Growth parameters influencing uptake of chlordecone by Miscanthus species

Because of its high persistence in soils, t_1/2=30years, chlordecone (CLD) was classified as a persistent organic pollutant (POP) by the Stockholm Convention in 2009.The distribution of CLD over time has been heterogeneous, ranging from banana plantations to watersheds, and contaminating all environmental compartments. The aims of this study were to (i) evaluate the potential of Miscanthus species to extract chlordecone from contaminated soils, (ii) identify the growth parameters that influence the transfer of CLD from the soil to aboveground plant parts. CLD uptake was investigated in two species of Miscanthus, C4 plants adapted to tropical climates. M. sinensis and M.×giganteus were transplanted in a soil spiked with [¹⁴C]CLD at environmental concentrations (1mgkg^-1) under controlled conditions. Root-shoot transfer of CLD was compared in the two species after two growing periods (2 then 6months) after transplantation. CLD was found in all plant organs, roots, rhizomes, stems, leaves, and even flower spikes. The highest concentration of CLD was in the roots, 5398±1636 (M.×giganteus) and 14842±3210ngg^-1 DW (M. sinensis), whereas the concentration in shoots was lower, 152±28 (M.×giganteus) and 266±70ngg^-1 DW (M. sinensis) in soil contaminated at 1mgkg^-1. CLD translocation led to an acropetal gradient from the bottom to the top of the plants. CLD concentrations were also monitored over two complete growing periods (10months) in M. sinensis grown in 8.05mgkg^-1 CLD contaminated soils. Concentrations decreased in M. sinensis shoots after the second growth period due to the increase in organic matters in the vicinity of the roots. Results showed that, owing to their respective biomass production, the two species were equally efficient at phytoextraction of CLD.