北京市不同主干道绿地群落对大气PM2.5浓度消减作用的影响

为研究城市道路两侧不同绿化带宽度及不同植物群落配置模式对消减大气中PM2.5浓度的作用,选择北京市四环主干道旁3种典型植物群落配置类型作为试验监测点,对0 m、6 m、16 m、26 m、36 m不同绿带宽度下PM2.5浓度分布与变化进行监测,并对其消减能力进行计算,分析PM2.5浓度变化与道路车流量、绿化带宽度及植物群落配置模式之间的关系。结果表明：（1）PM2.5浓度的日变化与车流量的日变化特征一致,道路绿地空气中PM2.5浓度的日变化呈现双峰单谷型特征,即早晚高、白天低,PM2.5浓度在8：00-10：00的交通早高峰期间增加,而后开始下降,到12：00-14：00左右达到最低值,之后呈持续上升状态,直至晚高峰19：00浓度达一天中的最大值。（2）不同植物群落配置模式对大气中PM2.5浓度的消减作用不同,群落内郁闭度高的多复层结构绿地对PM2.5消减作用优于郁闭度低的单层配置绿地模式;（3）分别对3类空气质量条件下,道路绿地对PM2.5消减作用进行评价。无污染或轻度污染（PM2.5〈100μg·m-3）环境下,绿地对PM2.5消减作用明显,26 m及36 m的绿带处消减作用最强,最高可达12.22%;中度污染（101μg·m-3201μg·m-3）天气条件下3种绿地对PM2.5的消减作用均不明显。     

小试膜生物反应器(MBR)中活性污泥微生物种群结构的演变

以膜生物反应器中的活性污泥为研究对象,考察接种驯化至膜污染时期的微生物群落结构的特征和演变过程.在试验运行中,定期采集样品提取DNA,并应用PCR-DGGE技术探究微生物菌群的变化.结果表明,在反应器运行接种5 d后,微生物群落结构已发生较大改变,与接种污泥相似性指数下降到47.8%;在运行的整个过程中,微生物种群多样性都要低于接种污泥,随着处理工艺运行,种群间进行逐步有序的演替.在运行后期,跨膜压力增速提高,此时占优势地位的菌种是Enterococcus faecalis、Comamonas sp.、不可培养的Fusobacterium sp.,可能是导致膜污染的主要菌种.     

用酵母菌处理油田钻井废水的研究

从冀东油田钻井现场采集的受钻井废水污染的土壤样品中筛选到2株酵母菌种（Wickerhamiella domercqii和Candida boidinii）。将这2种酵母菌混合后在pH4.0的条件下处理钻井废水,TOC去除率为40．5％,略高于驯化后的活性污泥在中性条件下的处理效果（35．2％）。分子量的切割实验结果表明,在分子量为60000以上的有机质中,也有部分有机质具有生物可降解性。     

海湾围垦工程作用下的动力沉积响应

通过采用平面二维有限元数学模型模拟计算乐清湾边滩围垦前后的潮流变化分布 ,在此基础上 ,预测围垦工程建设后导致泥沙冲淤变化。据此说明海湾围垦工程作用下的动力沉积响应。结果表明 ,海湾围垦工程对流场及泥沙冲淤的影响局限于工程区临近水域。在围区两侧 ,工程前后流速减小 ,使水流挟沙力降低 ,导致泥沙局部淤积 ;在围堤的转角外侧 ,将存在流速略有增大的区域 ,而在此的海床冲刷状况并不明显     

春秋季长江口及其邻近海域营养盐污染研究

依据东海环境监测中心两个航次的资料和美国国家海洋大气管理局(NOAA)相关资料,开发Matlab计算机数值分析和图形显示技术,对长江口及其邻近海域的营养盐污染状况进行分析和探讨。结果表明:海域总体营养盐超标严重;氮、磷污染物的来源主要为径流携带入海,磷还受外海流系高质量浓度磷输入的影响;营养盐污染特征显示,表、底层营养盐均自入海口向外围、由近岸向远岸迅速递减,秋季冲淡水将污染物向外海携带,污染区也相应向外海推移;营养盐结构显示,该区w(N)/w(P)比值最高达到了405,无机氮异常丰富,海域浮游植物生长的限制因子存在时空变化。分析得到营养盐污染特征与长江河口锋位置及冲淡水流向的关系密切,可以考虑由长江河口锋位置及冲淡水流向来确定污染物的聚集位置和扩展方向。     

Source and spatial distribution of airborne heavy metal deposition studied using mosses as biomonitors in Yancheng,China

Environmental Science and Pollution Research - Naturally growing mosses have been successfully used as biomonitors of atmospheric heavy metal (HM) deposition. In recent years, with rapid economic...     

老填埋场竖向加高扩容工程的沉降计算与分析

针对老填埋场竖向加高扩容时垃圾堆体沉降机理的特殊性,将老垃圾堆体的沉降分为3部分:主固结沉降、次应力沉降、降解沉降,并研究各部分沉降的计算方法。结合工程实例,对沉降计算公式中有关参数取值进行探讨,并对扩容垃圾荷载作用下原垃圾堆体的沉降发展趋势进行分析,为扩容工程设计采取相应的沉降控制措施提供了依据。     

粉尘颗粒在单纤维表面沉积的计算机模拟

采用随机模拟方法模拟研究了粉尘颗粒在单纤维表面上的沉积过程,Kuwabara流场用于计算粉尘颗粒运动的轨迹,模拟中考虑了粉尘颗粒的粒径分布和单纤维在气流作用下的扭曲行为对粉尘颗粒沉积的影响.模拟结果表明.粉尘颗粒在单纤维表面上的沉积形态与分布特征依赖于Stokes数、粉尘颗粒粒径分布和纤维扭曲程度;模拟获得的粉尘树枝结构与相关文献提供的实验结果相似.     

Simulations of the impacts of building height layout on air quality in natural-ventilated rooms around street canyons

Numerical simulations were conducted to investigate the effects of building height ratio (i.e., HR, the height ratio of the upstream building to the downstream building) on the air quality in buildings beside street canyons, and both regular and staggered canyons were considered for the simulations. The results show that the building height ratio affects not only the ventilation fluxes of the rooms in the downstream building but also the pollutant concentrations around the building. The parameter, outdoor effective source intensity of a room, is then proposed to calculate the amount of vehicular pollutants that enters into building rooms. Smaller value of this parameter indicates less pollutant enters the room. The numerical results reveal that HRs from 2/7 to 7/2 are the favorable height ratios for the regular canyons, as they obtain smaller values than the other cases. While HR values of 5/7, 7/7, and 7/5 are appropriate for staggered canyons. In addition, in terms of improving indoor air quality by natural ventilation, the staggered canyons with favorable HR are better than those of the regular canyons.     

Dietary exposure estimates of 16 polycyclic aromatic hydrocarbons (PAHs) in Xuanwei and Fuyuan, counties in a high lung cancer incidence area in China

Xuanwei and Fuyuan are located in the southwest of China and have the highest lung cancer incidence in China, possibly even highest in the world. Dietary samples were collected from these two counties and the contamination status of sixteen polycyclic aromatic hydrocarbons (PAHs) were determined. PAH components, food constituents, dietary exposure level, as well as spatial difference, were studied in the different groups. The percentage of dietary intake to total intake of PAHs was calculated and the relationship between the dietary intake of PAHs and the abnormal lung cancer incidence was primarily discussed. The results showed that rice and potatoes were the main foods of the local residents in Xuanwei and Fuyuan. The daily exposure doses of Bap (benzo[a]pyrene), total PAHs, and TEQs (toxic equivalents) based on Bap toxicity in two counties were estimated to be 458 ng d(-1), 14,532 ng d(-1), and 896 ng d(-1), respectively, which were much less than those in other cities reported previously. The lower ingestion amount of food with a relatively higher content of PAHs, such as meat and fish, could account for the lower exposure doses. PAHs with less than 4 rings occupied a high percentage of the total PAHs in food samples. The exposure doses varied significantly among different sites and even different families at the same site. Dietary exposure was not the main exposure route of PAHs at most sites. It appears that there was not a direct relationship between dietary exposure and the lung cancer incidence. However, high ratios of dietary intake to total PAHs intake (1.33%-70.61%) were found in several areas and rational diet suggestions should be given in these areas in the future.