Spatial and temporal variation in precipitation isotopes at 2 locations
in southwest Spain
Abstract
The δ2H and δ18O composition of 77 precipitation samples collected
between January 2014 and April 2019 from two sites across the
Guadalquivir Basin, SW Spain, were analyzed. Sampling was performed
within intervals of at least 14 days basis if rain occurred but
frequently intervals were longer according to the rainfall incidence.
Precipitation weighted averages and local meteoric water lines are
presented for use in hydrological applications. δ2H and δ18O values show
a remarkably high variability attributed to the influence of Atlantic
and Mediterranean vapor sources. Precipitation weighted average d-excess
values of 12.5-13 ‰ confirm the Western Mediterranean influence.
Temperature and amount effects were found to be weak but significant
influence of secondary evaporation for single rainfall events during
summer was identified by reduced d-excess values and enriched isotopic
signatures plotting close or below the Global Meteoric Water line
(GMWL). Isotopic signatures of both sites are very similar in general
and any temperature related urban effects of Seville city compared to
the rural site Doñana could not be identified with the present data