Dechlorination of pentachloroethane by commercial Fe and ferruginous smectite

Short-term experiments were conducted to investigate the effect of a commercial Fe and an iron-bearing clay mineral, ferruginuous smectite (SWa-1), on the degradation of pentachloroethane (PCA). After 3 h of contact time, SWa-1 catalyzed PCA dehydrochlorination to tetrachloroethene (PCE, 65% conversion), whereas commercial Fe promoted PCA stepwise dechlorination via dehydrochlorination (approximately 40% conversion) and subsequent PCE hydrogenolysis to trichloroethene (TCE). The addition of unaltered SWa-1 to commercial Fe led to a complete inhibition on TCE production, whereas the addition of reduced SWa-1 barely resulted in a 30% decrease.     

Effects of metabolites of benzo(a)pyrene on unschedule DNA synthesis in BALB/3T3 cell line

In order to explore the damage from metabolites of benzo(a)pyrene on DNA of mammalian cells, the effects of four metabolites of benzo(a)pyrene (anti-BPDE, syn-BPDE, 3-OH-BP and 9-OH-BP) on synthesis of DNA and unschedule DNA synthesis (UDS) in BALB/3T3 cells were assayed, by methods of single-labeling and double-labeling. The results showed that all of the four agents were able to increase the synthesis of DNA, but only three of them (apart from syn-BPDE) induced UDS in BALB/3T3 cells. The above indicates that the metabolites of benzo(a)pyrene are able to damage DNA in BALB/3T3 cells, and that this effect may be relative to the sterical structure of metabolites of benzo(a)pyrene.     

Biodegradation of benzene, toluene; and other aromatic compounds by Pseudmonas sp. D8

Pseudmonas sp. D8 strain, which has the potential to utilize toluene as a sole carbon source, was isolated. At a concentration of 100 mg/l, this strain was found to efficiently degrade toluene and benzene (both individually and in mixture) in culture medium at 30°C and pH7. Following a two-hour lag phase, complete biodegradation of 100 mg/l toluene or benzene occurred within 6 to 8 hours. The addition of nitrate, phosphate, or sulfate at various concentrations were found to have significant influence on both toluene and benzene degradation. In addition, results show that the D8 strain has the ability to degrade monochlorophenols, nitrophenols, and phenol, but not aliphatic compounds. Inoculation of groundwater samples containing 100 mg/1 toluene or benzene with Pseudmonas sp. D8 resulted in rapid degradation within 24 33 hours.     

Arbuscular mycorrhizae enhance metal lead uptake and growth of host plants under a sand culture experiment

A sand culture experiment was conducted to investigate whether mycorrhizal colonization and mycorrhizal fungal vesicular numbers were influenced by metal lead, and whether mycorrhizae enhance host plants tolerance to metal lead. Metal lead was applied as Pb(NO3)2 in solution at three levels (0, 300 and 600 mg kg(-1) sand). Five mycorrhizal host plant species, Kummerowia striata (Thunb.) Schindl, Ixeris denticulate L., Lolium perenne L., Trifolium repens L. and Echinochloa crusgalli var. mitis were used to examine Pb-mycorrhizal interactions. The arbuscular mycorrhizal inoculum consisted of mixed spores of mycorrhizal fungal species directly isolated from orchard soil. Compared to the untreated control, both Pb concentrations reduced mycorrhizal colonization by 3.8-70.4%. Numbers of AM fungal vesicles increased by 13.2-51.5% in 300 mg Pb kg(-1) sand but decreased by 9.4-50.9% in 600 mg Pb kg(-1) sand. Mycorrhizae significantly enhanced Pb accumulation both in shoot by 10.2-85.5% and in root by 9.3-118.4%. Mycorrhizae also enhanced shoot biomass and shoot P concentration under both Pb concentrations. Root/shoot ratios of Pb concentration were higher in highly mycorrhizal plant species (K.striata, I. denticulate, and E. crusgalli var. mitis) than that in poorly mycorrhizal ones (L. perenne and T. repens,). Mycorrhizal inoculation increased the root/shoot ratio of Pb concentration of highly mycorrhizal plant species by 7.6-57.2% but did not affect the poorly mycorrhizal ones. In the treatments with 300 Pb mg kg(-1) sand, plant species with higher vesicular numbers tended to show higher root/shoot ratios of the Pb concentration. We suggest that under an elevated Pb condition, mycorrhizae could promote plant growth by increasing P uptake and mitigate Pb toxicity by sequestrating more Pb in roots.     

Investigation on the influence of methanol on adsorption and leaching of pesticides with soil column liquid chromatography

The effect of methanol of low concentration on adsorption and leaching of atrazine and tebuconazole was studied in this paper. The adsorption coefficients and the retardation factors (R^m) of pesticides on EUROSOIL 3# log-linearly decreased as volumetric fraction of methanol (f^c) was increased in the binary solvent mixtures of methanol and water. These data are consistent with solvophobic theory formerly outlined for describing the adsorption and transport of hydrophobic organic chemicals from mixed solvents. Nevertheless, the adsorption of these pesticides in soil–water system slightly increased when the soil was pre-washed with methanol in comparison with that pre-washed with water (pure water system). Furthermore, their adsorption coefficients were still higher in binary solvent systems with methanol of very low concentrations, i.e. f^c<0.03 for atrazine and f^c<0.01 for tebuconazole, than those in pure water system. The adsorption coefficients (logK^w) of atrazine and tebuconazole predicted by solvophobic theory were 0.5792 and 1.6525, respectively, and their experimental logK^w were 0.3701 and 1.6275 in pure water system. Obviously, the predicted logK^w of the two pesticides was higher than the experimental log K^w in pure water system. The predicted K^w and the retardation factor (R^w) in pure water system by solvophobic theory are thus possibly inaccurate.     

等离子体协同光催化去除模拟烟气中SO2的实验研究

近年来,低温等离子体技术以及纳米TiO₂光催化技术在烟气脱硫中的应用越来越引起人们的关注。利用填充床反应器将这2种技术有机地结合起来，进行了大量脱硫实验研究。研究结果表明，等离子体协同光催化去除烟气中的SO₂与单独采用等离子体技术相比，其SO₂的去除率可提高5%～20%。同时，探讨了等离子体协同TiO₂光催化剂的脱硫机理，分别研究了外加电压、气体流量和SO₂初始浓度等因素对脱硫效率的影响。实验结果表明，当SO₂初始浓度为800 mg/m³，输入电压为17.5 kV，气体流量为0.2 m³/h时，SO₂脱除率可以达到77.6%。     

新型高效污水处理设备--集成一体化生物转筒反应器

介绍了一种新型高效污水处理设备--集成一体化生物转筒反应器(IBDR).IBDR具有微生物浓度高、活性强、生物相分级明显、耐冲击负荷、污泥沉降性能好和不产生污泥膨胀、操作简单灵活、运行成本低等显著特点;并成功地运用于处理餐饮污水和深圳某厂洗涤剂生产废水.在处理餐饮污水时,IBDR比传统的生物转盘处理效果高出20%.     

印刷线路板废弃物的热解与动力学实验研究

分别应用管式炉反应器和热重分析手段对印刷线路板废弃物的热解行为和热解动力学进行了实验研究。在管式炉中，研究不同的热解温度：700～950℃，对产物分布和气体成分分布的影响。实验结果表明：PCB热解气体的主要成分是H2和CO2，气体的热值较低，仅为2．09～5．41MJ/m^3，PCB不适合以气体产物为目标的能源利用方式。应用Friedman方法对PCB的热解动力学进行了研究，求得PCB的热解动力学参数分别是：表观活化能190．92kJ/mol，反应级数5．97，指前因子lnA47．14min^-1。     

地下水环境中反硝化作用

地下水氮污染已是全球性的环境问题 ,反硝化作用是地下水脱氮的主要机制。本文综述了地下水环境中反硝化作用的判据、速率、影响因素以及人工强化措施 ,指出了存在的问题和今后的发展方向     

可持续发展的"零排放"生态城市模式初探

20世纪90年代初,联合国大学提出"零排放"概念,将可持续发展理论进一步深化.本文在研究循环经济、"零排放"农业、"零排放"工业的基础上,对"零排放"概念进行扩展,首次提出"零排放"生态城市模式的构想,这是一种有利于环境、资源与经济协调发展的绿色生活、工作、生产和消费方式.