Control division of agricultural non-point source pollution at medium-sized watershed scale in Southeast China

This paper presents the study carried out for controlling agricultural non-point source pollution (NSP) in a medium-sized watershed covering 1.47 × 10⁴ km² in Southeast China using quantitative analysis coupled with geographic information system (GIS), universal soil loss equation (USLE), soil conservation service-curve number (SCS-CN), nutrient loss equations, and annualized agricultural nonpoint source model (AnnAGNPS). Based on the quantitative results derived from GIS and environmental models, five control division units were generated for NSP control in Jiulong River watershed, namely, controlling unit for soil losses, controlling unit for livestock breeding and soil losses, controlling unit for excessive fertilizer use and livestock breeding, controlling unit for soil losses and fertilizer use, and controlling unit for excessive fertilizer use and soil losses. This study proved that integrating GIS with environmental models can be adopted to efficiently evaluate major sources and contributors of NSP, and identify the critical source areas of NSP, which enables adjusting measures to local conditions by further control division units developed through such study for control and management of water quality degradation induced by NSP in the Jiulong River watershed.     

Leaching characteristics of heavy metals during cement stabilization of fly ash from municipal solid waste incinerators

The leaching characteristics of heavy metals in products of cement stabilization of fly ash from a municipal solid waste incinerator were investigated in this paper. The stabilization of heavy metals such as Cd, Pb, Cu, and Zn in fly ash from such incinerators was examined through the national standard method in China based on the following factors: additive quantity of cement and Na₂S, curing time, and pH of leaching liquor. The results showed that as more additives were used, less heavy metals were leached except for Pb, which is sensitive to pH of the leachate, and the worse effect was observed for Cd. The mass ratio of cement to fly ash = 10% is the most appropriate parameter according to the national standard method. When the hydration of cement was basically finished, stabilization of heavy metals did not vary after curing for 1 d. The mixtures of cement and fly ash had excellent adaptability to environmental pH. The pH of leachate was maintained at 7 when pH of leaching liquor varied from 3 to 11.     

人工湿地污水处理对三种植物光合作用及叶绿素荧光特性的影响

人工湿地环境下,湿地植物的光合代谢过程与陆生自然环境有较大的不同.通过对人工湿地三种中生植物即薏米(Coixaquatica Roxb)、文殊兰(Crinum asiaticum)和蜘蛛兰(Hymenocallis Americana)进行污水处理,研究人工湿地对植物的光合作用和叶绿素荧光特性的影响.结果表明:(1)与陆地自然环境相比,在人工湿地环境下,薏米,文殊兰和蜘蛛兰的净光合速率(Pn),蒸腾速率(Tr),气孔导度(Gs),叶绿素含量,最大荧光(Fm)和PSII最大光化学效率(Fv/Fm)均降低,而胞间CO2浓度(Ci)和初始荧光(Fo)升高.其中叶绿素含量,Fo和Fv/Fm在四月份生长旺盛期差异极显著(P<0.01),Gs差异显著(P<0.05).(2)在整个生长期,三种植物的光合参数和荧光参数的变化趋势不是单一的上升或下降,不同植物其变化过程和变化幅度也不一样.蜘蛛兰在生长旺盛期较薏米和文殊兰Pn,Gs,Fv/Fm,Fm,Fo大,而Ci较薏米和文殊兰低.可见人工湿地污水处理对三种植物光合作用和叶绿素荧光特性均有影响,但对各植物影响不一致.综合各项参数,蜘蛛兰耐性强于薏米和文殊兰.     

太湖不同湖区沉积物重金属含量季节变化及其影响因素

以太湖东北部梅梁湾、胥口湾、贡湖沉积物中重金属为研究对象,研究各湖区沉积物中As、Cd、Cu、Pb、Zn含量的年际变化规律及其与沉积物间隙水温度、pH、Eh值以及沉积物有机质、总氮、总磷、粒径等理化指标的相关关系.结果表明:沉积物中重金属含量及其年际的变化与其污染状况有一定的相关关系;富营养化程度较高的梅梁湾沉积物中重金属含量的最大值出现在9月,其他两个湖区的最大值均出现在6月;沉积物中重金属含量受到温度、pH值、Eh值等物理因素的影响,且与温度、pH值和Eh值有一定的正相关关系;沉积物有机质、总氮、总磷、粒径等因素也会对沉积物中重金属含量产生影响;有机质含量与重金属含量有很好的正相关性,粒径与重金属含量呈正相关,总氮、总磷与重金属含量呈负相关.     

动态浸出模拟实验系统与静态浸出试验的对比

建立了动态浸出试验－－小柱模拟实验系统,研究在非饱和水条件下危险物质在填埋场中的迁移和浸出规律,并和静肪浸出实验进行比较,结果表明,在非饱和入渗条件下危险物质的浸出浓度要比静态浸出实验的结果小１００倍左右,危险发的浸出速率也远小于静实验的结果,同时,危险物质的浸出速率随废物层饮水度的增加而迅速增加。     

强化混凝去除尖针杆藻

嘉陵江水系藻类暴发,水源水中的藻类在水厂前处理工艺中难以去除,造成该流域附近10余个水厂发生滤池堵塞现象,其中个别水厂滤池反冲洗周期由正常情况的24 h缩短至2~3 h,严重影响净水厂的正常运行,使得制水能力大幅降低。针对藻类(优势藻为硅藻中的针杆藻)暴发问题,通过对比PAFS、PAC和PFC3种混凝剂的除藻除浊效果,选取PAFS为最佳混凝剂;通过添加预氧化剂和助凝剂强化混凝除藻效果,其结果表明,使用助凝剂PDMDAAC的对PAFS的助凝效果最好,其余药剂结合PAFS的除藻效果为PPC>ClO2>PAM>H2O2>HCA-1,并将其应用到现有水厂,结果表明,0.6mg/L PDMDAAC+25 mg/L PAFS在水厂混凝沉淀,尖针杆藻含量降至49×104~55×104cells/L,其除藻率可达70%~75%,大大减轻了滤池的运行负荷,使得水厂运行恢复到正常水平。     

Smoke aerosols dispersion and transport from the 2013 New South Wales (Australia) bushfires

Environmental monitoring and modelling, especially in the regional context, has seen significant progress with the widely usage of satellite measurement in conjunction with local meteorological and air quality monitoring to understand the atmospheric dispersion and transport of air pollutants. This paper studies the application of these data and modelling tools to understand the environment effects of a major bushfire period in the state of New South Wales (NSW), Australia, in 2013. The bushfires have caused high pollution episodes at many sites in the greater Sydney metropolitan areas. The potential long-range transport of aerosols produced by bushfires to other region and states has been seen by regulators as a major concern. Using data and images collected from satellites, in addition to the results obtained from different simulations carried out using HYSPLIT trajectory model and a regional meteorological model called Conformal Cubic Atmospheric Model (CCAM), we were able to identify at least 2 days on which the smoke aerosols from bush fires in NSW has been transported at high altitude to the northern state of Queensland and the Coral Sea. As a result, widespread high particle concentration in South East Queensland including the Brisbane area, as measured by nearly all the air quality monitoring stations in this region, occurred on the day when the smoke aerosols intruded to lower altitude as indicated by the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) Lidar measurements on the CALIPSO (Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observation) satellite. The use of meteorological or air quality modelling to connect the ground-based measurements with satellite observations as shown in this study is useful to understand the pollutant transport due to bushfires and its impact on regional air quality.     

基于多层次灰色评价理论的海洋输油管道安全评估方法

针对海上输油管道在多层次、多变量、多种非定量因素的影响下缺乏有效定量评估手段的情况,建立输油管道体系的多层次安全评估指标,结合层次分析法,确定各层指标对应的权重,提出采用多层次灰色理论,对输油管道体系进行安全评估,将风险影响程度进行定量化处理,给出了在役输油管道的可靠性量化结果。多层次灰色评估方法针对少数据、小样本、信息不完全和经验缺乏的不确定性问题有着计算简便、直接、科学和实用的特点,可为海上输油管道的在役安全评估提供一种有效手段。     

石溪岷江特大桥薄壁高墩安全施工技术

1工程概述 石溪岷江特大桥是乐宜高速公路上的一座特大桥,位于乐山市犍为县境内,全桥长1226m,其跨径分布为：16×40m（简支T梁）＋103m＋180m＋103m（连续钢构）＋3×40m＋2×30m（简支T梁）（见图1）。     

Crowding in platform staircases of a subway station in China during rush hours

Crowding during the morning peak hours at a platform staircase in a subway station in China was studied in this paper. Passenger flow was surveyed with normal evacuation time recorded. The evacuation process was simulated with the software buildingEXODUS. Predicted results on the total evacuation time and maximum flow capacity of the selected staircase were compared with the field observations. Two parameters, the width of staircase utilized per person and the maximum upstairs walking speed used in the software were identified to be noticeably different from the field studies. Predictions agreed better with the observations after tuning these two parameters. It is concluded that the evacuation simulation software can be applied for safety design with appropriate tuning on the key parameters through field tests.