Luis Recatalá

THE RELEVANCE AND CONSEQUENCES OF MEDITERRANEAN DESERTIFICATION INCLUDING SECURITY ASPECTS

33 paginas, 5 figuras, 4 tablas. Proceedings of the NATO Mediterranean Dialogue Workshop on Desertification in the Mediterranean Region. A Security Issue -- Part I. Introducction: Desertification in the Mediterranen Region: Linking environmental condition to security. Valencia, Spain 2-5 December 2003

Testing the validity of a Cd soil quality standard in representative Mediterranean agricultural soils under an accumulator crop

The validity of a quality standard for cadmium (Cd) in representative agricultural Mediterranean soils under an accumulator crop (Lactuca sativa L.) is evaluated in this work considering both its effect on the crop growth (biomass production) and the metal accumulation in the edible part of the plant. Four soils with different properties relevant to regulate the behaviour of heavy metals were selected from the Valencian Region, a representative area of the European Mediterranean Region. For all soils, the effective concentration of added Cd causing 50% inhibition (EC(50)) on the biomass production was much higher than the minimum legal concentration used to declare soils as contaminated by cadmium, i.e. 100 times the baseline value for Cd, in Spain (Spanish Royal Decree 9/2005). As expected, Cd toxicity in the crop was higher in the soils having less carbonate content. On the other hand, for all soils, from the second dose on, which represents 10-times the baseline value for Cd, the metal content in crops exceeded the maximum level established for leaf crops by the European legislation (Regulation EC no. 466/2001). Soil salinity and coarse textures make the accumulation of Cd in the edible part of the plant easier. Therefore, the legal baseline soil cadmium content established by the Spanish legislation seems not valid neither from the point of view of the effect on the crop growth nor from the point of view of the metal accumulation in the edible part of the plant. In order to realistically declare contaminated soils by heavy metals, soil quality standards should be proposed taking into account the soil properties. Further research in other agricultural areas of the region would improve the basis for proposing adequate soil quality standards for heavy metals as highlighted by the European Thematic Strategy for Soil Protection.

Trace Element Analysis via Open‐Vessel or Microwave‐Assisted Digestion in Calcareous Mediterranean Soils

Abstract Different digestion methods can be applied for analyzing trace elements in soils. Selection of the most useful and convenient method is critical for the adequate determination of their concentrations in each type of soil to appropriately detect potential environmental pollution. Open‐vessel digestion using a digester block (method 1) and microwave‐assisted digestion (method 2) were compared using a certified reference material (CRM) with similar properties and characteristics to calcareous Mediterranean soils. Both methods were contrasted in terms of accuracy by calculating the recovery of cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in the CRM and precision of replicate analysis through the relative standard deviation (RSD). Recoveries from the digester block method were slightly higher than recoveries from microwave digestion because the use of perchloric acid (HClO4), whereas RSD values for microwave digestion were generally lower but with higher measured precision than values obtained by open‐vessel digestion. The digestion methods were compared for analyzing trace elements in calcareous agricultural soils devoted to vegetable crops in the Alicante province (southeast Spain), as a representative area of the European Mediterranean region. Results of the paired‐sample t‐test showed significant differences between both methods for Co, Cr, Cu, and Pb in calcareous Mediterranean soils, whereas regression analysis indicated a good correlation between both methods for Cu, Ni, Pb, and Zn. Consequently, the choice of the digestion method is more relevant for minor elements such as Co and Cr. Microwave‐assisted digestion seems to be the best option to determine most of the trace elements in calcareous Mediterranean soils, because closed‐vessel digestion exhibited lower variability according to the RSD values obtained in the study area, particularly for Co and Cr. Trace element concentrations were in agreement with background levels, except for Cu and Pb in some soils, which seem to be related to anthropic activities.