Banca de QUALIFICAÇÃO: SELMA MARIA DE ARRUDA SILVA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : SELMA MARIA DE ARRUDA SILVA
DATE: 01/12/2025
TIME: 14:30
LOCAL: Google Meet
TITLE:

COMPLEX GEOENVIRONMENTAL INTERACTIONS: SUPPLY OF MICROPLASTICS IN THE WESTERN AMAZON

KEY WORDS:

Polymers, Microplastic particles, Freshwater, Sediment, Zooplankton, Cyanobacteria.

PAGES: 96
BIG AREA: Ciências Humanas
AREA: Geografia
SUBÁREA: Geografia Regional
SUMMARY:

Currently, the mass production and consumption of plastics is driven by contemporary lifestyles, marked by practicality and the use of disposable materials. The aim of the research was to analyze microplastics and the interface with microorganisms (zooplankton, protozoa and cyanobacteria), considering the seasonal water scale in cities in the interior of the state of Rondonia in urban effluents, fish farm effluents and preservation areas. The experiment was carried out in a completely randomized factorial design of 3 fish farm effluents x 3 urban effluents x 3 preservation areas, using three replicate samples and two seasonal replicates, as described by Dantas Filho (2023), modified based on the National Oceanic and Atmospheric Administration (NOAA). 500 mL of water were used, filtered through 6.0 mm sieves and quantified using a Neubauer chamber. Microplastics (MPs) were classified by color and expressed as (MPs/250 mL). Zooplankton were collected with a plankton net (mesh size 50 μm) and stored at 7 °C. The abundance of zooplankton and cyanobacteria was assessed directly with a binocular optical microscope (bioval) at up to 400x magnification. Photomicrographs of the pheoplankton were taken with a Canon EOS Rebel T8i camera and Olympus Stream software, and identification was based on species frequency and density expressed in Inds. mL-¹. The abundance of microplastics was shown in terms of mean counts for each site, with standard deviation between the two counts and statistically contrasted using the student's t-test. The abundance of cyanobacteria was identified based on frequency of occurrence (F%) in constant (>50%), accessory (25%-50%) and rare (<25%) categories, density was expressed in cells per mL (cels mL-¹) and calculated according to Weber (1973). For the analysis of protozoa, the study was carried out in a completely randomized 20x3x3 design (20 fish farms, 3 ponds and 3 repetitions per pond), using the method of Costa et al. (2016), 3 water samples at 3 different collection points, in the supply channel, in the water column. The analyses were carried out using a Trinocular stereoscopic microscope (Sigma, USA) with 10x magnification and equipped with a digital camera. The images were then taken using a professional camera (Canon Rebel T8i EF-S 18-55 mm). To aid interpretation, the photomicrographs were analyzed using Olympus Stream image analysis software. The protozoa were counted and identified in triplicate in 1 mL Neubauer chambers, Patterson (1996), the abundance was calculated by taxonomic level, phylum, order, class, family and species, and the density presented by individuals in mL (Ind./mL-1). The results of the analysis of zooplankton richness showed a greater predominance of Copepoda, Rotifera and Ostracoda in fish farm effluents, while the abundance of cyanobacteria varied significantly between the dry and rainy periods, providing moderate tolerance to seasonal changes. Protozoa reduced in density in the dry season, which may have been influenced by the accumulation of organic matter and its potential as an environmental indicator. In conclusion, the results highlight the impacts of microplastics on the dynamics of these ecosystems, pointing to the need for structural changes in plastic consumption and greater awareness of sustainable practices.

COMMITTEE MEMBERS:
Presidente - 1680831 - ADRIANA CRISTINA DA SILVA NUNES
Externo à Instituição - FRANCISCO CARLOS DA SILVA - São Lucas
Interno - ***.118.225-** - JULIEN MARIUS REIS THEVENIN - UNESP
Interno - 2313615 - MICHEL WATANABE
Interno - 1692690 - RANIERE GARCEZ COSTA SOUSA