Banca de QUALIFICAÇÃO: ALDANI BRAZ CARVALHO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : ALDANI BRAZ CARVALHO
DATE: 01/03/2025
TIME: 13:00
LOCAL: Google Meet: https://meet.google.com/qbn-qibx-dhs
TITLE:

Identification, Typification, and Dynamics of Microplastics in Rainfall in Urban and Forest Areas of the Brazilian Amazon

KEY WORDS:

Microplastics; Jaru Biological Reserve; Porto Velho; Rainfall.

PAGES: 134
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geografia Física
SPECIALTY: Climatologia Geográfica
SUMMARY:

Microplastics are synthetic plastic particles less than 5 mm in length. Due to their size, resistance to the elements and presence in different biomes, they have been a growing concern as they can pose risks to both wildlife and humans. Therefore, the objective of this research was to investigate the relationship between microplastics and atmospheric processes, as well as to examine the presence, concentration and typology of these precipitated particles in two areas of the Brazilian Amazon: Porto Velho-RO and the Jaru Biological Reserve-RO. In this context, eight sampling campaigns were carried out at 15-day intervals throughout the period from 2022 to 2023. This time window was defined as covering both the rainy and dry periods. During the collections, two Ville de Paris rain gauges were used to capture rainwater samples. Furthermore, microplastics were quantified and characterized according to their shape, chemical composition and color. The results found suggest that the presence of microplastics may be related not only to land use and coverage, but also to atmospheric circulation. The concentration of microplastics was higher in the site with a predominance of anthropogenic action - Porto Velho - with an average of 7.3 particles/m²/day, than in REBIO Jaru, with an average of 1.7 particles/m²/day. In relation to the dominant circulation, in Porto Velho the concentration of these particles was higher when the atmospheric circulation was long-distance - 16.7 particles/m²/day - than in situations of regional circulation - average of 2.55 particles/m²/day. Fragments (69%), followed by fibers (31%) were the predominant forms of microplastics in rainwater from the two sampled sites. An additional source of these particles can be attributed to waste incineration, an aspect particularly relevant in the region studied. This is due to the common practice of burning household waste on vacant land. Regarding climatological variables, wind speed proved to be a relevant component for the concentration of these particles. At REBIO Jaru, the Pearson correlation was negative and extremely strong (p= -0.96), so that at this site days with stronger winds tend to have lower concentrations of microplastics. On the other hand, Porto Velho showed a moderate correlation (p= 0.6) and this is indicative that in this place days with stronger winds tend to have higher concentrations of microplastics. In relation to rainfall, Porto Velho has a very weak negative correlation (p = -0.03). While in REBIO Jaru the negative correlation was moderate (p = -0.61). Therefore, surveys carried out at REBIO Jaru show a more pronounced correlation with both rainfall indices and wind speed. In this context, climatological attributes assume greater relevance for the concentration of these particles compared to Porto Velho, where the nature of the environment provides a variety of local sources that can conceal the impact of climatological components. In relation to the average size per format, at REBIO Jaru the fibers had an average size of 35 µm and fragments were 25 µm. In Porto Velho, the fragments had an average size of 34 µm and fibers 140 µm. This difference may be associated with the contrast in land use and cover of the sample sites. In the biological reserve, there is less anthropogenic activity than Porto Velho and, therefore, fewer sources of microplastics in the local environment. As a consequence, smaller particles - which face less air resistance to atmospheric transport - prevail in the reserve. Regarding the predominant wind direction, there was no relationship that stood out from the analysis horizon. Regarding color, microplastics in the black category were the most abundant (42%), followed by red (32%), blue (16%) and white-transparent (11%). Therefore, the results obtained showed that microplastics are contaminants present in the Brazilian Amazon and their concentration and distribution is mainly influenced by anthropogenic activities, wind speed and dominant atmospheric circulation.

COMMITTEE MEMBERS:
Presidente - 3102827 - JOAO PAULO ASSIS GOBO
Interno - 396929 - DORISVALDER DIAS NUNES
Interno - 2313615 - MICHEL WATANABE
Externa à Instituição - ANDREIA NEVES FERNANDES - UFRGS
Externo à Instituição - EMERSON GALVANI - USP