微塑料对变形杆菌生物膜生长发育的影响

微塑料对生物膜的影响现阶段主要集中于对成熟生物膜群落组成结构变化的研究,缺乏对不同发育阶段生物膜的研究.为探究微塑料对不同发育阶段生物膜的影响,选用环境中广泛存在的变形杆菌和1 μm聚苯乙烯微塑料(PS-MPs)作为研究对象,通过暴露实验研究PS-MPs对生物膜生物量、胞外聚合物(EPS)组成和胞外酶活性的影响.结果表...     

Thermodynamic analysis and kinetic modelling of dioxin formation and emissions from power boilers firing salt-laden hog fuel

Both organic chlorine (e.g. PVC) and inorganic chlorides (e.g. NaCl) can be significant chlorine sources for dioxin and furan (PCDD/F) formation in combustion processes. This paper presents a thermodynamic analysis of high temperature salt chemistry. Its influence on PCDD/F formation in power boilers burning salt-laden wood waste is examined through the relationships between Cl2, HCl, NaCl(g) and NaCl(c). These analyses show that while HCl is a product of combustion of PVC-laden municipal solid waste, NaCl can be converted to HCl in hog fuel boilers by reactions with SO2 or alumino-silicate materials. Cl2 is a strong chlorinating agent for PCDD/F formation. HCl can be oxidized to Cl2 by O2, and Cl2 can be reduced back to HCl by SO2. The presence of sulphur at low concentrations thus enhances PCDD/F formation by increasing HCl concentrations. At high concentrations, sulphur inhibits de novo formation of PCDD/Fs through Cl2 reduction by excess SO2. The effect of NH3, CO and NOx on PCDD/F formation is also discussed. A semi-empirical kinetic model is proposed. This model considers both precursor and de novo formation mechanisms. A simplified version is used as a stack emission model. The kinetic model indicates that stack dioxin emissions will increase linearly with decreasing electrostatic precipitator (ESP) efficiency and exponentially with increasing ESP temperature.     

环保制度改革下网格化环境监管发展对策建议

以环境监测监察执法垂直管理制度、镇域综合执法改革、排污许可证"一证式"管理为例,简述环保制度改革要求及各项制度可能对网格化监管产生的影响,结合江苏省各地网格化监管调研情况,分析网格化监管与制度改革的关系,提出网格化环境监管与各项制度未来协同发展的对策建议。     

浙江省地方环境标准建设对策

分析了加强地方环境标准建设在弥补国家环境标准建设的不足、增强地方政府环境保护责任、为制定国家环境标准提供实践基础、提高地方执行和实施环境标准的能力等方面的重要意义,总结了浙江省地方环境标准建设现状和存在问题,明确了地方环境标准建设原则和主要内容,并从制定规划、完善地方环境标准管理制度、加强环境标准研究队伍建设等方面提出了加强浙江省地方环境标准建设的建议。     

光伏发电有功自动控制技术

进行了两根足尺预应力型钢混凝土简支梁在火灾高温和竖向恒定加载耦合作用下的耐火性能试验,分析了试验梁的温度场分布规律、竖向变形特点和承载性能劣化过程。通过在试验梁端部预设压力传感器,实测了升温过程中梁端部预压力与升温时间的关系曲线。试验结果表明,预压力对火灾高温作用较为敏感,当标准升温100 min时预压力已降至初始预压力的一半,试验中一根梁出现了侧向弯曲变形。因此,对于预应力混凝土结构,火灾高温作用下应考虑构件可能的侧向变形影响。     

Assessing Conservation Value Using Centers of Population Density

We present an index of centers of density for identifying areas of high conservation value. This index represents the average importance of an area to species occurring there as measured by comparisons of relative densities of each species among areas. We evaluated the index using collections of stream fishes from the Clinch River system above Norris Reservoir in Virginia and Tennessee (U.S.A.). A strong correlation between index values measured at the same sites at different times suggested that the index could be applied to sites without replicated samples in the region and still allow centers of density to be distinguished from noncenters. Species richness showed no relationship to the index, suggesting that conservation priorities based solely on species richness can be inadequate. A species-accumulation curve based on the index performed nearly as well as one based on an algorithm for identifying the minimum number of sites in which all species in the region are represented. This pattern reflected the tendency of the index to weight regionally rare species more heavily than common species. But sites with high index values were not necessarily those selected by the algorithm because the algorithm used only presence/absence, whereas the index used the additional information present in relative densities. Our index represents an additional tool for identifying "hot spots" of diversity, but conservation of biodiversity over the long term will also require that the ecological integrity of regional landscape be maintained.     

可溶性微生物产物的产生及影响因素分析

对可溶性微生物产物(SMP)的产生和性质进行了概述,指出SMP是影响生化出水水质的重要因素;建立了完全混合反应器中SMP浓度的计算公式。基质降解量(△S)、污泥龄(@)、污泥产率因数(y)和衰减速率系数(b)是影响SMP浓度的4个重要因素,SMP浓度同污泥浓度、水力停留时间无关。分析表明,对应某污泥龄,反应器中SMP浓度可达到最低,控制污泥龄可以达到降低出水中SMP浓度的目的。     

Climate change,Atlantic storm activity and the regional socio-economic impacts on the Caribbean

Forecasting the likely economic losses arising from North Atlantic hurricanes is high on the agenda of both Caribbean and North American stakeholders. This paper develops a general equilibrium framework to conduct an impact assessment of climate change and hurricane formation. General equilibrium analysis accounts for not only primary effects but also feedback effects. The model simulations suggest that output losses occurring due to hurricanes are likely to have economy-wide effects. However, the rural economies of the region are likely to suffer the greatest (relative) effects. The findings of this study suggest that rural livelihoods should be mainstreamed in any adaptation initiatives adopted by the region. Ignoring these neighbourhood features in adaptation plans could negatively impact on poverty and unemployment in rural areas.     

Analyzing pedestrian crash injury severity under different weather conditions

Objective: Pedestrians are the most vulnerable road users due to the lack of mass, speed, and protection compared to other types of road users. Adverse weather conditions may reduce road friction and visibility and thus increase crash risk. There is limited evidence and considerable discrepancy with regard to impacts of weather conditions on injury severity in the literature. This article investigated factors affecting pedestrian injury severity level under different weather conditions based on a publicly available accident database in Great Britain.

Method: Accident data from Great Britain that are publicly available through the STATS19 database were analyzed. Factors associated with pedestrian, driver, and environment were investigated using a novel approach that combines a classification and regression tree with random forest approach.

Results: Significant severity predictors under fine weather conditions from the models included speed limits, pedestrian age, light conditions, and vehicle maneuver. Under adverse weather conditions, the significant predictors were pedestrian age, vehicle maneuver, and speed limit.

Conclusions: Elderly pedestrians are associated with higher pedestrian injury severities. Higher speed limits increase pedestrian injury severity. Based on the research findings, recommendations are provided to improve pedestrian safety.     

基于遥感和GIS技术的墨西哥湾溢油动态分析

利用多时相的遥感影像数据和地理信息系统(GIS)的空间分析功能,对2010年发生在墨西哥湾的溢油事故进行了动态监测,并结合洋流等信息对溢油漂移趋势进行了预测。结果显示,至2010年5月1日溢油面积已达到4月25日的4倍,并且溢油漂移趋势受到洋流的作用,漂移方向与洋流方向一致。研究表明,至5月1日对溢油处理与漏油处封堵的努力效果甚微,油污面积有继续扩大趋势,油污漂移方向与洋流具有较强相关性。该研究验证了光学遥感图像可以很好地对溢油事故造成的溢油范围进行监测,结合GIS的空间分析功能和洋流等信息可对溢油面积和溢油漂移趋势进行监测与分析,从而为溢油控制与清理提供重要参考信息。