Influência do tratamento de lavagem de resíduos de perfuração de poços de petróleo no desenvolvimento de plantas de arroz (Oryza sativa)

Abstract

A major environmental issue is the impact caused by the extraction of primary materials and the waste disposal. The industry tries to change that with adjustments in the production chain to reduce impacts to the environment. However, this is a subject that has few studies. This study aimed to evaluate the development of rice plants (Oryza sativa) in soils incubated with waste from drilling oil wells, treated by washing to eliminate the influence of sodium and under two moisture conditions. Two residues generated during the drilling of the well 7-SMC- 50D AL were selected. Subsequently, the residue washing was done in water with the 1:5 proportions, to reduce the effects of sodium. Thus, the washing treatment defined two conditions: washed and unwashed residues. The amount of residue added to the soil was set to achieve concentrations of barium of 300 mg kg-1, 600 mg kg -1 and 900 mg kg-1. The soils were kept in two moisture conditions (70% of field capacity and waterlogged to get a reduced condition). During the incubation of vessels the redox potential (Eh) was monitored until values close to -200 mV was reached, in the reduction condition. After reaching these values, we waited up to 30 days before transplanting the rice seedlings and the test starting. Samples were collected from each experimental unit, and the elements barium, iron, manganese, calcium, sodium and potassium were analyzed. The rice was planted, and went throughout the vegetative cycle (approximately 3 months) until the plants were harvested for analysis. The results showed that the residues from the dryer and the centrifuge, with and without washing, in the oxidized condition, did not affect the dry matter yield of the rice plants. However, the soil reduction condition promoted increasing concentrations of barium absorbed by plants, and reduced the iron level. In the treatments with the residue and reduction condition, the solubilization of barium combined with a moderate iron deficiency possible interfered on dry matter production.