Banca de DEFESA: IRENE CIBELLE GONÇALVES SAMPAIO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : IRENE CIBELLE GONÇALVES SAMPAIO
DATA : 28/01/2019
HORA: 14:00
LOCAL: Auditório do NTB
TÍTULO:

Dynamics of Dissolved Carbon and Nitrogen in the Amazon River, in the Óbidos narrow.

PALAVRAS-CHAVES:

Amazon River, Carbon, Nitrogen and Land cover change.

PÁGINAS: 93
GRANDE ÁREA: Outra
ÁREA: Ciências Ambientais
RESUMO:

Carbon and nitrogen are fundamental to the structure and physiology of organisms and play a key role in the connection between terrestrial and aquatic ecosystems, carbon balance and global climate change. Monthly samples of surface water (filtered at 45μm) were collected from the Amazon River, in the Óbidos Narrow, from January 2012 to May 2017, to investigate seasonal and internal variations of dissolved carbon and dissolved nitrogen, identifying its correlation with water flow, water chemistry and vegetation cover change of the drainage basin. Samples of water for quantification of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), nitrate (NO₃) and ammonium (NH₄) were preserved frozen and for quantification of DIC, alkalinity and pH were preserved with mercury chloride. The DOC was analyzed by Shimadzu TOC-V®, NO₃ and NH₄ by colorimetry in the Astoria 2®. NOD was obtained by subtraction of total inorganic nitrogen (detected by chemiluminescence).The DIC was analyzed in the Apollo SciTEch, Model AS-C3 via acidification. Alkalinity by Gran titration (AS-ALK2, Appolo SciTech) and pH by electrode sensor (Thermo Scientific). The river flow was obtained from the Agencia Nacional de Águas (ANA) station (17050001). The transport of the constituents was estimated in the LoadRunner program and the DIC species in the CO2SYS program. In the High Water, DOC and NOD increased their transport significantly (average 0.096 and 0.004 Tg.day ^-1 respectively), compared to the Low Water (0.036 and 0.001 Tg.day^-1, respectively).NO₃ did not have its transport seasonally modified (0.003 Tg.day^-1). The mean NH₄ transport was 0.0003 Tg.day^-1 and seasonality were not considered. For the CID, C_HCO₃ and C_CO₂*, transports in Rising Water (0.09, 0.06 and 0.03 TgC, day^-1, respectively) was not different from the transport in the High Water (0.13, 0.07 e 0.05 TgC, day^-1, respectively) and in both phases the transport was higher than in the Dry Phase (0.04, 0.03 and 0.01 TgC, day^-1, respectively). The transport of C_CO₂* also showed a significant difference between the Rising (0.04 TgC, day^-1) and Low Phase. For Spearman correlation analysis, COD was not correlated with alkalinity, with pH or with CO₂*. COD was positively correlated with river flow, but CID showed no correlation with flow. The results of this work are numerically similar to other previous estimates for the Amazon River. This shows that, apparently, changes in land use and land cover in the last decades appear do not effect on carbon and nitrogen transport. Climatic phenomena such as El Niño and La Niña also did not influence the annual transport of organic carbon and nitrogen dissolved in the river during the present study. However, only frequent and long-term observations will be able to conclusively evaluate the effect of extreme weather phenomena and possible climate changes on the dynamics of dissolved carbon and nitrogen in the river.

MEMBROS DA BANCA:
Presidente - 1794276 - JOSE MAURO SOUSA DE MOURA
Interno - 1466772 - KEID NOLAN SILVA SOUSA
Interno - 1549120 - RODRIGO DA SILVA
Interno - 1693122 - SERGIO DE MELO
Externo ao Programa - 2160653 - AMANDA FREDERICO MORTATI
Externo à Instituição - VÂNIA NEU - USP