Luiz Fernando Coutinho de Oliveira

Sorption isotherm of heavy metals in soils of 'Cerrado' of Goiás

A contaminacao do solo e das aguas subterrâneas por metais pesados e, extremamente perniciosa por serem basntante persistentes no ambiente. Objetivou-se, com este trabalho, a analise da sorcao do Cu, Cr, Zn, Cd, Pb e Ni em Latossolo Vermelho Acriferrico (LVwf), Argissolo Vermelho Eutrofico (PVe), Nitossolo Vermelho Eutroferrico (NVef) e Neossolo Quartzarenico (RQ) pelos modelos potencial e linear da isoterma Freundlich. Para o estabelecimento de isotermas de sorcao adicionaram-se a 5,0 mL de solo e 50,0 mL de solucao contendo o metal pesado a ser avaliado com diferentes concentracoes, respeitando-se os limites aceitaveis. As isotermas de sorcao potencial e linear apresentaram bom ajuste para descrever o comportamento de adsorcao dos metais pesados nas diferentes classes de solo estudadas. A sequencia da retencao dos metais pesados em ordem decrescente, foi, para: o PVe: Cr+3 > Cr+6 > Ni+2 > Zn+2 > Cu+2 > Pb+2 > Cd+2; o LVwf: Cr+3 > Cr+6 > Ni+2 > Cu+2 > Cd+2 > Zn+2 > Pb+2; o RQ: Cr+6 > Cr+3 >Cu+2 > Pb+2 > Ni+2 > Zn+2 > Cd+2 e, para, o NVef: Cr+3 > Cr+6 > Pb+2 > Cu+2 > Zn+2 > Ni+2 >Cd+2. O RQ foi a classe de solo que apresentou menor retencao de metais em comparacao com as demais classes de solo sendo, portanto, mais vulneravel a contaminacao de aguas subterrâneas.

Adsorption and displacement of the cadmium ion in savannah soils.

Cadmium is commonly found in industrial and urban residues, sewer sludge and fertilizers, and when disposed in the soil can represent risks of pollution of the soil and water. This study aimed to analyze the adsorption and movement of cadmium in Red Latosol, Red Argisol, Red Nitosol and Quartzarenic Neosol found in cultivated areas in the State of Goias. In order to quantify the adsorbed cadmium, 5 mL of oven-dried soil were stirred in beaker, for 24 h, with 50 mL of CaCl2.2H2O (0.01 mol L-1) solution containing different quantities of cadmium (0.10, 1.80, 19.00, 46.60 and 105.70 mg L-1). In the trial of the transport of Cd in soil columns a displacement solution of 105.70 mg L-1 was used. Sorption of Cd was evaluated by potential and linear models of the Freundlich isotherm and the retardation factor (R) and hydrodynamic dispersion coefficient (D) were adjusted by minimizing the sum of squares of deviations between the experimental and simulated breakthrough curve. Both isothermal and linear potential and the adjustment of the transport parameters D and R showed a good fit for describing the adsorption and the displacement of Cd in the different studied soils. The Quartzarenic Neosol showed lower retention of Cd in comparison to other classes of soil, and therefore more vulnerable to contamination of groundwater, followed by the Latosol, Argisol and Nitosol.

Equipamento para determinação da erodibilidade e tensão crítica de cisalhamento do solo em canais de estradas

Water erosion on unpaved roads is directly related with poor drainage. The knowledge of the soil erodibility and critical shear stress is essential for correct design of drainage systems. In this paper equipment was developed which allows to simulate the surface runoff in the road channels and to determine, consequently, the soil erodibility and the critical shear stress for the soil. The equipment consists of a water reservoir, a box to control water level, a channel where the surface runoff simulation is made and a system to store the water and the sediments which are detached by surface runoff. The equipment had a good performance to determine the soil erodibility and the critical shear stress for the soil; however it has inconvenience with respect to labor and the amount of water necessary.