Effect of soil amendments and extractant solutions on soil with high Hg concentration

摘要

The objective of this work was to evaluate the mercury mobilization in a soil, from Almaden mercury mining area, where EDTANas. NPK-fertilizer and organic matter amendment were added. The experimental work was divided in two parts. The first one consisted in applying EDTANa<,2> salt in concentrations 0.5mM and 0.05M, and, the second one consisted in applying NPK-fertilizer, a peat and a liquid organic amendment at different doses. The experimental work was carried out using glass columns filled with a fraction of the Ah and/or Bt horizons from an Almaden soil profile. Physic-chemical parameters as well as mercury content were determined in all the leacbate samples. Results obtained from EDTANa<,2> experimental work shows that the last leachate obtained from both fractions and with the two EDTA solutions presented a slight increase of mercury content with a maximum of 300μg·L<'-1> in the organic fraction. After the EDTA application, the soil impoverished due to the lost of macro and micronutrients, and heavy metals were mobilised. Also, EDTA (0.05M) mobilised Al, B, Ba, Ca, Cu, Fe, K, Mg, Pb, Sr and Zn, in one or two order of magnitude greater than EDTANA<,2> (0.5mM), depending on the element. And results obtained from fertilizer and organic amendments show that mercury content in all samples was under detection limit. It is according to the fact that mercury is mainly in a cinnabar form, which had a very low solubility. The addition of fertilizers and organic matter amend ment do not increase the mercury content in the leachates either in the soil solution.