Plant communities and potential native phytoremediator species in petroleum hydrocarbon-polluted desert systems

This paper reported the recovery of desert plant communities after twenty years of oil-derived hydrocarbon contamination in desert habitats of Kuwait, caused by the First Gulf War (1990 – 1991). The hypothesis that certain native desert plant species can tolerate weathered oil-polluted soils with oil breakdown products (i.e., polycyclic aromatic hydrocarbons ( PAHs)) and have the potential to function as bioindicators and phytoremediator species for oil-polluted soil was tested. A field survey of 200 quadrat sampling plots at seven hydrocarbon-contaminated and unpolluted desert areas in Kuwait was performed that recorded 42 plant species, with Haloxylon salicornicum, Cyperus conglomeratus and Rhanterium epapposum as the most dominant species. Analysis of plant tissues indicated plant uptake and accumulation of some PAHs. H. salicornicum was used as a representative species in a controlled field study that included growth of plants in hydrocarbon-polluted and unpolluted soils in two separate desert areas under similar growth conditions. Results showed a significant decrease in plant biomass in oil-contaminated soil compared to those from the uncontaminated site. However, the plants appeared green and healthy in both sites, and showed no overt stress. The results suggest that some desert plant communities exhibit signs of recovery after severe oil pollution, and that H. salicornicum may serve as a phytoremediator of oil-contaminated desert soils. Our results also demonstrated that some desert plant communities could be cultivated in oil fields to reduce hydrocarbon contamination and provide guide to other ecosystem services through improving soil quality and biodiversity.

Winter Species Promote Phytoremediation of Soil Contaminated with Protox-Inhibiting Herbicides

ABSTRACT: Phytoremediation comprises one of the main forms of decontamination of organic and inorganic substances in the soil, being economically viable and with a low environmental impact. The aim of this study was to verify the efficiency of winter plant species in the phytoremediation of soil contaminated with fomesafen and sulfentrazone using cucumber as an indicator species to the presence of residue. The experimental design was a completely randomized design arranged in a 6 x 4 factorial scheme with four replications for each herbicide. Factor A consisted of the phytoremediator species black oats, garden vetch, radish, bird’s-foot trefoil, white lupine, and a treatment without prior cultivation. Factor B, on the other hand, consisted of the doses of fomesafen (0.000, 0.125, 0.250, and 0.500 kg h-1) or sulfentrazone (0.000, 0.300, 0.600 and 1,200 kg ha-1) applied in crop pre-emergence. At 45 days after sowing, the phytoremediator species were cut close to the soil. Subsequently, the bioindicator species of herbicide residues in the soil (cucumber) was sown in the pot. Phytotoxicity of herbicides to cucumber plants was assessed at 7, 14, 21, and 28 days after emergence (DAE). At 28 DAE, leaf area, height, and dry matter were determined in the bioindicator plant. Fomesafen and sulfentrazone doses interfered negatively with the assessed variables of cucumber when cultivated in succession to phytoremediator species. Cucumber phytotoxicity increased for all potential phytoremediator species as fomesafen and sulfentrazone doses increased. Sulfentrazone residues promoted the highest toxic effects on the bioindicator plant when compared to fomesafen. In general, black oats, radish, and white lupine were the species with the highest capacity to phytoremediate soil contaminated with fomesafen and sulfentrazone when applying the dose and twice the recommended doses of the herbicides.