Resumo

MORALES-BAUTISTA, Carlos; DOMINGUEZ-RODRIGUEZ, Verónica  e  ADAMS, Randy H. Kinetic study of cation exchange with Ca(OH)₂ and fertility evaluation in a clay soil contaminated with saline process water. Bioagro [online]. 2011, vol.23, n.2, pp.129-134. ISSN 1316-3361.

The saline process water is found in the rock associated with the presence of hydrocarbons, and the high concentration of its components may cause negative impacts to the environment when handling and disposal are inadequate. The objective of this study was to evaluate the feasibility of using Ca(OH)₂ for the treatment of a clay soil impacted by process water (a petroleum production waste) including the reaction kinetics and the primary productivity of forage pastures in treated soil. A spill was simulated contaminating the soil with process water, and the material was treated with 21.5 Mg·ha^-1 of the product per application into two lots with four different times: in one lot treatments were applied for two and four days, and in the other, treatments were applied for three and six days. The reaction kinetics indicated a treatment period of about 26 hours to reduce the ESP from 47.2 to 15 %, and almost six days to reduce the EC from 14 down to 4 dS·m^-1. Problems were encountered with the establishment of the grass Brachiaria humidicola, probably due to the alkalinity of the freshly treated material (pH = 9).  None-the-less, the grass Brachiara decumbens was tolerant to the alkalinity and showed a good development.  On the other hand, on weather conditions, the soil showed important reductions in the pH due to natural precipitation (from 9.4 to 7.2 in six months).  The results indicate that it is possible to use Ca(OH)₂ for the treatment of soils contaminated with process water, and still obtain adequate reductions in salinity and sodicity, thus allowing adequate crop productions.

Palavras-chave : Petroleum wastes; remediation; salinity; exchangeable sodium.