Mobility and phytoavailability of arsenic in an abandoned mining area

The mobility and phytoavailability of arsenic in an area affected by the abandoned exploitation of an arsenical tungsten-tin deposit was studied to establish the current and eventual environmental risks and to propose possible remediation practices. Soil and plant samples were collected at different distances from the polluting sources and analyzed for their As content and distribution. Critical soil total concentrations of As were found, with values in the range 175-2300 mg kg^− 1. The readily labile As contents represent < 0.2% of the total concentrations, whereas the As contents more prone to be mobilized could rise up to 25%. Different phytostabilizing plants were identified, namely, Agrostis castellana (Boiss. & Reut.), Centaurea jacea L., Eryngium campestre L. and Scirpus holoschoenus L.. Such plants show important root bioaccumulation factor values in relation to the labile As contents (up to 197, 58, 201 and 88, respectively) and low translocation factor values (down to 0.170, 0.032, 0.173 and 0.036, respectively). Additionally to promote the revegetation with these plants, the species Rumex acetosella L. should be eliminated as this behaves as an index plant, reaching above-ground As concentrations up to 218 mg kg^− 1.     

Optimization of plant growth-promoting bacteria-assisted phytostabilization of mine tailings

Recent studies have indicated that plant growth-promoting bacteria (PGPB) can improve revegetation of arid mine tailings as measured by increased biomass production. The goals of the present study were first to evaluate how mode of application of known PGPB affects plant growth, and second to evaluate the effect of this inoculation on rhizosphere microbial community structure. PGPB application strategies investigated include preliminary surface sterilization of seeds (a common practice in phytoremediation trials) followed by a comparison of two application methods; immersion and alginate encapsulation. Results with two native desert plant species, Atriplex lentiformis and Buchloe dactyloides, suggest that seed surface sterilization prior to inoculation is not necessary to achieve beneficial effects of introduced PGPB. Both PGPB application techniques generally enhanced plant growth although results were both plant and PGPB specific. These results demonstrate that alginate encapsulation, which allows for long-term storage and easier application to seeds, is an effective way to inoculate PGPB. In addition, the influence of PGPB application on B. dactyloides rhizosphere community structure was evaluated using PCR-DGGE (denaturing gradient gel electrophoresis) analysis of bacterial DNA extracted from rhizosphere samples collected 75 d following planting. A comparative analysis of DGGE profiles was performed using canonical correspondence analysis (CCA). DGGE-CCA showed that rhizosphere community profiles from PGPB-inoculated treatments are significantly different from both uninoculated tailings rhizosphere profiles and profiles from the compost used to amend the tailings. Further, community profiles from B. dactyloides inoculated with the best performing PGPB (Arthro Mix) were significantly different from two other PGPB tested. These results suggest that introduced PGPB have the potential to influence the development of the rhizosphere community structure found in plants grown in mine tailings.     

Differential expression of zinc accumulation during two growing seasons of Acacia victoriae

It is important to understand seasonal heavy metal accumulation in different parts of plants in order to develop the best phytoremediation practices for con-taminated soils. For this purpose we exposed...     

The effect of lime and compost amendments on the potential for the revegetation of metal-polluted, acidic soils

The revegetation of soils affected by the historic pollution of an industrial complex in central Chile was studied. Spontaneous and assisted revegetation and changes in the physicochemical properties of the soils were evaluated in field plots that were amended with lime or lime + compost. Lime had no effect on plant productivity in comparison with the control, whereas the incorporation of lime + compost into the soil increased the plant cover and aboveground biomass. The application of lime + compost increased the plant productivity of Chrysanthemum coronarium (a species sensitive to the atmospheric emissions from the industrial complex), thus showing effective in situ stabilization of soil contaminants. Regression analyses suggested that the plant response was due to the increase in the soil organic matter content rather than to the increase in the soil pH. The aboveground biomass and plant cover did not differ under the spontaneous and assisted revegetation regimes. The native soil seed bank was sufficient for attainment of the proper plant cover and biomass production after the application of the soil amendments. Although the pCu²⁺ in the amended soils was 4 orders of magnitude higher than in the unamended control, the shoot Cu concentration was similar among most of the combinations of plant species and amendments.     

安徽省沿江铜矿区金属型植物调查及其应用研究

对安徽省境内分布的4个铜矿区进行了植被和土壤调查,各个采样点土壤理化分析结果显示,铜矿土壤中Cu含量远超出正常水平,土壤基质中的Cu毒性是限制和决定区域内植物分布的主要因素。野外植物调查共记录植物82种,隶属45科,其中有6个优势科和12个优势种,各种植物在Cu转运系数和Cu积累特征上表现出较大差异。综合植物分布区土壤中的Cu含量及植物体的Cu积累特征,认为海州香薷（Elsholtzia haichowensis）、鸭跖草（Commelina communis）、茵陈嵩（Artemisia capillaries）以及酸模（Rumex acetosa）等耐性强、分布范围广的乡土物种及物种组合能够有效地提高铜污染区域土壤固定效率,在铜矿区污染环境的修复及稳定植被系统恢复重建中具有广阔的应用前景。     

铅锌冶炼厂周边野生植物调查及铅镉携带量研究

研究了在某铅锌冶炼厂周边2 km范围内所采集的18科34种野生植物,并分析了土壤铅、镉含量及植物地上部铅、镉的携带量,结果表明:象草、小花山桃草、益母草、鹅观草、葎草和杠柳吸收铅镉较少,富集能力较弱;紫草、抱茎小苦荬、蒲公英、白屈菜、水蓼、一年蓬、板蓝根和播娘蒿的镉富集系数均大于1;酸模和曼陀罗地上部的镉含量较大,分别达35.63和26.17 mg/kg;两者携带的铅、镉也最多,铅分别为20.27和37.40 mg,镉分别为2.12和7.16 mg。由此可知,象草、小花山桃草、益母草、鹅观草、葎草和杠柳可作为植物稳定化技术备选材料,在污染土壤植被复垦等方面的潜力巨大;酸模和曼陀罗对铅、镉的耐性强,转运能力强,经过进一步验证后在复合污染土壤提取修复技术具有应用价值。     

Inoculation with arbuscular mycorrhizal fungus Acaulospora mellea decreases Cu phytoextraction by maize from Cu-contaminated soil

A pot culture experiment was carried out to study the growth of and Cu uptake by maize (Zea mays) inoculated with or without arbuscular mycorrhizal (AM) fungus Acaulospora mellea in sterilized soil with different Cu amounts added (0, 100, 200, 400, 800 mg kg⁻¹). Root colonization rates were significantly lower with the addition of 400 and 800 mg kg⁻¹ Cu. AM inoculation increased shoot dry weights at 200 and 400 mg kg⁻¹ Cu added but showed no effects at other levels, while increased root dry weights at all Cu addition levels except 800 mg kg⁻¹. Compared with the nonmycorrhizal plants, shoot Cu concentrations in mycorrhizal plants were higher when no Cu was added but lower at other levels, while root Cu concentrations were lower at 400 and 800 mg kg⁻¹ Cu added but not affected at other levels. Thus, shoot Cu uptake in mycorrhizal plants increased with no Cu added but decreased at other levels, while mycorrhizal effects on root Cu uptake varied. Compared with nonmycorrhizal controls, Cu uptake efficiency and phytoextraction efficiency in mycorrhizal plants were higher when no Cu was added but lower at other levels, and Cu translocation efficiency was lower at all Cu addition levels. AM inoculation improved shoot and root P nutrition at all Cu addition levels. Soil pH was higher in mycorrhizal treatment than in the control when 200 mg kg⁻¹ or more Cu was added. These results indicate that A. mellea ZZ may be not suitable for Cu phytoextraction by maize, but shows a potential role in phytostabilization of soil moderately polluted by Cu.