Metal (Al, Mn, Pb and Zn) soils extractable reagents for available fraction assessment: Comparison using plants, and dry and moist soils from the Braçal abandoned lead mine area, Portugal

• Published in: Journal of geochemical exploration Vol. 113; pp. 45 - 55
• Main Authors: Anjos, Carla, Magalhães, M. Clara F., Abreu, Maria Manuela
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-02-2012
• Subjects: Abandoned lead mine; Acacia; Available extraction methods; Cistus; Erica arborea; Eucalyptus globulus; Metals phytoavailability; Pinus pinaster; Quercus robur; Spontaneous shrubs; Ulex minor; ANE, Portugal; Portugal; Metals phytoavailability; Available extraction methods; Abandoned lead mine; Spontaneous shrubs
• ISSN: 0375-6742; 1879-1689
• DOI: 10.1016/j.gexplo.2011.07.004

Eleven composite soil samples, developed either on schist materials or fine heterogeneous waste materials and coarse metallurgical slags, were collected in the Braçal (Portugal) abandoned lead mine. Plants growing in each sampling area were identified. A total of 49 plant samples of eight species –Acacia dealbata Link, Acacia melanoxilon R. Br., Cistus inflatus Pourr. ex Demoly, Erica arborea L., Eucalyptus globulus Labill., Pinus pinaster Aiton, Quercus robur L., and Ulex minor Roth – were collected. This study intends to evaluate the available fraction of aluminium, lead, manganese, and zinc in the soils using dry and moist samples in contact with five extractant solutions, degasified distilled water, and calcium chloride, calcium nitrate, ammonium acetate and DTPA aqueous solutions, and to compare together these results with the total elemental amounts in the aboveground part of the plant species. The available fraction is higher in moist than in the dry soil samples. The correlations between the soil available fraction of the elements and its concentration in the plants suggest that DTPA is not the best extractant for lead bioavailability evaluation. Variable results were observed for the bioavailable fraction of the elements evaluation suggesting that, in multielemental contaminated soils, calcium chloride seems to be a good extractant medium, once it correlates with the higher number of plant species.
► The available fractions of Al, Pb, Mn, and Zn are higher in moist than in the dry soil samples. ► CaCl2 is a good extractant medium for the bioavailable fraction of Al, Pb, Mn, and Zn. ► DTPA does not correlate with the available fraction of Al, Pb, Mn, and Zn for plants. ► Cistus inflatus and Erica arborea present high lead concentrations in shoots.