Publications des scientifiques de l'IRD

Crampon M., Copard Y., Favreau Guillaume, Raux J., Merlet-Machour N., Le Coz M., Ibrahim M., Peulon-Agasse V., Portet-Koltalo F. (2014). Occurrence of 1,1 '-dimethyl-4,4 '-bipyridinium (Paraquat) in irrigated soil of the Lake Chad Basin, Niger. Environmental Science and Pollution Research, 21 (18), p. 10601-10613. ISSN 0944-1344.

Titre du document
Occurrence of 1,1 '-dimethyl-4,4 '-bipyridinium (Paraquat) in irrigated soil of the Lake Chad Basin, Niger
Année de publication
2014
Type de document
Article référencé dans le Web of Science WOS:000342132500005
Auteurs
Crampon M., Copard Y., Favreau Guillaume, Raux J., Merlet-Machour N., Le Coz M., Ibrahim M., Peulon-Agasse V., Portet-Koltalo F.
Source
Environmental Science and Pollution Research, 2014, 21 (18), p. 10601-10613 ISSN 0944-1344
Increased use of agrochemical products to improve yields for irrigated crops in sub-Saharan Africa has been accompanied by a significant increase in the risk of environmental contamination. Detailed examples of the fate of pesticides after initial spreading on crop fields are scarce in tropical regions, where safe practices and related health risks are poorly understood by smallholder farmers. In the semi-arid environment of the Lake Chad Basin, SE Niger, both intrinsic properties of pesticides and extrinsic factors such as soil and climate helped to characterize processes leading to an accumulation of pesticides in soils. Analysis by HPLC-UV of a 6 m deep soil profile showed the presence of Paraquat at concentrations from 953 +/- 102 mu g kg(-1) to 3083 +/- 175 mu g kg(-1) at depths between 0.80 and 2.75 m below the land surface. Soil analysis revealed that up to approximately 15 % of the total soil matrix consists of smectites, a clay mineral capable of retaining cationic pesticides such as Paraquat, and a very low content of organic matter (<0.15 wt.% TOC). Paraquat could be stored and not bioavailable in a clayey barrier at approximately 2-m depth and therefore does not represent an immediate risk for populations or environment in this form. However, if the Paraquat application rate remains constant, the clayey barrier could reach a saturation limit within 150-200 years and 180-220 years if we consider a DT50 in soil of similar to 1,000 days (FAO). Consequently, it could lead to a deeper infiltration and so a pollution of groundwater. Such a scenario can represent a health risk for drinking water and for the Lake Chad, which is a major resource for this densely populated region of semi-arid Africa. Further analyses should focus on deeper layers and groundwater Paraquat contents to validate or invalidate the hypothesis of storage in this clay-rich layer.
Plan de classement
Pollution [038] ; Hydrologie [062] ; Pédologie [068]
Description Géographique
NIGER ; TCHAD LAC
Localisation
Fonds IRD [F B010062571]
Identifiant IRD
fdi:010062571
Contact