Avaliação dos impactos ambientais associados ao descarte inadequado de óleos vegetais residuais em solos Brasileiros

Abstract

When disposed directly into the soil, the residual vegetable oil occupies spaces that would, naturally, be occupied by water and air, causing it s waterproofing of the same. In addition, the fauna and the flora in this place are prevented from absorbing nutrients and end up dying, as well as preventing seeds germination, turning the soil unsuitable for cultivation. Depending on the soils physical-chemical caracteristics and other characteristics such as relief and pluviometric regime, it can migrate to reach water bodies and even the water table. The present study evaluated the impacts associated with the inadequate disposal of residual vegetable oil in the water-soil-plant system. For this, two soils with different textures were used. The effects of OVR on physical and chemical soil aspects (leaching column) were also analyzed. As well as the potential for OVR biodegradation in soils. Different test organisms were used for each component of the system, such as Brachydanio for aquatic toxicity, Eisenia fetida for soil toxicity, as well as seed and lettuce (Lactuca sativa L.) as test organism for higher plants. From obtained results, was verified that the OVR is a potentially contaminant residue when unduly disposed on the soil, compromising the soil-plant system. After the saturation test, the sandy soil had a slightly lower adsorption capacity of OVR than the clayey soil. It was observed that the introduction of OVR caused severe compaction for the clayey soil. The toxicity for earthworm leakage test was obtained with the doses of 20 mL and 26 mL, that lettuce (Lactuca sativa L.) had low tolerance to OVR and negatively influenced the germination process, radicle growth and hypocotyl in the tests of Ecotoxicity for sandy and clayey soil respectively. It can be inferred that the different treatments tested with OVR in lettuce (Lactuca sativa L.) cultivation caused changes in plant morphology for all physical parameters analyzed in both soils. The results indicated that the OVR had expressive percentages of biodegradation, in relation to the treatment with 1% of glucose, for both soils. The treatment with 20 mL in sandy soil was more impacting for 50% of the analyzed parameters. The treatment with 26 mL in clay soil was more impacting for 67% of the analyzed parameters. The introduction of OVR in the columns promoted pH acidification for all treatments in both soils in the first sections (0-10 cm). For sandy soil, the first section was the most impacted for pH, Ca2+, Mg2+, and V%. The last sections (30-40 cm) were more impacted for H+ + Al3+ and the last one for K+. For clayey soil, the first section (0-10 cm) was the most impacted for pH, H+ + Al3+ and V%. The second section (10-20 cm) was the one with the greatest impact on K+. The doses that produced the greatest negative impact were 20 mL for the sandy soil and 26 mL for clayey soil. The fish test (Brachydanio) did not present any mortality for the analyzed period