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71.
Background Recent studies indicated that arbuscular mycorrhizal fungi (AMF) play important roles in plant accumulation of uranium (U) from contaminated environments, but the impacts of fertilization practices on functioning of the symbiotic associations, which are crucial factors influencing plant nutrition and growth responses to mycorrhiza, have rarely been considered. Materials and Methods In a greenhouse experiment, a bald root barley mutant (brb) together with the wild type (wt) were used to test the role of root hairs and AMF in uranium (U) uptake by host plants from a U contaminated soil. Nil, 20 and 60 mg KH2PO4-P kg–1 soil were included to investigate the influences of phosphorus (P) fertilization on plant growth and accumulation of U. Results Dry matter yield of barley plants increased with increasing P additions and wt produced significantly higher dry weight than brb. Mycorrhiza markedly improved dry matter yield of both genotypes grown at nil P, whereas only brb responded positively to mycorrhiza at 20 mg P kg-1. At the highest P level, mycorrhiza resulted in growth depressions in both genotypes, except for the roots of wt. In general, plant P concentrations increased markedly with increasing P additions and in response to mycorrhiza. Mycorrhiza and P additions had no significant effects on shoot U concentrations. However, root U concentrations in both genotypes were significantly increased by mycorrhiza. On the other hand, shoot U contents increased with increasing P levels, while 20 mg P kg-1 stimulated, but 60 mg P kg-1 marginally affected the U accumulation in roots. Root length specific U uptake was moderately enhanced both by root hairs and strongly enhanced by mycorrhiza. Moreover, non-inoculated plants generally had higher shoot-root ratios of U content than the corresponding inoculated controls. Conclusion Our study shows that AMF and root hairs improves not only P acquisition but also the root uptake of U, and mycorrhiza generally decreases U translocation from plant root to shoot. Hence, mycorrhiza is of potential use in the phytostabilization of U contaminated environments. Perspectives The complex impacts of P on U accumulation by barley plants suggested that U behavior in mycorrhizosphere and translocation along the soil-fungi-plant continuum as affected by fertilization practices deserve extensive studies for optimizing the function of mycorrhizal associations for phytoremediation purposes.  相似文献   
72.
73.
Increasingly intensive strategies to maintain biodiversity and ecosystem function are being deployed in response to global anthropogenic threats, including intentionally introducing and eradicating species via assisted migration, rewilding, biological control, invasive species eradications, and gene drives. These actions are highly contentious because of their potential for unintended consequences. We conducted a global literature review of these conservation actions to quantify how often unintended outcomes occur and to elucidate their underlying causes. To evaluate conservation outcomes, we developed a community assessment framework for systematically mapping the range of possible interaction types for 111 case studies. Applying this tool, we quantified the number of interaction types considered in each study and documented the nature and strength of intended and unintended outcomes. Intended outcomes were reported in 51% of cases, a combination of intended outcomes and unintended outcomes in 26%, and strictly unintended outcomes in 10%. Hence, unintended outcomes were reported in 36% of all cases evaluated. In evaluating overall conservations outcomes (weighing intended vs. unintended effects), some unintended effects were fairly innocuous relative to the conservation objective, whereas others resulted in serious unintended consequences in recipient communities. Studies that assessed a greater number of community interactions with the target species reported unintended outcomes more often, suggesting that unintended consequences may be underreported due to insufficient vetting. Most reported unintended outcomes arose from direct effects (68%) or simple density-mediated or indirect effects (25%) linked to the target species. Only a few documented cases arose from more complex interaction pathways (7%). Therefore, most unintended outcomes involved simple interactions that could be predicted and mitigated through more formal vetting. Our community assessment framework provides a tool for screening future conservation actions by mapping the recipient community interaction web to identify and mitigate unintended outcomes from intentional species introductions and eradications for conservation.  相似文献   
74.
Exposure to iron oxides dusts may lead to lung cancers among exposed population. To evaluate the involvement of iron‐containing particles in lipid peroxidation by production of reactive oxygen species, hematite, magnetite (iron oxides), and crocidolite (asbestos compound) were tested. The peroxidation was followed by the evaluation of some degradation products of lino‐lenic acid. In a buffered medium, magnetite is higher active than hematite. The addition of an iron chelator (EDTA) or of a reducing agent (ascorbate) in this medium enhances the activity of hematite and magnetite, and the combination of both EDTA and ascorbate increases their activity. Crocidolite is the most active whatever the medium. The appearance of the EDTA‐iron‐oxygen complexes related to the reactivity of these oxides is postulated. These results suggest that the oxidizing activity triggered by hematite and magnetite, in a medium containing an iron chelator and a reducing agent, may lead to damages in biological medium.  相似文献   
75.
Biodegradability of the plant growth retardant paclobutrazol by a microbial consortium in which Pseudomonas was the predominant strain was investigated in batch culture. The consortium which had been isolated from an industrially contaminated sediment was proven to be useful for the treatment of effluents containing paclobutrazol. Paclobutrazol was degraded by the pure isolated strain of Pseudomonas sp. as well as the microbial consortium. Paclobutrazol was utilized as the sole source of carbon and energy. Sixty percent of the paclobutrazol was degraded by the microbial consortium from an initial concentration of 54 mg L?1 within 48 h and more than 98% of an initial concentration of 3.4 mg L?1 was degraded within 36 h. The optimum temperature and pH were determined to be 30°C and 7.0, respectively. A pure strain of a bacterium, isolated from the enrichment culture was identified as Pseudomonas sp. The microbial consortium was tolerant of high pH and could degrade paclobutrazol faster than the pure strain. The degradation rate of this plant growth regulator in an aerobic environment was greater than that under anaerobic conditions.  相似文献   
76.
Ethyl alcohol, acetone, and petroleum ether extracts of three plant species belonging to three different botanical families [Strychnos nux-vomica (Loganiaceae), Euphorbia lathyrus (Euphorbiaceae), and Datura stramonlum (Solanaceae)], a chemical insecticide; profenofos and their combinations were tested against second and fourth instars of Spodoptera littoralis under lab conditions. Results revealed that the ethanol extract of S. nux-vomica was the most effective among all plant extracts, where the corrected mortality% were 92, 81, 58, and 27% to 2nd instar and 89, 74, 34, and 11% to 4th instar at concentrations 0.5, 0.25, 0.125, and 0.0625%, respectively. Calculated LC50's were 0.11, 0.22, and 0.34% to 2nd instar and 0.17, 0.37, and 0.52% to 4th instar for ethanol, petroleum ether, and acetone extracts, respectively. Acetone extracts of all plants were of lower effect. The chemical insecticide profenofos displayed higher efficacy than plant extracts (LC50 = 0.002 and 0.003% for S. littoralis 2nd and 4th larval instars, respectively). The co-toxicity factor reached 76 and 60 when mixing S. nux-vomica + profenofos and D. stramonlum + profenofos at ratio 1:1 against S. littoralis 2nd instar larvae, thus indicating a potentiating effect. While treatment of the 4th instar larvae by the same mixtures resulted in a co-toxicity factor below 20 at all mixing ratios indicating, only, an additive effect against this instar.  相似文献   
77.
For the determination of 15 potentially toxic elements (V, Cr, Fe, Mn, Co, Ni, Cu, Zn, As, Se, Ag, Cd, Sn, Hg, and Pb) in plant and sediment samples of the Akaki River, Ethiopia, inductively coupled plasma–mass spectrometry, inductively coupled plasma–optical emission spectrometry, and a RA-915+ mercury analyzer were applied. Sediment and plant samples were mineralized using a closed-vessel microwave-assisted digestion system. The elemental concentrations varied considerably in plant and sediment samples. The minimum concentration was observed for known toxic elements (As, Hg, and Cd) while the highest concentration was observed for the elements of relatively low toxicity Zn, Mn, and Fe. The concentration of Cr, Fe, Pb, Zn, and As in Swiss chard surpassed the maximum permissible levels at specific sites. At some of the sites, the sediment quality guidelines are surpassed for Cu, Zn, and Pb.  相似文献   
78.
Examination of vapor above commercial sodium humate and above 10wt% aqueous humate solution by gas chromatography (GC) revealed the presence of chloroform and trichloroethylene. Further examination of the aqueous humate by the purge and trap procedure confirmed the association of chloroform and trichloroethylene with the humate. GC/mass spectrometry analyses of methylene chloride extract of the humate established the association of LMHs with the humate. Improved headspace capillary GC technique showed that the humate contained not only chloroform, trichloroethylene but several other LMHs in the range 190 to 4000ng·kg‐1.  相似文献   
79.
Photodegradation of parathion ethyl in presence of unsaturated biomolecules takes place by sufficient reduction of the phenyl nitro group. Main products are N,0‐dialkenyl hydroxylamino, cis/trans azo, and azoxy derivatives of parathion.  相似文献   
80.
Benthic communities on soft bottoms off Barcelona, at and around two main pollution sources, the mouth of the Besòs River and the outlet of the submarine pipeline draining wastewater and organic sludges from the wastewater treatment plant of Sant Adrià del Besòs, have been studied. Samples were obtained with a Van Veen grab from 36 stations covering a 100 km2 grid, between 10 and 70 m in depth. The effect of both pollution sources is clearly seen both at the species (the following macrofauna groups have been studied: Polychaeta, Mollusca, Echinodermata and Crustacea Decapoda) and community levels. The distribution of species and individuals numbers, species diversity and a pollution index, and of some selected (indicator) polychaeta species, all clearly define the degree of environmental degradation and the extent of the areas under the influence of the organic pollution.  相似文献   
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