Dinâmica do Carbono e do Nitrogênio Dissolvidos no Rio Amazonas, no Estreito de Óbidos
Visualizar/ Abrir
Data
2019-01-28Autor
http://lattes.cnpq.br/1181052395103997
SAMPAIO, Irene Cibelle Gonçalves
Metadata
Mostrar registro completoResumo
Carbon and nitrogen are fundamental to the structure and physiology of organisms. They play a key role connecting terrestrial and aquatic ecosystems, carbon balance and global climate regulation. To investigate the seasonal and interannual variations of dissolved carbon and nitrogen, and the cause-effect relationship of chemical elements dissolved in the Amazon River, it was performed monthly water sampling in the Óbidos Narrow from January 2012 to May 2017. It were quantified dissolved organic carbon (DOC), dissolved organic nitrogen (DON), nitrate (NO3-), ammonium (NH4+), dissolved inorganic carbon (DIC), alkalinity and pH. The water discharge was obtained through Brazilian Water Agency hydrological station database. DOC was analyzed by Shimadzu TOC-V®, and NO3- and NH4+ by colorimetry on Astoria 2 ®. DON 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 titration Gran (Appolo SciTech, Model AS-ALK2) and pH by electrode sensor (Thermo Scientific). The transport of the constituents was estimated in the LoadRunner program and the chemical species of the DIC, as well as the pCO2 were estimated in the CO2SYS program. In the high water phase, DOC and DON had their transport significantly increased (0.096 and 0.004 Tg. day-1, respectively) compared to the low water phase (0.036 and 0.001 Tg. day-1, respectively). NO3- transport was not seasonally modified (0.003 Tg. Day-1). The NH4+ transport was in mean 0.0003 Tg. day-1 and its seasonal differences were not considered. For the DIC, C_HCO3- and C_CO2* transports, the rising water phase (0.09, 0.06 and 0.03 TgC. day-1, respectively) was not different from the high water phase (0.13, 0.07 and 0.05 TgC. day-1, respectively), and in both phases the transport was higher than in the low water phase (0.04, 0.03 and 0.01 TgC. day-1, respectively ). The transport of C_CO2* did not present a statistically difference between the rising, high and falling water phase (0.04 TgC. day-1). In the Spearman correlation analysis, DOC did not showed a statistical correlation with total alkalinity, pH, CO2, or pCO2. The DOC showed a statistical correlation with the river discharge, but the DIC showed no correlation with the river discharge. The results of present work are numerically similar to other previously made in the Amazon River. It shows that changes in land cover in the last decades appear to have had no significant effect on carbon and nitrogen transport. Climatic phenomena events, such as El Niño and La Niña, also did not influence the 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 climatic phenomena on the dynamics of dissolved carbon and nitrogen in the river.
Os arquivos de licença a seguir estão associados a este item: