Browsing by Author "Benidire, Leila"
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- Do metal contamination and plant species affect microbial abundance and bacterial diversity in the rhizosphere of metallophytes growing in mining areas in a semiarid climate?Publication . Benidire, Leila; Pereira, Sofia I. A.; Naylo, Ahmed; Castro, Paula M. L.; Boularbah, AliPurpose Mining areas are low-quality habitats for macro- and microorganisms' development, mainly due to the degradation of the soil quality by metal pollution. The present work aimed to analyze the influence of metal contamination and of plant species on the rhizospheric microbial communities of four indigenous metallophytes (Ononis natrix, Haloxylon scoparium, Peganum harmala, and Aizoon canariense) growing along a metal contamination gradient in Kettara mine near Marrakech, Morocco. Materials and methods In pyrrhotite mining areas (Kettara mine, Morocco), rhizosphere soil samples were collected from four predominant indigenous metallophytes (O. natrix, H. scoparium, P. harmala, and A. canariense) growing along a metal contamination gradient (ZC, control zone; Z1, high metal contamination; Z2, moderate metal contamination; Z3, low metal contamination). Microbial communities were analyzed by using microbial counts and by denaturing gradient gel electrophoresis (DGGE). The physicochemical properties (pH, conductivity, total organic carbon, nitrogen, P Olsen, and metal concentrations) of soils were also determined. Results and discussion The physicochemical analysis revealed that rhizospheric soils from Z1, Z2, and Z3 were relatively poor in nutrients as they presented low levels of total organic carbon and nitrogen, organic matter and available P. Moreover, these rhizospheric soils showed high concentrations of metals, especially Cu and Pb, which significantly reduced the abundance of the different groups of soil microorganisms (bacteria, fungi, and actinomycetes) and the activity of soil dehydrogenase. The analysis of bacterial communities by DGGE revealed that bacterial diversity was not negatively affected by metal contamination being higher in the most contaminated area (Z1). Conclusions Overall, the microbial abundance, the composition, and the diversity of rhizospheric bacterial communities were more influenced by the environmental factors in sampling zones than by plant cover. Microbial counts and enzymatic activity were both systematically affected throughout the metal gradient, evidencing as good indicators of the harmful effects of anthropogenic disturbances in soils. H. scorparium and P. harmala proved to be good candidates for the development of phytotechnological programs aiming the revegetation of mining degraded areas.
- Physical, chemical, and microbiological characterization of Kettara Mine Tailings, MoroccoPublication . Benidire, Leila; Pereira, Sofia I. A.; Loqman, Souad; Castro, Paula M. L.; Boularbah, AliThe mining industry is of major importance to Morocco’s economy. However, the abandoned pyritic mines are a source of potentially toxic elements that can cause the disruption of the surrounding ecosystems, constituting a huge threat to wellbeing and human health. The present study aimed to analyze the physical and chemical characteristics of different types of tailings and to investigate the microbial populations of acidophilic bacteria involved in the oxidation of pyrite. Coarse and fine tailings collected from different zones of the mine (dike and pond) at two different depths (oxidized and non-oxidized residues) were analyzed for their pH, electrical conductivity, total organic carbon, total nitrogen, available P, major elements, and pseudo-total metal concentrations. The abundance of acidophilic bacteria was determined, and some acidophilic bacterial strains were isolated and tested for their metal tolerance. Tailings showed a pH ≈ 2, very low nutritional content, and high concentrations of Cu, As, Zn, and Pb, which were higher in the non-oxidized samples. The microbial counts of iron- and sulfur-oxidizing bacteria were higher than heterotrophic bacteria, with the highest numbers detected in the oxidized fine tailings. The five acidophilic bacteria isolated from the tailings were affiliated to genera Alicyclobacillus and Sulfobacillus, commonly found in this kind of environment.
- Remediation of metal-contaminated mine tailings by the application of organic and mineral amendmentsPublication . Benidire, Leila; Pereira, Sofia; Aboudrar, Wafae; Hafidi, Mohamed; Castro, Paula; Boularbah, AliPurpose Tailings are generally characterized by severe physicochemical conditions that limit the establishment of vegetation. The present study aimed to select suitable combinations of organo-mineral amendments to improve the physicochemical, biochemical, and biological properties of spolic technosols, highly contaminated with metals. Materials and methods Several substrates were prepared by mixing mine tailings (MT) of an abandoned mining area with non-contaminated agricultural soil (anthrosol), green waste compost, lime, and rock phosphate at different rates: S1 - 50% of MT + 50% of agricultural soil; S2 - S1 + 3% of lime (CaCO3); S3 - S1 + 6% of rock phosphate; S4 - S1 + 10% of compost; S5 - S1 + 10% of compost + 3% of lime; S6 - S1 + 10% of compost + 6% of rock phosphate. Untreated MT and agricultural soil were analyzed immediately, and 8 months after incorporating the amendments. Results and discussion Heterotrophic microorganisms were not recovered from untreated MT due to the highly acidic pH and available metal concentrations. However, the addition of organo-mineral amendments ameliorated the tailings' characteristics by increasing pH, conductivity, total organic carbon, and available P levels. Moreover, after 8 months, heterotrophic microorganisms were recovered from those substrates and dehydrogenase activity was enhanced. The incorporation of agricultural soil and green waste compost mixed either with lime (S5) or rock phosphate (S6) was the most effective treatment. Conclusions Both S5 and S6 mixtures successfully reduced the environmental risk posed by tailings, suggesting the potential use of these amendments for the remediation of pyrite mines.
- Trace and major element contents, microbial communities, and enzymatic activities of urban soils of Marrakech city along an anthropization gradientPublication . Naylo, Ahmed; Almeida-Pereira, Sofia I.; Benidire, Leila; El Khalil, Hicham; Castro, Paula M.L.; Ouvrard, Stéphanie; Schwartz, Christophe; Boularbah, AliDue to their close proximity with the population, urban soils are extensively affected by human activities that release considerable technogenic inputs resulting in an overall soil degradation and leading to an increase of water-extractable fraction of trace elements. This work aimed to determine the influence of anthropization on trace and major element concentrations and to assess how it might also affect soil biochemical and microbiological parameters in an urban area of Marrakech city, Morocco.