| 1. |
- Javed, Muhammad Tariq, 1983-, et al.
(författare)
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Cadmium triggers Elodea canadensis to change the surrounding water pH and thereby Cd uptake
- 2011
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Ingår i: International journal of phytoremediation. - : Informa UK Limited. - 1522-6514 .- 1549-7879. ; 13:1, s. 95-106
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Tidskriftsartikel (refereegranskat)abstract
- This study was aimed to investigate the influence of Elodea canadensis shoots on surrounding water pH in the presence of cadmium and the effect of plant-induced pH on cadmium uptake. The pH change in the surrounding nutrient solution and Cd uptake by Elodea shoots were investigated after cultivation of various plant densities (1, 3, 6 plants per 500 ml) in hydroponics at a starting pH of 4.0 and in the presence of different concentrations of cadmium (0, 0.1, 0.5 µM). Cadmium uptake was also investigated at different constant pH (4.0, 4.5, 5.5 and 6.5). To investigate if the pH change arose from photosynthetic activities, plants were grown under light, darkness or in the presence of a photosynthetic inhibitor, 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), and 0.5 µM cadmium in the solution. Elodea had an ability to increase the surrounding water pH, when the initial pH was low, which resulted in increased accumulation of Cd. The higher the plant density, the more pronounced was the pH change. The pH increase was not due to the photosynthetic activity since the pH rise was more pronounced under darkness and in the presence of DCMU. The pH increase by Elodea was triggered by cadmium.
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| 2. |
- Neuschütz, Clara, et al.
(författare)
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Ability of various plant species to prevent N, P, and metal leakage from sewage sludge
- 2010
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Ingår i: International journal of phytoremediation. - : Informa UK Limited. - 1522-6514 .- 1549-7879. ; 12:1, s. 67-84
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Tidskriftsartikel (refereegranskat)abstract
- The preventive effect of vegetation on nutrient and metal leakage from sewage sludge (SS) used in treatment of mine waste was investigated. In a 10-week greenhouse study, the release of ammonium, nitrate, phosphate, Cd, Cu, and Zn from SS was analyzed in the absence (control) and presence of basket willow, fireweed, reed Canary grass (RCG), and Scots pine. Plants significantly decreased the leakage by reducing the amount of leachate, and lowered the concentrations of phosphate (to 0.1 mg L-1), Cu (0.8 mg L-1), and Zn (2.2 mg L-1); and plants increased the pH in the leachate towards the end of the experiment. The most efficient plant was RCG that significantly decreased the total leakage of all pollutants. However, plants could not counteract high initial concentrations of ammonium and nitrate (< 400 mg L-1 of both) and drop in pH (to 4.5), or increasing Cd release (< 9.7 μg L-1). RCG and fireweed used both ammonium and nitrate as nitrogen source and were more efficient in preventing nitrate leakage, compared with willow and pine that mainly used ammonium. This study indicates that introduction of RCG is a promising method for phytostabilization of SS, but that alkaline additives are needed to prevent an initial decrease in pH.
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| 3. |
- Pizzul, Leticia, et al.
(författare)
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Degradation of PAH in a Creosote-Contaminated Soil. A Comparison Between the Effects of Willows (Salix Viminalis), Wheat Straw and A Nonionic Surfactant
- 2010
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Ingår i: International Journal of Phytoremediation. - : Informa UK Limited. - 1522-6514 .- 1549-7879. ; 12, s. 54-66
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Tidskriftsartikel (refereegranskat)abstract
- The degradation of polyaromatic hydrocarbons (PAH) in an aged creosote-contaminated soil in the presence of Salix viminalis was investigated in a greenhouse experiment. Phenanthrene and pyrene were degraded 100% and 80%, respectively, in the presence of plants but only 68% and 63% without plants. The effects of the nonionic surfactant Triton X-100 or the addition of straw, without plants, were also studied. The addition of straw had no effect on PAH degradation compared to the control. Pyrene degradation with Triton X-100 at low concentrations (0.06 l g-1 DW) was comparable to that with plants but was less for anthracene and phenanthrene. The treatments with plants were, according to SIR measurements, dominated by active microorganisms (98.8% of the biomass), whereas all treatments without plants contained mostly dormant or non-growing microorganisms (1.7-2.0% active). Viable counts and active biomass were highly correlated in all treatments and demonstrated that S. viminalis greatly increased microbial populations. Dominant bacteria were grouped according to Gram, fluorescence and oxidase tests and revealed differences between treatments. The presence of S. viminalis or the surfactant enhanced PAH degradation, primarily by a rhizosphere effect on the microbial activity in the former case and by increased bioavailability in the latter case.
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