菌根真菌重金属耐性机制研究进展

菌根真菌在自然界中广泛存在,能与大多数陆地植物形成共生体,菌根共生体系对于植物适应各种逆境胁迫具有重要意义.在重金属污染土壤中通常也能发现菌根真菌,某些菌根真菌对重金属表现出较强的耐受性,在污染土壤修复方面显示出应用潜力.本文从生境选择、生理适应、功能基因表达调控等层面综述了菌根真菌重金属耐性机制方面的最新研究进展,并对今后的研究方向进行了展望,旨在推进相关机制研究及菌根技术在重金属污染土壤修复中的应用.     

Molecular and functional characterisation of cadmium-resistant Proteus vulgaris strain KNP3 to unravel its resistance mechanistic

Cadmium-resistant Proteus vulgaris strain KNP3 was originally isolated from the soil of Panki Thermal Power Plant, Kanpur, India. The strain was effective under in situ conditions for improving the physiological parameters of soybean plants. Nevertheless, the concentration of cadmium was significantly decreased in both plants and soil in the presence of this bioinoculant. Moreover, to unravel the mechanism involved in cadmium resistance, plasmid DNA was isolated from the strain and subjected to amplification of the czc gene, which is responsible for the efflux of three metal cations, viz. Co, Zn and Cd, from the cell. Further, the amplicon was cloned into pDrive cloning vector and sequenced. When compared with the available database, the sequence homology of the cloned gene showed the presence of a partial czcA gene sequence, thereby indicating the presence of an efflux mechanism for resistance in the strain. These results were further confirmed by atomic absorption spectroscopy, scanning electron microscopy and EDAX analysis.     

Reduction of hexavalent chromium using fungi and bacteria isolated from contaminated soil and water samples

The reductive adsorption of hexavalent chromium (Cr⁶⁺) using six indigenous microorganisms isolated from contaminated soil and water samples was investigated. Quantification of Cr⁶⁺ reduction was determined using the 1,5-diphenylcarbazide method followed measuring the absorbance at OD₅₄₀. Bacterial isolates identified as Klebsiella pneumoniae, Bacillus firmus and Mycobacterium sp. were capable of absorbing Cr⁶⁺ efficiently into their biomass, whereas the fungal isolates, Aspergillus flavus, Aspergillus sp. and A. niger were capable of transforming Cr⁶⁺ to Cr³⁺ relative to cell-wall-binding properties. Infrared spectral analysis of functional groups showed that ?OH, ?NH₂ and C?O with conjugated ?NH were the binding groups responsible for adsorption of Cr⁶⁺ within the biomass of isolates. The data highlight the promising biotechnological application of these isolates in removing carcinogenic and mutagenic Cr⁶⁺ from contaminated ecosystems.     

Improving the prediction of air pollution peak episodes generated by urban transport networks

This paper illustrates the early results of ongoing research developing novel methods to analyse and simulate the relationship between trasport-related air pollutant concentrations and easily accessible explanatory variables. The final scope is to integrate the new models in traditional traffic management support systems for a sustainable mobility of road vehicles in urban areas.This first stage concerns the relationship between the hourly mean concentration of nitrogen dioxide (NO₂) and explanatory factors reflecting the NO₂ mean level one hour back, along with traffic and weather conditions. Particular attention is given to the prediction of pollution peaks, defined as exceedances of normative concentration limits. Two model frameworks are explored: the Artificial Neural Network approach and the ARIMAX model. Furthermore, the benefit of a synergic use of both models for air quality forecasting is investigated.The analysis of findings points out that the prediction of extreme concentrations is best performed by integrating the two models into an ensemble. The neural network is outperformed by the ARIMAX model in foreseeing peaks, but gives a more realistic representation of the concentration's dependency upon wind characteristics. So, the Neural Network can be exploited to highlight the involved functional forms and improve the ARIMAX model specification. In the end, the study shows that the ability to forecast exceedances of legal pollution limits can be enhanced by requiring traffic management actions when the predicted concentration exceeds a lower threshold than the normative one.     

Evaluation of the capacity of the cyanobacterium Microcystis novacekii to remove atrazine from a culture medium

The bioaccumulation of atrazine and its toxicity were evaluated for the cyanobacterium Microcystis novacekii. Cyanobacterial cultures were grown in WC culture medium with atrazine at 50, 250 and 500 μg L^?1. After 96 hours of exposure, 27.2% of the atrazine had been removed from the culture supernatant. Spontaneous degradation was found to be insignificant (< 9% at 500 μg L^?1), indicating a high efficiency for the bioaccumulation of atrazine by M. novacekii. There were no atrazine metabolites detected in the culture medium at any of the doses studied. The acute toxicity (EC₅₀) of atrazine to the cyanobacterium was 4.2 mg L^?1 at 96 hours demonstrating the potential for M. novacekii to tolerate high concentrations of this herbicide in fresh water environments. The ability of M. novacekii to remove atrazine combined with its tolerance of the pesticide toxicity showed in this study makes it a potential biological resource for the restoration of contaminated surface waters. These findings support continued studies of the role of M. novacekii in the bioremediation of fresh water environments polluted by atrazine.     

高效液相色谱及其联用技术在有机锡形态测定中的应用

本文对发展中高效液相色谱及其联用技术在有机锡形态测定的应用分两部分作了综述：第一部分，各类高效液相色谱分离有机锡：第二部分，从接口角度讨论高效液相色谱及其联用技术测定有机锡。共引３６ 篇文献。     

SYSTEMATIC APPROACHES TO ENVIRONMENTAL IMPACT ASSESSMENT: AN EVALUATION1

ABSTRACT. Increased public awareness of the environmental effects of large-scale projects and concomittant public participation in the environmental impact assessment process demand that assessment methods and procedures fulfill a wide range of desirable characteristics. These are developed and offered as specific criteria against which currently proposed environmental assessment procedures should be judged. Such procedures as checklists, matrices, networks (stepped matrices), overlays, linear vector analyses, and nonlinear evaluation systems are presented and judged in light of the proposed criteria. It is concluded that the use of checklists, the most common assessment format used to date, does not constitute a viable assessment procedure. Use of the matrix or stepped matrix techniques in conjunction with the linear vector or nonlinear evaluation systems, with the latter modified slightly, is seen as an approach to environmental assessment that will achieve most of the established criteria.     

浅论微生物技术控藻

富营养化水体会引起藻类增殖，影响人类的生存环境。阐述了利用病毒、原生动物、细菌等微生物技术控制富营养化藻类的研究进展，并对病毒控藻技术应用时的两个问题进行了讨论，认为利用微生物技术控藻需要对生态系统进行更加深入的认识和掌握。     

A Kinetic Study of Aerobic Propane Uptake and Cometabolic Degradation of Chloroform, cis-Dichloroethylene and Trichloroetylene in Microcosms with Groundwater/Aquifer Solids

The focus of this study was to compare the behavior of different consortiums of aerobic propane-utilizing microorganisms, with respect to both the lag time for growth after exposure to propane, and their ability to transform three chlorinated aliphatic hydrocarbons (CAHs): chloroform (CF), cis-dichloroethylene (c-DCE) and trichloroethylene (TCE). Thirty-three slurry microcosms, representing seven combinations of aquifer solids and groundwater were constructed for this study. The lag time required for establishing propane-utilizing consortiums ranged between 24 and 29 days in 6 of the 7 combinations. Kinetic tests were performed with respect to propane utilization and CAH transformation. After CAH exposure, the ability of the microorganisms to metabolize propane was significantly reduced. CF and TCE were transformed more slowly than c-DCE, the average values of the initial transformation rates being equal to 0.10 ± 0.04, 0.09 ± 0.05 and 0.98 ± 0.18 mol/(L h),respectively. CF caused the greatest reduction in propane uptake rates, whereas c-DCE exhibited an apparently reversible negative effect on propane uptake rates. The estimates of the Monod half-saturation constants relative to CF, TCE and c-DCE resulted in the 2–3 mol/L range, but were characterized by a high degree of uncertainty.     

试析平朔露天煤矿废弃地复垦的新技术

从理论上初步分析了１９９１－１９９７年在平朔安太堡露天煤矿４００余ｈｍ＾２废弃地复垦中试用的新技术，包括黄土母质直接铺覆工艺，污染岩层包埋压埋工艺，堆状地面排土工艺，暂时性，过渡性，永久性水土保持措施，硬化与非硬化排水渠道，草，灌乔木合理配置模式。