Water Research 37 (2003) 928–938
Evolution over time of the agricultural pollution of waters in
an area of Salamanca andZamora (Spain)
Rita Carabias-Mart
!
ınez
a,
*, Encarnaci
!
on Rodr
!
ıguez-Gonzalo
a
,
M. Esther Fern
!
andez-Laespada
a
, Lorenzo Calvo-Seronero
a
,
Francisco Javier S
!
anchez-San Rom
!
an
b
a
Departamento de Qu
!
ımica Anal
!
ıtica, Nutrici
!
on y Bromatolog
!
ıa, Facultad de Qu
!
ımica, Universidad de Salamanca,
37008 Salamanca, Spain
b
Departamento de Geolog
!
ıa, Facultad de Geolog
!
ıa, Universidad de Salamanca, 37008 Salamanca, Spain
Received18 January 2002; receivedin revisedform 16 July 2002; accepted19 July 2002
Abstract
A survey of the herbicides present in surface and groundwaters was conducted in 1999 in an area of the provinces of
Salamanca andZamora (Central-Western Spain) to assess the degree of pollution of the agricultural landandseasonal
changes in the presence of herbicide residues. Ten sites were sampled and screened for 17 herbicides commonly used in
the area; the compounds were ureas, triazines, amides, and others. A previously optimised method involving solid-
phase extraction with polymeric cartridges, followed by HPLC with diode array detection, was used to monitor the
herbicides. Of the 17 compounds examined, eight were found: chlorotoluron (41% of total detections), terbutryn
(21%), atrazine (14%), linuron (7%), isoproturon andmetolachlor (5.5% each), lenacil (4%) andmetamitron (2%). Of
the detections, 66% corresponded to river water samples (three sites). The herbicides found in groundwaters (seven
sites) were: chlorotoluron, atrazine, terbutryn, linuron, andisoproturon, all of which are classifiedas probable or
transient leachers in Europe. The temporal evolution of the herbicide content in river waters shows that the observed
pollution is a function of time andis relatedto the application anduse of the herbicides. By contrast, the pollution
found in groundwaters was lower than that seen in surface waters, except that due to chlorotoluron, which,
additionally, remained almost constant throughout the study period.
r 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Herbicides; Temporal evolution; Surface water; Groundwater; Salamanca; Zamora; Spain
1. Introduction
The pollution of water by pesticides is a topic of
considerable environmental interest owing to the in-
creasing number of pesticide detections in water and the
establishment of strict directives in North America and
Europe aimedat the protection of water sources usedfor
the production of drinking water.
Most of the non-point source pollution of groundand
surface waters by pesticides is of agricultural origin, such
that is it intimately linkedto the agricultural activities
carried out in the corresponding area during the
different seasons of the year (fertiliser use and pre-and
post-sowing herbicide treatment, etc). The content in
pesticides also depends on their physico-chemical
properties, such as water solubility, the capacity to be
retainedby the soil materials andtheir persistence in
them, andother factors such as the topography of the
terrain andthe frequency of rainfall.
Over the last decades, monitoring studies in aquatic
systems have been conducted to assess pollution with
pesticides. In the US, intensive data collection has been
carriedout in programs such as the NAWQA—
National Water Quality Assessment [1,2] or the
*Corresponding author. Tel.: +34-923-294483; fax: +34-
923-29-4483.
E-mail address: rcm@gugu.usal.es (R. Carabias-Mart
!
ınez).
0043-1354/03/$ - see front matter r 2002 Elsevier Science Ltd. All rights reserved.
PII: S 0043-1354(02)00366-4