Banca de QUALIFICAÇÃO: INGRID FERREIRA CHAGAS SONEGUETE

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : INGRID FERREIRA CHAGAS SONEGUETE
DATE: 15/07/2026
TIME: 08:00
LOCAL: Sala Licbio (semi-presencial) - Universidade Federal de Rondônia
TITLE:

THE ROLE OF SMALL TERRA FIRME STREAMS IN THE NITROGEN CYCLE (APONIÃ MICROBASIN – CUNIÃ ECOLOGICAL STATION – PORTO VELHO, RONDÔNIA).

KEY WORDS:

Keywords: nitrogen; phosphorus; hydrological seasonality; upland streams; Amazon; hydrobiogeochemistry; Cuniã Ecological Station

PAGES: 56
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUBÁREA: Ecologia de Ecossistemas
SUMMARY:

The dynamics of nutrients in Amazonian streams are influenced by hydrological, sedimentological, and biogeochemical processes that regulate the availability of nitrogen and phosphorus in aquatic ecosystems.

This study evaluated the spatial and seasonal variability of nitrate (NO₃⁻), nitrite (NO₂⁻), ammonia (NH₃), and orthophosphate (PO₄³⁻) concentrations in terra firme streams of the Aponiã Microbasin, located in the Cuniã Ecological Station, Porto Velho (RO). Sampling was carried out during periods of high and low water in first, second, and third-order streams.

The influence of environmental variables was investigated using principal component analysis (PCA), multiple factor analysis (MFA), and multiple regressions with model selection using the Akaike criterion.

Nitrate concentrations showed the greatest variability, reaching up to 10.6 mg L⁻¹ during the high water period, while ammonia varied between 0.011 and 0.064 mg L⁻¹, nitrite between 0.00055 and 0.00426 mg L⁻¹, and orthophosphate occurred at concentrations close to the detection limit.

PCA demonstrated that the first two axes explained 84.2% of the data variability and showed a strong association between nitrogenous forms and the high water period.

Multiple regressions identified the hydrological period as the main controlling factor for NO₃⁻, NO₂⁻, NH₃, and PO₄³⁻ concentrations, while sedimentological characteristics, especially clay and silt content, exerted a complementary influence on nutrient availability.

AFM indicated a weak association between the spatial structure of the microbasin and hydrobiogeochemical dynamics, suggesting greater importance of hydrological and local processes.

The results demonstrate that hydrological seasonality constitutes the main regulatory mechanism of nitrogen and phosphorus dynamics in the streams of the Aponiã Microbasin, while sedimentary characteristics modulate their retention and local distribution, contributing to the understanding of hydrobiogeochemical processes in preserved Amazonian aquatic ecosystems.

COMMITTEE MEMBERS:
Presidente - 1632974 - ANGELO GILBERTO MANZATTO
Interno - 359961 - WANDERLEY RODRIGUES BASTOS
Interno - 1905088 - RONALDO DE ALMEIDA
Externo ao Programa - ***.908.872-** - SUSAMAR PANSINI - UNIR