Nasim Salehi; Abooalfazl Azhdarpoor; Mohammadreza Shirdarreh
Abstract
Background: Pyrene is one of the polycyclic aromatic hydrocarbons that has carcinogenic, mutagenic and teratogenic effects for living organisms. Landfill leachate is another environmental pollutant that covers a wide range of pollutants, especially heavy metals. The simultaneous presence of two types ...
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Background: Pyrene is one of the polycyclic aromatic hydrocarbons that has carcinogenic, mutagenic and teratogenic effects for living organisms. Landfill leachate is another environmental pollutant that covers a wide range of pollutants, especially heavy metals. The simultaneous presence of two types of pollutants with organic and inorganic structures can increase their toxicity. Methods: In this experimental study, the single and simultaneous effect of Landfill leachate and pyrene on plant growth parameters and the number of heterotrophic soil bacteria was investigated. The study was conducted for 90 days at concentrations of 150, 300, 500, 750 and 1000 mg/kg-1 of pyrene and percentages 0, 30, 50, 70 and 100% of landfill leachate. Results: The results showed that after 90 days, the highest dry stem and root biomass were obtained in irrigation treatment with pyrene and Landfill leachate (Blank)-non-contaminated municipal water with quantities of 8.2 and 3.5 g, respectively; moreover, the lowest stem and root biomass related to the treatment were observed in the simultaneous presence of 30% leachate and pyrene with a concentration of 300 mg/kg-1 with quantities of 5 and 1.8 g, respectively. Leachate did not produce any biological toxicity at any of the surfaces used, but the use of pyrene at concentrations of 1500 mg/kg-1 and above reduced the number of heterotrophic bacteria. Conclusion: According to the results, the simultaneous presence of the two pollutants, pyrene and leachate, exacerbates the phytotoxicity due to possible interactions between them. Pyrene as a carbon source is decomposed by bacteria at low concentrations, but it inhibits metabolism and growth at high concentrations.
Amir Hossein Baghaie; Mohammad Fereydoni
Abstract
Background: This descriptive study was conducted to evaluate the interaction effects of sewage sludge and its biochar on anthracene biological degradation in a Pb polluted soil under sunflower cultivation Methods: Treatments consisted of applying three rates of anthracene (0, 12.5 ...
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Background: This descriptive study was conducted to evaluate the interaction effects of sewage sludge and its biochar on anthracene biological degradation in a Pb polluted soil under sunflower cultivation Methods: Treatments consisted of applying three rates of anthracene (0, 12.5 and 25 mg/kg soil), two levels of sewage sludge and its biochar (0 and 30 t/ha) in the presence of Azetobacter bacteria and Piriformospora indica (P. indica) fungus. After 60 days, plants were harvested and plant Pb concentration was measured using atomic absorption spectroscopy. In addition, the soil petroleum hydrocarbons concentration and soil microbial respiration were measured by the method described by Besalatpour et al. (2011). The catalyze enzyme activity was assayed. Results: Plant inoculation with P.indica and Azotobacter significantly increased the degradation of anthracene in soil by 12.8% in the soil treated with 25 mg anthracene/kg soil. In addition, the soil Pb availability was decreased by 14.6% in the mentioned treatment. Applying 30 t/ha sewage sludge and its biochar significantly increased the plant biomass and anthracene degradation in the soil treated by 12.5 mg anthracene /kg soil by 13.5% and 12.6%, respectively. Conclusion: Soil treated with sewage sludge and its biochar had a positive effect on plant resistance to abiotic stresses and degradation of anthracene in the soil. Among this, plant inoculation with P. indica and Azotobacter had also an additive effect on bio-remediation of anthracene in the soil that is a positive point in environmental studies. However, soil pollution with heavy metals had an adverse effect on it.
