34 ref. doi: 10.1016/j.envpol.2004.10.020 | International audience | More knowledge is needed concerning the disturbance of soil organic matter cycling due to heavy metal pollution. The present study deals with the impact of heavy metal pollution on litter breakdown. Our aim was to assess whether heavy metals initially present in the leaves of the metallophyte Arabidopsis halleri: (i) slow down the rate of C mineralization, in relation to metal toxicity towards microflora, and/or (ii) increase the amount of organic C resistant to biodegradation, in relation to an intrinsic resistance of metallophyte residues to biodegradation. We incubated uncontaminated soil samples with either metal-free or metal-rich plant material. Metal-free material was grown in a greenhouse, and metal-rich material was collected in situ. During the 2-month period of incubation, we measured evolved CO2-C and residual plant C in the coarse organic fraction. Our results of CO2-C evolution showed a similar mineralization from the microcosms amended with highly metal-rich leaves of A. halleri and the microcosms amended with the metal-free but otherwise similar plant material. Measuring residual plant C in its input size-fraction gave a more precise insight. Our results suggest that only the large pool of easily decomposable C mineralized similarly from metal-free and from metal-rich plant residues. The pool of less decomposable C seemed on the contrary to be preferentially preserved in the case of metal-rich material. These results support the hypothesis of an annual extra-accumulation in situ of such a slowly decomposable fraction of plant residues which could account to some extent for the observed accumulation of metallophyte litter on the surface of highly metal-polluted soils.

[Departement_IRSTEA]MA [TR1_IRSTEA]QSA / EXPER | International audience | Triggered by the detection of a large variety of pharmaceuticals in surface waters, soils and groundwaters across the world (e.g. Halling- Sørensen et al. 1998, Daughton & Ternes 1999, Jones et al. 2001, Heberer 2002) and the widespread occurrence of endocrine active compounds and related effects in the environment (e.g. Purdom et al. 1994, Tyler et al. 1998, Vethaak et al. 2002), pharmaceuticals in the environment have become an issue for both the scientific and the public community. During the last few years, our understanding of the fate and effects of pharmaceuticals in the environment has progressed significantly. However, there are still a number of uncertainties concerning the effects of pharmaceuticals on the environment and the assessment of potential exposure (e.g. Hanisch et al. 2004, Salomon 2005). These uncertainties will be addressed by the EU-project'Environmental risk assessment of pharmaceuticals' (ERAPharm). This project, a specific targeted research project, is carried out within the priority 'Global change and ecosystems' of the 6th framework programme of the European Union. ERAPharm has started on 1st October 2004; the project duration is three years.

chap. 7 | National audience

Distribution and behavior of many trace elements in the aquatic environment has been well characterized, but little is known about silver (Ag) concentrations in coastal waters, even though this element ranks among the most toxic to marine invertebrates (Calabrese et al., 1977 ; Fisher and Hook, 1997 ; Webb and Wood, 1998). Studies conducted by Flegal et al. (1995), River-Duarte et al. (1999), and Ndung'u et al. (2001), provided the first valuable data on Ag distribution in the oceanic environment, indicating that this element is found in very low concentrations in the dissolved phase. However, although silver concentrations in coastal waters do not reach the nanomolar range (Smith and Flegal, 1993 ; Squire et al., 2002), formation of a stable chloro complex enhances bioavailability and toxicity to biota (Luoma et al., 1995). Experimental studies have shown that Ag is toxic to some living organisms at environmentally realistic levels (Bryan and Langston, 1992). Silver found in the aquatic environment mainly originates in effluents from sewage treatment plants (Rozan and Hunter, 2001). Silver can therefore be used as a tracer of wastewater discharges in coastal waters (Martin et al., 1988 ; Sañudo-Wilhelmy and Flegal, 1992), for instance through the use of sentinel organisms, which concentrate bioavailable contaminants in their tissues (Stephenson and Leonard, 1994 ; Jiann and Presley, 1997 ; Riedel et al., 1998 ; Muñoz-Barbosa et al., 2000). This study concerns biological monitoring as a means of providing a synoptic view of silver contamination in French coastal waters. The National Network for the Observation of Marine Environment Quality (RNO, the French Mussel-Watch) which has been regularly measuring concentrations of various chemical contaminants in oyster and mussel tissues for 25 years (Claisse, 1989), has been monitoring silver levels since 2003. This valuable database including data collected at 80 sampling sites distributed along the French coasts (Fig. 1), is used as a reference to provide the spatial distribution of a given contaminant (Chiffoleau and Bonneau, 1994), identify trends of contamination/decontamination (Chiffoleau et al., 2001), and detect peak concentrations due to accidental events (Chiffoleau et al., 2004). Mussels (Mytilus edulis and Mytilus galloprovincialis) and oysters (Crassostrea gigas) are collected twice a year in February and November. Sample collection (size of samples, size of animals) and treatment (cleaning, depuration, removal of soft parts from the shells, draining, homogenization, and freeze-drying) are performed according to the OSPAR Convention guidelines and the method described by Claisse (1989).

National audience

In January and February 2002, the presence of certain agricultural pesticides throughout the coastline of the Caribbean island of Martinique was investigated. The tropical climate of the French West Indies is suitable for banana production, which requires intensive use of pesticides. An inventory of all pesticides used on the island (compounds and tonnage) was compiled. Surveys and analyses revealed the presence of pesticides in the plumes of seven rivers. The organochlorine chlordecone and metabolites of aldicarb were detected at nearly all of the monitored sites, even though the use of chlordecone has been prohibited since 1993. Two triazines (ametryn and simazine) were also identified. The concentrations of carbamates and triazines detected in the water and sediment samples from Martinique are comparable to those reported for mainland France. Chlordecone concentrations in the sediment and particulate matter samples were, however, particularly high in the samples from Martinique. Toxicological implications are discussed. Of particular concern are the high levels of chlordecone (which is bioaccumulating and carcinogenic) and further monitoring of this compound is recommended, especially in fish and other sea-food products.