Banca de DEFESA: Lilian de Castro Moraes Pinto

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Lilian de Castro Moraes Pinto
DATE: 01/07/2023
TIME: 08:30
LOCAL: Videoconferência
TITLE:

Mercury dynamics in the environment and in the aquatic trophic chain in lakes in the Cerrado.

KEY WORDS:

Araguaia River; Geology; Urbanization; Nested; Hg; Food chain; BSAF.

PAGES: 150
BIG AREA: Outra
AREA: Multidisciplinar
SUMMARY:

Mercury (Hg) is a chemical element naturally available in the Earth's crust; however, due to its ability to bioaccumulate in organisms, and biomagnify along the trophic chains, it has become a matter of global concern. In this research, a survey on mercury research in Brazil was initially carried out (Chapter 3). Because there were few studies on this topic in Biomes other than the Amazon, the general objective of this study was to determine the concentration of Hg in environmental and biological compartments of aquatic ecosystems in the Cerrado Biome, in order to assess the risk to the human population and the possibility of using mercury as a tool to identify the trophic level of fish species. For this research, there was sampling of water, sediments, plankton and fish in 50 lakes along 750km of the Middle Araguaia River floodplain. The results indicated that the interaction between land use and geological formation at each sampling point influenced the concentration of total mercury (THg) in bottom sediments and physicochemical parameters of the water: pH, conductivity and TDS (nested ANOVA: p < 0.05), revealing that this interaction is a relevant factor for the presence of THg in the Araguaia River. Mercury concentrations were significantly lower in Quaternary terrains (p < 0.0003) and differed significantly between non-urban and urban areas in Neoproterozoic terrains (p = 0,02) (Chapter 5). Results showed that mercury enters the aquatic trophic chain in this region, undergoing biomagnification as it approaches the top of the food chain. With regard to fish, species such as the “dourada” (Pellona castelnaeana) and the “cruzador” (Agoniates halecinus) were identified, among others, with mercury concentrations above the limit considered safe for human consumption, increasing the need for monitoring the environmental health of the Araguaia River (Chapter 6). The intraspecific comparison of mercury concentration in fish showed difference between individuals captured in different places. It is known that spatiality interferes with the trophic position of a species and statistical analyzes revealed that the trophic level of a species considering the size of each individual explains 97% of the variability in the concentration of THg in all fish species studied. Multiple regression analysis confirmed that standard length and FishBase values (trophic levels) are positively associated with THg (R2 = 0.980). These results point to Hg, and its biota-sediment accumulation factor, as viable indicators of the trophic position of a fish species, since they reflect local biological and environmental factors, as demonstrated here for the Middle Araguaia River (Chapter 7).

COMMITTEE MEMBERS:
Presidente - 1412797 - JOSE VICENTE ELIAS BERNARDI
Externo ao Programa - 1122801 - JURANDIR RODRIGUES DE SOUZA - nullInterno - 1524495 - LUDGERO CARDOSO GALLI VIEIRA
Externo à Instituição - OLAF MALM - UFRJ
Externo à Instituição - WANDERLEY RODRIGUES BASTOS - UNIR