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The impairment of root growth and photosynthetical functioning are the main impacts of trace elements on woody plant seedlings. In this work, we assessed the response of Holm oak (Quercusilex subsp. ballota) and mastic shrub (Pistacia lentiscus) seedlings to high concentrations of Cd and Tl in the rhizosphere. These are non-essential trace elements, with a potential high mobility in the soil-plant system. Seedlings of these species are frequently used in the afforestation of degraded soils in mining areas. Plants were exposed to different levels of Cd (20, 80 and 200 mg L−1) and Tl (2, 10 and 20 mg L−1) in a sand culture. Biomass allocation, growth rates, chlorophyll fluorescence and gas exchange were studied. Both metals affected root biomass. Cadmium produced an increase in the root mass ratio and a decrease in the specific leaf area of the plants in oak seedlings, while Tl did not provoke such response. Mastic plants were more sensitive to Tl and Cd than oak plants. Between elements, Tl provoked more severe toxic effects in the plants, affecting the antennae complexes and reaction centers of the photosystem II. Both elements decreased net assimilation rates (down to a 20% of the control plants) and stomatal conductance (5-10% of the values for the control plants). Cadmium was highly retained in the roots of both species, while Tl was highly translocated into the leaves. In general, Holm oak showed a higher tolerance for Cd than for Tl, and a higher resistance to both metals than mastic shrub, due to a high capacity for Cd retention at the root level. However, such accumulation in roots may induce water stress in the seedling exposed to Cd. 相似文献
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Sas-Nowosielska A Galimska-Stypa R Kucharski R Zielonka U Małkowski E Gray L 《Environmental monitoring and assessment》2008,137(1-3):101-109
Phytoremediation, an approach that uses plants to remediate contaminated soil through degradation, stabilization or accumulation,
may provide an efficient solution to some mercury contamination problems. This paper presents growth chamber experiments that
tested the ability of plant species to stabilize mercury in soil. Several indigenous herbaceous species and Salix viminalis were grown in soil collected from a mercury-contaminated site in southern Poland. The uptake and distribution of mercury
by these plants were investigated, and the growth and vitality of the plants through a part of one vegetative cycle were assessed.
The highest concentrations of mercury were found at the roots, but translocation to the aerial part also occurred. Most of
the plant species tested displayed good growth on mercury contaminated soil and sustained a rich microbial population in the
rhizosphere. The microbial populations of root-free soil and rhizosphere soil from all species were also examined. An inverse
correlation between the number of sulfur amino acid decomposing bacteria and root mercury content was observed. These results
indicate the potential for using some species of plants to treat mercury contaminated soil through stabilization rather than
extraction. The present investigation proposes a practical cost-effective temporary solution for phytostabilization of soil
with moderate mercury contamination as well as the basis for plant selection. 相似文献
3.
重金属污染土壤及场地的治理工作迫在眉睫,植物修复技术以其成本低、不破坏土壤生态环境、无二次污染、易被公众接受等优点,受到了学术界的广泛关注.近年来,国内外在植物修复技术的植物资源筛选、调控技术、修复植物产后处理等方面进行了广泛的研究.植物修复已经从实验室阶段走向了田间示范和推广应用阶段.现就近年来植物修复技术在重金属污... 相似文献
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Bidar G Pruvot C Garçon G Verdin A Shirali P Douay F 《Environmental science and pollution research international》2009,16(1):42-53
Background, aim, and scope The reclamation of nonferrous metal-polluted soil by phytoremediation requires an overall and permanent plant cover. To select
the most suitable plant species, it is necessary to study metal effects on plants over the time, thereby checking that metals
remain stored in root systems and not transferred to aerial parts. In this purpose, the seasonal and annual variations of
metal bioaccumulation, transfer, and phytotoxicity in Trifolium repens and Lolium perenne grown in a Cd-, Pb-, and Zn-contaminated soil were also studied.
Materials and methods The experimental site was located near a closed smelter. In spring 2004, two areas were sown with T. repens and L. perenne, respectively. Thereafter, the samplings of plant roots and shoots and surrounding soils were realized in autumn 2004 and
spring and autumn 2005. The soil agronomic characteristics, the Cd, Pb, and Zn concentrations in the surrounded soils and
plant organs, as well as the oxidative alterations (superoxide dismutase [SOD], malondialdehyde [MDA], and 8-hydroxy-2′-deoxyguanosine
[8-OHdG]) in plant organs were carried out.
Results Whatever the sampling period, metal concentrations in soils and plants were higher than background values. Contrary to the
soils, the fluctuations of metal concentrations were observed in plant organs over the time. Bioaccumulation and transfer
factors confirmed that metals were preferentially accumulated in the roots as follows: Cd>Zn>Pb, and their transfer to shoots
was limited. Foliar metal deposition was also observed. The results showed that there were seasonal and annual variations
of metal accumulation in the two studied plant species. These variations differed according to the organs and followed nearly
the same pattern for the two species. Oxidative alterations were observed in plant organs with regard to SOD antioxidant activities,
MDA, and 8-OHdG concentrations. These alterations vary according to the temporal variations of metal concentrations.
Discussion Metal concentrations in surrounded soils and plant organs showed the effective contamination by industrial dust emissions.
Metals absorbed by plants were mainly stored in the roots. With regard to this storage, the plants seemed to limit the metal
transfer to their aerial parts over the time, thereby indicating their availability for metal phytostabilization. Aerial deposition
was another source of plant exposure to nonferrous metals. Despite the occurrence of metal-induced oxidative alterations in
plant organs, both plant species seemed to tolerate a high metal concentration in soils.
Conclusions Taken together, these results indicated that T. repens and L. perenne were able to form a plant cover on highly Cd-, Pb-, and Zn-polluted soils, to limit the metal transfer to their aerial parts
and were relatively metal-tolerant. All these characteristics made them suitable for phytostabilization on metal-contaminated
soils. These findings also highlighted the necessity to take into account seasonal and annual variations for a future phytomanagement.
Recommendations and perspectives In this work, the behavior of plant species grown in metal-polluted soil has been studied during 2 years. Obviously, this
time is too short to ensure that metals remain accumulated in the root system and few are transferred in aerial parts over
the time. It is why regular monitoring should be achieved during more than a decade after the settlement of the plant cover.
This work will be completed by the study of the T. repens and L. perenne effects on mobility of metals in order to evaluate the quantities of pollutants which could be absorbed by the biota and
transferred to groundwater. Bioaccessibility tests could be also realized on polluted soils in order to evaluate the phytostabilization
impacts on the exposition risks for humans. 相似文献
5.
Metal fractionation in a contaminated soil after reforestation: Temporal changes versus spatial variability 总被引:1,自引:0,他引:1
In a lysimeter experiment, topsoils were polluted with filter dust from a non-ferrous metal smelter and then planted with trees. Sequential extractions were used to follow the changes in metal fractionation of Cu, Zn, Cd, and Pb over 42 months. Plant-free and uncontaminated soils served as reference. In the contaminated and planted soils, the largest changes in speciation occurred within the first 6 months. The relative amounts of certain metal fractions were linearly related to each other, indicating systematic redistribution between fractions. The results indicate that under natural conditions with high heterogeneity in total metal contents spatial differences are more important than temporal variations in determining the fractionation and solubility of metals in contaminated soils. In the absence of plants soils exhibited a completely different fractionation 30 months after pollution, with much higher proportions in the more refractory phases. This suggests that plant activity kept the metals in a more soluble form. 相似文献
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