硝基苯类废水的预处理技术研究

Fe(OH)2对硝基苯具有强烈的还原作用，短时间内可把硝基苯还原为苯胺。催化铁屑法处理硝基苯类废水，除了包括铁屑法处理废水的各种反应外，还能使硝基苯在其表面直接还原，且反应在弱碱性条件下效果较好。m(Fe)：m(Cu)为10：1，pH为9．5，废水硝基苯进水质量浓度为250mg／L，反应时间为30min，硝基苯的去除率达100％。     

唐山市概况和灾害潜势分析

本文概述了唐山市的基本情况及其经受的自然灾害和发展趋势,这些内容为制定唐山市综合减灾规划的前提和基础。     

青龙县“四荒“治理开发的几点做法

青龙满族自治县被列为河北省桃林口水库上游重点治理区,境内大量“四荒”资源闲置浪费。该县立足县情,制定优惠政策,强化管理,因地制宜地开发这些资源,取得显著成效,其做法值得推广和借鉴。     

四川盆地油桐适宜栽培高度及分布

本文对油桐产油量立体变化与气候生态条件的关系进行了客观定量的研究,提出了油桐适宜栽培高度的气候生态指标;并结合四川盆地年平均气温分布特点,揭示了油桐适宜栽培高度的分布规律,还根据有关生态学和经济学原理,对油桐发展战略进行了探讨。     

石油类在河流中自净能力的研究

根据河流的特点,利用示踪剂对河流中石油类污染物的衰减情况进行了分析,建立了污染物扩散模式,确定了河流不同断面的石油通量,求出了石油类污染物的衰减系数。为污染物的排放量和河流环境容量的确定提供了保证。     

Simulating interactive effects of symbiotic nitrogen fixation, carbon dioxide elevation, and climatic change on legume growth

The underlying mechanisms of interaction between the symbiotic nitrogen-fixation process and main physiological processes, such as assimilation, nutrient allocation, and structural growth, as well as effects of nitrogen fixation on plant responses to global change, are important and still open to more investigation. Appropriate models have not been adequately developed. A dynamic ecophysiological model was developed in this study for a legume plant [Glycine max (L.) Merr.] growing in northern China. The model synthesized symbiotic nitrogen fixation and the main physiological processes under variable atmospheric CO2 concentration and climatic conditions, and emphasized the interactive effects of these processes on seasonal biomass dynamics of the plant. Experimental measurements of ecophysiological quantities obtained in a CO2 enrichment experiment on soybean plants, were used to parameterize and validate the model. The results indicated that the model simulated the experiments with reasonable accuracy. The R2 values between simulations and observations are 0.94, 0.95, and 0.86 for total biomass, green biomass, and nodule biomass, respectively. The simulations for various combinations of atmospheric CO2 concentration, precipitation, and temperature, with or without nitrogen fixation, showed that increasing atmospheric CO2 concentration, precipitation, and efficiency of nitrogen fixation all have positive effects on biomass accumulation. On the other hand, an increased temperature induced lower rates of biomass accumulation under semi-arid conditions. In general, factors with positive effects on plant growth tended to promote each other in the simulation range, except the relationship between CO2 concentration and climatic factors. Because of the enhanced water use efficiency with a higher CO2 concentration, more significant effects of CO2 concentration were associated with a worse (dryer and warmer in this study) climate.     

Influence of filtration velocity on DON variation in BAF for micropolluted surface water treatment

Biological aerated filters (BAFs) are widely used for the treatment of micropolluted surface water. However, the biological process produces dissolved organic nitrogen (DON), which, as precursors of nitrogenous disinfection by-products, pose potential threats to drinking water safety. Therefore, to control DON in BAF effluent, it is necessary to study the influence of BAF operation parameters on DON production. In this study, the influence of filtration velocity in a BAF on DON production was investigated. Under different filtration velocity (0.5, 2, and 4 m/h) conditions, profiles of DON concentrations along the media layer were measured. The profile at a filtration velocity of 0.5 m/h showed a decreasing trend, and the ones under filtration velocities of 2 and 4 m/h fluctuated in a small range (from 0.1 to 0.4 mg/L). Moreover, the relatively high filtration velocities of 2 and 4 m/h resulted in a lower level of DON concentration. Additionally, 3D excitation-emission matrix fluorescence spectroscopy was used to characterize DON. It is found that the patterns of DON at a relatively high filtration velocity condition (4 m/h) were obviously different from the ones under low filtration velocity conditions (0.5 and 2 m/h).     

Characterization of an efficient catalytic and organic solvent-tolerant azoreductase toward methyl red from Shewanella oneidensis MR-1

The acyl carrier protein (ACP) phosphodiesterase gene (SO 4396) of Shewanella oneidensis MR-1 which was analyzed to have azoreductase activity was heterologously expressed in Escherichia coli. The ACP phosphodiesterase was found to reach maximum enzyme velocity 220.59 U/mg, named azoreductase in this study. The azoreductase had highest specific activity (153.16 U/mg) at pH 6.5, which showed a preference for nicotinamide adenine dinucleotide (NADH) as electron donor. The phylogenetic tree analysis indicated that the azoreductase had preference for NADH and dependence for flavin mononucleotide (FMN). However, the azoreductase from S. oneidensis MR-1 still had high enzyme activity in the absence of FMN. The Mg²⁺ had a positive influence on the enzyme activity with 25 mM concentration, whereas Cr³⁺, Cd²⁺ usually had significantly negative effect on enzyme activity. The purified azoreductase retained nearly 100 % activity after incubating in 30 % dimethyl sulfoxide (DMSO), 30 % acetone, 30 % methanol, 20 % ethanol, 20 % isopropanol, and 10 % propanol.     

Effect of multiple washing operations on the removal of potentially toxic metals from an alkaline farmland soil and the strategy for agricultural reuse

Few studies have carried out soil washing experiments using pot experiments to simulate in situ soil washing operations, particularly for alkaline soils. This study explored the effects of multiple washing operations using pot experiments on the removal efficiencies of potentially toxic metals (PTM) from alkaline farmland soil and the reuse strategy of washed soil for safe agricultural production. The results showed that the removal efficiencies of Cd, Pb, Cu, and Zn after seven washings with a mixed chelator (EDTA, GLDA, and citric acid) were 41.1%, 47.1%, 14.7%, and 26.5%, respectively, which was close to the results of the EDTA treatment. For the alkaline soil studied, the second washing with the mixed chelators most effectively removed PTM owing to the activation of them after the first washing operation. The mixed chelator more effectively increased the proportion of stable fraction of PTM and maintained soil nutrients (e.g., nitrogen content) than EDTA, indicating little disturbance of alkaline soil quality after washing with the mixed chelator. After the amendment of the washed soil, there was no visible difference in the biomass weight of crops from the soils washed with different agents, indicating that the inhibitory effect of both washing agents on plant growth was effectively alleviated. The Cd and Pb contents in Z. mays were below the threshold of Hygienical Standard for Feeds of China (GB 13078–2017) (1 and 30 mg·kg^?1). Moreover, after three cropping operations, the available concentrations of PTM in the soil washed with the mixed chelator were lower than those in the soil washed with EDTA, indicating the value and potential of agricultural reuse of alkaline farmland soil washed with the mixed chelator.

Graphical abstract

     

硫酸铜和马度米星铵联合暴露对鲫鱼的毒性和效应标记物研究

为探究硫酸铜和马度米星铵对水产动物的生态毒性,本研究以鲫鱼为模型,从急性毒性、亚急性毒性和遗传毒性3个方面研究硫酸铜和马度米星铵单一与联合暴露对鲫鱼的毒性效应.结果 表明,硫酸铜对鲫鱼96 h的半数致死浓度(50％ lethal concentration,LC50)为3.6 mg·L-1,硫酸铜和马度米星铵联合暴露时...