共查询到20条相似文献,搜索用时 15 毫秒
1.
Nelly Y. Tsibakhashvili Tamaz L. Kalabegishvili Alexander N. Rcheulishvili Ivane G. Murusidze Olia A. Rcheulishvili Salome M. Kerkenjia Hoi-Ying N. Holman 《Microbial ecology》2009,57(2):360-366
We demonstrated previously that Cr(VI) is readily reduced to oxoCr(V)-diols at the surface of Arthrobacter oxydans—a Gram-positive aerobic bacteria isolated from Columbia basalt rocks originated from a highly contaminated site in the USA.
Here, we report an electron spin resonance (ESR) study of Cr(III) hydroxide formation from Cr(V)-diols by this bacterial strain
as cells were exposed to 35, 200, and 400 mg/L of Cr(VI) under aerobic conditions as a batch culture and as lyophilized cells.
The time-dependent ESR measurements show that the half-time of Cr(III) formation is almost equal to that of Cr(V) decomposition,
which is in the range of 3–6 days for all cases. This rate is at least 300 times slower than that of Cr(V) formation. Additionally,
atomic absorption spectrometry was also employed to examine the time course of total chromium in bacterial cells. This is
the first time the kinetics of Cr(III) complexes formation in bacteria is evaluated. 相似文献
2.
Interactions of the Pseudomonas stutzeri KC siderophore pyridine-2,6-bis(thiocarboxylic acid) (pdtc) with chromium(VI), mercury(II), cadmium(II), lead(II), and arsenic(III)
are described. Pdtc was found to reduce Cr(VI) to Cr(III) in both bacterial cultures and in abiotic reactions with chemically
synthesized pdtc. Cr(III) subsequently formed complexes with pdtc and pdtc hydrolysis products, and their presence was confirmed
using electrospray ionization-mass spectrometry (ESI-MS). Cr(III):pdtc complexes were found to slowly release Cr(III) as chromium
sulfide and possibly Cr(III) oxides. Pdtc also formed poorly soluble complexes with Hg, Cd, Pb, and As(III). Hydrolysis of
those complexes led to the formation of their respective metal sulfides as confirmed by energy dispersive X-ray spectroscopy
(EDS) elemental analysis. The pdtc-producing strain P. stutzeri KC showed higher tolerance to most of these metals as compared to a pdtc-negative mutant. A novel role of pdtc is postulated
as its involvement in providing an extracellular pool of thiols that are used for redox processes in detoxification of the
bacterial extracellular environment. These redox processes can be mediated by transition metal:pdtc complexes. 相似文献
3.
A chromium (Cr)-resistant bacterium isolated from soil containing 6,000 mg/kg of Cr was identified based on 16S rRNA gene
sequence analysis as Delftia, and designated as JD2. Growth of JD2 was accompanied with reduction of Cr(VI) to Cr(III) in liquid medium initially containing
100 mg/L Cr(VI), the maximum concentration allowing growth. JD2 showed NADH/NADPH-dependent reductase activity associated
with the soluble fraction of cells. The results suggest that JD2 might be a good candidate for the treatment of highly Cr(VI)-contaminated
water and/or industrial effluents. The isolate produced indole-3-acetic acid in the presence and absence of Cr(VI) and showed
free-living nitrogen-fixing activity possibly attributable to a V-nitrogenase. JD2 did not counteract the harmful effect of
Cr(VI) during leguminous plant growth and nodulation by rhizobial strains but functioned as a “helper” bacterium to enhance
the performance of rhizobial inoculant strains during inoculation of alfalfa and clover (used as model plants to study plant
growth-promoting activity) in the absence of Cr(VI). 相似文献
4.
Isolation and Characterization of Chromium(VI)-Reducing Bacteria from Tannery Effluents 总被引:3,自引:0,他引:3
Ilias M Rafiqullah IM Debnath BC Mannan KS Mozammel Hoq M 《Indian journal of microbiology》2011,51(1):76-81
Two chromium-resistant bacteria (IFR-2 and IFR-3) capable of reducing/transforming Cr(VI) to Cr(III) were isolated from tannery
effluents. Isolates IFR-2 and IFR-3 were identified as Staphylococcus aureus and Pediococcus pentosaceus respectively by 16S rRNA gene sequence analyses. Both isolates can grow well on 2,000 mg/l Cr(VI) (as K2Cr2O7) in Luria-Bertani (LB) medium. Reduction of Cr(VI) was found to be growth-associated in both isolates and IFR-2 and IFR-3
reduced 20 mg/l Cr(VI) completely in 6 and 24 h respectively. The Cr(VI) reduction due to chromate reductase activity was
detected in the culture supernatant and cell lysate but not at all in the cell extract supernatant of both isolates. Whole
cells of IFR-2 and IFR-3 converted 24 and 30% of the initial Cr(VI) concentration (1 mg/l) in 45 min respectively at 37°C.
NiCl2 stimulated the growth of IFR-2 whereas HgCl2 and CdCl2 significantly inhibited the growth of both isolates. Optimum temperature and pH for growth of and Cr(VI) reduction by both
isolates were found to be between 35 and 40°C and pH 7.0 to 8.0. The two bacterial isolates can be good candidates for detoxification
of Cr(VI) in industrial effluents. 相似文献
5.
Ksheminska H Jaglarz A Fedorovych D Babyak L Yanovych D Kaszycki P Koloczek H 《Microbiological research》2003,158(1):59-67
A comparative study has been made on the sensitivity of the yeast Pichia guilliermondii to Cr (III) and Cr (VI) as well as on the Cr uptake potential at growth-inhibitory concentrations of chromium. The strains used in the study were either isolated from natural sources or obtained from a laboratory strain collection. The results show that most of the natural strains were more tolerant to chromium and were able to grow in the presence of 5 mM Cr (III) or 0.5 mM Cr (VI), that is at concentrations which substantially inhibited the growth of laboratory strains. The cellular Cr content after treatment was similar for both strain types and ranged from 1.2-4.0 mg/g d.w. and 0.4-0.9 mg/g d.w., for Cr (III) and Cr (VI) forms, respectively, however, in one case of a natural strain it reached the value of 10 mg Cr (III)/g dry mass. Natural-source strains were grouped into four groups based on the yeasts' differential response to Cr (III) and Cr (VI). Hexavalent Cr-resistant mutants of a P. giuilliermondii laboratory strain, which revealed markedly changed capabilities of chromium accumulation, were obtained by means of UV-induced mutagenesis. Cr (VI) treatment triggered oversynthesis of riboflavin and the addition of exogenous riboflavin increased P. guilliermondii resistance to both Cr (III) and Cr (VI). Electrophoretic protein profiles revealed the induction and/or suppression of several proteins in response to toxic Cr (VI) levels. 相似文献
6.
ABSTRACT Chemical reduction of Cr(VI) can be a strategy to detoxify toxic metals in oxidized states, whereas reduction of Fe(III) could enhance the availability of Fe in the form of Fe(II) to boost plant growth. However, it creates another problem of chemical sludge disposal. Hence, microbial conversion of Cr(VI) to Cr(III) and Fe(III) to Fe(II) is preferred over the chemical method. Out of 11 bacterial strains isolated from the rhizospheric zone of Typha latifolia growing on fly ash dump sites, four isolates were selected for the reduction of Cr(VI) and Fe(III) and were identified as Micrococcus roseus NBRFT2 (MTCC 9018), Bacillus endophyticus NBRFT4 (MTCC 9021), Paenibacillus macerans NBRFT5 (MTCC 8912), and Bacillus pumilus NBRFT9 (MTCC 8913). These strains were individually tested for survival at different concentrations of Cr(VI) and Fe(III), pH, and temperature, and then, their ability for reduction of both metals was evaluated at optimum pH 8.0 and temperature 35°C. The results indicated that NBRFT5 was able to reduce the maximum amount, 99% Cr(VI) and 98% Fe(III). Other strains also reduced these metals to different levels, but less than NBRFT5. Hence, these strains may be used for decontamination of metal-contaminated sites, particularly with Cr(VI) and Fe(III) through the reduction process. 相似文献
7.
Aktham N. Jasim Azhar Kamel Nagham S. Al-Awadi Hussein Fares Abd-Alrazack 《Luminescence》2023,38(3):360-368
A simple, rapid, sensitive and inexpensive approach is described in this work based on a combination of solid-phase extraction of 8-hydroxyquinoline (8HQ), for speciation and preconcentration of Cr(III) and Cr(VI) in river water, and the direct determination of these species using a flow injection system with chemiluminescence detection (FI–CL) and a 4-diethylamino phenyl hydrazine (DEAPH)–hydrogen peroxide system. At different pH, the two forms of chromium [Cr(III) and Cr(VI)] have different exchange capacities for 8HQ, therefore two columns were constructed; the pH of column 1 was adjusted to pH 3 for retaining Cr(III) and column 2 was adjusted to pH 1 for retaining of Cr(VI). The sorbed Cr(III) and Cr(VI) species were eluted from columns using 3.0 ml of 0.1 N of HCl and 3.0 ml of 0.1 N of NaOH, respectively. The flow injection–chemiluminescence (FI–CL) method is based on light emitted due to the oxidation of DEAPH by the H2O2 in the presence of Cr(III), which catalyzes the reaction. The flow cell is a transparent coiled tube made from glass (2.0 × 4.0, inner and outer diameter) and located close to the photodetector. The flow parameters: flow rate, sample volume, flow cell length, and distance to the CL detector were studied and optimized. Under optimum flow conditions, the Cr(III) concentration can be determined over the range 5–350 μg L−1 with a limit of detection of 1.2 μg L−1, as the Cr(III) concentration is proportional to the intensity of the CL signal. The relative standard deviations (%) for 10 and 50 μg L−1 Cr(III) were 1.2% and 3.2%, respectively. The effects of Al(III), Cd(II), Zn(II), Hg(II), Pb(II), Co(II), Cu(II), Ni(II), Mn(II), Ca(II), and Fe(III) were investigated. The proposed method is highly selective and sensitive, enabling a rapid determination of the Cr(III) amount in the presence of other interfering metals. Finally, the FI–CL method was examined in five river water samples with excellent recoveries. 相似文献
8.
Hexavalent chromium reduction and accumulation by Acinetobacter AB1 isolated from Fez tanneries effluents were tested. The effects of some environmental factors such as pH, temperature,
and exposure time on Cr(VI) reduction and resistance were investigated. We found that this strain was able to resist to concentrations
as high as 400 mg/l of Cr(VI). Moreover, pH 10 and the temperature 30°C constitute favourable conditions to the growth and
reduction of Acinetobacter AB1. Complete reduction of Cr(VI) was observed at low initial Cr(VI) concentrations of 50 mg/l after 72 h of incubation.
Furthermore, Transmission electron microscope (TEM) analysis showed morphological changes in AB1 strain due 48H exposure to
100 mg/l chromate concentration and revealed circular electron dense (dark black point) inclusion within the cell cytoplasm
suggesting chromium deposition within the cells. 相似文献
9.
Hexavalent chromium is one of the most widely distributed environmental contaminants. Given the carcinogenic and mutagenic
consequences of Cr(VI) exposure, the release of Cr(VI) into the environment has long been a major concern. While many reports
of microbial Cr(VI) reduction are in circulation, very few have demonstrated Cr(VI) reduction under alkaline conditions. Since
Cr(VI) exhibits higher mobility in alkaline soils relative to pH neutral soils, and since Cr contamination of alkaline soils
is associated with a number of industrial activities, microbial Cr(VI) reduction under alkaline conditions requires attention.
Soda lakes are the most stable alkaline environments on earth, and contain a wide diversity of alkaliphilic organisms. In
this study, a bacterial isolate belonging to the Halomonas genus was obtained from Soap Lake, a chemically stratified alkaline lake located in central Washington State. The ability
of this isolate to reduce Cr(VI) and Fe(III) was assessed under alkaline (pH = 9), anoxic, non-growth conditions with acetate
as an electron donor. Metal reduction rates were quantified using Monod kinetics. In addition, Cr(VI) reduction experiments
were carried out in the presence of Fe(III) to evaluate the possible enhancement of Cr(VI) reduction rates through electron
shuttling mechanisms. While Fe(III) reduction rates were slow compared to previously reported rates, Cr(VI) reduction rates
fell within range of previously reported rates. 相似文献
10.
Codd R Lay PA Tsibakhashvili NY Kalabegishvili TL Murusidze IG Holman HY 《Journal of inorganic biochemistry》2006,100(11):1827-1833
Chromium(V) is an intermediate formed during the reduction of Cr(VI) to Cr(III) compounds by various bacteria. However, little is known about the nature, localization and reactivity of Cr(V) species in microbial systems. Electron paramagnetic resonance (EPR) spectroscopy was used to study the nature of Cr(V) complexes generated in basalt-inhabiting Gram-positive Arthrobacter oxydans bacteria after exposure to high concentrations of Cr(VI). Numerical simulations of the EPR spectroscopic data provide strong evidence for at least two different diolato-type oxoCr(V) complexes (I, g(iso)=1.9801; II, g(iso)=1.9796) involving bacterial cell wall macromolecules in the Cr(VI)-A. oxydans system. The relative concentrations of the two oxoCr(V)-diolato species differ when Cr(VI) is incubated with either untreated A. oxydans cells (I:II approximately 50:50) or lyophilized cells (I:II approximately 10:90). Based upon the magnitudes of the proton superhyperfine coupling constants ((1)H a(iso)) for species I and II, the EPR simulation model is unable to distinguish unambiguously whether the oxoCr(V)-diolato species are linear alkoxides or cyclic diols (carbohydrates). The oxygen-containing functional groups associated with teichoic acids are the most likely candidates for complexation with the Cr(V) ion. 相似文献
11.
Toxic effects of metals appear to be partly related to the production of reactive oxygen species (ROS), which can cause oxidative damage to cells. The ability of several redox active metals [Fe(III), Cu(II), Ag(I), Cr(III), Cr(VI)], nonredox active metals [Pb(II), Cd(II), Zn(II)], and the metalloid As(III) and As(V) to produce ROS at environmentally relevant metal concentrations was assessed. Cells of the freshwater alga Chlamydomonas reinhardtii P. A. Dang. were exposed to various metal concentrations for 2.5 h. Intracellular ROS accumulation was detected using an oxidation‐sensitive reporter dye, 5‐(and‐6)‐carboxy‐2′,7′‐dihydrodifluorofluorescein diacetate (H2DFFDA), and changes in the fluorescence signal were quantified by flow cytometry (FCM). In almost all cases, low concentrations of both redox and nonredox active metals enhanced intracellular ROS levels. The hierarchy of maximal ROS induction indicated by the increased number of stained cells compared to the control sample was as follows: Pb(II) > Fe(III) > Cd(II) > Ag(I) > Cu(II) > As(V) > Cr(VI) > Zn(II). As(III) and Cr(III) had no detectable effect. The effective free metal ion concentrations ranged from 10?6 to 10?9 M, except in the case of Fe(III), which was effective at 10?18 M. These metal concentrations did not affect algal photosynthesis. Therefore, a slightly enhanced ROS production is a general and early response to elevated, environmentally relevant metal concentrations. 相似文献
12.
Chromium(VI) resistance and removal by <Emphasis Type="Italic">Acinetobacter haemolyticus</Emphasis>
Quek Hsiao Pei Shafinaz Shahir A. S. Santhana Raj Zainul Akmar Zakaria Wan Azlina Ahmad 《World journal of microbiology & biotechnology》2009,25(6):1085-1093
The present work highlighted the studies on Cr(VI) reduction by cells of Acinetobacter haemolyticus (A. haemolyticus). The strain tolerated 90 mg Cr(VI) l−1 in LB broth compared to only 30 mg Cr(VI) l−1 in LB agar. From the FTIR analysis, the Cr(III) species formed was also most likely to form complexes with carboxyl, hydroxyl,
and amide groups from the bacteria. A TEM study showed the absence of precipitates on the cell wall region of the bacteria.
Instead, microprecipitates were observed in the cytoplasmic region of the cells, suggesting the transportation of Cr(VI) into
the cells. Intracellular reduction of Cr(VI) was supported by a reductase test using soluble crude cell-free extracts. The
specific reductase activity obtained was 0.52 μg Cr(VI) reduced per mg of protein an hour at pH 7.2 and 37°C. Our results
indicated that A. haemolyticus can be used as a promising microorganism for Cr(VI) reduction from industrial wastewaters. 相似文献
13.
Cathodic reduction of hexavalent chromium [Cr(VI)] coupled with electricity generation in microbial fuel cells 总被引:1,自引:0,他引:1
A novel approach to Cr(VI)-contaminated wastewater treatment was investigated using microbial fuel cell technologies in fed-batch
mode. By using synthetic Cr(VI)-containing wastewater as catholyte and anaerobic microorganisms as anodic biocatalyst, Cr(VI)
at 100 mg/l was completely removed during 150 h (initial pH 2). The maximum power density of 150 mW/m2 (0.04 mA/cm2) and the maximum open circuit voltage of 0.91 V were generated with Cr(VI) at 200 mg/l as electron acceptor. This work verifies
the possibility of simultaneous electricity production and cathodic Cr(VI) reduction. 相似文献
14.
A bacterial strain resistant to phenol and Cr (VI) was isolated from an industrial polluted soil of Córdoba province (Argentina), which was identified as Pantoea sp. FC 1. This microorganism was able to use phenol as sole carbon source. In addition it was capable of reducing Cr (VI) to Cr (III) in mineral and nutrient media. The isolated strain exhibited some properties as plant-growth promoting bacterium (PGPB), such as production of Indole Acetic Acid (IAA) and synthesis of siderophores, as well as being capable of solubilizing inorganic phosphates. A rhizoremediation system using the association Pantoea sp. FC 1-Brassica napus hairy roots (HRs) was tested for phenol and Cr (VI) removal in a hydroponic system. Microbial inoculation improved both phenol removal and chromium accumulation efficiency by HRs, showing a significant increase in Cr (III) accumulation compared to non-inoculated HRs, exceeding 1000 mg kg−1. Cr (III) was detected in HR biomass and supernatants, suggesting a possible Cr (VI) reducing activity of B. napus HRs. Basic studies in plant model systems, such as HRs, provide additional useful information that could facilitate the transition of this technology into plants suitable for practical rhizoremediation applications. 相似文献
15.
Bacterial strains, previously isolated from a chromium-polluted soil, were identified on the basis of Gram reaction and biochemical
characteristics (Biolog system). Moreover, chromate MICs, chromate reduction capability, multiple heavy metal tolerance, and
antibiotic susceptibility were tested for each isolate. All strains but one were Gram-positive and resistant to high concentrations
of chromate. The most Cr(VI)-resistant isolate (22mM) was identified as Corynebacterium hoagii. All Cr(VI)-resistant strains except the isolate ChrC20 were capable of catalyzing the reduction of Cr(VI) to Cr(III), a
less toxic and less water-soluble form of chromium. The only isolate Cr(VI)-sensitive, attributed to the Pseudomonas genus, also exhibited Cr(VI)-reduction. Isolates were also screened for the presence of plasmid DNA. The strains ChrC20 and
ChrB20 harbored one and two plasmids of high molecular mass, respectively. This approach permitted selection of some bacterial
strains, which could be used for bioremediation of Cr(VI)-polluted environments.
Received: 21 February 2002 / Accepted: 27 March 2002 相似文献
16.
《Chemical Speciation and Bioavailability》2013,25(2):31-39
AbstractChromium speciation in the presence of organic chromium(III) complexes was investigated using solid-phase extraction. The adsorptions of Cr(VI) and Cr(III) on alumina and pumice powder were studied. Maximum sorption of Cr(VI) was obtained by alumina (90.22%), while Cr(III) was highly adsorbed onto pumice powder (86.65%). This result shows that pumice may be a new and promising adsorbent for Cr(III). The experimental equilibrium data for Cr(VI) adsorption onto alumina and Cr(III) sorption onto pumice were analysed using Langmuir and Freundlich isotherms. The separation and adsorption of Cr(VI), Cr(III) and five organic chromium(III) complexes onto pumice and alumina at different pH values were evaluated. Ethylenediaminetetraacetate (EDTA), oxalate, citrate, glycine, alanine and 8-hydroxyqinoline were used as ligands. Sorption of alanine and ethylenediaminetetraacetate complexes was higher onto alumina than pumice at pH>3. The enhancement of adsorption of chromium(III) complexes onto pumice was achieved by surface modification of pumice using a surfactant, namely hexadecyltrimethylammoniumbromür (HDTMA). The presence of surfactant enhanced the adsorption of Cr(III) citrate, oxalate, glycine and 8-hydroxyquinoline complexes onto pumice. However, the adsorption of EDTA and alanine complexes decreased, with ratio of 13.40% and 4.00% respectively. Here we demonstrate that chromium speciation methods depending on adsorption onto various adsorbents including alumina may lead erroneous results. Analytical measurements were performed by flame AAS, data were obtained by standard addition method. 相似文献
17.
Jennifer L. Nyman Frank Caccavo Al B. Cunningham Robin Gerlach 《Bioremediation Journal》2002,6(1):39-55
Ferrous iron [Fe(II)] reductively transforms heavy metals in contaminated groundwater, and the bacterial reduction of indigenous ferric iron [Fe(III)] to Fe(II) has been proposed as a means of establishing redox reactive barriers in the subsurface. The reduction of Fe(III) to Fe(II) can be accomplished by stimulation of indigenous dissimilatory metal-reducing bacteria (DMRB) or injection of DMRB into the subsurface. The microbially produced Fe(II) can chemically react with contaminants such as Cr(VI) to form insoluble Cr(III) precipitates. The DMRB Shewanella algae BrY reduced surface-associated Fe(III) to Fe(II), which in batch and column experiments chemically reduced highly soluble Cr(VI) to insoluble Cr(III). Once the chemical Cr(VI) reduction capacity of the Fe(II)/Fe(III) couple in the experimental systems was exhausted, the addition of S. algae BrY allowed for the repeated reduction of Fe(III) to Fe(II), which again reduced Cr(VI) to Cr(III). The research presented herein indicates that a biological process using DMRB allows the establishment of a biogeochemical cycle that facilitates chromium precipitation. Such a system could provide a means for establishing and maintaining remedial redox reactive zones in Fe(III)-bearing subsurface environments. 相似文献
18.
de María Guillén-Jiménez F Morales-Barrera L Morales-Jiménez J Hernández-Rodríguez CH Cristiani-Urbina E 《Journal of industrial microbiology & biotechnology》2008,35(11):1277-1287
The main aim of this study was to investigate the influence of the sulfate ion on the tolerance to Cr(VI) and the Cr(VI) reduction
in a yeast strain isolated from tannery wastewater and identified as Candida sp. FGSFEP by the D1/D2 domain sequence of the 26S rRNA gene. The Candida sp. FGSFEP strain was grown in culture media with sulfate concentrations ranging from 0 to 23.92 mM, in absence and presence
of Cr(VI) [1.7 and 3.3 mM]. In absence of Cr(VI), the yeast specific growth rate was practically the same in every sulfate
concentration tested, which suggests that sulfate had no stimulating or inhibiting effect on the yeast cell growth. In contrast,
at the two initial Cr(VI) concentrations assayed, the specific growth rate of Candida sp. FGSFEP rose when sulfate concentration increased. Likewise, the greater efficiencies and volumetric rates of Cr(VI) reduction
exhibited by Candida sp. FGSFEP were obtained at high sulfate concentrations. Yeast was capable of reducing 100% of 1.7 mM Cr(VI) and 84% of 3.3 mM
Cr(VI), with rates of 0.98 and 0.44 mg Cr(VI)/L h, with 10 and 23.92 mM sulfate concentrations, respectively. These results
indicate that sulfate plays an important role in the tolerance to Cr(VI) and Cr(VI) reduction in Candida sp. FGSFEP. These findings may have significant implications in the biological treatment of Cr(VI)-laden wastewaters. 相似文献
19.
L. Ya. Babyak G. P. Ksheminskaya M. V. Gonchar D. V. Yanovich D. V. Fedorovich 《Applied Biochemistry and Microbiology》2005,41(2):177-181
Yeast Pichia guilliermondii strains L3 and L2, exposed to UV mutagenesis, produced over 80 mutants capable of growing on media containing 1.5 mM bichromate (Cr(VI)). The mutations making the strains resistant to Cr(VI) were dominant or semidominant. The mutants varied in Cr(VI) resistance, the degree of chromium accumulation in the cells (from 0.1 to 11.6 mg/g dry cells), and the degree of Cr(VI) reduction (from 50% to complete disappearance of bichromate from the culture liquid). Chromium accumulation in mutant cells depended on medium composition, Cr(VI) concentration, and the time of exposure to Cr(VI). The resistance to bichromate can be caused by various reasons: decrease in chromium absorption, altered ability to reduce Cr(VI), or damage of sulfate transport mechanisms.Translated from Prikladnaya Biokhimiya i Mikrobiologiya, Vol. 41, No. 2, 2005, pp. 204–209.Original Russian Text Copyright © 2005 by Babyak, Ksheminskaya, Gonchar, Yanovich, Fedorovich. 相似文献
20.
The single and joint toxicity effects of Cu, Cr(III), and Cr(VI) on the root elongation of pakchoi in solution and soil were
investigated. The median effective concentration (EC50) was determined to examine the toxic thresholds of the test elements. The results showed that individual contamination by
Cu, Cr(III), or Cr(VI) can inhibit the root elongation of pakchoi. The EC50 values of the test elements were 2.02 mg/L and 195.8 mg/kg, 62.2 mg/L and 1,773 mg/kg, and 6.88 mg/L and 8.08 mg/kg in solution
and soil, respectively. Toxic unit (TU) was introduced to determine the outcome in combined tests, and different behaviors
were observed in both solution and soil. The coexistence of Cu and Cr(III) in solution exhibited an antagonistic effect (EC50mix = 1.76 TUmix), whereas a synergistic effect was observed in soil (EC50mix = 0.76 TUmix). In contrast, combined Cu–Cr(VI) showed a less than additive toxicity both in solution and soil, with EC50mix values of 3.31 and 1.24 TUmix. In conclusion, the coexistence of toxicity in Cu–Cr(III) and Cu–Cr(VI) differs from the toxicity exhibited individually
by Cu, Cr(III), and Cr(VI). Heavy metal interaction also changes depending on the medium. 相似文献