Chemical tracers as indicator of human fecal coliforms at storm water outfalls

Indicators to distinguish between fecal coliforms of human and animal origin were investigated in water from storm sewer outfalls to a coastal lake during wet and dry weather. The ratio of fecal coliform relative to fecal streptococci count was used as the microbiological indicator. Concentrations of human-activities originated caffeine, anionic surfactant, fluoride, and fluorescence whitening agent (FWA) were used as chemical indicators. The ratio of fecal coliform to fecal streptococci ranged from 0.2 to 3.0, during wet weather making it difficult to interpret the origin of fecal pollution. However, concentrations of caffeine, anionic surfactant, fluoride, and FWA in storm water outflow during wet weather were much higher than those in the lake water during dry weather, indicating the presence of human waste at storm water outfall. Strong correlation between fecal coliform counts and chemical parameter values further indicated the human contribution to the fecal coliform count. In addition, a strong correlation among the chemical parameters suggested that only one of them is needed as chemical tracer to detect the presence of human input.     

Bioconcentration kinetics of PCBs in various parts of the lifecycle of the tadpoles Xenopus laevis

Polychlorinated biphenyls （PCBs） in Xenopus laevis have been reported only for a few congeners. Additionally, there is very little information on the ability of Xenopus laevis to bioconcentrate PCBs. To address these issues, the tadpole Xenopus laevis was exposed to Aroclor 1254 mixtures in water at room temperature for 110 d followed by an additional 110 d of nonspiked PCBs in the water for the control group. During the whole process, bioconcentration factors （BCFs） of PCBs ranged from 1180 to 15670. For most PCB congeners, the highest and lowest bioconcentrations of the kinetic curves were found to be remarkably simultaneous, respectively. All 141 PCB congeners under the same experimental conditions had no linear correlation on the lgBCF versus lgKow relationship. The relationship between lgBCFs and lgKow followed a parabolic pattern indicative of selective bioconcentration, suggesting that the kinetic curves of the PCB congeners observed in the lifecycle of the tadpoles may be concentrated due to the amphibian special species and internal metabolism. In contrast, lgBCFs for PCBs were inversely related to lgKow, suggesting that a metabolism of the higher Kow PCB congeners occurred. These results support the author＇s conclusion that the tadpole Xenopus laevis plays major roles in the bioconcentration of PCB congeners, and demonstrated that the exposure kinetic curves of PCB congeners are complex. Besides the amphibian metamorphous development, the lifecycle of the tadpole Xenopus laevis also may be of importance in determining the bioconcentration of PCB congeners.     

城区内涝条件下城市公交-地铁双层交通网络的脆弱性分析

为提高城市公共交通应对内涝的能力,利用复杂网络理论的Space-L方法构建了武汉市中心城区的地铁、公交无向加权网络,并在此基础上运用ArcGIS软件构建了不同耦合半径的公交-地铁双层交通网络,确定了连边的权重和节点的重要度,计算了静态下地铁网络、公交网络和不同耦合半径的公交-地铁双层交通网络的介数、平均路径长度和聚类系...     

无机-有机复合絮凝剂的制备及絮凝性能研究

以硫酸铁、硅酸钠、硼砂和聚丙烯酰胺为主要原料,制备了无机-有机复合絮凝剂。采取正交实验设计方法,以COD去除率为指标,研究了Si/Fe摩尔比、Si/B摩尔比、聚丙烯酰胺浓度三种因子对复合絮凝剂处理印染废水效果的影响。结果表明:复合絮凝剂最优制备条件为:Si/Fe为1.5/1、PAM浓度为250mg/L、Si/B为3.5/1;采用最优条件下制备的复合絮凝剂处理印染废水时,最佳投加量(以SiO_2计)为90mg/L,最佳pH值为8.5～9.0,絮凝效果明显好于聚合硅酸硫酸铁。     

大分子络合超滤技术去除溶液中镍离子的研究

采用聚丙烯酸(PAA)和羧甲基纤维素钠(CMC)去除Ni2 ,首先将Ni2 离子络合在大分子上形成大分子络合物,进而通过超滤膜,将其截留在膜的一侧,从而达到分离镍离子的目的.研究表明,采用这两种聚合物进行络合超滤可以使镍离子去除率达到95%以上;当Ni2 与聚合物的反应时间为30 min时,镍离子(170 mg/L)与PAA(0.5 wt%)、CMC(0.5wt%)的适宜配比分别为1:2.5和1:1.在分离体系中加入Na 、Mg2 后,对镍离子的去除具有不利影响.此外,考察了用大分子络合超滤法处理含有镍离子的实际废水,结果在透过液中未检测出Ni2 .     

2000 — 2018年哈尔里克山冰川高程遥感变化分析

冰川高程变化是冰川形态变化的重要特征之一,能为推算冰川体积变化及物质平衡提供基本参数。利用Sentinel-1A雷达数据,与SRTM数据进行差分干涉,得到2000—2018年哈尔里克山冰川高程变化结果。为进一步提高监测结果的可靠性,以裸地区域的高程变化量作为系统误差修正值,对冰川高程变化结果进行第一次优化。由于差分干涉结果受地形影响较大,为降低地形因素对高程变化的影响,分析地形因子与高程变化标准差之间的关系,去除标准差过大的冰川区域,提高冰川高程变化可靠性,对冰川高程变化结果进行第二次优化,并在此基础上进行精度评定。结果表明：过去18年来,哈尔里克山冰川高程平均下降(8.74±0.14) m;分析冰川高程变化的空间差异性,发现西北部冰川高程减少程度较东南部小;分析冰川高程变化与海拔的关系,发现总体上冰川高程下降程度随海拔升高而减小。     

广东的滨海沙土资源

滨海沙土是广东沿海重要而急待改造利用的一种国土资源。分布广、面积大,风沙为害较甚。它集中分布在琼东北和西南部、陆丰至海丰、阳江至广州湾沿岸一带。主要因河流和地表径流携带的泥沙受潮浪、风力作用逐渐发育而成。按形成时间和特性,可分流动、半固定、固定和耕型沙土等亚类。并具有沙瘦的共同特性。改造利用主要措施是营林绿化。其次,是因地制宜地积极发展果蔬、热作等经济作物,改造沙荒草地,发展畜牧业,施肥改土,兴修水利和开发其旅游资源。     

Detection of Coastal Saline Land Uses with Multi-Temporal Landsat Images in Shangyu City,China

Many coastal regions in China are confronted with pressing problems of scarce land resources and heavy population. Over the past 30 years, considerable parts of coastal tidelands have been enclosed and reclaimed for agricultural land uses. To assess, plan, and implement large-scale reclamation programs, up-to-date and reliable information concerning the nature, areal extent, and physical and chemical characteristics of coastal saline lands is essential. This paper reports a remote sensing approach to detecting coastal saline land uses in Shangyu City, China, by using multi-temporal Landsat images. First, with the aid of resolution-sharpened Landsat-7 ETM+ images and their enhanced linear features, a visual interpretation is applied to extract individual dikes. Based on time series images and local government records, a spatial zoning procedure is then used to define six sub-zones with different historical years of reclamation. It shows that a total of 15,668 ha of coastal saline lands were enclosed and reclaimed from 1969 to 1996. Second, a modified land-use classification system for the study area is prescribed, and both unsupervised and supervised classifiers are performed for land-use classifications of grouped sub-zones. Information obtained from the spatial zoning, Tasseled Cap transformation and Normalized Difference Vegetation Index, is also utilized to facilitate the supervised classification process. Finally, a detailed land-use map is produced, with an overall classification accuracy of 77.8%. Results show that dominant agricultural land uses of sub-zones are changed with historical reclamation years, from saline lands with wildgrass (very recently reclaimed) to aqua-farm ponds, to cotton fields, and to paddy fields and orchards (very early reclaimed). This transform process is primarily affected by soil salinities, and according to a soil survey an electrical conductivity of saturation extract decreased from 7.3 ds/m in the saline land reclaimed in 1996 to below 2 ds/m in the land reclaimed before 1969. The study concludes that multi-temporal remotely sensed images are important and effective data sources for monitoring the rapid changes of coastal land uses.     

压力脉冲波法复杂天然气管道堵塞检测实验研究*

为了解决复杂天然气管道堵塞定位难题,快速定位出堵塞位置,提出利用压力脉冲波法检测复杂管道堵塞。改造搭建长18.1 m、包含17个三通结构的压力波堵塞检测实验台,进行不同堵塞率以及气液混输管道的堵塞定位实验。结果表明:管道三通会引起频率范围为150~200 Hz的高频反射波,利用FFT谐波变换方法可以有效地对原始信号进行滤波分析,更利于对堵塞定位分析。在堵塞率100%时,定位误差为1.07%;在堵塞率50%时,定位误差最大,达到1.93%;对于含液率8%的气液混输管道,100%堵塞时,定位误差为0.48%。研究结果有效地证实了压力脉冲法检测复杂输运管道堵塞的可行性,可为该方法的现场应用提供指导和数据支撑。     

环境评价Petri网理论可移植性的方法学研究

从复杂系统、开放式巨系统仿真的角度分析,环境影响评价工程分析项目的系统属性为离散事件动态系统,而污染物的产生、排放过程属于随机过程,所以,需要采用复杂系统分析的方法对现有的环评工程分析理论进行改进。Petri网理论是分析离散事件动态系统的方法之一,其特点也非常适合对现今的环评工程分析方法进行改进。将Petri网的基础理论与环评理论相融合,使Petri网理论拥有了系统的环评学释义,进而为将Petri网理论引入环评科学开辟了道路。