An air quality forecasting system in Beijing - Application to the study of dust storm events in China in May 2008

An air pollution forecast system, ARIA Regional, was implemented in 2007-2008 at the Beijing Municipality Environmental Monitoring Center, providing daily forecast of main pollutant concentrations. The chemistry-transport model CHIMERE was coupled with the dust emission model MB95 for restituting dust storm events in springtime so as to improve forecast results. Dust storm events were sporadic but could be extremely intense and then control air quality indexes close to the source areas but also far in the Beijing area. A dust episode having occurred at the end of May 2008 was analyzed in this article, and its impact of particulate matter on the Chinese air pollution index (API) was evaluated. Following our estimation, about 23 Tg of dust were emitted from source areas in Mongolia and in the Inner Mongolia of China, transporting towards southeast. This episode of dust storm influenced a large part of North China and East China, and also South Korea. The model result was then evaluated using satellite observations and in situ data. The simulated daily concentrations of total suspended particulate at 6:00 UTC had a similar spatial pattern with respect to OMI satellite aerosol index. Temporal evolution of dust plume was evaluated by comparing dust aerosol optical depth (AOD) calculated from the simulations with AOD derived from MODIS satellite products. Finally, the comparison of reported Chinese API in Beijing with API calculated from the simulation including dust emissions had showed the significant improvement of the model results taking into account mineral dust correctly.     

Resource conservation in the pulp and paper industries—rational-use-of-energy approach

Sharp rises in energy prices have generated an interest in the pulp and paper industries in cogeneration and heat pump applications. However, the institutional and industry-specific barriers to their implementation, despite economic viability, indicate the inadequacies of the energy conservation and energy saving approaches to minimise energy costs. A systems approach, referred to as rational-use-of-energy, is proposed to overcome some of the barriers and to highlight the conservation potential of other resources, such as chemicals and water at appreciably low effluent loads.     

Assessment of ecotoxicological risks related to depositing dredged materials from canals in northern France on soil

The implementation of an ecological risk assessment framework is presented for dredged material deposits on soil close to a canal and groundwater, and tested with sediment samples from canals in northern France. This framework includes two steps: a simplified risk assessment based on contaminant concentrations and a detailed risk assessment based on toxicity bioassays and column leaching tests. The tested framework includes three related assumptions: (a) effects on plants (Lolium perenne L.), (b) effects on aquatic organisms (Escherichia coli, Pseudokirchneriella subcapitata, Ceriodaphnia dubia, and Xenopus laevis) and (c) effects on groundwater contamination. Several exposure conditions were tested using standardised bioassays. According to the specific dredged material tested, the three assumptions were more or less discriminatory, soil and groundwater pollution being the most sensitive. Several aspects of the assessment procedure must now be improved, in particular assessment endpoint design for risks to ecosystems (e.g., integration of pollutant bioaccumulation), bioassay protocols and column leaching test design.     

Fungal laccases: from structure-activity studies to environmental applications

Laccases are multicopper oxidases mainly secreted by filamentous fungi. Producing radical forms from organic substrates, they are involved in numerous reactions leading to the degradation and polymerization of xenobiotics. Our studies have led to a better knowledge of the structural, catalytic and genetic properties of laccases and allowed to develop a strategy for their evolution through genetic engineering. Here, we show that fungal laccases, wild or engineered, may be potent tools to develop bioremediation processes of soils polluted by organic compounds, and assays to assess the ecotoxicological impact of these pollutants on soil fungi.     

Gregarious behaviour in a salamander: attraction to conspecific chemical cues in burrow choice

Gregarious behaviour (i.e. living in groups in contrast to a solitary life) is commonly observed in mammals, but rarely documented in amphibians. Environmental features and/or animal mutual attractions can promote the formation of aggregations that may both reduce the risks of dehydration and predation and increase mate access and fitness. Luschan’s salamander (Mertensiella luschani) lives in permanently arid Mediterranean environments; individuals shelter in cracks and crevices and leave only during favourable periods. In this study we examined the role of chemical tracks, in self and conspecific recognition (i.e. gregarious/solitary behaviour), on the social structure of this species. Our results show that juveniles and adults of both sexes use chemical scents deposited on substrate to relocate their shelter. In contrast to numerous other salamander species, Luschan’s salamanders also use social information, conveyed by conspecific scents, to identify a safe shelter. Furthermore, this scent marking does not play a role in sexual attraction but allows sex discrimination. This species exhibits gregarious behaviour (i.e. conspecific attraction) as a possible adaptation to dry environments. We discuss both ultimate and proximate factors in the evolution from a solitary to a gregarious life.     

Degradation of azo dyes in water by Electro-Fenton process

The degradation of the azo dyes azobenzene, p-methyl red and methyl orange in aqueous solution at room temperature has been studied by an advanced electrochemical oxidation process (AEOPs) under potential-controlled electrolysis conditions, using a Pt anode and a carbon felt cathode. The electrochemical production of Fenton's reagent (H₂O₂, Fe²⁺) allows a controlled in situ generation of hydroxyl radicals (^·OH) by simultaneous reduction of dioxygen and ferrous ions on the carbon felt electrode. In turn, hydroxyl radicals react with azo dyes, thus leading to their mineralization into CO₂ and H₂O. The chemical composition of the azo dyes and their degradation products during electrolysis were monitored by high performance liquid chromatography (HPLC). The following degradation products were identified: hydroquinone, 1,4-benzoquinone, pyrocatechol, 4-nitrocatechol, 1,3,5-trihydroxynitrobenzene and p-nitrophenol. Degradation of the initial azo dyes was assessed by the measurement of the chemical oxygen demand (COD). Kinetic analysis of these data showed a pseudo-first order degradation reaction for all azo dyes. A pathway of degradation of azo dyes is proposed. Specifically, the degradation of dyes and intermediates proceeds by oxidation of azo bonds and aromatic ring by hydroxyl radicals. The results display the efficiency of the Electro-Fenton process to degrade organic matter. Electronic Publication     

Use of hydrophilic and hydrophobic microfiltration membranes to remove microorganisms and organic pollutants from primary effluents.

Primary-effluent wastewater from the Allegheny County Sanitary Authority (Pennsylvania) was used as a surrogate for combined-sewer-overflow waters contained in the sewershed. Pathogens contained in combined-primary-effluent wastewaters or combined-sewer overflows (CSOs) may pose a human-health threat to those coming in contact with such receiving waters. Polymeric ultra- and nano-membranes can be used to capture these microorganisms from CSOs. This research investigates the ability of polymeric hydrophobic and hydrophilic membranes, ranging in pore size from 0.2 to 0.8 microm, to remove pathogen-indicator organisms (Escherichia coli, enterococcus, and fecal coliforms). Membranes, with pore size 0.45 microm and smaller, were able to reduce the bacteria levels to nondetectable levels, with the sole exception of one membrane with pore size 0.3 microm.     

Groundwater management and socio-economic responses

The socio-economic aspects of groundwater development and management are briefly examined and set against a background of highly technical management. The variability of socio-economic responses to groundwater and the problems of engaging large numbers of individual users are highlighted. The paper argues that social, institutional and political factors are the primary obstacles to sustainable management of the world's groundwater resources.     

A double‐edged sword: Realities of artisanal and small‐scale mining for rural people in the Alaotra region of Madagascar

A growing number of people are entering the artisanal and small‐scale mining (ASM) sector worldwide. In Madagascar, millions of individuals depend on this informal activity. Through a case study in the Alaotra‐Mangoro region of Madagascar, our research aimed to understand the “bottom‐up” dynamics and ripple effects of the sector, by looking at the realities for rural communities where inhabitants are both directly and indirectly affected by ASM. We were interested in community members' and miners' perceptions of the socio‐economic and environmental impacts of ASM, and in identifying the factors attracting people living in one of the country's agricultural hubs to this activity. Our results show a wide diversity of push and pull factors leading people to enter the sector. Although many positive impacts of ASM exist for miners and communities within the vicinity of mines, most miner participants considered themselves worse off since starting to mine, highlighting the high risk and low probability of return of ASM. ASM's potential for local and national development will remain squandered if its negative impacts continue to go unmanaged. Accounting for local contexts and the ripple effects of ASM will be crucial in achieving safety and security for miners, and to tap into the benefits it may offer communities while minimising environmental damage.