A simple test for differentiation between E. coli and A. aerogenes

An important problem in water quality control is the ability to differentiate between E. coli (faecal) and A. aerogenes (non-faecal) coliforms. To perform this differentiation, a simple test, based on a modification of the selective mFC medium and optimal incubation temperature (37°C) is proposed. Under these specific conditions E. coli bacteria develop into dark blue colonies, whereas A. aerogenes into pink ones. The intermediate coliform bacteria appear greenish-blue or pink, depending on their relation (closeness) to E. coli or A. aerogenes.     

Indicator bacteria and limnological parameters in fish ponds

The populations of indicator bacteria (mesophilic, coliform and fecal streptococci) together with relevant limnological parameters (temperature, oxygen, BOD and chlorophyll-) were recorded during a 6 year study of three eutrophic ponds. Ecosystems were manipulated with fish (Cyprinus carpio) in 2-year management cycles: in spring of the first year, the pond was stocked with young fish, and in the fall of the second year it was drained and mature fish were harvested. Fish management had a direct influence on bacterial numbers and on the basic parameters of the systems. A statistical analysis using t-tests found significant differences in oxygen concentration, chlorophyll- and BOD during both years of fish management. A water temperature model was calculated on an extensive homogenous data set (197 measurements), by fitting a regression curve. During each season, populations of indicator bacteria increased with increasing water temperature, and maximal numbers of bacteria were recorded during the summer months. Correlation analysis (fitted Spearman correlation coefficient) confirmed that temperature had a positive significant effect on population dynamics. The results demonstrate that fish stocking can affect bacterial population, in the sense that during high fish biomass (second years) the numbers of indicator bacteria as well as BOD and phytoplankton were higher. If pond water quality must be optimised for the purposes of drinking or recreation, the planned fish yield may have to be reduced.     

水质安全在线生物预警技术及研究进展

采用在线生物监测技术可以实现水体突发性污染事故的安全预警,并可根据受试生物的生物学指标变化对水体内多种污染物的综合毒性进行监测.水质安全在线生物预警技术通过低压电信号采集受试水生生物的行为生态学变化,并通过信号分析系统和设定的行为变化阈值,对水质状况进行分析.根据设定的预警方式,可以实现水质变化定性和半定量预警.     

Rainfall-induced unstable slope monitoring and early warning through tilt sensors

Real-time unstable slope monitoring is essential for recognition of landslide occurrence, as well as for early warning to reduce landslide-induced damages. This study investigated an unstable slope monitoring system that consists of tilt sensors aiming to establish an advanced time prediction model (TPM) for landslide early warning. The monitoring process utilized additional support devices (e.g. pipe strain gauges, water level gauges and a rain gauge) installed on a natural cut slope site. The tilt sensors could detect movements (in tilt angle) within the slope generated by heavy rains. Analysis of the recorded data revealed that the rate of movement, or tilt, was influenced by groundwater table fluctuations and antecedent rainfalls. A relationship between the tilt rate and the horizontal displacement calculated from pipe strain value has been established. Subsequently, a new classification of slope movement was proposed according to the tilt rates obtained from the deformation process of the slope. Considering the movement characteristics, two warning levels were identified such as warning and evacuation. Further, an advanced TPM was proposed in relation to realtime slope surface tilt rates. The TPM could provide efficient results at the continuous acceleration phase of the landslide occurrence. Therefore, we suggest this technique can be applied for monitoring and early warning of rainfall-induced shallow landslides.     

水质在线安全生物预警系统模拟预警及应用

水质安全在线生物预警系统可以实现水体突发性污染事故安全预警,根据受试生物生物学指标变化对水体内多种污染物的综合毒性进行监测。模拟预警结果表明,水质安全在线生物预警技术通过低压电信号采集日本青鳉的行为变化,并通过信号分析系统,结合行为变化阈值的设定,对水质状况进行综合分析,实现对污染水体的水质变化报警。     

地铁盾构穿越富水砾砂地层渣土改良试验研究

富水砾砂地层具有内摩擦角大、渗透性强等特点,在盾构掘进时容易造成螺旋输送机堵塞或刀盘结泥饼等工程事故。通过改变含水率、泡沫剂浓度及膨润土泥浆浓度,测试砾砂渣土的坍落度得到其变化规律,同时观察土样的流塑状态,采用析因试验设计理论对多因素影响渣土改良试验效果的耦合作用进行显著性分析。研究结果表明:含水率是影响渣土改良试验的主要因素,最优坍落度范围为185～200 mm;当含水率为5%时,坍落度随着改良剂浓度的增高逐步降低;当含水率为16%时,坍落度随着改良剂浓度的增高而增大。对坍落度的显著性影响从大到小依次为含水率(A)、一级交互作用(A×C、A×B)、膨润土泥浆浓度(C)、一级交互作用(B×C)、泡沫剂浓度(B)、二级交互作用(A×B×C)。基于现场试验与等值关系图,得到最优坍落度对应的含水率、泡沫剂浓度、膨润土泥浆浓度范围分别为10.6%～14.2%、 2.5%～4%、11%～13%,研究结果对于提高富水砾砂地层的盾构掘进效率具有重要的指导意义。     

Behaviour of the three-spined stickleback, Gasterosteous aculeatus (Gasterosteidae, Teleostei) in the multispecies freshwater biomonitor: a validation of automated recordings at three levels of ammonia pollution

The validity of using an automated online biomonitoring system, the multispecies freshwater biomonitor (MFB), in recording the physiological and behavioural activities of the three-spined stickleback Gasterosteous aculeatus, is assessed. The direct impact of the alternating electrical current generated by the impedance converter on fish activity was measured using a repeated measures design, machine on/machine off. Twelve subjects were used in each of three experimental groups: (1). standard hard water environment (control), (2). 0.1mM NH(4)Cl and (3). 10mM NH(4)Cl. Impedance generated waves were compared to corresponding manually recorded behavioural observations in an attempt to calibrate the MFB, assigning particular behaviours to a particular frequency and amplitude range. Data analysis suggests that the MFB current did not affect fish behaviour at any of the three contamination levels studied. Furthermore, analysis of the frequency with which behavioural activity changed (activity phases classified as inactive or active) showed that MFB behavioural data was not significantly different from that recorded manually. This suggested that the MFB recorded the behaviours that were concurrently observed. The feasibility of using the MFB as an effective behavioural early warning system in an aquacultural environment and as a scientific tool for toxicity testing is discussed.     

Bacteriological, virological and chemical evaluation of a wastewater-aquaculture system

Levels of fecal coliforms (FC), fecal streptococci (FS), Salmonella spp and enteric viruses were monitored in the water, sediment and fish in experimental wastewater-fish ponds near Benton, Arkansas, U.S.A. Concentrations of five heavy metals were also monitored in the fish and wastewater. Concentrations of indicator bacteria were reduced by as much as 99.7% through the series of six ponds which had a calculated total retention time of 72 days. Two filter-feeding species of Chinese carp, Hypophthalmichthys molitrix (silver carp) and Aristichthys nobilis (bighead carp), grown in the last three ponds accumulated FC and FS in their digestive tracts and skin at levels as great or greater than in the surrounding water and sediment. Only low levels of FC and FS were found in the fish muscle tissue (maximum of 25 FS per 100 g) even when concentrations of bacteria in the gut exceeded 10⁵ per 100 g. Concentrations of bacteria in the water and sediment were not good predictors of concentrations in the fish. No Salmonella and no enteric viruses were isolated from the fish, but this lack of isolates was attributed to the extremely low levels which were present in the influent wastewater. Higher levels of copper and mercury were found in the fish flesh than in the surrounding water, with three of eleven fish samples containing higher than acceptable levels of mercury in the edible portion. Based on the efficiency of wastewater treatment, an aquaculture system using silver and bighead carp was judged to be a viable treatment system for domestic sewage resulting in a product suitable for animal or human consumption if proper precautions are taken in harvesting and processing the fish.     

Rates of experimental microbiological contamination of fish exposed to polluted water

Fish inhabiting fecally polluted bodies of water are often used for human consumption. Such fish can be contaminated by enteric human pathogens and may pose a potential risk to public health. Controlled experiments with 132 fish of 100 g average weight were conducted to evaluate the rate of contamination of various tissues of fish (tilapia hybrids). The fish were exposed to E. coli introduced into the ambient water at concentrations of up to 10⁶ cfu/ml. Additional experiments were conducted with diluted wastewater containing Aeromonas, enterococci, fecal coliform and F+ coliphages. In another experiment poliovirus I was also added. The highest bacterial concentrations were recovered from the digestive tract (DT), some 5–24 h following exposure, with DT levels essentially similar to those in the inoculated water. In the E. coli experiments, geometric mean levels of about 10² cfu/cm² were recovered from the skin, 26 cfu/g in the spleen and 10² cfu/g in the liver. Most of the muscle samples were not contaminated. Greater contamination was not found under conditions of stress such as high organic load, a water temperature of 37°C or low levels of dissolved oxygen.     

Microtox毒性检测系统与给水水质预警

介绍了供水系统中应急毒性检测技术的特点及其在给水水质预警中的重要性，重点说明了Microtox急检测系统的原理、应用及其优缺点。     

城市水源突发性污染水质预警理论探讨

针对水源水质预警系统概念的内涵及外延,提出可由水质监测仪表和装置、水质恶化验证、水质预测、水质恶化影响评估及供水系统反应等六部分构成预警系统。分析了预警系统建立的相关因素,例如水源水的具体情况、建设费用、水质监测技术现状、处理系统的现状、安全饮用水的重视程度、防恐要求等,并提出了系统建设的技术路线。最后对限制预警系统功能完善的主要因素及未来主要研究方向进行了说明。     

Early warning system for rainfall- and snowmelt-induced slope failure in seasonally cold regions

In 2005, the Japanese government launched a new nationwide early warning system for predicting debris flow and slope failure disasters based on rainfall intensity and the Soil Water Index (SWI). However, the Japanese government has not set early warning criteria in many mountain areas. In addition, the existing early warning criteria in some areas are much higher than realistic ones, and snowmelt water is not considered in the calculation of the SWI. These two factors have been the cause of many slope failures in seasonally cold regions, induced by rainfall and/or snowmelt, which were not predicted. Therefore, this study attempts to propose a new determination method for setting early warning criteria for rainfall- and/or snowmelt-induced slope failures in seasonally cold regions. For this purpose, the study firstly proposes a combination model for estimating snow density that incorporates the hourly snowmelt water into the Japanese early warning system more accurately by using meteorological monitoring data and modeled snow density. Next, based on case studies and parametric analyses for slope stability assessment, new early warning criteria are proposed for predicting three different patterns of slope failures under two typical types of precipitation (rainfall and snowmelt) conditions. Finally, a new determination method for setting early warning criteria in seasonally cold regions is proposed by referring to the existing early warning criteria near the target area, in accordance with the precipitation types and the local ground conditions of the slopes. Since the existing early warning criteria near the target area already take the effects of the variations in local geology and geography into account, the new determination method for early warning criteria can be applied to arbitrary areas in seasonally cold regions, without directly considering the local soil properties, in the actual design and maintenance works.     

三峡库区网箱养鱼对周围水质的影响

以朱衣河二道河湾回水区网箱养鱼水质的现场监测结果为基础,采用综合营养状态指数法对网箱养鱼水域的现状进行了营养状态评价,并用污染物浓度等值线法进行了网箱养鱼对周围水质的影响分析.结果表明:网箱养鱼及其影响区的水体综合营养状态均为轻度富营养,水质污染程度为轻度污染,其综合营养状态变化总趋势为网箱养鱼区大于网箱影响区;网箱养鱼影响区的Chla浓度明显高于网箱核心区,其余污染物浓度的平面分布总趋势是由网箱核心区向网箱影响区由高向低变化;若以超河流背景断面浓度5%作为划定超背景污染带的标准,则朱衣河二道河湾网箱养鱼引起CODMnNH3-N、TN、TP和Chla超背景的污染面积分别为35 000、22 500、23 760、54 000和16 000 m3,分别是网箱养鱼区面积(3 900 m2)的9、5.8、6.1、13.8和4.1倍.     

花岗岩巷道岩爆声发射振铃计数波动规律研究

开展室内岩爆模拟试验,利用声发射仪监测岩爆过程。分析了岩爆过程声发射振铃计数波动变化规律,运用散点数据差分求导的计算方法,提出一个刻画振铃计数波动特征的指标——振铃计数变化率ξ,基于统计学原理,分析了岩爆过程ξ值的异常变化特征,捕捉岩爆发生前兆。研究表明:岩爆发生前声发射振铃计数会连续出现大幅度波动,声发射ξ值超出稳定阶段波动范围。将稳定阶段声发射ξ值波动范围作为岩爆预警阈值ξ₀,提取ξ>ξ₀时声发射信号作为岩爆前兆信息,进行岩爆灾害预警。水平应力越大,岩爆预警阈值ξ₀越大,岩爆前兆响应系数σ越小。     

A toxicity warning monitor using the weakly electric fish, Gnathonemus petersi

A technically simple fish monitor was developed using the weakly electric fish, Gnathonemus petersi, as the test organism. The test system consists of a plexiglass test chamber (21., 27°C) with a flow-through of 4–5 times the chamber volume per hour. The spontaneous electric organ discharges (EOD) are recorded as activity signals. EODs, which have a potential of about 500 mV, last 0.3 ms and they can be converted to computer-compatible signals by a simple amplifier. The EOD-activity is analyzed by a low-cost desk-top computer. Two different modes of analysis which represent two levels of response sensitivity, are possible either alternatively or simultaneously. The toxicity response of Gnathonemus petersi was measured in experiments with the toxicants Hg²⁺, Cu²⁺, NaAsO₂ and CN⁻. The sensitivity to acutely toxic concentrations was found to be as high as that of trout or minnows.     

南海饮用水水源突发性污染应急处理系统的研发和建立

针对水源突发性污染频发的现状,开发和建立了南海饮用水水源突发性污染应急处理系统。在对北江水源地存在的污染物进行调查分析并确定目标污染物的基础上,研究了目标污染物的应急去除技术,建立水源水质预警系统和水厂应急强化处理系统。介绍了项目实施的技术思路以及取得的主要技术成果,可为同行业其他企业提供参考。     

Retracted: Study of the change of water quality for a lake in Central China

Water environment has undergone several state changes, and the factors responsible for causing these water state changes are different. In this paper, a fuzzy comprehensive-quantifying assessment (FCQA) is proposed to evaluate the water quality changes for a representative lake in central China in recent decades. The innovation assessment method develops an index, S_mid, by applying a quantifying method to the fuzzy comprehensive assessment (FCA). The water quality of the lake is evaluated, and the temporal and spatial variations are analysed based on the data of 1991–2006. The Gray Filling Model [GM (1,1)] was used to predict the water quality trends in the subsequent 5 years, and the possible factors responsible for causing water environmental changes were analysed. The temporal and spatial variations of water quality show that there is a strong relationship between human activities and the water quality, and that excessive pen fish farming is the key internal pollution source threatening the lake at present.     

Assessment and biomonitoring of aquatic pollution by heavy metals (Cd,Cr, Cu,Pb and Zn) in Hammam Grouz Dam of Mila (Algeria)

Concentrations of Cd, Cr, Cu, Pb and Zn were determined in water, sediment and tissues of fish (Cyprinus carpio and Barbus setivimensis) from November 2014 to August 2015, in order to estimate the aquatic pollution in Hammam Grouz dam, by the technique of atomic absorption spectrophotometry. The concentrations of heavy metals in the water and sediment were higher than the WHO standards. The calculation of Bioconcentration factor showed that all fish species studied have accumulated heavy metals in their tissues (gill, liver, muscle and kidney). The concentrations of metals in B. setivimensis were higher than those in C. carpio. The highest concentration of heavy metals was recorded in the gill while the lowest was recorded in the muscle and kidney. Our study reveals that these fish species can be used as bioindicators in the biomonitoring of metallic pollution in aquatic ecosystem.     

电热水器运行方式与能耗的理论分析

运用总传热系数法,建立电热水器的物理模型及相应耗热量的数学模型。通过对电热水器不同运行方式能耗的理论计算,指出电热水器连续运行更加节能,为电热水器的节能提供了新的方向。     

供水系统预警监测站的优化布置

城市供水系统易受到意外的污染或蓄意的破坏,建立预警系统是保障供水安全的重要途径。对给定数量的监测站,以检测到各污染源节点所需总体时间最短为目标,采用0-1整数规划法来对其进行优化布置。算例结果表明,当采用该方法优化布置监测站后能够及时检测到节点和管段上发生的外部污染事件,并确定污染源的位置。随着监测站数量的增加,则检测到单个污染源节点所需的时间及其总体时间都呈下降趋势。