Thermal structure of the Poraqu那 lake, Central Amazonian, Brazil = Estrutura t谷rmica do lago Poraqu那, Amaz nia Central, Brasil

作者：Fabio Marques Aprile

来源：Acta Scientiarum - Biological Sciences, 2011.

• stratification
• vertical mixing
• hydrological cycle
• TKE
• tropical lake
• Amazon floodplain
• estratifica o
• mistura vertical
• ciclo hidrologico
• energia cinetica turbulenta
• lago tropical
• planicie de inunda o

Thermal gradient of a Central Amazonian lake was studied to establish a link between seasonal variations in the water level, temperature, suspended particulate matter (SPM) and thermal stratification. Bimonthly measurements of temperature and PAR radiation were made at 0.25 m intervals from the surface to bottom from February 2004 to July 2006. Daily occurs full vertical mixing of the water column, and classic thermal stratification was not observed in the period. The effect of the winds associated to flood-pulse and the penetrativeconvection, transported the turbulent kinetic energy (TKE) into the lake mixing the column of water. This phenomenon was more expressive in the rainfall seasons when is generally higher contributing to the circulation of the water. The limit of the euphotic zone ranged from 1.36 to 1.77 m in the period studied. The results of the transmission curves for the sampling sites showed that, in general, less than 0.01% of the surface light reached the bottom. The trend curve developed can facilitate the understanding of the limnological and ecological processes in lentic systems of whitewaters of the Central Amazonian. Foi estudado o gradiente t谷rmico de um lago da Amaz nia Central para estabelecer associa o entre varia es sazonais no n赤vel de 芍gua, temperatura, material em suspens o e estratifica o t谷rmica. Bimestralmente, foram medidas a temperatura e a radia o luminosada superf赤cie ao fundo do lago no per赤odo entre fevereiro de 2004 e julho de 2006. Ocorreu completa mistura vertical di芍ria da coluna de 芍gua, n o sendo observada estratifica o t谷rmica cl芍ssica no per赤odo. A energia cin谷tica turbulenta (ECT) proveniente da a o dos ventos em associa o com o pulso de inunda o foi respons芍vel pela mistura da coluna de 芍gua. Esse fen meno foi mais expressivo no per赤odo chuvoso, quando a ECT 谷 geralmente mais alta, contribuindo para a circula o da 芍gua. A extens o da zona euf車tica variou de 1,36 a 1,77 m. Os resultados das curvas de transmiss o para os pontos de amostragem mostraram que menos de 0,01% da luz de superf赤cie alcan ou o fundo do lago. A curva de tend那ncia desenvolvida poder芍 facilitar a compreens o dos processos limnol車gicos e ecol車gicos em sistemas l那nticos de 芍guas brancas da Amaz nia Central.