Effect of arsenic on chloroplast ultrastructure and calcium distribution in arsenic hyperaccumulator Pteris vittata L

This study investigated the impacts of arsenic (As) on the chloroplast ultrastructure and calcium (Ca) distribution in Chinese brake (Pteris vittata L.) mainly by histochemical methods, with an emphasis on the possible function of Ca in As detoxification and accumulation in P. vittata. P. vittata was grown in an artificially contaminated soil added with different concentrations of Na(2)HAsO(4) (0, 100, 300 and 800 mg kg(-1) As dry soil) for 24 weeks in a greenhouse. The addition of As did not affect the chloroplast ultrastructure of young pinna, meanwhile most of the membrane systems of chloroplasts in mature pinna were severely damaged under high As condition. Calcium concentration in the fronds of P. vittata was not significantly affected by the addition of As, but Ca concentration in the mature pinna significantly increased by As addition, consistent with the position appearing As toxicity. When no As was added, most of calcium precipitates distributed around the inner membrane of vacuole. But when the pinna appeared plasmolysis, more calcium precipitates resided outside the cell membrane and bigger particles evenly distributed in the cytoplasm. All the results indicated that Ca had a close relation with As toxicity in P. vittata.     

生物膜填料塔SO2废气净化性能研究

采用生物膜填料塔净化SO2废气,研究结果表明:当气体流量从100L/h增加到300L/h时,SO2净化效率由86.4%下降到73.2%;生化去除量随着入口SO2气体浓度的升高而增大;随着温度的升高,SO2净化效率和生化去除量都随之提高,且20℃以上时,净化效率可达90.9%以上,生化去除量可达75 mg/L·h以上,更利于微生物降解SO2.     

The associations of air pollution exposure during pregnancy with fetal growth and anthropometric measurements at birth: a systematic review and meta-analysis

Environmental Science and Pollution Research - Fetal growth has been demonstrated to be an important predictor of perinatal and postnatal health. Although the effects of maternal exposure to air...     

Validation of temporal and spatial consistency of facility- and speed-specific vehicle-specific power distributions for emission estimation: A case study in Beijing,China

Vehicle-specific power (VSP) has been found to be highly correlated with vehicle emissions. It is used in many studies on emission modeling such as the MOVES (Motor Vehicle Emissions Simulator) model. The existing studies develop specific VSP distributions (or OpMode distribution in MOVES) for different road types and various average speeds to represent the vehicle operating modes on road. However, it is still not clear if the facility- and speed-specific VSP distributions are consistent temporally and spatially. For instance, is it necessary to update periodically the database of the VSP distributions in the emission model? Are the VSP distributions developed in the city central business district (CBD) area applicable to its suburb area? In this context, this study examined the temporal and spatial consistency of the facility- and speed-specific VSP distributions in Beijing. The VSP distributions in different years and in different areas are developed, based on real-world vehicle activity data. The root mean square error (RMSE) is employed to quantify the difference between the VSP distributions. The maximum differences of the VSP distributions between different years and between different areas are approximately 20% of that between different road types. The analysis of the carbon dioxide (CO₂) emission factor indicates that the temporal and spatial differences of the VSP distributions have no significant impact on vehicle emission estimation, with relative error of less than 3%.

Implications: The temporal and spatial differences have no significant impact on the development of the facility- and speed-specific VSP distributions for the vehicle emission estimation. The database of the specific VSP distributions in the VSP-based emission models can maintain in terms of time. Thus, it is unnecessary to update the database regularly, and it is reliable to use the history vehicle activity data to forecast the emissions in the future. In one city, the areas with less data can still develop accurate VSP distributions based on better data from other areas.     

自然生态系统中含硫气体的产生机理与环境归趋

基于当前可获得的与该课题相关的资料 ,本文综述了陆地生态系统产生挥发性含硫气体的微观和宏观机理过程。讨论了控制生物硫气体产生的环境因素。阐述了含硫气体释放进入大气后的环境归趋     

鼓泡式UV-Fenton法处理二甲苯废气

采用UV-Fenton法在自制鼓泡反应装置中处理二甲苯废气,考察了pH值、H2O2投加量、Fe2+浓度和气体停留时间等操作条件对二甲苯废气处理效果的影响,并分析了UV与Fenton技术的协同效应。研究表明,pH、停留时间（EBRT）、双氧水投加量及气液接触效率对二甲苯去除效果影响显著,少量批次投加双氧水可以显著提高其利用效率。UV-Fenton体系的最佳反应条件为：pH=3,H2O2每隔半小时投加一次且投加量为0.01%·次-1,Fe2+浓度为40 mg·L-1,EBRT为55 s,紫外波长为254 nm。UV和Fenton在反应过程存在较强的协同效应,协同因子达到81%以上。     

反硝化除磷的影响特性试验

采用SBR反应器（厌氧/缺氧/好氧工艺）,分别研究了乙酸盐及硝酸盐浓度变化对反硝化除磷的影响特性.试验结果表明,当进水COD浓度＞230 mg/L时,乙酸盐浓度的变化对释磷、除磷速率等影响并不显著.在硝酸盐浓度＜30 mg/L时,硝酸盐浓度越高,缺氧段除磷速率也就越高.在C/P＞23,C/N＞5条件下,SBR系统对磷、氮去除率在90%以上.     

等浓度配比法研究苯酚、硝基苯和问硝基苯胺对发光菌的联合毒性作用

分别测定了苯酚、硝基苯和间硝基苯胺对发光菌的单一毒性，以及等浓度配比和等毒性配比的二元及三元混合体系的联合毒性，采用相加指数法对其联合效应进行了评价。结果表明，等浓度比和等毒性比混合体系的联合作用结果一致：苯酚＋间硝基苯胺二元体系为协同作用，其他各体系为相加作用。为简化联合毒性实验方法，建议在研究相关系列化合物的联合毒性作用机制中，可采用等浓度配比方法。     

生化黄腐酸对污染水体生物修复的强化作用

研究了生化黄腐酸（BFA）对污染水体生物修复的强化作用。生化黄腐酸能提高水体中微生物活性,加快微生物对目标污染物的降解。在污染水体生物修复强化作用的试验中,投加生化黄腐酸,CODCr、NH3-N、TP和浊度的去除率分别增加了29．47％、20．61％、35％和19．86％,同时有利于水体DO的提升。     

《水库大坝安全管理条例》修订必要性及建议

1991年3月我国制定了《水库大坝安全管理条例》(以下简称条例),至今已经20年。在过去的20年经济社会发生了重大变化,法律环境已经改变,条例难以满足当前水库管理的实际需求,迫切需要修订。1条例产生的历史背景和作用我国的大坝安全管理可以分为三个发展阶段,1949～1978年,1978～2000年和2000年至今。