Total and Extractable Trace Elements in Lebanese River Sediments: Dry Season Data

Years of political instability have left Lebanon with significant gaps in environmental knowledge. This paper reports new results for trace metals in bed sediments of the river Nahr-lbrahim. The drainage basin of the river Nahr-lbrahim is largely floored by karstified limestone. Metal pollution is operative within the catchment. The objectives of this study were first to identify possible sources of metals (geological and/or anthropogenic) and then to characterise the chemical partitioning of the metals in the sediments. Bed load sediments were sampled at five locations along a 13km stretch from the river mouth, during the dry season. Samples were collected on two dates, dried and then sieved into three mechanical fractions. We report total Fe, Cu, Pb and Zn contents of the <75m sediment fraction for the dry season and interpret the results in terms of geology and point and non-point discharges to the river. Total metal contents were derived from summing the concentrations of metals in the chemical fractions of the sediments. A sequential chemical extraction procedure was applied to the <75m fraction and the data showed that, except for Fe, the carbonate fraction had the largest role in metal sediment deposition.     

SEDIMENT DISPERSION IN SALMON SPAWNING STREAMS: THE INFLUENCE OF FLOODS AND SALMON REDD CONSTRUCTION1

ABSTRACT: Magnetically tagged particles were used to investigate the effects of sockeye salmon (Oncorhynchus nerka) and floods on the dispersion of coarse bed material in the Stuart‐Takla region, British Columbia, Canada. The dominant annual sediment transporting event in the channels is the snowmelt flood events, with lesser activity usually accomplished during summer floods. Annually in August, the channel bed material is reworked by the Early Stuart sockeye salmon spawning, as the fish excavate the streambed to deposit and bury their eggs. These nesting cavities are called redds. Results from 67 tracer recovery experiments over five years were highly variable, subject to the magnitude of floods and the returning population of salmon. Overall, the depositional pattern from nival flood events usually demonstrated a high degree of clast mobilization, long travel distances (up to 150 m), and mean depths of burial up to 18 cm. Summer flood events showed somewhat lower rates of mobilization, distances of travel, and depths of burial. Although the fish did not move the tracers very far, their effect on the bed was generally quite pervasive ‐ up to 100 percent of the clasts were mobilized, and the depth of burial was considerable (mean burial depths up to 14 cm). The amount of vertical mixing of sediment by salmon was often on the same order of magnitude as flood events. The significant vertical mixing of sediments by the fish has important implications for the mobility of sediment in the stream. Since any armoring layer formed during high flows throughout the year is subject to the bioturbation of salmon, this suggests that the transport threshold in the creeks remains relatively low. Salmon likely play an integral role in the sediment transport dynamics and annual sediment budget of the lower reaches of these creeks.     

气体中硫化氢催化焚烧催化剂的制备和性能研究

考察了制备方法对催化剂活性的影响，评价了活性组分的添加量，操作温度和空速对催化剂活性和选择性的影响，在温度290℃，空速5000h^-1条件下，催化剂连续使用200h性能稳定，H2S转化率为SO2生成率在99．9％以上，该催化剂具有优良的性能，适合在硫化氢焚烧装置上使用。     

非稳态过滤除尘压力损失的研究

提出用于建立过滤层非稳态过滤压力损失模型的微观分析法和宏观分析法新概念，归纳出无论是纤维层过滤，还是颗粒层过滤，所反映的压力损失随过滤时间变化的规律是相同的，由此提出筇同观分析法和宏观分析法相结合的对纤维层过滤和颗粒层过滤均适用的非稳态过滤简化式，通过实验探讨了非稳态过滤压力损失比例常数的确定方法，并由此验证了该简化式的正确性。     

废弃物焚烧产物中HCl的检测研究

选取几种典型废弃物燃料样品,在5 T/d循环流化床焚烧实验装置上进行了焚烧实验.采集实验装置不同位置的焚烧后烟气,用"NaOH吸收～AgNO3滴定"的方法对其中的Cl-进行了检测.实验结果表明,HCl的生成在很大程度上是受到烟气中氯盐的作用,湿法可以有效去除烟气中的HCl.在150 T/d大型工业化装置上进行的实际测试表明湿法处理可以满足排放要求.     

人工湿地床示踪剂的研究

本文介绍了对适宜于人工湿地床的示踪剂筛选的原则和方法，从四种染料和食盐中，选定食盐作为人工湿地床的示踪剂，并介绍了食盐示踪剂的注入方法和检测系统。     

SURFACE HEAT LOSS AND FRAZIL ICE PRODUCTION IN THE ST. LAWRENCE RIVER1

ABSTRACT: The rates of ice production due to surface heat loss in open water reaches of the St. Lawrence River, between the Ogdensburg-Prescott Boom and the Moses-Saunders Dam, are analyzed for the past 20 winters. Simple statistical parameters for ice production rates and air temperature are determined. Regression analyses for relationships between surface heat loss rates and freezing degree days indicate that an excellent linear correlation exists between these two variables. The study also shows that it is important to consider other heat exchange components, such as the bed heat flux and viscous dissipation, in the total ice production analysis for the river reach.     

SEDIMENTATION CHARACTERISTICS OF GORGE-TYPE RESERVOIRS1

ABSTRACT. An investigation of the hydraulics of gorge-type reservoirs was conducted with scale models. Reservoir shapes were moulded within a large basin. Water was circulated using a centrifugal pump-motor unit and uniform sediment (specific gravity 2.65) with mean diameters of 0.20 mm and 0.60 mm were utilized. Observations were made to study sedimentation patterns from the commencement of sediment inflow until the final stage of a fully silted reservoir. In particular, the mode of deposition of the sediment beds, the mechanics of transportation and sediment bed slopes were investigated. These aspects of reservoir siltation were examined in relation to the factors which influence it, which included sediment characteristics and flow parameters. Bed slopes and flow depths were analyzed by various methods; the Kalinske equation in conjunction with the Manning and Einstein-Barbarossa relations as proposed by Doland-Chow produced the best results.     

污水地下渗滤系统基质床特性模拟

为提高污水地下渗滤系统(Subsurface Waste-water Infiltration System,SWIS)的生物脱氮效率,改进了基质床体结构组成,采用土柱模拟试验对比了基质床改进前后ORP特征及氨化、硝化及反硝化细菌数量的变化。结果表明,在地下渗滤系统中,氨氮的去除率(Q)随基质层深度的变化规律为Q(100 cm)Q(80 cm)Q(20 cm)≈Q(40 cm)Q(60 cm)。改进后基质铺设顺序依次为:0~60 cm填充炉渣和草甸棕壤(两者体积比为3∶7),60~130 cm铺设活性污泥、炉渣和草甸棕壤(三者体积比为1∶2∶7)。基质床结构组成改进后,20~60 cm区域氧化电位(ORP)大幅提高,尤其60 cm深度处ORP从0提高到180 m V,有效促进了硝化反应的进行;床体氨化、硝化及反硝化细菌数量大幅度提高,对NH+4-N及TN的脱除效率分别较改进前提高了12.6%和10.5%,出水NH+4-N及TN质量浓度满足城市景观地表水水质标准(GB/T 18921—2002)。     

芦苇床中古细菌的群落多样性分析

为了描述剩余污泥稳定化芦苇床系统中有机质矿化、甲烷排放及相关微生物多样性之间的内在关系,采用PCR-DGGE技术分析了不同芦苇床、不同季节的稳定化污泥中古细菌群落结构及其多样性。序列分析发现,与DGGE条带序列亲缘关系最近的种属为未培养古细菌和未培养产甲烷古细菌。古细菌群落结构呈季节性变化,且同一季节不同芦苇床的群落结构存在一定差异。具有通气结构芦苇床的剩余污泥中产甲烷古细菌的丰度较低,同时甲烷排放量也较低,因此设置通气结构的芦苇床设计更合理。