聚烯烃类废塑料热分解技术中催化剂的选择和机理初探

研究使用不同催化剂情况下聚烯烃类废塑料热分解回收燃油的技术,并对废塑料的热分解机理进行了探讨．结果表明,自制的含大孔径分子筛的ＮＬＧ系列催化剂具有较好的催化性能,在裂解温度４３０℃,催化温度为３６０℃情况下,热分解后油产率为８７．５％,油品中汽油馏分达４１．３％,辛烷值为８８．３,每ｔ生产成本仅１２０００元左右,循环使用２０５余次后,仍保持良好的催化性能．     

水稻土中胱氨酸分解产生含硫气体的研究

测定在室内培养情况下南京水稻土中挥发性含硫气体的释放．结果表明,该土壤中产生Ｈ２Ｓ、羰基硫（ＣＯＳ）和二甲基硫（ＭＤＳ）气体．当土壤中加入胱氨酸后,检测到甲硫醇（ＣＨ３ＳＨ）、二硫化碳（ＣＳ２）、ＣＯＳ、Ｈ２Ｓ和ＤＭＳ气体．除ＤＭＳ之外,这些气体的释放量随胱氨酸添加量增加而增加．据此推测,水稻土中胱氨酸的分解可能是ＣＨ３ＳＨ、ＣＳ２、ＣＯＳ、Ｈ２Ｓ等４种气体产生释放的来源之一．在厌氧条件（充氮淹水）下检测到的含硫气体低于好氧条件（普通大气淹水）．光照、ｐＨ值、土壤含水量等对含硫气体的释放量均有影响     

基于贝叶斯网络的社区配电网系统动态风险评估

社区配电网系统的安全分析和动态风险评估是配电网系统安全运行的关键环节。传统的可靠性指标无法反映社区配电网系统中物理元器件的状态和短路故障事件等本质安全问题对风险评估的影响。针对现有风险评估方法的局限性,提出一种基于贝叶斯网络的社区配电网系统安全分析与动态风险评估框架。首先,在标准可靠性指标的基础上,创新性地将社区配电网系统中物理元器件的故障率和短路故障事件引入到风险评估中,提出一种新的社区配电网停电风险评估指标体系,该评估指标体系综合考虑了社区配电网的可靠性指标和本质安全特性,能够全面反映社区配电网系统的动态风险;其次,提出一种基于故障树-贝叶斯网络的社区配电网系统动态风险评估方法;最后,以一个实际社区的配电网系统为案例,验证了该动态风险评估框架的可行性和有效性。案例分析结果表明:所提出的框架能够充分评估社区配电网系统的停电风险,并可以给出合理的安全措施,以有效降低社区配电网系统的动态风险。     

Toxic effect of sodium perfluorononyloxy-benzenesulfonate on Pseudomonas stutzeri in aerobic denitrification,cell structure and gene expression

• OBS inhibited the growth of P. stutzeri and destroyed its structure. • OBS was toxic to the aerobic denitrification process of P. stutzeri. • OBS induced the production of ROS in P. stutzeri. • OBS affected the expression of key genes involved in denitrification and SOD. The toxicities of sodium perfluorononyloxy-benzenesulfonate (OBS) to animals and plants are similar to those of perfluorooctane sulfonate. However, the mechanism of its toxicity to aerobic denitrifying bacteria is still unclear. In the present study, the ecotoxicity of OBS on an aerobic denitrifying strain, Pseudomonas stutzeri, was evaluated. The results showed that a dosage of OBS clearly affected the growth and aerobic denitrification of P. stutzeri. When compared with an unamended control, the degradation efficiency of the total nitrogen decreased by 30.13% during exposure to 200 mg/L of OBS, and the complete degradation time of nitrate-nitrogen was delayed by 4 h. The lactate dehydrogenase and superoxide dismutase produced by the bacteria increased with the concentration of OBS, and reactive oxygen species were also detected by confocal laser scanning microscope imaging. Transmission electron microscope imaging revealed chromosome deformation of the cells and damage to cell content; moreover, outer membrane vesicles were secreted from the bacteria, which was the important detoxification mechanism of P. stutzeri to OBS. Expression of the genes involved in aerobic nitrification and oxidative stress were also changed under OBS stress, which further confirmed the toxicity of OBS to P. stutzeri. This study reveals the environmental exposure risk of OBS from the perspective of microorganisms.     

The gas-photocatalytic degradation of trichloroethylene without water

The photocatalytic degradation of gaseous trichloroethylene (TCE) without water has been studied. The degradation products were determined to be CO₂, HCl and Cl₂, and the reaction stoichiometry, was described as

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. The degradation rate was found to be linear with 0.16 power of the illumination intensity. When the TCE concentration was low (10¹⁴ mol L⁻¹ or a little more), its degradation rate model could be considered as first order kinetics. A mechanism of valence band hole oxidation was proposed.     

水稻土中挥发性含硫气体的释放

通过建立野外采样系统,对一个生长周期内水稻土释放的挥发性含硫气体进行了检测.研究结果表明:水稻土中释放的含硫气体主要为COS、CS₂和DMS,并有少量的DMDS.估算出的各含硫气体的释放通量分别为81.11、6.33和10.71 mg·(m²·a)^-1.我国水稻土释放含硫气体的通量为(S)0.013662 Tg/a,全球为(S)0.07992Tg/a     

Removal,distribution and plant uptake of perfluorooctane sulfonate (PFOS) in a simulated constructed wetland system

• PFOS was removed by soil adsorption and plant uptake in the VFCW. • Uptake of PFOS by E. crassipes was more than that of C. alternifolius. • PFOS in wastewater can inhibit the removal of nutrients. • Dosing with PFOS changed the soil microbial community in the VFCW. A vertical-flow constructed wetland (VFCW) was used to treat simulated domestic sewage containing perfluorooctane sulfonate (PFOS). The removal rate of PFOS in the domestic sewage was 93%–98%, through soil adsorption and plant uptake, suggesting that VFCWs can remove PFOS efficiently from wastewater. The removal of PFOS in the VFCW was dependent on soil adsorption and plant uptake; moreover, the percentage of soil adsorption was 61%–89%, and was higher than that of the plants uptake (5%–31%). The absorption capacity of Eichhornia crassipes (E. crassipes) (1186.71 mg/kg) was higher than that of Cyperus alternifolius (C. alternifolius) (162.77 mg/kg) under 10 mg/L PFOS, and the transfer factor of PFOS in E. crassipes and C. alternifolius was 0.04 and 0.58, respectively, indicating that PFOS is not easily translocated to leaves from roots of wetland plants; moreover, uptake of PFOS by E. crassipes was more than that of C. alternifolius because the biomass of E. crassipes was more than that of C. alternifolius and the roots of E. crassipes can take up PFOS directly from wastewater while C. alternifolius needs to do so via its roots in the soil. The concentration of 10 mg/L PFOS had an obvious inhibitory effect on the removal rate of total nitrogen, total phosphorus, chemical oxygen demand, and ammonia nitrogen in the VFCW, which decreased by 15%, 10%, 10% and 12%, respectively. Dosing with PFOS in the wastewater reduced the bacterial richness but increased the diversity in soil because PFOS stimulated the growth of PFOS-tolerant strains.     

无水条件下气相三氯乙烯的光催化降解机理

研究无水条件下气相三氯乙烯的光催化降解反应及其机理,结果表明三氯乙烯的降解产物对ＨＣｌ,ＣＯ２及其Ｃｌ２,,光催化降解速率方程符合Ｌａｎｇｍｕｉｒ－Ｈｉｎｓｈｅｌｗｏｏｄ公式,提出了无水条件下ＴＣＥ的光催化降解机理为空穴直接氧化机理。     

太湖流域丹阳市水体纳污能力分析及总量控制规划

文章分析了太湖流域丹阳市的水质状况及废水排放情况,并根据丹阳市各条河流的水质管理目标,由各河流水文资料及相关参数计算出水体纳污能力,同时提出了太湖流域丹阳市各条河流的NH3-N和COD总量控制方案,为水资源保护与管理提供依据。