For legacy and emerging persistent organic pollutants (POPs), surprisingly little is still known in quantitative terms about their global sources and emissions. Atmospheric transport has been identified as the key global dispersal mechanism for most legacy POPs. In contrast, transport by ocean currents may prove to be the main transport route for many polar, emerging POPs. This is linked to the POPs' intrinsic physico-chemical properties, as exemplified by the different fate of hexachlorocyclohexanes in the Arctic. Similarly, our current understanding of POPs' global transport and fate remains sketchy. The importance of organic carbon and global temperature differences have been accepted as key drivers of POPs' global distribution. However, future research will need to understand the various biogeochemical and geophysical cycles under anthropogenic pressures to be able to understand and predict the global fate of POPs accurately. Future studies into the global fate of POPs will need to pay more attention to the various biogeochemical and anthropogenic cycles to better understand emissions, transport and sinks.

Soybean [Glycine max (L.) Merr.] cultivars Essex and Forrest that exhibit differences in ozone (O3) sensitivity were used in greenhouse experiments to investigate the role of leaf extracellular antioxidants in O3 injury responses. Charcoal-filtered air and elevated O3 conditions were used to assess genetic, leaf age, and O3 effects. In both cultivars, the extracellular ascorbate pool consisted of 80e98% dehydroascorbic acid, the oxidized form of ascorbic acid (AA) that is not an antioxidant. For all combinations of genotype and O3 treatments, extracellular AA levels were low (1e30 nmol g 1 FW) and represented 3e30% of the total antioxidant capacity. Total extracellular antioxidant capacity was twofold greater in Essex compared with Forrest, consistent with greater O3 tolerance of Essex. The results suggest that extracellular antioxidant metabolites in addition to ascorbate contribute to detoxification of O3 in soybean leaves and possibly affect plant sensitivity to O3 injury.

Psidium guajava 'Paluma' saplings were exposed to carbon filtered air (CF), ambient non-filtered air (NF), and ambient non-filtered air + 40 ppb ozone (NF + O3) 8 h per day during two months. The AOT40 values at the end of the experiment were 48, 910 and 12 895 ppb h-1, respectively for the three treatments. After 5 days of exposure (AOT40 = 1497 ppb h-1), interveinal red stippling appeared in plants in the NF + O3 chamber. In the NF chamber, symptoms were observed only after 40 days of exposure (AOT40 = 880 ppb h-1). After 60 days, injured leaves per plant corresponded to 86% in NF + O3 and 25% in the NF treatment, and the average leaf area injured was 45% in NF + O3 and 5% in the NF treatment. The extent of leaf area injured (leaf injury index) was explained mainly by the accumulated exposure of ozone (r2 = 0.91; p < 0.05). Psidium guajava 'Paluma', a tropical species widely used in Brazilian food industry, is a potential sensitive bio-indicator of ozone.

Visible ozone symptoms on leaves are expressions of physiological mechanisms to cope with oxidative stresses. Often, the symptoms consist of stippling, which corresponds to localized cell death (hypersensitive response, HR), separated from healthy cells by a layer of callose. The HR strategy tends to protect the healthy cells and in most cases the efficiency of chlorophyll to trap energy is not affected. In other cases, the efficiency of leaves to produce biomass declines and the plant loses its photosynthetic apparatus replacing it with a new, more efficient one. Another strategy consists of the production of pigments (anthocyanins), and leaves become reddish. In these cases, the most significant physiological manifestation consists of the enhanced dissipation of energy. These different behavior patterns are reflected in the initial events of photosynthetic activity, and can be monitored with techniques based on the direct fluorescence of chlorophyll a in photosystem II, applying the JIP-test. Analytical techniques based on the direct fluorescence of chlorophyll a, allow us to discriminate species-specific physiological behavior in relation to ozone air pollution.

An open top chamber experiment was carried out in the summer of 2003 to examine the effect of nitrous acid (HONO) gas on the physiological status of Scots pine saplings (Pinus sylvestris). Four-year-old pine trees were exposed to two different levels of HONO gas (at ca. 2.5 ppb and 5.0 ppb) and a control (filtered air) from early evening to early morning (18:00-6:00), in duplicate open top chambers. Significant decreases in the ratios of chlorophylls a to b, an increase in the carbon to nitrogen (C/N) ratio, and a reduction of maximum yield of PS II (Fv/Fm) in pine needles were also observed after the 2 months' fumigation. Cation contents of pine needles were also decreased by the fumigation with HONO gas. The results could be explained by the harmful effects of OH radicals, generated from photolysis of HONO gas, and/or aqueous phase HONO (NO2-/HONO), on the photosynthetic capacity of pine needles. Exposure to HONO affects photosynthesis and nutrient status of pine trees.

Trace elements were analyzed in fish of commercial interest to determine their importance in marine systems of the Western Indian Ocean and their bioaccumulation patterns. The results are equivalent or lower than levels reported in ichthyofauna worldwide. Certain values of muscular Cd, Hg, Pb and Zn were, however, above thresholds for human consumption. Levels varied among tissues, species and fish length, but were seldom influenced by the nutritional condition of the fish, its gender and its reproductive status. Correlations between hepatic Hg and Se levels in Swordfish (r(2) = 0.747) and Yellowfin Tunas (r(2) = 0.226), and among metallothionein linking metals imply the existence of detoxification processes in these species. Level differences between fish from the Mozambique Channel and Reunion Island reflect differences of diets rather than differences of elemental availability in both environments. (c) 2006 Elsevier Ltd. All rights reserved.

[Departement_IRSTEA]MA [TR1_IRSTEA]QSA / HYDRECO | International audience | Scats of the European otter (Lutra lutra) were sampled along the Allier river (France) catchment for organochlorine toxic compounds (nine pesticides and 16 PCBs congeners) measurement. From early 2004 to June 2005, 90 sites of 40 rivers were twice investigated, and 71 scats samples collected, in four geographical areas being naturally re-colonized by the species since its legal protection. Detectable pesticides and PCBs were found in 100% of the samples. Mean values reached 2.72 and 13.58 mg kg-1 (lipid weight) for pesticides and PCBs, respectively. Amounts were significantly different between the four areas investigated. A significant increase in medium and absolute values is noted by going downstream of the catchment. Potential medium- and long-term consequences on the observed population increase are discussed.

The life history of the European Eel (Anguilla anguilla) begins in the Sargasso Sea in the Atlantic Ocean where the Leptocephalus larvae drift with the gulf stream in order to reach European coastal waters. After their metamorphosis into transparent juveniles "glass" eels and an acclimatising phase in the estuaries, they migrate upstream into the rivers to become yellow eels (sub-adult stage). The yellow eels spend between 2 and 20 years of their lifetime in freshwater until they change into silver eels (adult stage) and finally migrate back to the Atlantic Ocean for spawning (Gomez-Mourelo, 2005). A. anguilla is thus an organism able to tolerate a wide range of environmental conditions, such as variations in oxygen availability, different ranges of salinities and exposure to many anthropogenic compounds. In addition, it is a migratory, benthic and benthivorous species at the top of the food chain and is characterised by a high fat content (>30%). For all these reasons A. anguilla is prone to bioaccumulate a wide range of contaminants and it has been widely employed throughout the last years as a bioindicator of the pollution caused by metals (Batty et al., 1996; Has-Schön et al., 2006) and organic contaminants (Storelli et al., 2007; Yamaguchi et al., 2003). The environmental and toxicological impact of Hg bioaccumulation in fish is related to the methylation of inorganic mercury to form the more toxic methylmercury (MeHg) species. In this way, fish tend to concentrate in their tissues MeHg by a factor of 105-107, leading to dangerous levels even in areas with tolerable Hg concentrations (Mason et al. 1996). It has been reported that about 98% of the Hg present in aquatic systems is immobilised in the sediments (Stein et al., 1996) and that most of the MeHg is produced at the sediment water interface as a result of biotic or abiotic transformations caused by specific redox gradients and bacterial activity (Gilmour and Henry, 1998.). According to this, A. anguilla may be an effective biomagnificator and bioaccumulator of Hg due to its longevity during the continental development phase in freshwaters (where it forages and lives upwards 15 years) and its position at the top of the food chain as a carnivorous species feeding on the benthic fauna (Mancini et al., 2005).