Southeast Asia is a hotspot of anthropogenic emissions where episodes of recurrent and prolonged atmospheric pollution can lead to the formation of large haze events, giving rise to wide plumes which spread over adjacent oceans and neighbouring countries. Trace metal concentrations and Pb isotopic ratios in atmospheric particulate matter < 10 μm (PM) were used to track the origins and the transport pathways of atmospheric pollutants. This approach was used for fortnightly PM collections over a complete annual cycle in Haiphong, northern Vietnam. Distinct seasonal patterns were observed for the trace metal concentration in PM, with a maximum during the Northeast (NE) monsoon and a minimum during the Southeast (SE) monsoon. Some elements (As, Cd, Mn) were found in excess according to the World Health Organization guidelines. Coal combustion was highlighted with enrichment factors of As, Cd, Se, and Sb, but these inputs were outdistanced by other anthropogenic activities. V/Ni and Cu/Sb ratios were found to be markers of oil combustion, while Pb/Cd and Zn/Pb ratios were found to be markers of industrial activities. Pb isotopic composition in PM revealed an important contribution of soil dusts (45-60%). In PM, the Pb fraction due to oil combustion was correlated with dominant airflow pathways (31% during the north-easterlies and 20% during the south-easterlies), and the Pb fraction resulting from industrial emissions was stable (around 28%) throughout the year. During the SE monsoon, Pb inputs were mainly attributed to resuspension of local soil dusts (about 90%), and during the NE monsoon, the increase of Pb inPM was due to the mixing of local and regional inputs.

International audienceHydroxylated polycyclic arom. hydrocarbons (OH-PAHs), a group of metabolites produced during the biodegrdn. of PAHs by microorganisms, are known to be difficult to analyze from complex environmental or biol. matrixes. In the field of contaminated soils, where OH-PAHs are less studied, a new method was compared to a common method for the anal. of monohydroxylated PAH metabolites: 2-naphthol, 2-hydroxyfluorene, 9-phenanthrol and 1-hydroxypyrene. After optimizing the microwave assisted extn. (MAE) step, the obtained exts., contg. the OH-PAHs together with the corresponding PAHs, were purified by molecularly imprinted polymers (MIPs). MIPs showed an effective selectivity for the hydroxylated derivs. studied (and not for native PAHs), which allowed their identification and quantification by HPLC/FLD. By this method, good limits of detection (0.003-0.014 μg g-1) and limits of quantification (0.010-0.044 μg g-1) were achieved. On the other hand, following the common method, the sample ext. was concd. by evapn., silylated, and analyzed by GC/MS. The new method was more sensitive for all OH-PAHs and the anal. showed fewer matrix effects due to the use of MIP clean-up. In the present work the advantages and disadvantages of the new method are shown, as well as the possible application to soil biodegrdn. studies

In order to assess the effect of mixed pollutants, the influence of different concentration levels of a mixture of metals (Cr, Co, Pb, Mn, Ni, Cu, Zn) on the biodegradation of some PAHs (phenanthrene, fluoranthene, pyrene, benzo[b]fluoranthene and benzo[a]pyrene) in soil samples was evaluated. To do so, groups of microcosms of a natural soil from the region of Sabadell (Barcelona, Spain) were prepared as a reproduction of the native environment at laboratory scale, under controlled conditions. Mixtures of PAHs and metals were carefully selected, according to soil characterization and microbiological growth preliminary assays, and were added to microcosms. These microcosms were analyzed at various times, along two months, to obtain PAHs dissipation time-courses. A first-order kinetic modelling allowed obtaining different rate constants and DT50 values as a function of the metal levels introduced in microcosms. As a general observation, the higher the concentration of metals, the lower the biodegradation of PAHs of 3-4 rings (phenanthrene, fluoranthene and pyrene). On the other hand, no important effect on the biodegradation of higher molecular weight PAHs (benzo[b]fluoranthene and benzo[a]pyrene) was observed at the different concentration levels of metals tested.