Search

Contamination of soil with petroleum is common in oil-producing areas across the tropical regions of the world. There is limited knowledge on the sensitivity of endogeic tropical earthworms to the contamination of soil with total petroleum hydrocarbons (TPH) present in crude oil. Pontoscolex corethrurus is a dominant species in tropical agroecosystems around oil-processing facilities. The sensitivity of P. corethrurus to soil artificially contaminated with 'Maya' Mexican heavy crude oil was investigated through avoidance and acute ecotoxicity tests, using the following measured concentrations: 0 (reference soil), 551, 969, 4845, 9991 and 14,869 mg/kg. The avoidance test showed that P. corethrurus displayed a significant avoidance behavior to heavy crude oil at a concentration of 9991 mg/kg or higher. In contrast, acute toxicity tests indicate that the median lethal concentration (LC) was 3067.32 mg/kg; however, growth (weight loss) was more sensitive than mortality. Our study revealed that P. corethrurus is sensitive to TPH, thus highlighting the importance of P. corethrurus for petroleum ecotoxicological tests. [ABSTRACT FROM AUTHOR]

Microbiological activities are essential in the bioremediation of polluted soils. The enzymatic activities of microorganisms are usually used as a biological indicator of soil health. The aim of this work was to observe the catalase, acid phosphatase (AcP), and alkaline phosphatase (AlP) activities in soil that was amended with agro-industrial by-products and macronutrients during the process of total petroleum hydrocarbon (TPH) removal. To this end, microcosm tests were performed with soil and agro-industrial by-products ratios of 100:2:2, for soil:sugarcane bagasse pith:filter cake mud (SSF); 100:2, for both soil:sugarcane bagasse pith (SS); and for soil filter cake mud (SF). The macronutrients-carbon, nitrogen, and phosphorus-in the experimental treatments were adjusted to 100:10:1 with a solution of NHNO and KHPO. The best TPH removal (51.4%) was obtained with SSF at 15 days. In addition, a significant correlation was observed between TPH removal and AlP as well as AcP ( r = 0.74, p < 0.0001; r = 0.70, p < 0.0107, respectively). Fungi growth was also correlated with both AlP ( r = 0.97, p < 0.0001) and AcP ( r = 0.95, p < 0.0001) activities. Besides, bacterial and fungi growth showed a correlation with TPH ( r = 0.86, p < 0.001; r = 0.77, p < 0.0034, respectively). It could be said that the agro-industrial by-products and macronutrients contributed to pollutant removal from the oil-polluted soil at relatively short amount of time. In addition, the enzymatic activities were increased after the treatment; in this study, the high sensitivity enzyme was AlP, and it could be used as an indirect indicator of oil pollutant removal. [ABSTRACT FROM AUTHOR]