In the framework of an ecological risk assessment of seaport sediments for terrestrial ecosystems when deposited in quarries, we simulated the “ageing” of sediments exposed to rain. This experiment highlighted an inflection point at the solid/liquid ratio 1/25, after which the extraction of pollutants increases moderately. The raw sediments studied inhibited the germination of Lolium perenne and Armeria maritima (a halophytic species) seeds. Furthermore, they affected the early development of L.perenne. The same sediments, leached at a ratio of 1/25, presented a reduction of acute (germination) and chronic (growth) phytotoxicity. The bioconcentration factors of the metals studied decreased with the leached sediment, except for Cu which was still clearly identified in root parts. Thus rotary leaching tests and phytotoxicity bioassays can be used to provide an initial assessment of the ability of plants, particularly halophytes, to colonize deposits of dredged seaport sediments.

Elements uptake, histological distributions as well as mycorrhizal and physiological statuses of Atriplex halimus were determined on trace metal and metalloid polluted soils from the surrounding spray zones of a former lead smelter in the South-East coast of Marseille (France). Analyses of heavy metal and arsenic distribution in soil and plant organs showed that A. halimus tolerance is largely due to exclusion mechanisms. No specific heavy metal concentration in leaf or root tissues was observed. However, accumulation of salts (NaCl, KCl, Mg and Ca salts) on leaf bladders and peripheral tissues of roots was observed and may compete with metal element absorption. Occurrence of endomycorrhizal structures was detected in roots and may contribute to lower element transfer from root into the aerial parts of plants. The non-destructive measurements of leaf epidermal chlorophylls, flavonols and phenols showed a healthy state of the A. halimus population on the metal and metalloid polluted sites. Considering the low metal bioaccumulation and translocation factors along with a reduced metal stress diagnosis, A. halimus appeared as a good candidate for phytostabilization of trace metals and metalloids and notably arsenic in contaminated soils of the Mediterranean spray zone. However, its invasive potential has to be determined before an intensive in situ use.

Many polluted sites are typically characterized by contamination with multiple heavy metals, drought, salinity, and nutrient deficiencies. Here, an Australian native succulent halophytic plant species, Carpobrotus rossii (Haw.) Schwantes (Aizoaceae) was investigated to assess its tolerance and phytoextraction potential of Cd, Zn, and the combination of Cd and Zn, when plants were grown in soils spiked with various concentrations of Cd (20–320 mg kg⁻¹Cd), Zn (150–2,400 mg kg⁻¹Zn) or Cd + Zn (20 + 150, 40 + 300, 80 + 600 mg kg⁻¹). The concentration of Cd in plant parts followed the order of roots > stems > leaves, resulting in Cd translocation factor (TF, concentration ratio of shoots to roots) less than one. In contrast, the concentration of Zn was in order of leaves > stems > roots, with a Zn TF greater than one. However, the amount of Cd and Zn were distributed more in leaves than in stems or roots, which was attributed to higher biomass of leaves than stems or roots. The critical value that causes 10 % shoot biomass reduction was 115 μg g⁻¹for Cd and 1,300 μg g⁻¹for Zn. The shoot Cd uptake per plant increased with increasing Cd addition while shoot Zn uptake peaked at 600 mg kg⁻¹Zn addition. The combined addition of Cd and Zn reduced biomass production more than Cd or Zn alone and significantly increased Cd concentration, but did not affect Zn concentration in plant parts. The results suggest that C. rossii is able to hyperaccumulate Cd and can be a promising candidate for phytoextraction of Cd from polluted soils.

The low bioavailability of Pb and low number of Pb-tolerant plant species represent an important limitation for Pb phytoextraction. It was recently suggested that halophyte plant species may be a promising material for this purpose, especially in polluted salt areas while Pb mobility may be improved by synthetic chelating agents. This study aims to evaluate Pb extraction by the halophyte Sesuvium portulacastrum in relation to the impact of EDTA application. Seedling were cultivated during 60 days on Pb artificially contaminated soil (200, 400, and 800 ppm Pb) in the presence or in the absence of EDTA (3 g kg⁻¹soil). Results showed that upon to 400 ppm, Pb had no impact on plant growth. However, exogenous Pb induce a decrease in shoot K⁺while it increased shoot Mg²⁺and had no impact on shoot Ca²⁺concentrations. Lead concentration in the shoots increased with increasing external Pb doses reaching 1,390 ppm in the presence of 800 ppm lead in soil. EDTA addition had no effect on plant growth but strongly increased Pb accumulation in the shoot which increased from 1,390 ppm in the absence of EDTA to 3,772 ppm in EDTA-amended plants exposed to 800 ppm exogenous Pb. Both Pb absorption and translocation from roots to shoots were significantly enhanced by EDTA application, leading to an increase in the total amounts of extracted Pb per plant. These data suggest that S. portulacastrum is very promising species for decontamination of Pb²⁺-contaminated soil and that its phytoextraction potential was significantly enhanced by addition of EDTA to the polluted soil.

Marine macroalgae have evolved a different mechanism to maintain physiological concentrations of essential metal ions and non-essential metals. The objective of the present work was to evaluate the antioxidant response and DNA damage of copper and cadmium ions in three halophytes, namely, Acanthophora spicifera, Chaetomorpha antennina, and Ulva reticulata. Accumulation of copper was significantly higher (P < 0.05) than that of cadmium. Biochemical responses showed that copper was considerably more toxic than cadmium (P < 0.05). Decreases in glutathione content and fluctuations of super oxide dismutase, catalase, and glutathione peroxidase activities were observed corresponding to time and concentration of exposure. Interestingly, it was also observed that antioxidant levels decreased as a result of metal accumulation, which may be due to free radicals generated by copper and cadmium in seaweeds. The present study also showed that copper and cadmium increased oxidative stress and induced antioxidant defense systems against reactive oxygen species. The order of toxicity for metals in the studied seaweeds was U. reticulata > A. spicifera > C. antennina. DNA damage index analysis supported that copper was significantly (P < 0.05) more toxic than cadmium. Bioaccumulation, biochemical responses, and DNA damage observed in the here analyzed marine macroalgae after exposure to selected metals indicate that these marine organisms represent useful bioindicators of marine pollution.