Spatio-temporal variability of CO2 and CH4 concentration and flow in the lower Amazon region

• Grant number: 20/15375-3
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: January 01, 2022
• End date: August 31, 2024
• Field of knowledge: Biological Sciences - Ecology - Ecosystems Ecology
• Principal Investigator: Maria Victoria Ramos Ballester
• Grantee: Maria Gabriella da Silva Araújo
• Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Continental aquatic ecosystems are important contributors to the global carbon balance. The lower Amazon region alone is responsible for about 25% of global CO2 and CH4 emissions from rivers. With the justification of dedicating efforts to understand how the hydrodynamics of the final portion of the Amazon River basin influences environmental variables, this study aim evaluates the dynamics of CO2 and CH4 over 5 hydrological years (2014 to 2019) in the region of the lower Amazon. In all, eight campaigns were carried out in different hydrological periods (rising, high, falling, and low water), at 8 points. 6 in the main channel (Óbidos-PA, Almeirim-PA, north and south channels in front of Macapá- AP, Bailique-AP and Chaves-PA) and 2 points in the two main clear water tributaries (Xingu and Tapajós river). In all sampling campaigns and collection stations in the main channel, measurements of flow, water speed, and river depth were performed. The determination of pCO2, pCH4, and the ´13C isotopic composition of these gases in the river water was performed in real-time, in situ, using the analyzer coupled to a balancing system. Besides, samples of CO2 and CH4 were also obtained via headspace, for analysis in the laboratory by direct absorption spectroscopy. In situ, the CO2 flux of the river was determined in real-time using an infrared gas analyzer connected to a floating chamber. The flux of CH4 was determined using its concentration escaped from the river water and accumulated in floating chambers. Environmental parameters (dissolved oxygen, pH, electrical conductivity, water and air temperature and wind speed) were also determined in situ.

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

ARAÚJO, Maria Gabriella da Silva. Spatiotemporal variability of carbon dioxide (CO2) and methane (CH4) concentration and flux in the Lower Amazon region. 2024. Doctoral Thesis - Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) Piracicaba.