Mercury and Vitis vinifera L. relationship in the Almadén mining district

Abstract

Almadén (Ciudad Real province, SW of Castilla-La Mancha, South-Central Spain) is the center of the World’s largest mercury (Hg) mining district. Along with, Castilla-La Mancha region is an important viticulture region, with 500 000 hectares occupied by vineyards. During late years, the possibility of contamination by Hg in many alimentary products, including vine, is concerning our society. The aim of the present work is to summarize the different field and experimental works carried out by our team, in order to assess the possible uptake of Hg by the vine. Our first study surveyed Hg concentrations in soil and vine leaves in a transect trough the main contamination sources. Experimental work included experiences carried out in controlled conditions, including continuous monitoring of atmospheric Hg, and/or watering with solutions with high Hg concentrations. Field work showed significant correlation between Hg content in soils and leaves (R=0.934); total Hg contents in the soils ranged between 2376.67 and 0.04 mg/kg. Mercury contents measured in leaves ranged between 5.14 mg/kg and 0.03 mg/kg. This suggests a soil uptake of the mercury. However, in the experimental work we could assess in detail the possibilities of radicular and atmospheric uptake, and the results indicate that atmospheric uptake is much more important for the Hg leaf content than the radicular pathway. On these bases, the transference from soil to leaves should be related with the Hg emissions from polluted soils, and uptake directly of this Hg by the leaves across stomata.