Mercury.

PAGES: 95
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUMMARY:

The increasing environmental degradation witnessed in contemporary times, as a result of human activities on the environment, has brought about different problems. Among these is the degradation by inorganic contaminants, such as Mercury (Hg) and Arsenic (As), these elements do not undergo biodegradation processes, i.e., are bioaccumulated in different environmental compartments and, subsequently, can advance along the food chain and become bioaccessible. With this, studies in the environmental area have become a current necessity so that in the future nature will not become an inexhaustible source and society will not suffer even more with the impacts of this environmental imbalance. The present work developed a laboratory scale study to evaluate the toxicity mechanism of As(III) and As(V) using the Nile tilapia fish (Orechromis niloticus) as a model organism, as well as the monitoring of total mercury in samples of sururu, sediment and water, and the determination of mercury fractions (INOHg and ORGHg) in water samples. The determination of As and Hg was performed by atomic fluorescence spectrometry with hydride generation module (HG AFS) and by cold vapor (CV AFS), respectively. As for the 96 h acute toxicity assays, for As(III) the LC50 value determined was 42.92 ± 3.05 g L-1, for As(V), in the concentration range evaluated (50 to 300 mg L-1 ) it was not possible to determine the LC50 value, only the estimated value of 52.24 mg L-1 . After these tests it was possible to quantify the percentage retention of these arsenic species in water, the average retention percentage for both species being 80 %. From the analyses of lipid peroxidation in muscle, liver, and gill tissues, it can be stated that there was no increase in lipid peroxidation under the conditions evaluated for the liver and gill tissues. While for the muscle tissue there was a significant increase in the concentration of MDA, indicative of lipid peroxidation, consequently, causing some type of cellular damage. The analysis of the antioxidant enzymes (SOD and CAT) and detoxification (GST) in the muscle tissue indicated that As(III) did not cause a decrease in the activity of these enzymes. The low percentage of bioaccumulation of As(III) (0.01 %) corroborates with the toxicity mechanism data. Regarding the results of environmental monitoring at CELMM, for the water samples the average concentrations of total Hg, INOHg and ORGHg, respectively, were: sampling 1 (1.97 g L-1 , 0.37 g L-1 and 1.60 g L-1 ), sampling 2 (2.31 g L-1 , 0.42 g L-1 and 1.90 g L -1 ) and sampling 3 (0.63 g L-1 , 0.07 g L-1 and 0.58 g L-1 ). These concentrations were higher than the 0.02 g L-1 allowed by the current legislation (CONAMA 430/05). The average concentration of sururu for samples 1 and 2 was 0.29 and 0.22 mg Kg-1 , respectively, being within the allowed by the legislation (ANVISA 42/13). Comparing the results obtained with the work of Silva et al. (2021), where the authors determined the concentration of total Hg in water samples analyzed in 2017, in the last four years, there was an increase of up to 150 times of the concentration of total Hg. Given the results obtained, for the arsenic toxicity mechanism study, it can be inferred that Nile tilapia has high resistance to As(III) species, but that chronic toxicity studies should be conducted. Based on the results obtained in the monitoring study of CELMM, it can be stated that emergency public policies are needed to solve this contamination.

BANKING MEMBERS:
Externo à Instituição - Marco Tadeu Grassi - UFPR
Externa à Instituição - Lílian Lefol Nani Guarieiro
Interna - 2022362 - ANA CATARINA REZENDE LEITE
Presidente - 1997465 - DANIELA SANTOS ANUNCIACAO
Interno - 1613338 - JOSUE CARINHANHA CALDAS SANTOS