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).

This study examined the effects of heavy metals and plant arsenic uptake on soil arsenic distribution. Chemical fractionation of an arsenic-contaminated soil spiked with 50 or 200 mg kg-1 Ni, Zn, Cd or Pb was performed before and after growing the arsenic hyperaccumulator Pteris vittata L for 8 weeks using NH4Cl (water-soluble plus exchangeable, WE-As), NH4F (Al-As), NaOH (Fe-As), and H2SO4 (Ca-As). Arsenic in the soil was present primarily as the recalcitrant forms with Ca-As being the dominant fraction (45%). Arsenic taken up by P. vittata was from all fractions though Ca-As contributed the most (51-71% reduction). After 8 weeks of plant growth, the Al-As and Fe-As fractions were significantly (p < 0.01) greater in the metal-spiked soils than the control, with changes in the WE-As fraction being significantly (p = 0.007) correlated with plant arsenic removal. The plant's ability to solubilize soil arsenic from recalcitrant fractions may have enhanced its ability to hyperaccumulate arsenic. Arsenic taken up by P. vittata was from all fractions with most from the Ca-fraction.

Three experiments were conducted to optimize the use of ethylenediaminetetraacetic acid (EDTA) for reclaiming urban soils contaminated with trace metals. As compared to Na2EDTA, (NH4)2EDTA extracted 60% more Zn and equivalent amounts of Cd, Cu and Pb from a sandy loam. When successively saturating and draining loamy sand columns during a washing cycle, which submerged it once with a (NH4)2EDTA wash and four times with deionised water, the post-wash rinses largely contributed to the total cumulative extraction of Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn. Both the washing solution and the deionised water rinses were added in a 2:5 liquid to soil (L:S) weight ratio. For equal amounts of EDTA, concentrating the washing solution and applying it and the ensuing rinses in a smaller 1:5 L:S weight ratio, instead of a 2:5 L:S weight ratio, increased the extraction of targeted Cr, Cu, Ni, Pb and Zn. A single EDTA addition is best utilised in a highly concentrated washing solution given in a small liquid to soil weight ratio.

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.

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.

The growth of transgenic canola (Brassica napus) expressing a gene for the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase was compared to non-transformed canola exposed to flooding and elevated soil Ni concentration, in situ. In addition, the ability of the plant growth-promoting bacterium Pseudomonas putida UW4, which also expresses ACC deaminase, to facilitate the growth of non-transformed and transgenic canola under the above mentioned conditions was examined. Transgenic canola and/or canola treated with P. putida UW4 had greater shoot biomass compared to non-transformed canola under low flood-stress conditions. Under high flood-stress conditions, shoot biomass was reduced and Ni accumulation was increased in all instances relative to low flood-stress conditions. This is the first field study to document the increase in plant tolerance utilizing transgenic plants and plant growth-promoting bacteria exposed to multiple stressors. Using transgenic plants and plant growth-promoting bacteria as phytoremediation methods increased plant tolerance at a metal-contaminated field site under low flood conditions.

Two different indices have been proposed for estimation of the risk caused to forest trees across Europe by ground-level ozone, (i) the concentration based AOT40 index (Accumulated Over a Threshold of 40 ppb) and (ii) the recently developed flux based AFstY index (Accumulated stomatal Flux above a flux threshold Y). This paper compares the AOT40 and AFstY indices for three forest trees species at different locations in Europe. The AFstY index is estimated using the DO3SE (Deposition of Ozone and Stomatal Exchange) model parameterized for Scots pine (Pinus sylvestris), beech (Fagus sylvatica) and holm oak (Quercus ilex). The results show a large difference in the perceived O3 risk when using AOT40 and AFstY indices both between species and regions. The AOT40 index shows a strong north-south gradient across Europe, whereas there is little difference between regions in the modelled values of AFstY. There are significant differences in modelled AFstY between species, which are predominantly determined by differences in the timing and length of the growing season, the periods during which soil moisture deficit limits stomatal conductance, and adaptation to soil moisture stress. This emphasizes the importance of defining species-specific flux response variables to obtain a more accurate quantification of O3 risk. A new flux-based model provides a revised assessment of risks of ozone impacts to European forests.