Variability of invertebrate abundance in drinking water distribution systems in the Netherlands in relation to biostability and sediment volumes

A survey of invertebrates in drinking water from treatment works, internal taps and hydrants on mains was carried out by almost all water companies in the Netherlands from September 1993 to August 1995. Aquatic sow bugs (Asellidae, 1-12 mm) and oligochaeta worms (Oligochaeta, 1-100 mm), both known to have caused rare though embarrassing consumer complaints, were found to form 98% of the mean biomass in water flushed from mains. Their numbers in the mains water ranged up to 1500 (mean 37) Asellidae m⁻³ and up to 9900 (mean 135) Oligochaeta m⁻³. Smaller crustaceans (0.5-2 mm) dominated the numbers in water from mains. e.g. water fleas (Cladocera and Copepoda up to 14,000 m⁻³). Common invertebrates in treated water and in tap water were Rotifera (<1 mm) and nematode worms (Nematoda, <2 mm). No Asellidae, large Oligochaeta (>5 mm) or other large invertebrates were found in 1560 samples of 200 l treated water or tap water.Large variations in invertebrate abundance were found within and between distribution systems. Of the variability of mean biomass in mains per system, 55%, 60% and 63% could statistically be explained by differences in the Biofilm Formation Rate, non-particulate organic matter and the permanganate index of the treated water of the treatment works respectively. A similar correlation was found between mean invertebrate biomass and mean sediment volumes in the distribution systems (R² = 52%).     

有机保温板薄抹灰外墙外保温系统修复改造研究

结合有机保温板薄抹灰外墙外保温系统的特点,通过具体修复工程案例介绍,研究了注浆法和表层加固法在既有建筑修复改造工程中的应用。     

Relationship between dissolved organic and inorganic compounds in tributaries of the Lake Baikal

It was shown that the balance between organic and inorganic compounds is mostly conditioned by watershed size and relief, rather than chemistry. The rise and fall of dissolved organic carbon concentration are irreversely proportional to those of acid neutralizing capacity and follow the changes in water flowpaths. This relationship was used to distinguish between dissolved matter sources, and to characterize quantitatively and qualitatively their contribution to surface water chemistry. The proposed approach has restricted applicability to the watersheds composed of sedimentary materials and to the watersheds with high percentage of wetlands. The applicability of the approach is also limited to a variety of environmental conditions. Big watersheds should be divided into lower order subcatchments to reduce uncertainty in interpretation of results. In small and medium watersheds, the proposed approach can be used for predicting water chemistry under different environmental conditions and for tracing contaminants.     

信息化环境下人才创新素质的培养

在信息化环境下,人才的信息素质是人才创新素质培养的前提和基础。而信息意识淡薄、信息能力低下和信息道德缺失影响了人才的创新素质培养。因此,我们必须以信息意识培养为导向,更新教育观念;以信息品德培养为前提,塑造创新品德;以信息能力培养为目标,培育创新环境;以信息技术为手段,丰富创新实践内容。通过人才信息素质的培养,实现信息化环境下人才创新素质的提高。     

北方某城市给水管网水质生物稳定性研究

以我国东北某市市政给水管网为研究对象,采用AOC和BDOC指标共同评价了管网水的生物稳定性。研究结果表明：管网水中AOC为39—379μg/L,BDOC为0．8～2．8mg／L,属于生物略不稳定的饮用水;随着管网的延长,水中的AOC和BDOC浓度总体上处于降低趋势,余氯浓度对AOC和BDOC浓度的变化均有较大影响;冬、夏两季节,管网水中AOC占BDOC的比例分别为5．8％和6．2％。     

工学结合人才培养模式若干问题及对策

阐述了工学结合人才培养模式在我国推广应用中存在的若干问题,在此基础上提出了一些对策以及推广该模式的保障机制,以期进一步完善与推广工学结合人才培养模式,培养出高质量技能人才。     

常用电器对室内空气品质的影响

针对常用电器对室内空气品质的危害,分析了常用电器对室内空气品质的影响,提出了改善常用电器对室内空气品质影响的措施,有助于增加人们对常用电器与室内空气品质关系的认识,以帮助人们更好地保护室内空气品质。     

Removal of VUV pre-treated natural organic matter by biologically activated carbon columns

A potential alternative water treatment process using VUV (185 nm+254 nm) irradiation followed by a biological treatment is described. The system uses sufficient VUV radiation (16J cm(-2)) to significantly enhance the production of biologically degradable moieties prior to treatment with biologically activated carbon (BAC). Two similar activated carbons were used, one virgin and one taken from a water treatment plant with an established biofilm. The VUV-BAC process decreased the overall dissolved organic carbon (DOC) concentration of a natural water sample by 54% and 44% for the virgin carbon and previously used BAC, respectively. Furthermore, VUV-BAC treatment decreased the trihalomethane (THM) formation potential (THMFP) by 60-70% and the haloacetic acid (HAA) formation potential (HAAFP) by 74%. The BAC systems effectively removed the hydrogen peroxide residual produced by VUV irradiation. Although nitrite formation can result from VUV treatment of natural organic matter (NOM), none was detected before or after BAC treatment.     

胶凝时间、pH值变化和水玻璃有机酯目硬砂性能的关系

将水玻璃混合液的胶凝时间、pH值变化与水玻璃有机酯自硬砂性能相比较表明：胶凝时间、pH值变化可间接反映自硬砂的性能。     

Nitrogenous disinfection byproducts formation and nitrogen origin exploration during chloramination of nitrogenous organic compounds

Formation of nitrogenous disinfection by-products (N-DBPs) of cyanogen chloride (CNCl), dichloroacetonitrile (DCAN) and chloropicrin was evaluated during chloramination of several selected groups of nitrogenous organic (organic-N) compounds, including α-amino acids, amines, dipeptides, purines, and pyrimidines, The intermediates generated, reaction pathways, and nitrogen origin in N-DBPs were explored as well. CNCl was observed in chloramination of all tested organic-N compounds, with glycine giving the highest yields. DCAN was formed during chloramination of glutamic acid, cytosine, cysteine, and tryptophan. Chloramination of most organic-N compounds except for cysteine and glutamic acid generated chloropicrin. Aldehydes and nitriles were identified as the intermediates by negative mode electrospray ionization mass spectrometry during reactions of NH₂Cl and organic-N compounds. Labeled ¹⁵N-monochloramine (¹⁵NH₂Cl) techniques showed that nitrogen in N-DBPs may originate from both NH₂Cl and organic-N compounds and the nitrogen partition percentages vary as functions of reactants and pH.