EVALUATION AND APPLICATION OF A FUGACITY MODEL TO EXPLAIN THE PARTITIONING OF CONTAMINANTS IN THE ST. LAWRENCE RIVER VALLEY

A fugacity-based model to explain the partitioning of contaminants in the environment is evaluated. Using emission inventories, air and water concentrations predicted by the model for the southwestern Québec region generally agree with field data for phenanthrene,α-HCH, lindane, and DDT. For pyrene, air concentrations are in agreement but water concentrations were in error by a factor of nearly 20. There is also a possibility for using the model to predict emissions from known air and water concentrations. The model was run over 120 times each for phenanthrene, HCB, and lindane while randomly varying the input parameters each time. A Principal Components Analysis and a partial correlation analysis indicate that certain input parameters are more important for some compounds than for others and that log K _ow is the physical-chemical property of greatest importance.     

Iron availability from iron-fortified spirulina by an in vitro digestion/Caco-2 cell culture model

Iron deficiency, one of the most important nutritional problems in the world, can be caused not only by foods deficient in iron but also by poor availability of dietary iron. Iron food fortification in combination with highly available iron from supplements could effectively reduce this deficiency. The aim of this study was to examine the iron availability from iron-fortified spirulina. We have used an in vitro digestion/Caco-2 cell culture system to measure iron spirulina availability and made a comparison with those of beef, yeast, wheat floor, and iron sulfate plus ascorbic acid as a reference. Iron availability was assessed by ferritin formation in Caco-2 cells exposed to digests containing the same amount of iron. Our results demonstrate a 27% higher ferritin formation from beef and spirulina digests than from digests of yeast and wheat flour. When iron availability was expressed per microgram of iron used in each digest, a 6.5-fold increase appeared using spirulina digest in comparison with meat. In view of this observed high iron availability from spirulina, we conclude that spirulina could represent an adequate source of iron.     

Alternative method for the quantification by gas chromatography triacylglycerol class analysis of cocoa butter equivalent added to chocolate bars

Directive 2000/36/EC allows chocolate makers to add up to 5% of only six specific cocoa butter equivalents (CBEs) to cocoa butter (CB). A quantification method based on triacylglycerol (TAG) class analysis by gas chromatography with an unpolar column was set up for routine control purposes of chocolate bars. Mixtures of CBEs/CB were elaborated according to a Placket-Burman experiment design and analyzed by gas chromatography. A matrix was built with the normalized values of TAG classes (C50, C52, C54, and C56) of pure CBs of various origins, homemade CB/CBE mixtures (1 CB type), and mixtures containing CBE with CBs of various origins. A multivariate calibration equation was computed from this matrix using a partial least-squares regression technique. CBE addition can be detected at a minimum level of 2%, and the mathematical model allows its quantification with an uncertainty of 2% with respect to the cocoa butter fats. The model has also been applied for deconvolution and quantification of each CBE of a CBE mixture in chocolate bars.     

Ovalbumin, ovotransferrin, lysozyme: three model proteins for structural modifications at the air-water interface

Structural modifications of ovalbumin, ovotransferrin, and lysozyme at the air-water interface have been investigated using SDS-PAGE, both intrinsic and ANS fluorometry, and circular dichroism experiments. Ovalbumin contact with an interface induced an exposure of aromatic residues, a slight decrease in alpha-helix structures (-1.7%), and an increase in both beta-sheet (+3.4%) and beta-turn (+7.9%) structures. Moreover, these conformational changes led to the formation of insoluble polymers of ovalbumin through intermolecular disulfide bonds. Ovotransferrin contact with an interface led to an increase in its surface hydrophobicity (+30%) and modifications of its secondary structure (-33% of alpha-helices, +96.4% of beta-sheets, +13.2% of beta-turns, and +21.2% of random coils), characteristic of major conformational changes. On the other hand, lysozyme did not undergo any structural modification. These results clearly underscore that at the air-water interface proteins are susceptible to denaturation.     

Flazasulfuron: alcoholysis, chemical hydrolysis, and degradation on various minerals

The herbicide flazasulfuron undergoes rapid alcoholysis. High yields of the corresponding carbamate and aminopyrimidine are obtained after the alcoholysis process (methanol or ethanol) at 30 degrees C, in the course of which the concomitant rearrangement reaction remains minor. Hydrolysis (pH ranging from 5 to 11) of flazasulfuron at 30 degrees C principally involves the rearrangement into urea after elimination of SO(2) and can lead, in a small proportion, to both aminopyrimidine and pyridinesulfonamide. First-order kinetics correctly describes the rates of alcoholysis and hydrolysis. The sulfonylurea-bridge contraction and final transformation into the correspondent amine were evaluated with a first-order kinetics hypothesis. Transformations in amine and urea in aqueous medium are pH dependent. The chemical degradation of flazasulfuron on various dry minerals (calcium bentonite, kaolinite, silica, montmorillonite, and alumina) was investigated at 30 degrees C. The rearrangement reaction is the only one observed in the presence of kaolinite and alumina. However, hydrolysis and rearrangement have the same reaction rate in the presence of silica. The hydrolysis paths of flazasulfuron are comparable to the ones described for rimsulfuron.     

Origin of the nitrogen assimilated by soil fauna living in decomposing beech litter

We investigated the nitrogen source for main taxa of soil fauna in two beech forests of contrasted humus type using ¹⁵N-labelled beech litter and ¹⁵N analysis of soil fauna. ¹⁵N-labelled beech litter was deposited on the topsoil in December 2000 in four stands of different ages at Leinefelde (Germany) with mull humus and in one mature stand at Sorø (Denmark) with moder humus. The fate of the tracer isotope was measured in litter and soil, as well as in the soil fauna, and for each taxa, we calculated the proportion of N in the animal derived from the labelled substrate. Of the original N contained in the litter, 20-41% was lost after 9 months at Leinefelde, and only 10% at Sorø. This loss was counterbalanced by the incorporation of 24-31% external N at Leinefelde, and 31% at Sorø, partly originating from fungal colonisation of the added litter. The proportion of N assimilated from the labelled litter by the different soil animals varied in relation to their mobility and feeding preferences. Large and mobile soil animals, especially predators, derived on average less ¹⁵N because they were also able to feed outside the labelled litter boxes. Detritivores assimilated at most 15% of their nitrogen content at Leinefelde and 11% at Sorø from the decomposing labelled litter. The most labelled taxa at Leinefelde were small fungivorous and coprophagous species, mainly isotomid Collembola such as Isotomiella and Folsomia. At Sorø, best labelled taxa were saprophagous species such as Enchytraeidae, Glomeridae and Phthiracaroidea. These low rates of ¹⁵N assimilation indicate that fresh litter is not directly the main N source for soil animals. The results obtained suggest that soil fauna fed preferentially upon microorganisms colonising the litter at Leinefelde (mull) and from litter itself at Sorø (moder).     

Changes in Collembola richness and diversity along a gradient of land-use intensity: A pan European study

Changes in Collembola richness and diversity along a land-use intensity gradient were studied in eight European countries (Portugal, Spain, France, Switzerland, Hungary, UK, Ireland and Finland). In each country a set of six 1 km² land-use units (LUUs) were selected forming a gradient ranging from natural forest to agricultural dominated landscapes, passing through mixed-use ones. In addition to data on Collembola, detailed information regarding landscape diversity and structure was collected for each LUU. A total of 47,774 individuals were identified from 281 species. Collembola reacted not only to changes in the diversity of the landscape, but also to the composition of that diversity and the area occupied by each land-use type at each LUU. Although species richness patterns were not concordant among the different countries, the total number of species per LUU (landscape richness) was generally higher in natural forests and mixed-used landscapes, and lower in agricultural dominated landscapes. Moreover, high richness and diversity of Collembola at each LUU were associated with a diverse landscape structure, both in terms of number of patches and patch richness. Despite this comparable species richness between mixed-use landscapes and those dominated by natural forests, average species richness on forested areas (local richness) decreased along the gradient, showing that forest patches on mixed-use landscapes support a lower richness than in landscapes dominated by forest. This aspect is important when addressing the role of native forests in structuring biodiversity in disturbed and fragmented landscapes. Although a diverse landscape can support a high biodiversity, the results suggest that intensive fragmentation should be avoided with the risk of collapsing local species richness with the consequent result for regional biodiversity.     

Identification of trace volatile compounds in freshly distilled Calvados and Cognac using preparative separations coupled with gas chromatography-mass spectrometry

Gas chromatography coupled with mass spectrometry (GC-MS) using both electron impact and chemical ionization detection modes led to the determination of the volatile composition of two samples of freshly distilled Cognac and two samples of freshly distilled Calvados. A total of 169 volatile compounds were directly identified in dichloromethane extracts obtained by liquid-liquid extraction. Trace compounds present in both spirits were characterized with the help of preparative separations. In a first step, groups of compounds were separated by preparative GC, and the fractions were analyzed on a polar stationary phase by GC-MS. In a second step, silica gel fractionation was used to separate them by polarity. In this study, 331 compounds, of which 162 can be considered as trace compounds, were characterized in both freshly distilled Cognac and Calvados. Of these, 39 are common to both spirits; 30 are specific to Cognac with numerous hexenyl esters and norisoprenoidic derivatives, whereas 93 are specific to Calvados with compounds such as unsaturated alcohols, phenolic derivatives, and unsaturated aldehydes.     

Plasma levels of six carotenoids in nine European countries: report from the European Prospective Investigation into Cancer and Nutrition (EPIC)

BACKGROUND: In addition to their possible direct biological effects, plasma carotenoids can be used as biochemical markers of fruit and vegetable consumption for identifying diet-disease associations in epidemiological studies. Few studies have compared levels of these carotenoids between countries in Europe. OBJECTIVE: Our aim was to assess the variability of plasma carotenoid levels within the cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC). METHODS: Plasma levels of six carotenoids--alpha-carotene, beta-carotene, beta-cryptoxanthin, lycopene, lutein and zeaxanthin--were measured cross-sectionally in 3043 study subjects from 16 regions in nine European countries. We investigated the relative influence of gender, season, age, body mass index (BMI), alcohol intake and smoking status on plasma levels of the carotenoids. RESULTS: Mean plasma level of the sum of the six carotenoids varied twofold between regions (1.35 micromol l(-1) for men in Malm?, Sweden vs. 2.79 micromol l(-1) for men in Ragusa/Naples, Italy; 1.61 micromol l(-1) for women in The Netherlands vs. 3.52 micromol l(-1) in Ragusa/Naples, Italy). Mean levels of individual carotenoids varied up to fourfold (alpha-carotene: 0.06 micromol l(-1) for men in Murcia, Spain vs. 0.25 micromol l(-1) for vegetarian men living in the UK). In multivariate regression analyses, region was the most important predictor of total plasma carotenoid level (partial R(2)=27.3%), followed by BMI (partial R(2)=5.2%), gender (partial R(2)=2.7%) and smoking status (partial R(2)=2.8%). Females had higher total carotenoid levels than males across Europe. CONCLUSIONS: Plasma levels of carotenoids vary substantially between 16 different regions in Italy, Greece, Spain, France, Germany, the UK, Sweden, Denmark and The Netherlands. Compared with region of residence, the other demographic and lifestyle factors and laboratory measurements have limited predictive value for plasma carotenoid levels in Europe.