Banca de DEFESA: ALDANI BRAZ CARVALHO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : ALDANI BRAZ CARVALHO
DATE: 10/05/2025
TIME: 08:00
LOCAL: Google Meet: meet.google.com/vhb-bmss-pgy,
TITLE:

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

KEY WORDS:

Microplastics; Amazon; Jaru Biological Reserve; Porto Velho; Rainfall.

PAGES: 201
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geografia Física
SPECIALTY: Climatologia Geográfica
SUMMARY:

Microplastics are synthetic plastic particles smaller than 5 mm in length. Due to their size,
resistance to weathering, and presence in different biomes, they have become a growing
concern. The objective of this research was to investigate the relationship between
microplastics, meteorological variables (wind, rain, air temperature, and relative humidity), and
local characteristics, 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 conducted at 15-day
intervals from 2022 to 2023. This time frame was chosen to cover both the rainy and dry
seasons. During the collections, two Ville de Paris rain gauges were used to capture rainwater
samples. Additionally, microplastics were quantified and characterized according to their
shape, chemical composition, and color. The results showed average concentrations of 4
particles/m2/day in Porto Velho and 1 particle/m2/day in the Jaru Biological Reserve, with no
statistically significant difference (Mann-Whitney test, p-value = 0.2873), suggesting that the
sources of these particles are regional. The polymer composition varied between the sites:
chlorinated polyethylene (59%) and crosslinked sulfonated polystyrene (35%) predominated in
Porto Velho, while nylon (80%) was the main polymer in the Jaru Biological Reserve. The
particles in Porto Velho were larger (54 μm for fragments and 156 μm for fibers) compared to
those in the Jaru Biological Reserve (25 μm for fragments and 35 μm for fibers), reflecting the
influence of local sources and anthropogenic activities in the urban area. The analysis of
meteorological variables revealed distinct patterns. In the Jaru Biological Reserve, relative
humidity, wind speed, and precipitation showed strong negative correlations with microplastic
concentrations (rs = -0.76, -0.80, and -0.80, respectively), indicating that these factors acted as
removal mechanisms for particles from the atmosphere. In Porto Velho, only relative humidity
showed a strong negative correlation (rs = -0.85), while wind speed showed a moderate positive
correlation (rs = 0.41), suggesting that winds acted as vectors for the resuspension and transport
of microplastics from local sources. Seasonality also influenced concentrations, with higher
values during the dry season at both sites. In Porto Velho, the total concentration was 21
particles/m2/day during the dry season, decreasing to 7 particles/m2/day during the rainy season.
In the Jaru Biological Reserve, no particles were detected during the rainy period, while the
total concentration during the dry season was 8 particles/m2/day. This pattern can be attributed
to reduced precipitation and increased temperatures during the dry season, which favored the
retention and resuspension of particles in the atmosphere. The analysis of atmospheric
circulation, wind direction, and the HYSPLIT model product did not reveal a clear and
consistent relationship between air masses and microplastic concentrations. Therefore, although
anthropogenic activity and land use and cover are relevant factors, they are not the sole
determinants in the distribution of these pollutants, indicating the influence of other
mechanisms that are not yet understood.

COMMITTEE MEMBERS:
Interna - 1680831 - ADRIANA CRISTINA DA SILVA NUNES
Interno - 396929 - DORISVALDER DIAS NUNES
Externo à Instituição - EMERSON GALVANI - USP
Presidente - 3102827 - JOAO PAULO ASSIS GOBO
Interno - 2313615 - MICHEL WATANABE