High‐frequency water quality monitoring in an urban catchment: hydrochemical dynamics,primary production and implications for the Water Framework Directive

This paper describes the hydrochemistry of a lowland, urbanised river‐system, The Cut in England, using in situ sub‐daily sampling. The Cut receives effluent discharges from four major sewage treatment works serving around 190 000 people. These discharges consist largely of treated water, originally abstracted from the River Thames and returned via the water supply network, substantially increasing the natural flow. The hourly water quality data were supplemented by weekly manual sampling with laboratory analysis to check the hourly data and measure further determinands. Mean phosphorus and nitrate concentrations were very high, breaching standards set by EU legislation. Although 56% of the catchment area is agricultural, the hydrochemical dynamics were significantly impacted by effluent discharges which accounted for approximately 50% of the annual P catchment input loads and, on average, 59% of river flow at the monitoring point. Diurnal dissolved oxygen data demonstrated high in‐stream productivity. From a comparison of high frequency and conventional monitoring data, it is inferred that much of the primary production was dominated by benthic algae, largely diatoms. Despite the high productivity and nutrient concentrations, the river water did not become anoxic, and major phytoplankton blooms were not observed. The strong diurnal and annual variation observed showed that assessments of water quality made under the Water Framework Directive (WFD) are sensitive to the time and season of sampling. It is recommended that specific sampling time windows be specified for each determinand, and that WFD targets should be applied in combination to help identify periods of greatest ecological risk. © 2015 The Authors. Hydrological Processes published by John Wiley & Sons Ltd.     

The role of biogenic structures on the biogeochemical functioning of mangrove constructed wetlands sediments - A mesocosm approach

Benthic metabolism (measured as CO₂ production) and carbon oxidation pathways were evaluated in 4 mangrove mesocosms subjected daily to seawater or 60% sewage in the absence or presence of mangrove trees and biogenic structures (pneumatophores and crab burrows). Total CO₂ emission from darkened sediments devoid of biogenic structures at pristine conditions was comparable during inundation (immersion) and air exposure (emersion), although increased 2-7 times in sewage contaminated mesocosms. Biogenic structures increased low tide carbon gas emissions at contaminated (30%) and particularly pristine conditions (60%). When sewage was loaded into the mesocosms under unvegetated and planted conditions, iron reduction was substituted by sulfate reduction and contribution of aerobic respiration to total metabolism remained above 50%. Our results clearly show impacts of sewage on the partitioning of electron acceptors in mangrove sediment and confirm the importance of biogenic structures for biogeochemical functioning but also on greenhouse gases emission.     

柴达木盆地马海钾盐矿床沉积环境与开发

马海钾矿床是柴达木盆地内重要的盐类矿床之一。从盐类矿床沉积物的物相分析入手,着重揭示该成盐盆地沉积环境和古地理变迁特征,论述湖盆由形成、发展至老化衰亡的演变规律,反映了从上新世末期以来新构造运动在矿区地质构造上的典型表现,由这些成矿因素构建的矿床地质构造特征也得到总结。依照持续稳定发展的要求,就矿床开发过程中出现的急功近利局面,提出调整产品结构和重新布局开采对象的新策略,对企业生产实践具有指导意义。     

城镇雨污分流非开挖工程中的工程勘察内容和要求

论述在城镇雨污分流工程中采用非开挖技术需要工程勘察的内容和要求。针对非开挖技术特点,与常规市政工程勘察的对比分析,得出采用非开挖技术施工所需要的工程勘察特性。结合廊坊市雨污分流非开挖试验段工程,分析了前期工程勘察对后期非开挖工程施工的影响,具体分析工程地质勘察和施工区域地下管线探测特殊性对非开挖工程设计、施工的意义。最后从雨污分流非开挖试验段工程结论出发,总结采用非开挖技术施工进行工程勘察的常规性内容,为以后类似工程采用非开挖技术施工提供参考.     

青岛李哥庄地下咸水体恢复方案的数值优化

海水入侵导致地下水变咸对青岛李哥庄地区经济发展产生了不利影响,急需开展治理该地区咸水体的工作。根据研究区已有的降雨、蒸发及水文地质等资料,结合现场调查和监测,利用地下水模拟软件Visual-MODFLOW中的SEAWAT模块建立了该地区的数值模型,并利用实测资料识别和验证了该模型参数,表明所建模型能反映李哥庄地区的实际水文地质条件。为了模拟研究区地下咸水体的恢复治理情况,提出了连续抽水、间歇式抽水和抽注水结合三种咸水恢复方案,并利用该模型对三种恢复方案进行了模拟优化。结果表明,抽取地下咸水只是咸水恢复的一个因素,周边淡水的驱替作用则是咸水恢复另一个的因素,抽注水结合恢复方案为三种方案中最优的方案。     

Distribution of Arsenic in Sewage Irrigation Area of Pearl River Delta,China

The aim of the present work is to investigate the distribution of arsenic(As) in sewage ir-rigation area,to deduce the migration and transformation mechanism of As in soil and groundwater,and to infer the source of As in soil and groundwater.This study is carried out in a sewage irrigation area of the Pearl River Delta,China.Surface water samples,soil samples,and groundwater samples from sewage irrigation area were analyzed for As and other elements.As contents in water samples were analyzed by hydride gene...     

人工湿地的构建与应用

论述了人工湿地污水处理技术的机制和优势,阐述了人工湿地的构建和污水处理研究进展,表明人工湿地的污水处理效率与污染物的种类和污染程度、人工湿地的类型、湿地植物种类、基质类型、水力停留时间和水力负荷等密切相关.在中国,典型人工湿地有3种类型,分别为垂直流人工湿地、潜流式人工湿地和表面流人工湿地,主要用于处理来自化粪池、养殖...     

Provisional Elemental Values for IAEA‐Sewage Sludge by Instrumental Neutron Activation Analysis

The International Atomic Energy Agency (IAEA) organised a proficiency test (PT), IAEA‐CU‐2010‐02, for the determination of elements in sewage sludge. The PT sample was analysed by semi‐absolute standardless k₀‐instrumental neutron activation analysis (k₀‐INAA). Results for seven elements (As, Co, Cr, Fe, Hg, Se, Zn) were submitted to the IAEA by our laboratory. All of our results were scored ‘acceptable’ by the ‘result evaluation criteria’ adopted by the IAEA. The same analytical methodology produced quantitative results for twenty‐six additional elements. In total, thirty‐six elements were determined with uncertainty varying from 4 to 11%. This paper presents the provisional mass fractions of twenty‐six additional elements (Ag, Al, Br, Ca, Ce, Cl, Dy, Eu, Ga, Hf, I, K, La, Mg, Mn, Na, Rb, Sb, Sc, Sm, Ta, Tb, Th, V, U, W) not reported by the IAEA. The analytical methodology was discussed with important sources of spectral, nuclear and fission‐product interferences. It was shown that the important components of uncertainties were the k₀ factor, Q₀ factor, detector efficiency, mass and counting statistics. The methodology was validated by analysing the IAEA‐S7 reference material.     

西藏古大湖成盐模式的提出与分析探讨

根据目前对青藏高原第四系及古环境研究的最新进展,提出了西藏地区盐湖成盐的模式———古大湖成盐模式,并列举了诸多具有说服力的证据,为研究盐湖矿产形成规律和进一步开发利用,促进西藏经济发展,将产生积极的影响。