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1.
Changes in Hg fractionation in soil induced by willow 总被引:1,自引:0,他引:1
This study investigated the effect of willow (Salix viminalis × S. schwerinii) on soil characteristics, including changes in Hg fractionation in the soil solid phase, and Hg accumulation and distribution
in pot-grown plants cultivated for 32 and 76 days in aged Hg-contaminated soil (30 mg Hg kg−1DW). Changes in soil pH and organic carbon content as well as in Hg fractionation were monitored in both rhizospheric soil
and in soil without plants. Mercury fractionation was performed by a 5-step sequential soil extraction procedure. Organic
carbon content increased while pH decreased in the rhizospheric soil. Both chemically defined exchangeable Hg (0.1) and Hg
bound to humic and fulvic acids (1.1) decreased in the rhizospheric soil, whereas plant accumulation of Hg increased with
cultivation time. The sum of the decrease of these two soil Hg fractions after 76 days of cultivation was approximately equal
to the amount of Hg accumulated in plants. Furthermore, the major Hg fractions (Hg bound to residual organic matter (53),
sulphides (43), and the residual fraction (2.5)) remained stable. Neither whole plant accumulation of Hg from the soil, approximately
0.2 of total Hg in soil after 76 days cultivation, nor the fraction of total plant Hg in the shoots, which accounted for about
3 of the total plant Hg pool regardless of the cultivation time, were high. The overall results suggest that plants might
be suitable for phytostabilization of aged Hg-contaminated soil, where root systems trap bioavailable Hg and help to control
both leaching of Hg and re-entrainment of Hg-containing particulates from a contaminated site. 相似文献
2.
3.
Rhizoremediation of petroleum contaminants is a phytoremediation process that depends on interactions among plants, microbes, and soils. Trees and grasses are commonly used for phytoremediation, with trees typically being chosen for remediation of BTEX while grasses are more commonly used for remediation of PAHs and total petroleum hydrocarbons. The objective of this review was to compare the effectiveness of trees and grasses for rhizoremediation of hydrocarbons and address the advantages of each vegetation type. Grasses were more heavily represented in the literature and therefore demonstrated a wider range of effectiveness. However, the greater biomass and depth of tree roots may have greater potential for promoting environmental conditions that can improve rhizoremediation, such as increased metabolizable organic carbon, oxygen, and water. Overall, we found little difference between grasses and trees with respect to average reduction of hydrocarbons for studies that compared planted treatments with a control. Additional detailed investigations into plant attributes that most influence hydrocarbon degradation rates should provide data needed to determine the potential for rhizoremediation with trees or grasses for a given site and identify which plant characteristics are most important. 相似文献
4.
When subjected to stress, plants produce reactive oxygen species (ROS) as a part of the defense response. The oxidative response is also used to degrade organic pollutants. Hairy roots of Helianthus annuus (sunflower) are shown to oxidize oxytetracycline (OTC) through the action of the ROS released to the nutrient medium by the hairy root cultures. Methyl jasmonate (MeJA) elicits ROS formation in the hairy root cultures. The activities of the antioxidant enzymes, ascorbate peroxidase (APX), catalase (CAT), and guaiacol peroxidase (GPX), are reported for hairy root cultures treated with increasing concentrations of MeJA. A bioassay using Enterococcus hirae as the test microorganism demonstrates the root-catalyzed oxidation process results in conversion of OTC into product(s) devoid of antibiotic activity. Direct evidence for putative ROS oxidation of OTC is obtained by mass spectrometry (MS) and HPLC/MS showing first quinone formation followed possibly by ring cleavage, which disrupts UV absorption and destroys antibiotic activity. 相似文献
5.
Mohammadi M Chalavi V Novakova-Sura M Laliberté JF Sylvestre M 《Biotechnology and bioengineering》2007,97(3):496-505
Optimized plant-microbe bioremediation processes in which the plant initiates the metabolism of xenobiotics and releases the metabolites in the rhizosphere to be further degraded by the rhizobacteria is a promising alternative to restore contaminated sites in situ. However, such processes require that plants produce the metabolites that bacteria can readily oxidize. The biphenyl dioxygenase is the first enzyme of the bacterial catabolic pathway involved in the degradation of polychlorinated biphenyls. This enzyme consists of three components: the two sub-unit oxygenase (BphAE) containing a Rieske-type iron-sulfur cluster and a mononuclear iron center, the Rieske-type ferredoxin (BphF), and the FAD-containing ferredoxin reductase (BphG). In this work, based on analyses with Nicotiana benthamiana plants transiently expressing the biphenyl dioxygenase genes from Burkholderia xenovorans LB400 and transgenic Nicotiana tabacum plants transformed with each of these four genes, we have shown that each of the three biphenyl dioxygenase components can be produced individually as active protein in tobacco plants. Therefore, when BphAE, BphF, and BphG purified from plant were used to catalyze the oxygenation of 4-chlorobiphenyl, detectable amounts of 2,3-dihydro-2, 3-dihydroxy-4'-chlorobiphenyl were produced. This suggests that creating transgenic plants expressing simultaneously all four genes required to produce active biphenyl dioxygenase is feasible. 相似文献
6.
Shuiping Cheng Feng Ren Wolfgang Grosse Zhenbin Wu 《International journal of phytoremediation》2002,4(3):239-246
The effects of cadmium (Cd2+) on growth status, chlorophyll (Chl) content, photochemical efficiency, and photosynthetic intensity were studied on Canna indica Linn. Plant specimens that were produced from a constructed wetland and precultivated hydroponically in 20 L of 1/10 Hoagland solution under greenhouse conditions for 1 week were exposed to cadmium in concentrations of 0, 0.4, 0.8, 1.6 and 3.2 mg L―1 Cd2+, respectively. The results show that leaves were injured in the Cd2+ solution by the third day of exposure and the injury became more serious with an increase in the applied heavy metal. Under 3.2 mg L―1 Cd2+ treatment, growth retardation, the decrease of chlorophyll content from 0.70 to 0.43 mg g―1 FW, and a decrease in Chl a/b ratio from 2.0 to 1.2 were observed. Chl a was more sensitive than Chl b to Cd2+ stress. The decrease was the same with photochemical efficiency. Photosynthetic intensity decreased by 13.3% from 1.5×104 μmol m―2s―1 CO2 in control to 1.3×104 μmol m―2s―1 CO2 in the treatment of 3.2 mg L―1. Because Canna species are used in heavy metal phytoremediation, these results show that C. indica can tolerate 0.4 to 0.8 mg L―1 Cd2+. Therefore, it is a potential species for phytoremediation of cadmium with some limitations only at higher concentrations. 相似文献
7.
Poppy Intan Tjahaja Putu Sukmabuana Dwina Roosmini 《International journal of phytoremediation》2015,17(10):951-956
Soil contamination with radiocaesium is a significant problem at any countries when a nuclear accident occurred. Recently, phytoextraction technique is developed to remediate the contaminated environment. However, the application is limited by the availability of the contaminant for root uptake. Therefore, a green house trial experiment of soil amendment with ethylene diamine tetraacetic acid (EDTA) has been conducted to examine 134Cs availability for root uptake. Two groups of Indian mustard (Brassica juncea) were cultivated in 134Cs contaminated soil. The soil in the first group was treated with EDTA amendment, while the other was not. Plant growth was observed gravimetrically and the 134Cs concentration in soil as well as plants were determined using gamma spectrometry. The plant uptake capacity was determined as transfer factor (Fv), and the Fv values of 0.22 ± 0.0786 and 0.12 ± 0.039 were obtained for the soil treated with and without EDTA amendment, respectively. The phytoextraction efficiency of the plant cultivated in 134Cs contaminated soil both with and without EDTA amendment was low. The EDTA amendment to the soil seems to enhance the 134Cs availability for root uptake of Indian mustard and can still be considered to assist the field phytoremediation of contaminated soil. 相似文献
8.
Jwan H. Ibbini Lawrence C. Davis Larry E. Erickson 《International journal of phytoremediation》2009,11(5):451-462
Phytoremediation, the use of plants to clean up contaminated soil and water, has a wide range of applications and advantages, and can be extended to scientific education. Phytoremediation of textile dyes can be used as a scientific experiment or demonstration in teaching laboratories of middle school, high school and college students. In the experiments that we developed, students were involved in a hands-on activity where they were able to learn about phytoremediation concepts. Experiments were set up with 20—40 mg L?1 dye solutions of different colors. Students can be involved in the set up process and may be involved in the experimental design. In its simplest forms, they use two-week-old sunflower seedlings and place them into a test tube of known volume of dye solution. Color change and/ or dye disappearance can be monitored by visual comparison or with a spectrophotometer. Intensity and extent of the lab work depends on student's educational level, and time constraints. Among the many dyes tested, Evan's Blue proved to be the most readily decolorized azo dye. Results could be observed within 1–2 hours. From our experience, dye phytoremediation experiments are suitable and easy to understand by both college and middle school students. These experiments help visual learners, as students compare the color of the dye solution before and after the plant application. In general, simple phytoremediation experiments of this kind can be introduced in many classes including biology, biochemistry and ecological engineering. This paper presents success stories of teaching phytoremediation to middle school and college students. 相似文献
9.
Albert D. Venosa Kenneth Lee Makram T. Suidan Susana Garcia-Blanco Susan Cobanli Moustafa Moteleb John R. Haines Gilles Tremblay Melynda Hazelwood 《Bioremediation Journal》2002,6(3):261-281
Biostimulation by nutrient enrichment and phytoremediation were studied for the restoration of an acutely stressed freshwater wetland experimentally exposed to crude oil. The research was carried out along the shores of the St. Lawarence River at Ste. Croix, Quebec, Canada. The research determined the effectiveness of fertilizer addition in enhancing the biodegradation rates of residual oil. It further examined the rate at which the stressed ecosystem recovered with and without the addition of inorganic fertilizers and the role of nutrients in enhancing wetland restoration in the absence of healthy wetland plants. Chemical analysis of integrated sediment core samples to the depth of oil penetration within the experimental plots indicated that addition of inorganic nutrients did not enhance the disappearance of alkanes or PAHs. In surface samples, however, hydrocarbon disappearance rates were higher when the metabolic activity of wetland plants was suppressed by the removal of emergent plant growth. These results suggest that oxygen limitation plays a major role in preventing rapid biodegradation of hydrocarbons in anoxic wetland sediment. 相似文献
10.
Uptake of lead (Pb), copper (Cu), zinc (Zn), and cadmium (Cd) as +2 ions by excised roots of Indian mustard was demonstrated to be an ion-exchange process with existing Ca or protons released to the solution. This initial reaction at the root-aqueous interface is important in the uptake of these toxic metals from contaminated soil. Ethylene diamine tetraacetic acid (EDTA)-amended soil for phytoremediation has Pb in anionic form as [Pb-EDTA]2-, which was not taken up by excised roots. In nonliving B. juncea, Pb2+ was translocated from a solution through a cut stem to petiole and leaves much more quickly than anionic [Pb-EDTA]2-. However, in living plants [Pb-EDTA]2- was more quickly translocated from a solution through roots and petiole to leaves than Pb2+. The final amount of uptake on roots of the living plants was the same for both forms of Pb. The present results are important toward understanding the mechanism of phytoremediation of toxic metal-contaminated soil for two reasons: 1) the initial process, uptake of metal ions by roots, was shown to occur by cation exchange and 2) since [Pb-EDTA]2- was not sorbed by excised roots, other factors such as transpiration and active transport are important in applications using EDTA-amended soils contaminated by Pb. 相似文献