事故树分析法在桥梁施工危险源辨识中的应用

在人类文明发展的历程中,桥梁一直占据着重要的位置,,桥梁工程建设工期长、投资金额大、技术要求复杂,一旦发生事故,后果严重、影响重大。因此,加强桥梁施工当中危险源的辨识便成为预防事故发生的重要手段。本文提出了事故树分析法在桥梁施工危险源辨识中的应用,并结合具体案例进行分析．制定出了相应的预防措施．保证了施工的安全进行。事故树分析方法是进行桥梁施工危险源分析的有效工具,为安全、科学的生产提供了有效保障。     

Combined stack effect in houses and eskers explaining transients in radon source

Concentrations of radon indoors and temperatures indoors and outdoors have been recorded every hour with some interruptions for one 12-week period in a dwelling situated on top of an esker outside Stockholm.The concentration of radon in the house shows variations, which can be explained as a combined stack effect in the esker and in the building.The stack effect is not only dependent on temperature differences, but also on the pressure effect that the wind creates. In this study no local wind observations have been made as this was not the main purpose on this occasion.The temperature in the esker is assumed to be at a constant level equivalent to groundwater temperature.From these data the pressure gradient has been calculated and then compared with the radon source.     

分析认定起火点和引火源的探讨

准确认定起火点,是正确认定起火原因的前提条件。查清引火源、起火物是认定起火原因的重要保证。探讨分析认定起火点和引火源的条件,提出了应当注意的问题。     

Cost effectiveness analysis of radon remediation programmes

The economic implications of regulations governing radon gas level identification and remediation in buildings are poorly understood, and attempts to address these issues have been criticised for lack of comparability. It is imperative therefore that a general model for the economic evaluation of radon remediation programmes is adopted to ensure comparability between studies and settings and to increase the usefulness of the results to decision makers. This paper presents general guidelines for the use of cost-effectiveness analysis (CEA) as an economic appraisal tool in the evaluation of radon reduction and prevention programmes. The data requirements for a CEA of radon remediation programmes concern both costs and outcomes. These components are discussed with respect to: programme objectives, comparator choice, perspective, time horizon, discounting, uncertainty, and final ratios. Adhering to clear guidelines concerning these aspects of evaluations will facilitate meaningful evaluation of radon remediation programmes. Finally, by evaluating the radon remediation programmes using methods applied to other health interventions (such as lung cancer prevention interventions), comparisons using the same metric can be made across policy areas.     

Changes in dissolved organic carbon during artificial recharge of groundwater in a forested esker in Southern Finland

Sprinkling infiltration in a forested esker leading to artificial recharge of groundwater was studied in Southern Finland. Changes in dissolved organic carbon (DOC) and the molecular size distribution and chemical properties of the organic carbon were investigated during the infiltration process. Artificial groundwater was produced using sprinkling infiltration directly onto the forest floor. One result of lake water infiltration through the organic horizon and 1 m thick mineral soil layer was a slight net increase in the DOC concentrations from 9.4 mg/L in the infiltration water to 13.2 mg/L in percolation water. This indicates that the forest soil represents a potential input of organic matter into infiltration water. However, the DOC concentrations decreased by 27–38% as the infiltration water percolated down through the unsaturated soil layer into the groundwater zone. At a distance of 1450 m from the infiltration area, the mean DOC concentration in the groundwater was below the recommended value for drinking water in Finland of 2.0 mg/L. There was a strong reduction in the concentrations of hydrophilic and hydrophobic acids, but only a slight decrease in hydrophilic neutral organic compounds during the infiltration process. The DOC in the production well consisted of low molecular size fractions. Larger molecular size fractions were removed effectively from the water during the infiltration process.     

Spatial variability and source identification of rural precipitation chemistry in France

The precipitation chemistry in France has been examined for large-scale spatial variability using the MERA/WMO-GAW network of 13 rural sites equipped with wet-only collectors. Three classes of mean chemical compositions of MERA sites, corresponding to three different geographical regions in France have been identified by applying hierarchical clustering analysis. Factor analysis has also been performed on the deposition and concentration data sets for the three MERA sites. All the factors could be interpreted as falling into one of four categories: Acid, Sea, Neutralization, or an Agriculture/Soil association. Both sulfate and nitrate were found to be significant components of the acid factor for two stations (Morvan and Donon). These individual site analyses indicate that the sea has a strong influence on the precipitation chemistry at these continental stations. A comparison between factor analysis of concentrations and factor analyses of depositions suggests on the one hand that the acid forms, H₂SO₄ and HNO₃, seem preferentially present in cloud and on the other hand that the neutralization of precipitation acidity by soil-derived particles and by ammonia emissions seems to depend on the geographical and climatic characteristics of a site (altitude, proximity to human activity and precipitation amount).     

Enrichment of anaerobic polychlorinated biphenyl dechlorinators from sediment with iron as a hydrogen source

Little is known about anaerobic polychlorinated biphenyl (PCB) dechlorination, although it is believed that some microorganisms are capable of respiring PCBs, gaining energy for growth from PCB dechlorination. If this is the case, the amendment of appropriate electron donors to contaminated sediment should stimulate dechlorination. The effect of elemental iron (Fe0) addition, an easily amended electron donor, on the microbial dechlorination of the PCB congeners 3,4,5-trichlorobiphenyl (3,4,5-CB) and 2,2',3,4,4',5,5'-heptachlorobiphenyl (2,2',3,4,4',5,5'-CB) was investigated in microcosms containing estuarine sediment from Baltimore Harbor. Results showed that the addition of 0.1 g Fe0/g sediment reduced the lag time for removal of doubly flanked para chlorines by approximately 100 days. Because Fe0 is a source of cathodic hydrogen (H2), the effect of direct H2 addition to sediment microcosms was also tested. The addition of 0.001 atm H2 in the headspace generated the same dechlorination activity and reduction in lag time as the addition of 0.1g Fe0/g. Higher concentrations of Fe0 or H2 increased the lag prior to dechlorination. Additional results showed that an alkaline pH (> or = 7.5), high [Fe2+] (3.3 g/L), or HS- (0.1 mg/L total sulfide) inhibited dechlorination. Elevated concentrations of Fe2+, OH-, and HS- are products of Fe0 oxidation or increased microbial activity (methanogenesis, homoacetogenesis, and sulfate reduction), both of which would result from the amendment of large quantities of Fe0 or H2 to sediment. This research shows that not only can PCB dechlorination be stimulated through the addition of electron donor, but implies that the dechlorinators are enriched by the continuous addition of low concentrations of H2, similar to other known dechlorinators, such as the dehalorespirer Dehalococcoides ethenogenes. These results suggest that the direct addition of controlled amounts of Fe0 to sediments may be an effective remediation tool to reduce the lag period prior to dechlorination at PCB-impacted sites. They also suggest that PCB dechlorinators may be enriched using techniques similar to those used with known dehalorespirers.     

Faecal pollution source identification in an urbanising catchment using antibiotic resistance profiling, discriminant analysis and partial least squares regression

Increasing urbanisation and changes in land use lead to adverse impacts on the quality of natural water resources. The specific sources of contamination are often difficult to identify using conventional water quality monitoring techniques. This acts as a significant constraint to the development of appropriate management techniques to protect natural water resources. Consequently, alternative means of identifying pollutant sources and their locality are necessary. In this study, Antibiotic Resistance Patterns (ARP) were established for a library of 1005 known Escherichia coli source isolates obtained from human and non-human (domesticated animals, livestock and wild) sources in an urbanising catchment in Queensland State, Australia. Discriminant Analysis (DA) was used to differentiate between the ARP of source isolates and to identify the sources of faecal contamination. Partial Least Square (PLS) regression was then utilised on identified human source isolates to correlate their locality with specified sampling locations within the catchment. The resulting ARP DA indicated that a majority of the faecal contamination in the rural areas was non-human. However, the percentage of human isolates increased significantly in urbanised areas using onsite systems for wastewater treatment. The PLS regression was able to develop predictive models which indicated a high correlation of human source isolates from the urban area. The study results confirm the feasibility of using ARP for source tracking faecal contamination in surface waters, as well as predicting their point of origin.     

The identification of highly chlorinated ethers and diethers in river sediment near an epichlorohydrin plant

In harbour sediment samples taken near an epichlorohydrin production plant, a series of highly chlorinated ethers and diethers were detected viz. three isomeric bis(dichloropropyl)ethers, several structurally closely related ethers with 9 carbon atoms (C₉ ethers), a number of C₁₂ ethers and diethers, and finally several C₁₅ ethers. The formation of this new class of ether compounds can be explained on the basis of the chemistry of the addition of HOCl to allylchloride. After initial addition of Cl⁻, a reactive intermediate is formed which may react with the product dichloropropanol, to give the C₆ ethers, or may polymerize with the starting compound allylchloride followed by reaction with the product, to give the C₉, C₁₂ and C₁₅ ethers.     

Ecological problems of radon in construction

Causes of the radioactive risk of radon during construction are addressed and a program, whose implementation will make it possible to lower the risk ofradon, is proposed. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, pp. 26–28, September–October, 1994.     

Nitrogen pollution and source identification in the Haicheng River basin in Northeast China

A survey was conducted in the Haicheng River near Liaodong Bay to analyze the characteristics and sources of the in-stream nitrogen pollution throughout the year 2010. The results indicated that the total nitrogen (TN) concentrations in the river water all exceeded the GB3838-2002 standard for Class V guideline of 2.0 mg/l at all sampling sites during the sampling seasons. Ammoniacal nitrogen (NH₃-N) dominated TN during the spring season, while nitrate nitrogen (NO₃-N) dominated during the summer and autumn seasons. Different forms of nitrogen had significant seasonal variations (p < 0.01 or p < 0.05). Only NH₃-N and NO₃-N displayed distinct spatial differences at p < 0.05 and p < 0.001, respectively. Most forms of nitrogen were interrelated with physicochemical parameters during different seasons, displaying nitrification and denitrification processes that occurred in the river rather than seasonal biological demand. Based on the nitrogen parameters, the 30 sampling sites were divided into three clusters, by which the pollution sources from chemical nitrogen fertilizers, animal wastes, domestic sewage, and industrial wastewater were identified. Generally, the Haicheng River basin provided about 700 tons of the annual TN flux, contributing to the eutrophication of the Liaodong Bay and Bohai Sea.     

Assessment of river Po sediment quality by micropollutant analysis

Trace metals, PCB congeners and DDT homologues were determined in composite sediment samples collected from 10 representative sites along the river Po in two separate seasons. The aim was to identify the most anthropogenically impacted areas for future monitoring programmes and to aid development of Italian sediment quality criteria. The surface samples were collected during low flow conditions. Trace metal concentrations were assayed by electrothermal (Cd, Co, Cr, Cu, Ni, Pb), flame (Fe, Mn, Zn) or hydride generation (As) atomic absorption spectrometry after microwave assisted acid digestion. Hg was determined on solid samples by automated analyser. Organic microcontaminants were determined by gas-chromatography with 63Ni electron capture detector after Soxhlet extraction. Concentrations of trace metals, total PCB and DDT homologues showed two distinct peaks at the sites immediately downstream of Turin and Milan, respectively, and in each case decreased progressively further downstream. Principal component analysis identified three major factors (from a multi-dimensional space of 35 variables) which explained 85-90% of the total observed variance. The first and second factors corresponded to anthropogenic inputs and geological factors on sediment quality; the third included seasonal processes of minor importance. Sediment quality assessment identified Cd, Cu, Hg, Pb, Zn and organic microcontaminants as posing the most serious threats to river sediment quality. A reference site within the Po basin provided useful background values. Moderate pollution by organochlorine compounds was ascribed both to local sources and to atmospheric deposition.     

非市政给水水源用作消防供水水源可靠性分析

分析了我国城市消防给水水源不足,消防供水水源可靠性较低的原因及危害,从节约用水和保证消防水源可靠性的角度,探讨了天然水体、建筑中水、工业废水处理后达标排放水及回用水等非市政给水用作消防水源的可靠性问题.     

Solvent displacement of sediment interstitial waters before trace metal analysis

The use of an inert, dense fluorocarbon solvent, FC-78, has been examined for the displacement by centrifugation of sediment interstitial waters. This technique has been compared with centrifugation in the absence of solvent, using both conventional tubes and those with basal collection cups. While the latter are satisfactory for sandy sediments, and the former for fine sediments, solvent displacement offers advantages of increased recoveries after shorter times at low speeds (1600 RCF) with greater ease of operation. The effect of rotation speed on interstitial water recovery was studied. Detailed experiments showed that the solvent did not extract organic compounds or heavy metal species from the interstitial water sample. The method is therefore suitable for the separation of waters for heavy metal speciation studies in both aerobic and anaerobic samples.     

谈施工阶段垂直运输机械危险源辨识及风险评价

结合危险源和风险评价的定义,介绍了施工阶段垂直运输设备重点关注的活动及风险,主要对观察法、安全检查法、"LEC"风险评价法在施工阶段垂直运输机械危险源辨识及风险评价中的应用作了阐述,以提高施工企业的管理水平,降低安全事故的发生。     

Prioritization of sediment management alternatives using stochastic multicriteria acceptability analysis

Decision-making for sediment management is a complex task that requires the consideration of temporal and spatial impacts of several remedial alternatives as well as the associated economic, social and political impact. Multicriteria decision analysis (MCDA) is becoming increasingly recognized as an important environmental management tool that can be used to support the selection of suitable remediation alternatives and prioritization of management units in space and time. This paper proposes an MCDA framework for prioritizing sediment management alternatives. This framework involves identifying of a set of feasible options, as well as defining and evaluating criteria which integrate relevant technical, economic, social and environmental aspects of remedies. The methodology allows an explicit consideration of uncertainty in criteria scores and weights by assigning probability distributions and analyzing subsequent Monte-Carlo simulations. The consideration of different stakeholder simulated values is used to assess the robustness of alternative rankings and to guide the selection of remediation options. An application of this methodology to a case study in the Bay of Santander, Spain, is presented. An assessment is conducted for the case of unknown preferences as well as for hypothetical preferences profiles for four types of stakeholders: Idealist, Politician, Environmentalist and Balanced. The results are used to visualize stakeholder positions and potential disagreements, allowing for the identification of a group of least preferred alternatives for each stakeholder. Stakeholder involvement has the potential to ease the remedy selection process during all stages of the decision-making process and to eventually remedy implementation.     

中水水源热泵适用性分析

比较了建筑物负荷和中水所能提供的能量的关系,认为中水水源热泵不能完全满足整个取水区域的冷热负荷需求,建议在设计时要严格核算中水量,并可以将中水水源热泵与其他系统结合,以满足使用需要.     

多热源环状管网可靠性分析

介绍了供热系统可靠性的含义,从系统的角度与供热系统可靠性指标两个方面阐述了多热源环状管网系统的可靠性,对多热源环状管网可靠性指标进行了分析,并将其与枝状管网做了比较,指出多热源环状管网的可靠性高于单热源枝状管网的可靠性。     

北流市乡镇饮用水源地污染源调查分析及对策

以北流市乡镇集中式饮用水水源保护区划分调查资料为基础,对北流21乡镇的集中式饮用水水源地污染源进行分析计算,针对计算成果反映的问题进行评价,并提出相应的保护策略,为决策部门提供一定的理论依据。