Urban road traffic is a major joint emission source for particles and ambient noise. This study explores the relationship between both environmental stressors at an urban traffic site and analyses the potential to model particle number size distributions (NSD) from measurements of ambient noise frequency levels. Thus, a measurement campaign was conducted within an urban street canyon covering a period of 50 days. First, noise frequency levels were used to successfully model traffic intensity at the street canyon site on a half-hourly basis (R2 = 0.78). Thereafter, two multiple linear regression models were built to calculate NSD using noise frequency levels in combination with meteorological quantities (wind speed and air temperature) and air pollutant data (NO2) as explanatory variables. Implementation of meteorological quantities in Model 1 captured the diurnal variation of measured NSD. However, total particle number concentration (TNC) as derived from modelled NSD underestimated observed TNC. Implementation of NO2 led to higher model performance for TNC (R2 = 0.57) but not for particle NSD. Detailed information about urban background particle concentrations as a proxy for local conditions and about boundary layer conditions (e.g. atmospheric stability, mixing layer height) might help improving the model. The spatial characteristics of the site and their acoustical effects were not considered in the present approach (e.g. distance to road or buildings, road surface), hence, the results should be transferred to other sites with some caution.

International audience | Major and trace elements in soils originate from natural processes and different anthropogenic activities which are difficult to discriminate. On a 17-ha impacted site in northern France, two industrial sources of soil contamination were xidentified: a former iron foundry and a current secondary lead smelter. To discriminate and map natural and anthropogenic sources of major and trace elements on this site, the rarely applied MULTISPATI-principal component analysis (PCA) method was used. Using a 20-m x 20-m grid, 247 topsoil horizons were sampled and analysed with a field-portable X-ray fluorescence analyser for screening soil contamination. The study site was heavily contaminated with Pb and, to a lesser degree, with Sn. Summary statistics and enrichment factors allowed the differentiation of the main lithogenic or anthropogenic origin of the elements. The MULTISPATI-PCA method, which explained 73.9% of the variability with the three first factors, evidenced strong spatial structures. Those spatial structures were attributed to different natural and artificial processes in the study area. The first axis can be interpreted as a lithogenic effect. Axes 2 and 3 reflect the two different contamination sources. Pb, Sn and S originated from the secondary lead smelter while Fe and Ca were mainly derived from the old iron foundry activity and the old railway built with foundry sand. This study demonstrated that the MULTISPATI-PCA method can be successfully used to investigate multicontaminated sites to discriminate the various sources of contamination.

International audience

International audience | Climate change and increasing demography press local authorities to look after affordable water resources and replacement of drinking water for city necessities like street and pavement cleaning by more available raw water. Though, the substitution of drinking by non-drinking resources demands the evaluation of sanitary hazards. This article aims therefore to evaluate the contribution of cleaning water to the overall exposure of city dwellers in case of wet pavement cleaning using crossed physical, chemical and biological approaches. The result of tracer experiments with fluorescein show that liquid water content of the cleaning aerosol produced is about 0.24 g m(-3), rending possible a fast estimation of exposure levels. In situ analysis of the aerosol particles indicates a significant increase in particle number concentration and particle diameter, though without change in particle composition. The conventional bacterial analysis using total coliforms as tracer suggests that an important part of the contamination is issued from the pavement. The qPCR results show a more than 20-fold increase of background genome concentration for Escherichia coli and 10-fold increase for Enterococcus but a negligible contribution of the cleaning water. The fluorescence analysis of the cleaning aerosol confirms the above findings identifying pavement surface as the major contributor to aerosol organic load. The physical, chemical and microbiological approaches used make it possible to describe accurately the cleaning bioaerosol and to identify the existence of significantly higher levels of all parameters studied during the wet pavement cleaning. Though, the low level of contamination and the very short time of passage of pedestrian in the zone do not suggest a significant risk for the city dwellers. As the cleaning workers remain much longer in the impacted area, more attention should be paid to their chronic exposure.

International audience | Phytoextraction of Cd is a growing biotechnology although we currently know few Cd-hyperaccumulators, i.e. plant species able to accumulate at least 0.1 mg Cd g-1 dry weight in aerial organs. Owing their deep root system and high biomass, trees are more and more preferred to herbaceous species for phytoextraction. Assuming that conifers could be relevant models under cold climates, we investigated cadmium tolerance of the hybrid larch Larix × eurolepis Henry (L. decidua × L. kaempferi) and the efficiency of this species to store this metal. In vitro grown larches were chosen in order to reduce time of exposure and to more rapidly evaluate their potential efficiency to accumulate Cd. One-month-old plantlets were exposed for 2 and 4 weeks to 250 and 500 µM Cd. Results showed that they tolerated a four-week exposure to 250 µM Cd whereas the content of photosynthetic pigment strongly dropped in plantlets growing in presence of 500 µM Cd. In presence of 250 µM Cd, shoot growth slightly decreased but photosynthetic pigment and total soluble carbohydrate contents were not modified and no lipid peroxidation was detected. In addition, these plantlets accumulated proline, particularly in shoots (2 - 3 times more than control). In roots, Cd concentration in the intracellular fraction was always higher than in the cell wall fraction contrary to shoots where Cd concentration in the cell wall fraction increased with time and Cd concentration in the medium. In shoots, Cd concentration was lower than in roots with a ratio of 0.2 after 4 weeks of exposure but stayed around 0.2 mg g-1 dry weight, thus a value higher than the threshold requested for Cd-hyperaccumulators. Hybrid larch would thus be a relevant candidate for field test of Cd-phytoextraction.

International audience

This study investigated ambient concentrations and potential sources of polychlorinated biphenyls (PCBs) in surface sediments from the Zhoushan Archipelago and adjacent Xiangshan Harbor. The ∑18PCB (total 18 PCB) concentrations ranged between 1.48 and 7.94ng/g d.w., average at 4.20ng/g d.w., presenting a low adverse environmental risk. Penta-CB was the dominant congener, contributing 46.01%–86.44% of the total PCBs. Concentrations of PCBs were highest in the northeastern part of the Zhoushan Archipelago and Xiangshan Harbor. Principal component analysis (PCA) showed that PCBs have a mixed origin; atmospheric deposition and PCB dispersion from paint flakings being the main sources of PCB pollution. Aroclor 1245 and Clophen A50 were the potential PCB sources in all sampling sites. This paper provides the first intensive survey and statistical analyses of PCB distributions and sources in the Zhoushan Archipelago and adjacent Xiangshan Harbor. This study may provide a reference to environmental protection and monitoring of PCB pollution in the East China Sea.

Lead (Pb) and zinc (Zn) concentrations from surface sediments were determined at 17 stations in riverine, estuarine, and marine environments during the wet and dry seasons. The geochemical fractionations were obtained by a sequential extraction procedure in five geochemical forms: exchangeable, bound to carbonate, iron–manganese oxide, organic, and residual fractions. The concentrations of Pb and Zn in the water were higher during the wet season than the dry season and higher in the riverine and marine samples than the estuarine samples. Following geochemical fractionation, the metals were found mainly in the residual fraction. The results indicated that the concentrations were influenced by season, with the sources of Pb and Zn derived mainly from rivers and natural sources. The contamination status in the estuary of the Jeneberang River was classified as weak to moderate pollution and the risk level to aquatic biota attributed was no risk to low risk.

Diverse marine bacterial species predominantly found in oil-polluted seawater produce diverse surface-active agents. Surface-active agents produced by bacteria are classified into two groups based on their molecular weights, namely biosurfactants and bioemulsifiers. In this study, surface-active agent-producing, oil-degrading marine bacteria were isolated using a modified Bushnell–Haas medium with high-speed diesel as a carbon source from three oil-polluted sites of Mumbai Harbor. Surface-active agent-producing bacterial strains were screened using nine widely used methods. The nineteen bacterial strains showed positive results for more than four surface-active agent screening methods; further, these strains were characterized using biochemical and nucleic acid sequencing methods. Based on the results, the organisms belonged to the genera Acinetobacter, Alcanivorax, Bacillus, Comamonas, Chryseomicrobium, Halomonas, Marinobacter, Nesterenkonia, Pseudomonas, and Serratia. The present study confirmed the prevalence of surface-active agent-producing bacteria in the oil-polluted waters of Mumbai Harbor.