Intercontinental transport of air pollution: will emerging science lead to a new hemispheric treaty?

We examine the emergence of InterContinental Transport (ICT) of air pollution on the agendas of the air quality and climate communities and consider the potential for a new treaty on hemispheric air pollution. ICT is the flow of air pollutants from a source continent (e.g., North America) to a receptor continent (e.g., Europe). ICT of air pollutants occurs through two mechanisms: (i) episodic advection and (ii) increasing the global background, which enhances surface concentrations. We outline the current scientific evidence for ICT of aerosols and ozone, both of which contribute to air pollution and radiative forcing. The growing body of scientific evidence for ICT suggests that a hemispheric-scale treaty to reduce air pollutant concentrations may be appropriate to address climate and air quality concerns simultaneously. Such a treaty could pave the way for future climate agreements.     

Microbially derived inputs to soil organic matter: are current estimates too low?

Soil microbes are central to many soil processes, but due to the structural complexity of soil organic matter, the accurate quantification of microbial biomass contributions continues to pose a significant analytical challenge. In this study, microbes from a range of soils were cultured such that their molecular profile could be compared to that of soil organic matter and native vegetation. With the use of modern NMR spectroscopy, the contributions from microbial species can be discerned in soil organic matter and quantified. On the basis of these studies, the contributions of microbial biomass to soil organic matter appear to be much higher than the 1-5% reported by other researchers. In some soils, microbial biomass was found to contribute >50% of the extractable soil organic matter fractions and approximately 45% of the humin fraction and accounted for >80% of the soil nitrogen. These findings are significant because organic matter is intimately linked to nutrient release and transport in soils, nitrogen turnover rates, contaminant fate, soil quality, and fertility. Therefore, if in some cases soil organic matter and soil organic nitrogen are predominately of microbial origin, it is likely that this fraction, whether in the form of preserved material or living cells, plays an underestimated role in several soil processes.     

Unemployment and smoking: does psychosocial stress matter?

Aim: Research indicates that cigarette smoking is strongly associated with unemployment. However, little is known regarding the underlying mechanisms explaining this relationship. The aim of this study is to examine the role of psychosocial factors as potential mediators between unemployment and smoking. Participants: 4002 non-institutionalised, civilian adults living in the Veneto region of Italy. Design: The study was based on a computer assisted telephone interview (CATI). Linear by linear association tests were used to examine bivariate associations between unemployment, psychosocial factors, and smoking. Logistic regression models were developed to analyse the relationship between unemployment and smoking when adjusting for psychological factors. Results: The odds of smoking among the unemployed was 2.78 times (95% confidence interval (CI) 1.68 to 4.62) greater than that of higher managers and professionals controlling for demographic factors. The relationship between unemployment and smoking weakened (odds ratio 2.41, 95% CI 1.43 to 4.05) when psychosocial factors were entered into the analysis. The odds of the inability to control important things in life was 1.39 times (95% CI 1.11 to 1.75) greater, and the odds of emotional isolation was 1.45 times (95% CI 1.06 to 1.99) greater, among smokers compared to non-smokers controlling, for all other factors. Conclusions: Given that the data were cross sectional, firm conclusions cannot be drawn regarding the causal pathway connecting unemployment and smoking. However, this study suggests that psychosocial factors such as the inability to control and emotional isolation may be plausible mediators for the relationship.     

Electric power deregulation: will it mean dirtier air?

When U.S. utility restructuring arrives, it may bring more polluting power production, critics say.     

The sediment-water flux of HOCs due to "diffusion" or is there a well-mixed layer? If there is, does it matter?

In most present modeling of the sediment-water flux of hydrophobic organic chemicals (HOCs), the flux due to sediment erosion/deposition is described explicitly by means of a sediment transport model, while the remaining components of the flux (molecular diffusion, bioturbation, and groundwater flow) are lumped together and modeled as a "diffusive" flux. This diffusive flux is usually described by means of a mass transfer approximation with the implicit assumption of a well-mixed contaminant layer of thickness h in the sediments. On the basis of recent experiments and theoretical modeling, the justification forthis assumption and the quantification of this diffusive flux are discussed here. In particular, for HOCs with large partition coefficients, it is argued that a well-mixed layer often may not exist, and, when it does, it is slow to form; that h is difficult to define and even harder to quantify; and that, as far as long-term predictions (up to 100 years) of this diffusive flux are concerned, the exact value for h probably does not matter. What does matter are the magnitudes and time dependencies of each of the components of the flux and the interactions between the diffusive flux and the flux due to erosion/deposition.     

What does it mean to check-all-that-apply? Four case studies with beverages

The use of check-all-that-apply (CATA) questions in product-focused consumer research on foods and beverages is now common, and the method is known to provide valid sensory product characterisations. Extensive methodological research has been conducted and has supported uptake, but understanding of how consumers complete CATA questions is incomplete, particularly with regard to their decision to select or not a term to describe the sensory properties of products. The present research was situated within this gap, and using open-ended questions participants (n = 636) were asked to describe how they perceived a pair of samples with regard to an attribute and link this to CATA term selection. The results, obtained for taste (‘sweet’ and ‘sour/acidic’) and flavour (‘cinnamon’ and ‘smoky’) confirmed consumers’ ability to accurately perform sensory characterisation tasks. In particular, it was found that: i) the great majority of the consumers accurately used the CATA terms for describing the sensory characteristics they perceived in a sample, ii) when a term was not selected for describing samples, the majority of the consumers indicated that the corresponding sensory attribute was not perceived, iii) when a term was selected for describing only one of the samples in a pair, consumers reported to have perceived a difference in attribute intensity between the samples. Thus, CATA questions remain a desirable option for sensory product characterisation tasks with consumers, but should be selected with thought as they may not always be able to achieve desired sample discrimination due to the binary nature of the responses.     

Development of new probiotics by strain combinations: is it possible to improve the adhesion to intestinal mucus?

We evaluated the ability of commercial probiotic strains (Lactobacillus rhamnosus GG, L. rhamnosus LC705, Bifidobacterium breve 99, and Propionibacterium freudenreichii ssp. shermanii JS) to adhere alone or in different combinations to immobilized mucus. Probiotic combinations were clearly able to enhance the adhesion of L. rhamnosus GG, L. rhamnosus LC705, and P. freudenreichii ssp. shermanii JS. For L. rhamnosus GG and P. freudenreichii JS, all the combinations significantly improved adhesion to intestinal mucus, from 29.7 to 34.9% and from 1.9 to 2.3%, respectively. The adhesion of L. rhamnosus LC705 was improved from 0 to 46.4%. The adhesion of B. breve 99 was improved only in combination with L. rhamnosus GG and P. freudenreichii JS. Our results suggest that probiotic combinations could increase the beneficial health effects as compared with individual strains. Combinations of probiotic strains may therefore have synergistic adhesion effects, and such combinations also should be assessed in clinical studies.