An integrated geochemical and mineralogical investigation on soil-plant system of Pinus halepensis pioneer tree growing on heavy metal polluted mine tailing

The plant species Pinus halepensis grows spontaneously on heavily polluted mine tailings dumps of Campo Pisano (Sardinia, southwestern Italy). The area is characterized mainly by Zn, Pb, and Cd. Sampling campaign was done, related to soils and plant materials (roots, barks, wood, and needles), aimed at evaluating the main mineralogical characteristics, metal content, plant accumulation, and translocation behavior. The polluted substrates were composed of pyrite, dolomite, calcite, quartz, gypsum, and barite with iron sulfate, and iron oxide. Zn ore minerals (smithsonite) and muscovite detected mostly in the deeper soil layers. Zn was the most abundant metal in the substrate as well as plant tissues. Roots accumulated high metal concentrations (664.65-2710 Zn, 58.39-735.88 Pb, and 4.86-11.02 mg kg(-1) Cd) reflecting high metal contamination in soil. The biological accumulation and translocation values were reported below one for all plant tissues. Pb, Zn and Cd Translocation Factor (TF) in needles ranged 0.03-0.32, 0.03-0.19, 0.04-0.14. Biological Concentration Factor (BCF) estimated up to 0.17, 0.18, and 0.19, respectively. The results indicate that P. halepensis is an excluder, tolerates high Zn, Pb, and Cd concentrations, restricts their accumulation and translocation to the aerial parts and may be applied for long-term phytostabilization and revegetation processes in abandoned mine tailing sites.

Automated summary

This study investigated the adaptation of Pinus halepensis to heavy metal pollution in Campo Pisano, southwestern Italy. The results showed that P. halepensis can grow in contaminated soils, but its roots have a high metal accumulation capacity and can restrict metal translocation to the aboveground parts.