1. The soils on the flat parts are alluvial deposits with sandy clay and terra rosa.

2. The study area, which extends approximately 1036 km2, is mainly composed of quaternary alluvial deposits (clay, sandy clay, gravels, limestone).

3. The region forms part of the old Iberian plateau, with sandy clay soils of the lacustrine pleistocene era and modern alluvial soils (lowlands).

4. Holden and Hodgetts (1991) have also indicated that, Colluvium may comprise firm to stiff sandy clay with pockets of plastic clay and gravel to boulder-sized angular fragments of rock

5. The results indicated that citric acid was a more consistent leaching agent compared to tartaric acid and EDTA, which were efficient mainly in treating the clay loam and the sandy clay loam, respectively.

6. The objective was to determine the heavy metal desorption rates for three heavily contaminated soils (clay loam, loam, and sandy clay loam), treated under optimum conditions with either citric acid, tartaric acid, or EDTA for comparison.

7. Sand, silty sand, Clayey sand, silty gravel and Clayey gravel (SW, SP, SM, SC, GM and GC) 2,000 Clay, sandy clay, silty clay, Clayey silt, silt and sandy silt (CI, ML, MH, and CH) 1,500b For S1: 1 pound per square foot = 0.0479 kN/m2 a