Temporal variations of concentrations of currently used pesticides in the atmosphere of Strasbourg, France

Atmospheric samples have been collected in Strasbourg between April 18 and May 29, 2007 and were analyzed for 71 current-use pesticides, of which 38 were detected. Average concentrations ranged from 0.09 ng m⁻³ for Fenarimol to 110.42 ng  m⁻³ for Dimethachlor, which was slightly higher than the concentrations reported from other, comparable agricultural regions.Significant temporal variations were observed for 30 pesticides, and for most of them it could be shown that these were linked to time, temperature or atmospheric pressure. In several cases this helped to identify pesticide application just before or at the beginning of the sampling period, or ongoing treatment. Humidity, in contrast to previous reports, could not be linked to these variations. For the other 8 pesticides, only very little temporal variations were observed. Generally, these concentrations were low (less than 1 ng m⁻³), and it was assumed that they are not in use in Alsace at present.     

Follow-up of pregnancies complicated by placental mosaicism diagnosed by chorionic villus sampling

Thirty-nine (2.3 per cent) of 1724 chromosome studies from diagnostic chorionic villus samplings (CVS) done between 1983 and 1990 showed either level III (true) mosaicism (1.2 per cent) or level II (pseudo-) mosaicism (1.1 per cent) for chromosomal aneuploidy. Follow-up information on these 39 pregnancies was collected from questionnaires to families, paediatricians, and obstetricians. For all cases in which the pregnancy was continued and further testing was accomplished, the mosaicism was felt to be confined to the placenta. As compared with a control group of pregnancies evaluated by CVS with normal karyotypes, there was no increased incidence of pregnancy loss, congenital malformations, or developmental delay in the infants. Although intrauterine growth retardation occurred in several of the level III mosaic cases, adequate catch-up growth has been demonstrated.     

Habitat structure affects intraguild predation

Intraguild predation is thought to be ubiquitous in natural food webs. Yet, theory on intraguild predation predicts the intraguild prey to persist only under limited conditions. This gap between theory and empirical observations needs scrutiny. One reason might be that theory has focused on equilibrium dynamics and a limited set of species (usually three) that interact in well-mixed populations in unstructured habitats, and these assumptions will often not hold in natural systems. In this review, we focus on the effects of habitat structure on intraguild predation. Habitat structure could reduce encounter rates between predators and prey and could create refuges for prey. In both cases, habitat structure could reduce the strength of intraguild interactions, thereby facilitating species coexistence. A meta-analysis of studies on manipulation of habitat structure shows that intraguild prey indeed suffer less from intraguild predation in structured habitats. This was further confirmed by a meta-analysis in which studies on intraguild predation were classified according to habitat structure. Intraguild predation reduced densities of the intraguild prey significantly more in habitats with little structure than in habitats rich in structure. The effect of intraguild predation on the shared prey was negative, and not significantly affected by habitat structure. We conclude that habitat structure may increase persistence of the intraguild prey by decreasing the strength of the interaction between intraguild predator and intraguild prey.     

A new approach to graphical and numerical analysis of links between plant chemotaxonomy and secondary metabolism from HPLC data smoothed by a simplex mixture design

Summary. HPLC analysis of secondary metabolites represents an efficient tool for the studying of plant chemical diversity under different aspects: chemotaxonomy, metabolomics, adaptative responses to ecological factors, etc. Statistical analyses of HPLC databases, e.g. correlation analysis between HPLC peaks, can reliably provide information on the similarity/dissimilarity degrees between the chemical compounds. The similarities, corresponding to positive correlations, can be interpreted in terms of analogies between chemical structures, synchronic metabolisms or co-evolution of two compounds under certain environment conditions, etc. . In terms of metabolism, positive correlations can translate precursor-product relationships between compounds; negative correlations can be indicative of competitive processes between two compounds for a common precursor(s), enzyme(s) or substrate(s). Furthermore, the correlation analysis under a metabolic aspect can help to understand the biochemical origins of an observed polymorphism in a plant species. With the aim of showing this, we present a new approach based on a simplex mixture design, Scheffé matrix, which provides a correlation network making it possible to graphically visualise and to numerically model the metabolic trends between HPLC peaks. The principle of the approach consisted in mixing individual HPLC profiles representative of different phenotypes, then from a complete mixture set, a series of average profiles were calculated to provide a new database with a small variability. Several iterations of the mixture design provided a smoothed final database from which the relationships between the secondary metabolites were graphically and numerically analysed. These relationships were scale-dependent, namely either deterministic or systematic: the first consisted of a monotonic global trend covering the whole variation field of each metabolites’ pair; the second consisted of repetitive monotonic variations which gradually attenuated or intensified along a global trend. This new metabolomic approach was illustrated from 404 individual plants of Astragalus caprinus (Leguminoseae), belonging to four chemical phenotypes (chemotypes) on the basis of flavonoids analysed in their leaves. After smoothing, the relationships between flavonoids were numerically fitted using linear or polynomial models; therefore the co-response coefficients were easily interpreted in terms of metabolic affinities or competitions between flavonoids which would be responsible of the observed chemical polymorphism (the four chemotypes). The statistical validation of the approach was carried out by comparing Pearson correlations to Spearman correlations calculated from the smoothed and the crude HPLC database, respectively. Moreover, the signs of the smoothed relationships were finely supported by analogies and differences between the chemical structures of flavonoids, leading to fluent interpretation in relation to the pathway architecture.     

Habitat-specific chemical cues influence association preferences and shoal cohesion in fish

The structure of social animal groups can be dynamic, characterized by high rates of group fission and fusion. Despite this, group composition is often well ordered by factors such as species, body size and by numerous other phenotypic traits. Research in shoaling fishes has revealed that individuals refine group membership decisions still further and are capable of assimilating chemical cues pertaining to recent habitat and prey use by prospective group mates, preferring to associate with others whose recent resource use history closely matches their own. In this study, we firstly examined the dynamics of the formation and breakdown of these preferences, revealing that they can be acquired and replaced in a matter of just a few hours. Using such cues enables individuals to accurately assess the resource use of conspecifics, allowing them to indirectly sample the local environment while reducing the chances of acquiring outdated information that can precipitate maladaptive behaviors. Secondly, we found that shoals composed of individuals with shared recent habitat use history were more cohesive compared to those where the constituent individuals differed in recent habitat use. Increased shoal cohesion may reduce predation risk, and could enhance the ability of individuals to detect and use social information.     

Persistent organic pollutants in the atmosphere from urban and industrial environments in the Rhine Valley: PCBs, PCDD/Fs

Polychlorinated biphenyls (PCBs) and polychlorinated dibenzodioxin and furan (PCDD/F) concentrations in the atmosphere were analysed using passive air samplers (PAS) close to the Rhine River between France and Germany. Collectors were placed in industrial, urban, rural and remote areas (Vosges Mountains) between March 2009 and August 2010, and the mean PCB concentrations (sum of 22 congeners) were 3.3, 3.9, 4.1 and 1.4 ng?PAS^?1?day^?1, respectively. Two events during the sampling period were observed in April 2009 and February–March 2010 with the highest PCB concentrations found in the industrial area (19.6 ng?PAS^?1?day^?1). PCDD/F level were measured during these periods, and the maximum concentration observed was from 37.5 fg?WHO?PAS^?1?day^?1     

Epidemiological Aspects of Air Pollution

An urban air pollution incident, like a natural or man-made catastrophe, presents a crisis situation which can only be relieved if adequate contingency plans have been prepared in advance and an effective control organization is in a state of operational readiness to meet the threatened emergency. Although many air pollution incident control plans have been proposed in the past, most have remained in the conceptual or theoretical stages of preparation, because the relative infrequency of serious urban air pollution crises and the disruptive nature of major emission control operations tend to limit the opportunities available for field testing of these plans. In this respect, air pollution incident control planning is analogous to strategic planning for a military operation, where the only completely legitimate test of a strategy is applied on the battlefield. In order to accomplish the transition from conceptual planning to a practical, operational field strategy for air pollution incident control, a program of incident control tests has been initiated in Chicago. These field tests, which use the city as a laboratory for the development of control strategies, are analogous to a series of military war games in which communication systems, command and control organizational structures, personnel roles, surveillance and monitoring equipment, control resources and pollution source controllability are tested under conditions which approximate as closely as possible the situation which prevails during an actual air pollution incident. This paper discusses the evolution of an incident control strategy from an initial, fixed response emission control exercise, through a meteorologically initiated control test to a fairly realistic war game series which is still developing.     

Standards for Air Quality in California

Abstract

During the 1950s and 1960s, hundreds of thousands of underground storage tanks (and above-ground storage tanks) containing petroleum products and hazardous chemicals were installed. Many of these tanks either have been abandoned or have exceeded their useful lives and are leaking, thereby posing a serious threat to the nation’s surface and groundwater supplies, as well as to public health. Cleaning up releases of petroleum hydrocarbons or other organic chemicals in the subsurface environment is a real-world problem,

Biological treatment of hydrocarbon-contaminated soil is considered to be a relatively low-cost and safe technology; however, its potential for effectively treating recalcitrant wastes has not been fully explored. For millions of years, microorganisms such as bacteria, fungi, actinomycete, protozoa, and others have performed the function of recycling organic matter from which new plant life can grow.

This paper examines the biological treatment technology for cleaning up petroleum product-contaminated soils, with special emphasis on microbial enzyme systems for enhancing the rate of biodegradation of petroleum hydrocarbons. Classifications and functions of enzymes, as well as the microbes, in degrading the organic contaminants are discussed. In addition, the weathering effect on biodegradation, types of hydrocarbon degraders, advantages associated with enzyme use, methods of enzyme extraction, and future research needs for development and evaluation of enzyme-assisted bioremediation are examined.