Numerical Investigation of the Effects of Boundary-Layer Evolution on the Predictions of Ozone and the Efficacy of Emission Control Options in the Northeastern United States

This paper examines the effects of two different planetary boundary-layer (PBL) parameterization schemes – Blackadar and Gayno–Seaman – on the predicted ozone (O₃) concentration fields using the MM5 (Version 3.3) meteorological model and the MODELS-3 photochemical model. The meteorological fields obtained from the two boundary-layer schemes have been used to drive the photochemical model to simulate O₃ concentrations in the northeastern United States for a three-day O₃ episodic period. In addition to large differences in the predicted O₃ levels at individual grid cells, the simulated daily maximum 1-h O₃ concentrations appear at different regions of the modeling domain in these simulations, due to the differences in the vertical exchange formulations in these two PBL schemes. Using process analysis, we compared the differences between the different simulations in terms of the relative importance of chemical and physical processes to O₃ formation and destruction over the diurnal cycle. Finally, examination of the photochemical model's response to reductions in emissions reveals that the choice of equally valid boundary-layer parameterizations can significantly influence the efficacy of emission control strategies.     

南京市臭氧、VOCs和PANs污染特征及变化趋势

对2013—2016年基于国家环境空气质量监测站以及省建大气多参数站所获取的南京市O_3、NO_2、CO、VOCs、PANs观测结果进行综合评价,结果表明:2016年南京市O_3第90百分位日最大8 h平均质量浓度比2013年上升33.3%,超标天数中O_3引起的超标占比增至32.0%。南京市区大气中非甲烷总烃冬季浓度高于夏季,含氧挥发性有机物则与之相反;在5—9月,含氧挥发性有机物组分在日变化过程中出现峰值的时间先后顺序依次为醚、醛、酮类,且O_3和过氧乙酰硝酸酯(PANs)生成存在有一定的线性关系。VOCs/NOx比值表明南京市处于VOCs控制区,因此对NO_2浓度下降不敏感,植物源挥发性有机物连续3年上升,夏季大气光化学反应活性未显著下降,这些现象是城市O_3浓度维持在较高水平的重要因素。     

鸟粪石循环利用处理高氨氮废水的热解行为

为了循环利用鸟粪石处理高氨氮废水,探讨了鸟粪石煅烧与加碱热解的脱氮率,利用电镜扫描(SEM)和X射线衍射(XRD)对2种热解产物进行了分析。鸟粪石煅烧条件为:温度100～225℃,时间1～5 h;加碱热解条件为:温度60～95℃,时间0.5～4 h,加碱量OH-∶NH4+摩尔比值0.4～1.5。结果表明,虽然XRD分析显示2种热解产物都已失去鸟粪石的特征峰,但是鸟粪石加碱热解效果更好,最佳热解条件为:加碱量OH-∶NH4+摩尔比值1,温度90℃,时间2 h,鸟粪石脱氮率95%以上;加碱热解产物表面为多孔状,完全失去了晶体结构;煅烧热解鸟粪石脱氮率仅为80%左右,热解产物晶体结构破坏不完全。鸟粪石在最佳条件下热解循环处理高氨氮废水,可循环使用6次,氨氮去除率80%以上,出水磷浓度小于8 mg/L。     

负载型氧化铁对高毒气体PH3的催化分解

采用沉积-沉淀法制备了碳纳米管(CNTs)和二氧化硅(SiO2)负载的纳米Fe2O3催化剂,将其应用于高毒气体PH3分解反应.通过XRD,TEM,XPS,BET等一系列检测手段,对制备样品的相结构、形貌、组分和比表面积进行了表征.研究结果表明,在PH3催化分解反应过程,极少量的产物P迁移至Fe2O3中,形成金属磷化物FeP作为反应的活性相.与Fe2 O3/SiO2相比,Fe2O3/CNTs显示了较高的催化性能.在440℃反应温度下,Fe2O3/CNTs对PH3分解率达到99.8％.CNTs作为催化剂载体的优秀性能可归因于CNTs良好的导电性能和活性组分在其上的高度分散.     

A freshwater amphipod toxicity test based on postexposure feeding and the population consumption inhibitory concentration

Consumption inhibition in natural populations, namely due to contaminants, may have direct and immediate effects on ecosystems, by hampering ecosystem key functions (e.g., organic matter decomposition, grazing), long before effects at the individual level (e.g., reproduction, growth, emergence) have time-delayed consequences at successively higher levels of biological organization. The present study aimed at developing a cost-effective (short and easy) toxicity test based on the postexposure feeding of a freshwater amphipod present in the Iberian Peninsula and at evaluating the immediate impact of contamination on the population-level consumption rate. First, methodologies to quantify postexposure feeding were developed and optimized, the most important criterion being a feeding period as short as possible to minimize physiological recovery from the contaminant exposure. Second, the sensitivities of 48-h postexposure feeding and 48-h lethality tests were compared, using a reference chemical - copper. Third, the latter responses were integrated in a single parameter, the median population consumption inhibitory concentration. When Echinogammarus meridionalis males were fed on 100 defrosted Artemia franciscananauplii during 30 min in darkness at 19-21 °C, the eaten proportion was approximately 80%, without truncated data distributions. The 48-h median effective copper concentration for postexposure feeding was approximately two times lower than the 48-h LC50 - 91 versus 198 μg L⁻¹, respectively. Two techniques were used to quantify the median population consumption inhibitory copper concentration, both leading to similar values (75 and 68 μg L⁻¹). In conclusion, when contaminant concentrations elicit both lethality and feeding depression, the integration of both responses can provide an ecologically relevant evaluation on the potency of a contaminant to immediately disrupt ecosystem functioning.     

Growth, leaf traits and litter decomposition of roadside hybrid aspen (Populus tremula L.× P. tremuloides Michx.) clones

Road traffic contributes considerably to ground-level air pollution and is therefore likely to affect roadside ecosystems. Differences in growth and leaf traits among 13 hybrid aspen (Populus tremula × P. tremuloides) clones were studied in relation to distance from a motorway. The trees sampled were growing 15 and 30 m from a motorway and at a background rural site in southern Finland. Litter decomposition was also measured at both the roadside and rural sites. Height and diameter growth rate and specific leaf area were lowest, and epicuticular wax amount highest in trees growing 15 m from the motorway. Although no significant distance × clone interactions were detected, clone-based analyses indicated differences in genotypic responses to motorway proximity. Leaf N concentration did not differ with distance from the motorway for any of the clones. Leaf litter decomposition was only temporarily retarded in the roadside environment, suggesting minor effects on nutrient cycling.     

基于夏普里值过程的农村居民收入差距分解

认识农村居民收入差距现状并研究引致收入差距的因素,对缩小收入差距的政策制定有重要意义.本文利用内蒙古和甘肃2个省1500户农户的截面数据,采用夏普里值过程对Gini系数、Theil指数、Atkinson指数这三个不平等指标进行回归分解.分解结果稳健地发现,以县域为代理变量的外部环境因素对收入差距具有重要影响,非农劳动力、培训比和家庭男劳动力比对收入差距的相对贡献度较大,而平均年龄、家庭人口和平均教育对收入差距的相对贡献较小.作为社会网络的人情收支和作为物质资本的人均土地面积对收入差距的贡献极小.从缓解中国西部农村地区间的不平等的角度看,长期而言,支持和促进地区经济发展,增加非农就业机会,提供平等的教育和培训机会,有利于缓解收入不平等.而在城市化进程中,处理好土地问题,避免作为物质资本的土地成为引致不平等的因素,对于未来控制不平等状况有重要意义.     

基于IPAT等式的甘肃省用水影响因素分析

将经典的IPAT等式扩展为包含人口、富裕程度、用水强度和产业结构4种影响因素的用水分析等式;并利用结构分解模型,将4种影响因素对总用水量变化的贡献分解开,得到不同因素对用水变化的影响.利用模型对1999-2008年甘肃省用水状况进行了实证分析,结果表明:富裕程度对用水量的增加效应最大,最高为2003-2004年(21.07×108m3);而人口变化对用水量的增加效应相对较小,均小于1×108m3;尽管用水效率的提高和产业结构的变化都减少用水量,但产业结构变化对用水量变化的贡献比用水效率的贡献小;此外,单纯地提高用水效率或调整产业结构,并不能保证在环境约束下实现社会经济的发展.因此,随着人口和经济规模的不断扩大,为了满足人民群众不断增长的需求,不仅要从提高用水效率、调整产业结构出发,实现水资源的高效优化配置;更重要的是调整发展思路,摆正人和自然的位置,才能真正实现人和自然的和谐发展.     

中国城镇化与土地集约利用关系的动态计量分析

在测度城镇化与土地集约利用的基础上,运用动态计量经济模型探讨城镇化与土地集约利用的相互作用。研究结果表明：（1）城镇化与土地集约利用均为一阶单整序列;（2）城镇化与土地集约利用之间存在长期均衡关系,但短期内却存在失衡,短期波动向长期均衡趋近的调整幅度达到18.98%;（3）城镇化是土地集约利用的Granger原因,而反向关系得不到实证支持;（4）土地集约利用对来自城镇化的冲击响应强烈,城镇化的冲击对土地集约利用的解释水平达到了90%,而城镇化对来自土地集约利用的冲击响应较弱,土地集约利用的冲击对城镇化的解释水平仅为3%。因此,应采取长期而非短期的策略,有序推进城镇化进程,加强土地利用监督管理,不断提高土地资源集约利用水平     

Deactivation and regeneration of ZSM-5 zeolite in catalytic pyrolysis of plastic wastes

In this work, a study of the regeneration and reuse of ZSM-5 zeolite in the pyrolysis of a plastic mixture has been carried out in a semi-batch reactor at 440 °C. The results have been compared with those obtained with fresh-catalyst and in non-catalytic experiments with the same conditions. The use of fresh catalyst produces a significant change in both the pyrolysis yields and the properties of the liquids and gases obtained. Gases more rich in C3-C4 and H₂ are produced, as well as lower quantities of aromatic liquids if compared with those obtained in thermal decomposition. The authors have proved that after one pyrolysis experiment the zeolite loses quite a lot of its activity, which is reflected in both the yields and the products quality; however, this deactivation was found to be reversible since after regeneration heating at 550 °C in oxygen atmosphere, this catalyst recovered its initial activity, generating similar products and in equivalent proportions as those obtained with fresh catalyst.