Efeitos provocados por agroquimicos livre ou ancorados em silica gel na microbiota do solo

AUTOR(ES)
DATA DE PUBLICAÇÃO

2001

RESUMO

The herbicides 2,4-D, diuron and picloram have been chemically immobilized onto silica gel surface producing new materiais named SiD, SiDi e SiPi, respectively. Immobilized amounts of the pesticides 2,4-D, diuron and picloram were 1.03; 0.79 and 1.11 mmol g, respectively. Free and immobilized herbicides have been applied in red Latossol soil and effects caused in soil microbiota was followed by microcalorimetry. The herbicides diuron and picloram affected toxically the soil microbial activity, delaying the metabolism and also presented a inhibition of 96,4 % to 333,33 mg g of diuron dose and 87,4 % to 10,00 mg g of picloram dose, while the same doses of these immobilized pesticides caused an inhibition of only 39,5 e 54,6 %, respectively. The herbicide 2,4-D presented adverse effects, firstly it was biodegraded and in sequence it presented toxic effects to soil microbiota. The silica modified with 2,4-D presented a reduction of tre biodegradation rate. The silicas modified with 2,4-D and picloram was applied in removing and in separating cations from solvents as well. The maximum adsorbed amounts for divalent cations Cu, Ni, Zn and Cd were 4.42; 3.25; 2.67 and 1.35 x 10-4 mol g-1 to SiD surface and 9,27; 7,59; 5,12 and 1,54 x 10 mol g to SiPi, respectively. These modified silicas also present a high ability to separate and preconcentrate these cations with concentration factor of 16 times. SiD surface presented a high adsorption and preconcentration capacity of the pesticide 2,4-D. The immobilization proposed of the pesticides onto silica gel surface showed a new research way to develop pesticides with lowest toxicity, and besides, these matrices can be applied to remove inorganic contaminants from solvents.

ASSUNTO(S)

biodegradação pesticidas pesticidas

ACESSO AO ARTIGO

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