On uncertainty and sensitivity of LCA-based priority setting

Life-cycle assessments are normally made without quantitative estimations of their uncertainty. More interest has been focused on sensitivity analysis. In ISO 14040, LCA standard and SETAC's ‘code of practice’ sensitivity and uncertainty analysis are recommended or even requested. In the EPS system, an analysis of significance and sensitivity has been carried out for several years. The article describes this procedure in ISO terms and generalises it for other types of life-cycle assessments.     

Formation, release and control of dioxins in cement kilns

Co-processing of hazardous wastes in cement kilns have for decades been thought to cause increased emissions of PCDD/PCDFs--a perception that has been evaluated in this study. Hundreds of PCDD/PCDF measurements conducted by the cement industry and others in the last few years, on emissions and solid materials, as well as recent test burns with hazardous wastes in developing countries do not support this perception. Newer data has been compared with older literature data and shows in particular that many emission factors have to be reconsidered. Early emission factors for cement kilns co-processing hazardous waste, which are still used in inventories, are shown to be too high compared with actual measurements. Less than 10 years ago it was believed that the cement industry was the main contributor of PCDD/PCDFs to air; data collected in this study indicates however that the industry contributes with less than 1% of total emissions to air. The Stockholm Convention on POPs presently ratified by 144 parties, classifies cement kilns co-processing hazardous waste as a source category having the potential for comparatively high formation and release of PCDD/PCDFs. This classification is based on early investigations from the 1980s and 1990s where kilns co-processing hazardous waste had higher emissions compared to those that did not burn hazardous waste. However, the testing of these kilns was often done under worst case scenario conditions known to favour PCDD/PCDF formation. More than 2000 PCDD/PCDF cement kiln measurements have been evaluated in this study, representing most production technologies and waste feeding scenarios. They generally indicate that most modern cement kilns co-processing waste today can meet an emission level of 0.1ngI-TEQ/m(3), when well managed and operated. In these cases, proper and responsible use of waste including organic hazardous waste to replace parts of the fossil fuel does not seem to increase formation of PCDD/PCDFs. Modern preheater/precalciner kilns generally seems to have lower emissions than older wet-process cement kilns. It seems that the main factors stimulating formation of PCDD/PCDFs is the availability of organics in the raw material and the temperature of the air pollution control device. Feeding of materials containing elevated concentrations of organics as part of raw-material-mix should therefore be avoided and the exhaust gases should be cooled down quickly in long wet and long dry cement kilns without preheating. PCDD/PCDFs could be detected in all types of solid samples analysed: raw meal, pellets and slurry; alternative raw materials as sand, chalk and different ashes; cement kiln dust, clinker and cement. The concentrations are however generally low, similar to soil and sediment.     

Safety-culture in a Norwegian shipping company

Problem: Although there has been considerable interest in safety culture and safety climate in many industries, little attention has been given to safety culture in one of the world's riskiest industries, shipping. Method: Using both self developed items and items from published research on safety culture, safety climate, and quality and management style, a 40-item safety culture questionnaire was developed. The questionnaire was distributed in a self-administered form to sailors onboard 20 vessels and to officers attending a seminar in Manila. A total of 349 questionnaires were collected (total response rate, 60%). Results, discussion and impact on industry: Principal component analysis (PCA) revealed 11 factors when the Kaiser eigenvalue rule was used and four factors when the scree test criterion was used. The factor structure in the material confirmed structures found in other industries. The relative importance of the factors from the factor analysis on “level of safety” measures was tested by canonical correlation analysis and regression analysis. The results confirmed previous research and showed that the most important factors were influential across industries. To determine weather differences existed between nationalities, occupations, and vessels the factors from the PCA was subjected to Multiple Discriminant Analysis. Significant differences between occupations, nations, and vessels were found on one or more of the factors from the PCA.     

Effect of an uncontrolled fire and the subsequent fire fight on the chemical composition of landfill leachate

Landfill leachates sampled during and after an accidental landfill fire were analysed and the levels of selected metals and chemical compounds compared to those occurring in the leachate under normal conditions. The fire at the landfill site was put out by excavation and cooling by use of water. The investigation during the fire and fire fight revealed a moderate increase in the level of nitrogen and also in pH and conductivity. Heavy metals and COD in the leachate showed considerably increased levels. In general, the determined variables appeared to normalise within one week after the fire was extinguished. It can be concluded that landfill fires extinguished by excavation may lead to elevated leachate levels of especially COD and heavy metals, but that this is only a short-term effect.     

Work performance,affective commitment,and work motivation: the roles of pay administration and pay level

The purpose of this study was to investigate employee attitudes and behaviors among knowledge workers under different forms of pay administration and pay levels. To examine these issues, I collected data from two business units in a large Norwegian multinational company with pay plans combining individual and collective performance and behaviors as the foundations for individual bonuses; one with two collective components (profit and behavior of the unit and the organization) and one with an individual component in addition to the two collective components. After controlling for organizational tenure, education, gender, perceived unit support, perceptions of distributive and procedural justice, and type of pay plan, the key findings are that base pay level, but not bonus level, was positively related to both self‐reported work performance and affective unit commitment, and that these relationships were partly mediated by intrinsic motivation. Furthermore, moderation analyses revealed that the relationships between bonus level and the outcome variables were not affected by type of pay plan. Implications and directions for future research on pay in knowledge intensive organizations are discussed. Copyright © 2006 John Wiley & Sons, Ltd.     

Distribution of lipolytic,proteolytic, and amylolytic marine bacteria between the lipid film and the subsurface water

The biochemical activity of marine bacteria adhering to the lipid film at the airwater interface was compared to that of bacteria inhabiting the subsurface water. The bacteria were isolated from the two levels at 7 stations, all located along Brofjorden on the Swedish West Coast. The isolates were tested for their ability to attack lipids, proteins, and carbohydrates. A higher percentage of active isolates was found in samples from the subsurface water than from the surface film. The accumulation of marine bacteria at the air-water interface is not due to their biochemical activity.     

Quantitative determination of de-conjugated chrysene metabolites in fish bile by HPLC-fluorescence and GC--MS

Two analytical methods have been evaluated for quantitative determination of de-conjugated chrysene metabolites in fish bile. High performance liquid chromatography-fluorescence (HPLC-F) and gas chromatography-mass spectrometry (GC--MS) were compared regarding instrumental and overall limits of detection (LOD) as well as recoveries for the following nine chrysene compounds: 1-, 2,- 3-, 4- and 6-hydroxychrysene (1-, 2-, 3-, 4- and 6-OH-chr), 1,2-dihydroxy-1,2-dihydrochrysene (1,2-DHD-chr), 3,4-dihydroxy-3,4-dihydrochrysene (3,4-DHD-chr), 5,6-dihydroxy-5,6-dihydrochrysene (5,6-DHD-chr) and chrysene. Instrumental LODs were comparable for the two methods whereas the overall LOD was better for HPLC-F. Recoveries varied per chrysene compound for both HPLC-F (62-107%) and GC-MS (48-124%). In vivo formed chrysene metabolites were studied in the bile of Atlantic cod (Gadus morhua) exposed to chrysene (1 mg/kg) via intra-peritoneal (i.p.) and inter-muscular (i.m.) injection. Total amounts of chrysene metabolites were three times higher in i.p. compared to i.m. exposed cod bile, but the relative distribution of determined metabolites was very similar. 1,2-DHD-chr was the most prominent metabolite in de-conjugated bile and constituted more than 88% of the total chrysene metabolites. Additional chrysene metabolites formed were 3,4-DHD-chr and 1-, 2-, 3- and 4-OH-chr. K-region chrysene metabolites (oxidation at carbons 5 and 6) were not detected and seem to be a less favoured biotransformation route. The two methods were applied and evaluated for analysis of chrysene metabolites in two bile reference materials (BCR 720 and 721) and a limited number of field exposed cods.     

Review and assessment of models for predicting the migration of radionuclides from catchments

The present paper summarises the results of the review and assessment of models developed for predicting the migration of radionuclides from catchments to water bodies. The models were classified and evaluated according to their main methodological approaches. A retrospective analysis of the principles underpinning the model development in relation to experimental finding and results was carried out. It was demonstrated that most of the various conceptual approaches of different modellers can be integrated in a general, harmonised perspective supported by a variety of experimental evidences. Shortcomings and advantages of the models were discussed.     

Combustion of gasolines in premixed laminar flames European certified and California phase 2 reformulated gasoline

Two gasoline qualities, European unleaded certified gasoline (EUCG) and California phase 2 reformulated gasoline (P2 RFG), were analysed. EUCG contained about twice the amount of alkyl benzenes compared to P2 RFG and a large amount of cyclohexane. As a balance, P2 RFG contained higher amounts of isooctane and MTBE. The gasolines were burned in a premixed laminar flame burner at 1 atm and at about stoichiometric fuel/air ratio. The species profiles were measured using on-line GC/MS. About 40 compounds were be detected in the gasoline flames. The EUCG resulted in formation of more reactive and toxic compounds. The combustion profiles of the fuel components showed a similar slope, which suggests that the fuel components burn quite independently of each other. Ethene and propene were the dominating species produced from the two gasolines. Commonly, substantial amounts of higher alkenes were found. Combustion of P2 RFG produced higher amounts of isobutene, propene, propyne, propadiene and methanol compared to combustion of EUCG. The high amount of isobutene is reasonably a result of high concentration of isooctane and MTBE in the fuel. The high amount of methanol formed is probably due to the MTBE present in the gasoline. EUCG produced significantly higher amounts of 1,3-butadiene, which quite likely is formed from the cyclohexane in the fuel. The benzene profiles from both gasolines shows an almost constant level up to 800 microm from the burner surface; this is probably due to formation of benzene from alkyl benzenes.