@article{Arias Trinidad_Rivera Cruz_Roldán Garrigós_Aceves Navarro_Quintero-Lizaola_Hernández Guzmán_2017, title={Use of Leersia hexandra (Poaceae) for soil phytoremediation in soils contaminated with fresh and weathered oil}, volume={65}, url={https://revistas.ucr.ac.cr/index.php/rbt/article/view/22967}, DOI={10.15517/rbt.v65i1.22967}, abstractNote={The oil industry has generated chronic oil spills and their accumulation in wetlands of the state of Tabasco, in Southeastern Mexico. Waterlogging is a factor that limits the use of remediation technologies because of its high cost and low levels of oil degradation. However, <em>Leersia hexandra</em> is a grass that grows in these contaminated areas with weathered oil. The aim of the study was to evaluate the bacteria density, plant biomass production and phytoremediation of <em>L. hexandra </em>in contaminated soil. For this, two experiments in plastic tunnel were performed with fresh (E1) and weathered petroleum (E2) under waterlogging experimental conditions. The E1 was based on eight doses: 6 000, 10 000, 30 000, 60 000, 90 000, 120 000, 150 000 and 180 000 mg.kg<sup>-1</sup> dry basis (d. b.) of total petroleum hydrocarbons fresh (TPH-F), and the E2, that evaluated five doses: 14 173, 28 400, 50 598, 75 492 and 112 142 mg. kg<sup>-1</sup> d. b. of total petroleum hydrocarbons weathered (TPH-W); a control treatment with 2 607 mg.kg<sup>-1</sup> d. b. was used. Each experiment, with eight replicates per treatment, evaluated after three and six months: a) microbial density of total free-living nitrogen-fixing bacteria (NFB) of <em>Azospirillum</em> (AZP) and <em>Azotobacter</em> group (AZT), for viable count in serial plate; b) dry matter production (DMP), quantified gravimetrically as dry weight of <em>L. hexandra</em>; and c) the decontamination percentage of hydrocarbons (PDH) by Soxhlet extraction. In soil with TPH-F, the NFB, AZP y AZT populations were stimulated five times more than the control both at the three and six months; however, concentrations of 150 000 and 180 000 mg.kg<sup>-1</sup> d. b. inhibited the bacterial density between 70 and 89 %. Likewise, in soil with TPH-W, the FNB, AZP and AZT inhibitions were 90 %, with the exception of the 14 173 mg.kg<sup>-1</sup> d. b. treatment, which stimulated the NFB and AZT in 2 and 0.10 times more than the control, respectively. The DMP was continued at the six months in the experiments, with values of 63 and 89 g in fresh and weathered petroleum, respectively; had no significant differences with the control (p≤0.05). The PDH reached values of 66 to 87 % both TPH-F and TPH-W at six months, respectively. These results demonstrated the ability the <em>L. hexandra</em> rhizosphere to stimulate the high NFB density, vegetal biomass production and phytoremediation of contaminated soils (with fresh and weathered petroleum), in a tropical waterlogging environment.}, number={1}, journal={Revista de Biología Tropical}, author={Arias Trinidad, Alfredo and Rivera Cruz, María del Carmen and Roldán Garrigós, Antonio and Aceves Navarro, Lorenzo Armando and Quintero-Lizaola, Roberto and Hernández Guzmán, Javier}, year={2017}, month={Mar.}, pages={21–30} }