Pinus halepensis in Contaminated Mining Sites: Study of the Transfer of Metals in the Plant–Soil System Using the BCR Procedure

Abstract

The study aimed at evaluating the geochemical fractions of Zn, Pb, Cd and their bioavailability in soil in-depth and around the root of Pinus halepensis grown on heavily contaminated mine tailing in south-western Sardinia, Italy. The contaminated substrates were partly investigated in a previous study and are composed of pyrite, dolomite, calcite, quartz, gypsum, barite, iron-sulfate and iron-oxide. The geochemical fractions and bioavailability of Zn, Pb and Cd were measured through the BCR extractions method. Cadmium in the superficial contaminated substrates was mainly found in the exchangeable BCR fraction. Zinc and lead were often found in the residual BCR fraction. PCA confirmed that the uppermost alkaline-calcareous layers of mine waste were different with respect to the deeper acidic layers. We demonstrated that Pb and Zn were less present in the exchangeable form around the roots of P. halepensis and in soil depth. This can be due to uptake or other beneficial effect of rhizospheres interaction processes. Further studies will shed light to confirm if P. halepensis is a good candidate to apply phytostabilization in mine tailing.

Using Mediterranean Native Plants for the Phytoremediation of Mining Sites: An Overview of the Past and Present, and Perspectives for the Future

“…Considering wood taxa, Pinus halepensis (Pinaceae) is a widespread Mediterranean evergreen tree growing in neutral or slightly alkaline and low fertile soil. It is also able to grow on multi-metal(loid)-polluted mine sites [188][189][190][191][192][193]. In the studies of Kharazian et al [188,189], P. halepensis behaves as an excluder species, tolerating high Zn, Pb, and Cd concentrations and restricting their presence in its hypogeal tissues (BCF and TF < 1, see Table A1).…”

“…It is also able to grow on multi-metal(loid)-polluted mine sites [188][189][190][191][192][193]. In the studies of Kharazian et al [188,189], P. halepensis behaves as an excluder species, tolerating high Zn, Pb, and Cd concentrations and restricting their presence in its hypogeal tissues (BCF and TF < 1, see Table A1).…”

Helichrysum microphyllum subsp. tyrrhenicum, Its Root-Associated Microorganisms, and Wood Chips Represent an Integrated Green Technology for the Remediation of Petroleum Hydrocarbon-Contaminated Soils

“…bicolor (Sm.) Greuter on metal(loid) contaminations [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. For the reasons mentioned above, Helichrysum microphyllum subsp.…”

Editorial for the Special Issue “Phytotoxicity of Heavy Metals in Contaminated Soils”

“…The fractionation of heavy metals in the soil is directly influenced by soil properties, conditioning their solubility, mobility and bioavailability in the soil and ultimately their toxicity. Kharazian and co-authors [ 4 ] used the European Community Bureau of Reference (BCR) three-step sequential extraction method to identify the fractionation of heavy metals (Zn, Cd and Pb) in soils with a P. halepensis vegetation cover from an old mine located in the Metalliferous Ring of the Sulcis–Iglesiente mining district (Sardinia, Italy). The relationship between soil properties, metal fractionation and metal concentration in the plant allowed for the evaluation of the bioavailability of metals, showing that Cd was more available in pine trees while Zn and Pb, which are mainly associated with the BCR residual fraction, showed a low availability and bioaccumulation in pine trees.…”