Metals and metalloid bioconcentrations in the tissues of Typha latifolia grown in the four interconnected ponds of a domestic landfill site

The uptake of metals in roots and their transfer to rhizomes and above-ground plant parts（stems, leaves） of cattails（Typha latifolia L.） were studied in leachates from a domestic landfill site（Etueffont, France） and treated in a natural lagooning system. Plant parts and corresponding water and sediment samples were taken at the inflow and outflow points of the four ponds at the beginning and at the end of the growing season. Concentrations of As, Cd, Cr, Cu, Fe, Mn, Ni and Zn in the different compartments were estimated and their removal efficiency assessed, reaching more than 90% for Fe, Mn and Ni in spring and fall as well in the water compartment. The above-and below-ground cattail biomass varied from 0.21 to 0.85, and 0.34 to 1.24 kg dry weight/m^2, respectively, the highest values being recorded in the fourth pond in spring 2011. The root system was the first site of accumulation before the rhizome, stem and leaves. The highest metal concentration was observed in roots from cattails growing at the inflow of the system＇s first pond. The trend in the average trace element concentrations in the cattail plant organs can generally be expressed as： Fe 〉 Mn 〉 As 〉 Zn 〉 Cr 〉 Cu 〉 Ni 〉 Cd for both spring and fall. While T. latifolia removes trace elements efficiently from landfill leachates, attention should also be paid to the negative effects of these elements on plant growth.

Spring phytoplankton variability along a south coast of Sfax at the water-sediment interface(Tunisia,Eastern Mediterranean Sea)

Objective:To compare the composition of the phytoplankton classes during the two spring studies,to study whether the spatial distribution of the phytoplankton is stable or not between spring 2010 and spring 2011 and to estimate the abiotic factor that mostly affects the structure and the richness of phytoplankton.Methods:Phytoplankton sub-samples were counted under an inverted microscope using the Utermöhl method.Phytoplankton identification was made from morphological criteria after consulting various keys.Results:Results showed a significant difference from spring 2010 to spring 2011 regarding nitrate/phosphate ratio,with high value in spring 2010(30.19±25.70).Relatively low nitrate/phosphate ratio(1.13±0.53)during spring 2011 might result from phosphogypsum.Phytoplankton was characterised by the proliferation of Bacillariophyceae(46%–78%of the total microphytoplankton)and by the large number of Euglenophyceae.Thirty two Bacillariophyceae species were identified at every station,represented essentially by Amphora sp.,Navicula sp.,Coscinodiscus sp.and Grammatophora sp.The results advise that Bacillariophyceae are usually adapted to particular ecological environment.Conclusions:This study shows that hydrological conditions in the south coast of Sfax present a high spatial and seasonal variability.The phytoplankton community distribution showed clear variations along the coastal stations during a spring cruises conducted in May 2010 and May 2011.The phytoplankton community found along the coast was dominated by opportunistic Bacillariophyceae species.