『Abstract
The alluvial aquifer of the Alto Guadalquivir River is one of
the most important shallow aquifers in Jaen（eの頭に´）,
Spain. It is located in the central-eastern part of the province,
and its groundwater resources are used mainly for crop irrigation
in an agriculture-dominated area. Hydrochemical and water-quality
data obtained through a 2-year sampling (2004-2006) and analysis
program indicate that nitrate pollution is a serious problem affecting
groundwater due to the use of nitrogen (N)-fertilizers in agriculture.
During the study, 231 water samples were collected from wells
and springs to determine water chemistry and the extent of nitrate
pollution. The concentration of nitrate in groundwater ranged
from 1.25 to 320.88 mg/l. Considerable seasonal fluctuations in
groundwater quality were observed as a consequence of agricultural
practices and other factors such as annual rainfall distribution
and the Guadalquivir River flow regime. The chemical composition
of the water is not only influenced by agricultural practices,
but also by interaction with the alluvial sediments. The dissolution
of evaporites accounts for part of the Na+, K+,
Cl-, SO42-, Mg2+,
and Ca2+, but other processes, such as calcite precipitation
and dedolomitization, also contribute to groundwater chemistry.
Keywords: Nitrate pollution; Alluvial aquifer; Guadalquivir River;
Southern Spain; Hydrochemistry』
Introduction
Geological and hydrogeological framework
Sampling and analytical procedures
Results and discussion
Guadalquivir River
Groundwater
Impact of agriculture on groundwater
Seasonal changes in groundwater quality
Hydrochemical analysis
Conclusions
Acknowledgements
References