2.1. Study area
The study area includes the Guadiamar Green Corridor (GGC), affected by
the toxic spill from the Aznalcóllar mine (Seville, Spain), this area is
characterized by a smooth topography associated with the Guadiamar river
basin (Figure 1). The affected area was around 4600 ha and was
characterized by its agricultural use before the accident, where the
main soil groups found were Fluvisols and Regosols, according to WRB
(IUSS, 2015) or Entisols, according to
SSS (2014). In all cases, these are soils with
poorly developed profiles, relatively high fertility and anthropogenic
influence, with grazing and fruit and cereal crops predominating
(Cabrera et al., 1999,
Martín Peinado, 200l). The climate of
the area is conditioned by its location within the Guadalquivir
Depression and the influence of the Mediterranean climate. The annual
average temperature is 17.7° C (with average temperatures in the coldest
months higher than 10°C) and the average annual precipitation is 612.7
mm. The annual insolation is greater than 2800 hours
year-1, so the potential evapotranspiration values are
higher than those of precipitation in more than 6 months a year
(Martín Peinado, 200l). According to
the classification of Rivas Martínez (1987),
the climate is Mediterranean with drought in the summer season.
Regarding the edaphic profile, the temperature regime is Thermic and the
humidity regime is Xeric (USDA, 1999).