Recycling of an industrial sludge and marine clay as light-weight aggregates

The geographical limitations of Singapore, its restricted natural resources and voluminous municipal and industrial waste streams, make environmental management a major challenge for the island state. In an attempt to find ways to reduce importation of raw materials and the waste sent to landfill, light weight aggregates were produced from marine clay and a CaF(2)-rich semiconductor industry sludge. Aggregates were produced in a bench-scale rotary kiln with three clay/sludge loadings (90/10, 70/30 and 50/50%). All three mixtures showed good bloating behavior during firing and the ceramic pellets (1-1.5cm diameter) had densities well below that required for light-weight aggregates. In the initial tests, the pore sizes of the aggregates were in general too large resulting in high water absorption. Comparisons between the composition of the two waste products and the aggregates showed a significant loss of fluorine (40-60%) during processing; a problem which may require flue gas treatment. Leach testing showed that the formed aggregates would not pose a human or environmental hazard in terms of fluorine mobilization.     

What is most important for safety climate: The company belonging or the local working environment? – A study from the Norwegian offshore industry

Obtaining knowledge about factors affecting health, safety and environment (HSE) is of major interest to the petroleum industry, but there is currently a severe shortage of relevant studies. The aim of this study was to examine the relative influence of offshore installation (local working environment) and company belonging on employees’ opinions concerning occupational health and safety. We analyzed data from a safety climate survey answered by 4479 Norwegian offshore petroleum employees in 2005 on the dimensions “Safety prioritisation”, “Safety management and involvement”, “Safety versus production”, “Individual motivation”, “System comprehension” and “Competence” using one way analysis of variance (ANOVA), effect size and mixed model. The companies differed significantly for “Safety prioritisation”, “Safety versus production”, “Individual motivation”, “System comprehension” and “Competence”. The local offshore installation explained more of the safety climate than the company they were employed in or worked for did.     

Vertical and horizontal distributions of microbial abundances and enzymatic activities in propylene-glycol-affected soils

The natural microbial activity in the unsaturated soil is vital for protecting groundwater in areas where high loads of biodegradable contaminants are supplied to the surface, which usually is the case for airports using aircraft de-icing fluids (ADF) in the cold season. Horizontal and vertical distributions of microbial abundance were assessed along the western runway of Oslo Airport (Gardermoen, Norway) to monitor the effect of ADF dispersion with special reference to the component with the highest chemical oxygen demand (COD), propylene glycol (PG). Microbial abundance was evaluated by several biondicators: colony-forming units (CFU) of some physiological groups (aerobic and anaerobic heterotrophs and microscopic fungi), most probable numbers (MPN) of PG degraders, selected catabolic enzymatic activities (fluorescein diacetate (FDA) hydrolase, dehydrogenase, and β-glucosidase). High correlations were found between the enzymatic activities and microbial counts in vertical soil profiles. All microbial abundance indicators showed a steep drop in the first meter of soil depth. The vertical distribution of microbial abundance can be correlated by a decreasing exponential function of depth. The horizontal trend of microbial abundance (evaluated as total aerobic CFU, MPN of PG-degraders, and FDA hydrolase activity) assessed in the surface soil at an increasing distance from the runway is correlated negatively with the PG and COD loads, suggesting the relevance of other chemicals in the modulation of microbial growth. The possible role of potassium formate, component of runway de-icers, has been tested in the laboratory by using mixed cultures of Pseudomonas spp., obtained by enrichment with a selective PG medium from soil samples taken at the most contaminated area near the runway. The inhibitory effect of formate on the growth of PG degraders is proven by the reduction of biomass yield on PG in the presence of formate.     

Species distribution modelling—Effect of design and sample size of pseudo-absence observations

We explored the effect of varying pseudo-absence data in species distribution modelling using empirical data for four real species and simulated data for two imaginary species. In all analyses we used a fixed study area, a fixed set of environmental predictors and a fixed set of presence observations. Next, we added pseudo-absence data generated by different sampling designs and in different numbers to assess their relative importance for the output from the species distribution model. The sampling design strongly influenced the predictive performance of the models while the number of pseudo-absences had minimal effect on the predictive performance. We attribute much of these results to the relationship between the environmental range of the pseudo-absences (i.e. the extent of the environmental space being considered) and the environmental range of the presence observations (i.e. under which environmental conditions the species occurs). The number of generated pseudo-absences had a direct effect on the predicted probability, which translated to different distribution areas. Pseudo-absence observations that fell within grid cells with presence observations were purposely included in our analyses. We discourage the practice of excluding certain pseudo-absence data because it involves arbitrary assumptions about what are (un)suitable environments for the species being modelled.     

Multi-elemental EDXRF mapping of polluted soil from former horticultural land

The distribution of major and trace elements was systematically investigated by use of energy dispersive X-ray fluorescence spectrometry (EDXRF) on a former horticultural soil. The purpose of the study was to combine mapping of soil element concentration levels with multivariate statistics for characterisation of soil metal pollution in relation to previous and present land use. A 1-ha study site was chosen from a former horticulture where a previous preliminary survey indicated increased concentration levels of toxic elements. The soil was sampled from the top 20 cm of the soil surface in a 10 x 10-m grid-like pattern covering the 1-ha study area. In addition, three soil profiles were studied. The elemental composition of the soil samples was investigated by EDXRF while the composition of aqueous soil extracts was determined by total reflection X-ray fluorescence spectrometry (TXRF). Based on mapping and multivariate statistically analysis of the data obtained by EDXRF, most elements were found in almost constant concentration levels in the top soil throughout the investigated site. However, the contents of the toxic elements Zn, Cu, As, and Pb were found to vary significantly within the area. Hence, the samples with high accumulations of As also contained relatively high amounts of Zn, Cu, and Pb, which indicates that toxic-element-containing pesticides have been applied to the soil surface in the area of the former green houses at the study site. The Pb/As mass ratio in the soil indicates that PbHAsO3 was the preferential lead arsenate used for pest management at the investigated site, while Cu as Bordeaux liquid (CuSO4) and Zn were applied to minimize the leaf damaging effect from the former compounds. Calculations indicated that As annually was applied to the soil in the former greenhouses in doses up to 4 kg As/ha while Pb had been annually applied in doses up to 12 kg Pb/ha. The enrichment of Zn, Cu, As and Pb was greatest in the top 20 cm of the soil and no anthropogenic enrichment of these elements occurred below a depth of 50 cm, indicating that the toxic elements are rather immobile in this soil. The results of this investigation suggest that EDXRF used in combination with multivariate statistics is a strong tool for multi-element mapping of elemental contents, sources and mobility in the terrestrial environment.     

The relative role of age and experience in determining variation in body mass during the early breeding career of the Common Tern (<Emphasis Type="Italic">Sterna hirundo</Emphasis>)

Body mass is a consistent individual trait that characterises the state of adult birds and mammals and is positively related with long-term reproductive success. However, whether and to what extent body mass changes over lifetime in long-lived birds is poorly studied. In this paper, we investigate how individual body mass varies with age. Furthermore, we try to separate possible effects of age and experience on body mass. This study was conducted in a Common Tern colony on the German Wadden Sea coast. Transponders allowed registration of individuals throughout the breeding season and consecutive years with an antenna system combined with electronic balances for recording individual body-mass changes within and between years. Individual body masses of males and females were measured during three stages of the breeding season: at arrival, during incubation and chick rearing when mass was lowest in both sexes. Individual-based longitudinal analyses clearly showed that body mass during arrival, incubation and chick rearing increased up to an age of 5 or 6 years. First-time breeders had lower body mass than experienced breeders. Experience had stronger effects on incubation mass than age. Recruiting age also affected body-mass development of breeders: Three-year-old recruits showed a stronger increase in mass with experience than 4-year-old recruits. We assume that increasing experience enables birds to cope better with the physiological challenge of reproduction. To explain the general phenomenon of higher body mass in older birds, our results support the constraint hypothesis rather than either the selection or restraint hypothesis.     

Pregnancy-associated plasma protein A: A possible marker in the classification and prenatal diagnosis of Cornelia de Lange syndrome

The concentration of human placental lactogen (hPL), pregnancy specific beta-1 glycoprotein (SP-1) and pregnancy-associated plasma protein A (PAPP-A) were analysed in consecutive serum samples from a patient who gave birth to a child with Cornelia de Lange syndrome. HPL and SP-1 were present in normal concentrations from week 20 to week 35 of gestation whereas PAPP-A could not be detected in any of the samples examined. Immunohisto-chemical examination of two placentae from Cornelia de Lange syndrome revealed normal localization of hPL and SP-1 but the absence of PAPP-A from the syncytiotrophoblast. The significance of association between Cornelia de Lange syndrome and compromised synthesis of PAPP-A is discussed.