[Biodegradability in soil of residual hydrocarbons in petroleum tank bottoms]. / Biodegradabilidad en suelo de hidrocarburos residuales en fondos de tanques de almacenamiento de petróleo.

Biodegradability of hydrocarbons on soils can be applied to the treatment of residues (land treatment) from petroleum refinery as well as the cleaning of contaminated soils (bioremediation). In this paper we have studied the biodegradability of hydrocarbons from petroleum tank bottom sludges on soil by the autochthonous microbial community. Lab assays were conducted in 1l-beakers under the following conditions: hydrocarbon load 5.3%, total aerobic microorganisms 2.7 x 10(7) CFU/g, hydrocarbon degrading microorganisms (HDM) 2.5 x 10(5) cells/g, incubation temperature 25 degrees C, pH 7.0-7.6, and moisture 10-15%. Soil had the following composition: sand 25%, silt 15%, and clay 20%. Different levels and kind of fertilizers were evaluated. Fertilization increased the rate and the quantity of hydrocarbons degraded. It was degraded about 40% of hydrocarbons in 30-90 days according to the fertilization effected. During biodegradation, the HDM increased 760 times. Assays conducted outdoor on trays showed a similar limit of biodegradation. Changes with time in the fungi population, hydrocarbon class, carbon level, and saturated hydrocarbon profiles were measured too. Data suggests the use of microorganisms having a greater metabolic capacity, specially to degrade those hydrocarbon classes that they have shown to be more resistant to biodegradation (aromatics, resins and asphaltenes).

Ten-year follow-up in pediatric patients with allergic bronchial asthma: evaluation of specific immunotherapy.

Specific immunotherapy as a treatment for bronchial asthma has been a controversial field. A collaborative study was designed in an attempt to further define the possible contribution of specific immunotherapy in a pediatric population. One hundred and sixty-six patients were treated with immunotherapy and 248 received no immunotherapy. The results were compared during 10 years of follow-up in both groups. There was a significant decrease in the number of acute crisis in the treated group (p < 0.05). However, no differences were seen in the number of hospital admissions or in the quality of life between the treated and untreated groups. The treated group required significantly fewer drugs (p < 0.05). Thus, it is probable that the untreated group shows the same clinical indexes as the treated group due to their increased use of medication. Specific immunotherapy represents an effective treatment that changes the natural course of allergic bronchial asthma in pediatric patients.