Pesticides in rain and roof runoff waters from an urban region

The levels of organonitrogen, organochlorine and organophosphorus pesticides were monitored in rain and roof runoff waters in Gdańsk (Poland) over a period of 6 months (October 2000 – March 2001). Buildings included in the study were of different ages, and covered with a variety of roofing materials. Samples were collected during the precipitation events. Pesticides were determined by gas chromatography combined with NPD and ECD detection. Bromofos, heptachlor epoxide and o,p′-DDE were detected the most often in the samples collected. In general, pesticide concentrations were higher in roof runoff than in rainwater. The type of the roofing material had a significant effect on the pesticide levels in runoff waters. The highest analyte levels were recorded in October and November, when the temperature was the highest.     

Laboratory analysis of the outflow and detention processes from modular tray-based blue roofs

ABSTRACT

Novel laboratory experiments were carried out to investigate the outflow process and the detention effects of a tray module of a blue roof (BR) system designed for runoff control from building roofs. The experiments revealed the outflow from the tray to decline during time, due to a number of complex dynamics occurring in proximity of the outlet orifice. The tests also showed the system to provide potential for relevant attenuation of the flow peak during inflow events (i.e. precipitation) of different magnitude. Based on regression analysis, an empirical relationship was developed for the evaluation of the tray outflow as a function of time, thus providing a tool for improved design of BRs. Finally, combination of the identified relationship with a routine for the water balance simulation of the tray was shown to describe reliably the detention process in the BR tray module.     

Bacterial contamination due to point and nonpoint source pollution in a rapidly growing urban center in an arid region

The distribution of bacterial contaminants (Escherichia coli and total coliforms) and nutrients (nitrogen and phosphorus) in a rapidly growing metropolitan area, the Las Vegas Valley, were studied to assess the contributions of point and nonpoint pollution sources under dry weather flow (pre rainfall) and wet weather flow (post rainfall) events. Nonpoint sources emanating from urban centers and septic seepage were found to be a primary source of bacterial contamination in the Las Vegas Wash, a mainstream wash channel where the Las Vegas Valley watershed drains. Contribution of point sources (wastewater treatment plants) to E. coli and total coliforms were found to be negligible. However, data in the Tropicana/Flamingo Wash, a tributary of the Las Vegas Wash, showed high bacterial activities in the wet antecedent rainfall condition as compared to the pre-rain dry antecedent condition suggesting that the rainfall increased bacterial activities.     

山地城市空间形态生长特征分析

山地城市由于其周围复杂的地形地貌条件,其空间生长比之平原城市,具有较大不同,往往呈渐进式和跳跃式两种方式交替拓展.通过聚焦城市边界,并以此来构建城市模型,可以进一步深入分析山地城市形态生长的内在机理.山地城市在其生长过程中具有跨越生长、循环生长的特征,并且要经历两次大的跨越,历经三个阶段.据此,山地城市形态生长可以通过合理的规划手段来调节城市边界力量的平衡,进行有效引导,以促进其健康生长.     

民国时期南京、武汉、重庆三座城市的历史文化内涵与建筑个性的比较分析(上)

民国时期先后作为首都和陪都的南京、武汉、重庆,同属长江流域,具有类似的地理环境,其时兴建的民国建筑,开创了我国传统建筑吸收西方技术开展城市设计的先河。三地又依城市所处环境不同而保持了各自的地域建筑特色,这为当下提供了有益的借鉴:既要传承历史,又要合理吸收西方先进设计理念,同时兼顾自然地理环境和市场需求,以建设具有中国特色的城市文化。     

城市轨道交通物业开发模式浅析——以重庆为例

通过与深圳、香港、纽约、东京等国内外城市轨道交通物业开发模式的比较,对重庆轨道交通物业开发现状进行了剖析,归纳出轨道交通物业开发的四种模式,即站点零散空间开发模式、上盖物业一体化开发模式、开发圈层化模式和新城TOD开发模式,为后续轨道交通物业开发建设提供参考。     

山地高落差地形焦化升级改造项目的设计和建设

由于鑫泰能源处山地地形且无法进行空间扩展,焦化升级改造项目需建设在水平标高高于原生产系统12 m的地形位置,且在凉焦台和运焦通廊的下方是无法占用的国家铁路线,需综合利用山地地形高落差的特点进行项目设计和建设。通过大跨度输送物料,悬空在火车轨道上方建设凉焦台、拦焦轨道、人员行走平台等设备设施,设置天车转运检修熄焦车等方式,合理布置XJL6253D型捣固焦炉的装置和环保除尘设施,解决了物料输送和装置安装等方面的问题,在不影响原有焦化系统正常运行的情况下,完成升级改造项目的设计和建设工作,并综合利用原有煤气净化系统。     

山地城市地铁牵引与制动工况下钢轨波磨成因对比研究

目的 探究山地城市地铁牵引与制动工况下的钢轨波磨成因。方法 基于摩擦自激振动理论,结合山地城市地铁长大坡道区段现场调研,分别构建上坡牵引和下坡制动工况下车辆−轨道系统的动力学模型,对比研究长大坡道区段牵引与制动工况下车辆−轨道系统的动力学特性。分别构建对应区段的轮对−钢轨−牵引系统和轮对−钢轨−制动系统的有限元模型,并采用复特征值法对比研究山地城市地铁牵引与制动工况下的钢轨波磨成因。采用最小二乘法和粒子群算法提出抑制长大坡道区段钢轨波磨的车辆−轨道参数的最优解。结果 在轮对−钢轨−牵引系统中存在不稳定振动频率369.93 Hz,其复特征值实部为19.36。在轮对−钢轨−制动系统中存在不稳定振动频率443.92 Hz,其复特征值实部为4.970 5。结论 在牵引摩擦副与轮轨摩擦副的共同作用下产生的摩擦自激振动,在制动摩擦副与轮轨摩擦副的共同作用下产生的摩擦自激振动,分别是长大坡道牵引与制动区段钢轨波磨的主要诱因,且牵引区段发生的可能性高于制动区段。在制动工况下设置制动压力为5 kN,在牵引工况下设置牵引运行速度为80 km/h,并结合优化后的扣件参数,能有效抑制长大坡道区段钢轨波磨。     

暗河发育区岩溶隧道突涌水洪峰流量估计

地下暗河是岩溶隧道建设与运营重大的安全风险,暗河发育区岩溶隧道突涌水洪峰估计是岩溶隧道施工抢险与后期处治方案制定的重要基础数据。地下暗河洪峰流量不仅由岩溶区水文地质条件控制,而且还受到暴雨期地表径流补给的影响。本文结合实测数据和统计数据,围绕小流域暴雨资料推求出地表汇流洪峰和地下暗河汇泄流洪峰,提出了一种考虑地表径流补给的暗河发育区岩溶隧道突涌水洪峰估计方法,并结合翠屏隧道的地形地貌、水文地质与实测涌水资料,开展了案例分析计算并比较实测涌水量。表明传统涌水预测方法无法考虑暗河与地表水补给的影响,与实测结果差距很大,本方法能够较好预测岩溶区因地表汇水补给暗河发育区隧道突涌水洪峰,为隧道防洪护堤高度、涵管过水容量设计、洪峰避险时间提供重要支撑,保障隧道施工与运营安全。