Groundwater resources of area of Abidjan are heavily impacted by nitrate pollution. A survey on 13 wells providing drinking water to the city was conducted in 2005, considering stable isotopes of the water molecule and of dissolved compounds (13C and 15N), and major and trace elements. Nitrogen isotopes allow defi nition of the origin of nitrate contamination, mainly from urban sewage, and the processes controlling its distribution. This information, coupled to hydrogeology and groundwater geochemistry highlights major changes in groundwater quality. Nitrate content is associated with increased acidity of poorly buffered solutions in a geochemically open system and therefore, is not affected by denitrifi cation. Dissolved inorganic carbon confirms an input from organic matter decomposition, related to both pollution and diagenesis. This geochemical evolution is observed in both Quaternary and Continental Terminal aquifers, and is independent of depth. Comparison with previous hydrochemical data suggests a rapid decline in groundwater quality.
Origin and effects of nitrogen pollution in groundwater traced by δ15N–NO3 AND δ18O–NO3: the case of Abidjan (Ivory Coast)
SACCHI, ELISA;
2007-01-01
Abstract
Groundwater resources of area of Abidjan are heavily impacted by nitrate pollution. A survey on 13 wells providing drinking water to the city was conducted in 2005, considering stable isotopes of the water molecule and of dissolved compounds (13C and 15N), and major and trace elements. Nitrogen isotopes allow defi nition of the origin of nitrate contamination, mainly from urban sewage, and the processes controlling its distribution. This information, coupled to hydrogeology and groundwater geochemistry highlights major changes in groundwater quality. Nitrate content is associated with increased acidity of poorly buffered solutions in a geochemically open system and therefore, is not affected by denitrifi cation. Dissolved inorganic carbon confirms an input from organic matter decomposition, related to both pollution and diagenesis. This geochemical evolution is observed in both Quaternary and Continental Terminal aquifers, and is independent of depth. Comparison with previous hydrochemical data suggests a rapid decline in groundwater quality.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
