摘要:

A variety of plant species are being considered for the phytoremediation of selenium (Se) contaminated soils in agricultural regions of central California. Use of this plant-based technology may also attract a wide range of insects to these Se-accumulating plants. The first field study surveyed the diversity of insects attracted to tall fescue, birdsfoot trefoil, kenaf, and Indian mustard. Over 7500 specimens were collected by a sweep net collection technique for one complete growing season. Most of the 84 families identified were associated with beneficial insects, although pestiferous insects, for example, thrips, aphids, lygus, and leafhoppers, were also found. In the second study the bioaccumulation of Se in the cabbage looper [Trichoplusia ni(Hübner)] was investigated on Indian mustard grown in Se-rich water culture solution. Neonate larvae were transferred to plants and fed on Se-treated and no Se treated plants (controls) for 14 days, respectively. Pupae were collected from each treatment and incubated until adult insects emerged. Almost 50% fewer pupae were collected from Se-treated plants compared with “controls”, resulting in fewer adult insects. Selenium concentrations were as high as 3173 μg Se kg-1DW in adult insects hatched from Se-treated plants compared with <5 μg Se kg-1DW in insects from “controls”. Based on both studies, we concluded that insect diversity should be determined and insects monitored for bioaccumulation of Se on phytoremediation sites in agricultural regions.

ISSN:1522-6514    

DOI:10.1080/15226519908500022

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Biscutella laevigataandIberis intermediawere sampled from sites near St Laurent le Minier, Southern France, andB. laevigatawas also sampled from Rocca San Silvestro, Tuscany, Italy. Soils associated with the rhizosphere of each plant were also sampled. BothBiscutella laevigataandIberis intermediaaccumulate inordinately high concentrations of thallium (1.94 and 0.4%, respectively) in their above-ground dry tissue. The levels of thallium accumulated by both species were strongly correlated with both the total and extractable concentrations of thallium in the soils. Concentrations of zinc, cadmium, and lead were below the threshold for hyperaccumulation. It is proposed thatB. laevigataand/orI. intermediacould be used for phytoremediation or phytomining of thallium-contaminated soils. Such an operation would involve the repeated cropping of either species, until an acceptable level of thallium in the soils was reached. Additionally, the harvested plant material could be burnt and the resulting ash smelted to produce an economically viable ‘crop’ of thallium.

ISSN:1522-6514    

DOI:10.1080/15226519908500023

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Aquatic sediments in industrial regions are often polluted by heavy metals. When removed by dredging, the sediments become an environmental risk. Because of the high costs and the deficient sustainability of landfill disposal, we intend to develop a remediation process for cleaning heavy metal-contaminated sediments by solid-bed bioleaching. Unfortunately, freshly dredged sediments are often impermeable to water. Therefore, they have to be conditioned to improve their hydrodynamic properties and make them suitable for solid-bed leaching. The treatment basin of 5.9 m × 7.5 m of a pilot-scale plant for sediment conditioning was filled with 0.5 m freshly dredged sediment, which originated from a trap in the Weisse Elster River near Leipzig, Germany, and was contaminated with Zn, Cr, Pb, Cu, Ni, and Cd. The sediment was planted with the helophytesPhragmites australis, Phalaris arundinacea, andAgrostis stolonifera.The vegetation evaporated large amounts of water and transported oxygen into the sediment. During conditioning the anoxic, black, muddy-pasty sediment changed to the oxic state and turned into a grayish brown, crumbly, soil-like material. Furthermore, the sediment turned acidic, its buffer capacity decreased, and, because of pore and particle enlargements, it became easily permeable to water. The plants on the sediment incorporated heavy metals in their biomass, especially Zn, Ni, Cd, and Co, but not enough for sediment remediation by phytoextraction.

ISSN:1522-6514    

DOI:10.1080/15226519908500024

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The resistance ofSalixto Cu, Cd, Ni, and Zn was investigated in hydroponic culture, with phytoextraction potential evaluated for Cu. Root elongation (indicative of resistance level) was significantly affected, with considerable variation between and within individual clones. Resistance appeared to be clone- or hybrid-specific, rather than species-specific.S. capreaclones (and hybrids) were among the most resistant, but a secondaryS. capreaclone from a different provenance was much less tolerant.S. viminalisandS. triandraclones were the most sensitive. Highest resistance was found in response to Cd, while Cu and Ni were extremely toxic. A resistantS. capreaecotype originating from a metalliferous mine spoil was identified using this technique. Copper concentration reached a maximum of 2000, 400, and 82 μg g-1(d.wt) in roots, wood, and foliage, respectively, after 1 month in hydroponic culture. The level of variation in the response ofSalixto metals may cause difficulties in phytoremediation screening programs, but may be essential in providing genetic variation for selection of metal resistance traits, where the contaminant profile is heterogeneous, mixed, or subject to change. Clone selection for metal phytoextraction is feasible, but a longer field-scale study on metal-contaminated soils is needed before their role in phytoremediation can be confirmed.

ISSN:1522-6514    

DOI:10.1080/15226519908500025

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Experiments in a laboratory chamber were used to investigate the influence of alfalfa plants on the fate and transport of trichloroethylene (TCE) fed at a concentration of 200 μl/L (~290 mg/L) in the entering groundwater. The dimensions of the chamber were 180 cm in axial length, 35 cm in depth and 10 cm in width. Concentrations of TCE were monitored in the aqueous and gas phases. Evapotranspirational fluxes of TCE from the soil to the headspace of the chamber were also measured. TCE concentration in the solid phase was measured as a function of depth. Mathematical modeling of the fate of TCE was developed assuming rate-independent physical equilibrium partitioning between solid, aqueous, and gas phases. The model included volatilization across a thin atmospheric boundary layer near soil surface. Numerical results were first validated with analytical results for simple cases and then compared with experimental data in the chamber. Results indicated that the water content and air content distributions significantly impact the transport and concentration of TCE in soils.

ISSN:1522-6514    

DOI:10.1080/15226519908500026

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor