Hydric balance and climatic classification of the city of Porto Nacional, state of Tocantins, inserted in the Legal Amazon, Brazil

The objective of this study was to carry out the Climatological Water Balance in conjunction with the climatic characterization, using precipitation and air temperature data in the municipality of Porto Nacional, belonging to the Legal Amazon, Tocantins state, by Thornthwaite and Mather (1955) for 20 years, from 1997 to 2016. From the results of potential evapotranspiration, real evapotranspiration, water surplus and water deficit, the water, aridity and humidity indices were established based on the number of continuous data from the conventional meteorological station , of WMO Code 83064, of the National Institute of Meteorology, located in the district Setor Aeroporto, municipality of Porto Nacional. The climatic formula obtained for the municipality of Porto Nacional was C2wA'a ', which characterized the climate in wet subhumid, with two well defined seasons, rainy and dry, being the dry season in the winter season where it presents moderate water deficiency and megatérmico, with values high annual evapotranspiration potential, with 28.29% of this evapotranspiration concentrated in the summer season

Adsorção de cobre em amostras de Plintossolo do Estado do Piauí, com diferentes características Copper adsorption in Plinthosol samples from Piauí State, Brazil, with different characteristics

A capacidade de adsorção de cobre pelo solo é um dado importante em estudos de movimentação de solutos uma vez que, se a capacidade adsortiva de um solo for ultrapassada, o metal ficará potencialmente disponível para ser lixiviado. Neste trabalho se analisam o comportamento da adsorção de cobre face às diferentes características de amostras de Plintossolo e a influência da variação de pH na adsorção do cobre, verificando-se a adequação das equações de Langmuir e Freundlich para descrever a adsorção deste elemento. Soluções de cloreto de cobre foram utilizadas nas concentrações 6, 10, 20, 40, 60 e 80 mg L-1 ajustadas a pH 4,0, 5,0 e 6,0. Os teores de matéria orgânica e a capacidade de troca catiônica das amostras de solo compõem as propriedades que mais influenciaram na adsorção do cobre. Os modelos de Langmuir e Freundlich mostraram-se igualmente capazes para descrever o comportamento do cobre nas diferentes amostras de solo estudadas. A adsorção do cobre variou em função do pH ocorrendo maior adsorção no pH 6,0.<br>Copper adsorption by soil is very important, as after soil adsorptive capacity is exceeded, the metal become potentially available for leaching. The objectives of this study were to analyze copper adsorption considering different properties of soil samples studied, to evaluate the influence of the pH level on copper adsorption and to verify if Langmuir and Freundlich isotherms describe adequately the copper adsorption. Solutions containing different copper concentrations (6, 10, 20, 40, 60 e 80 mg L-1) were adjusted to pH 4.0, 5.0 and 6.0. The organic matter content and cation exchange capacity were the soil properties that most influenced copper adsorption. Langmuir and Freundlich models offered a good fit for the experimental data. Copper adsorption varied with soil pH, with greater adsorption at pH 6.0