Dynamics of the toxic cyanobacterial microcystin-leucine-arginine peptide in agricultural soil

Sylvain Corbel (1) , Noureddine Bouaïcha (2) , Christian Mougin (1)

1 PESSAC - Physicochimie et Ecotoxicologie des SolS d'Agrosystèmes Contaminés
2 ESE - Ecologie Systématique et Evolution

Microcystin-leucine-arginine (MC-LR) is a cyclic heptapeptide hepatotoxin produced by cyanobacteria such as Microcystis aeruginosa. Being highly toxic, this compound is a threat to water quality, agriculture, and human and animal health. In particular, MC-LR has been frequently detected at high concentrations in surface waters. So far, the fate of MC-LR in soils is unknown. Here, we studied degradation and soil–plant transfer of 14C-radiolabelled MC-LR in an artificial system of agricultural soil and tomato seedlings. 14C-MC-LR was dissolved in water and applied by soil irrigation, one or two times with an interval of 28 days. Results show that the 14CO2 from the degradation of 14C-MC-LR amounted to 11 % of total 14C initial input; 74–80 % of 14C-MC-LR occurred in extractible fractions analysed by HPLC. Less than 14 % of 14C-MC-LR was adsorbed on soil particles. Overall, our findings evidence for the first time a high risk of toxin leaching from the soil toward groundwater.

Mots clés: Cyanotoxins; Microcystin-LR; Soil; Persistence; Mineralization; Plant transfer

Domaines: Sciences du Vivant [q-bio]

Sylvain Corbel, Noureddine Bouaïcha, Christian Mougin. Dynamics of the toxic cyanobacterial microcystin-leucine-arginine peptide in agricultural soil. Environmental Chemistry Letters, 2014, 12 (4), pp.535-541. ⟨10.1007/s10311-014-0482-2⟩. ⟨hal-01693174⟩