Are the soils and vegetation of a forest close to tailings ponds affected by metals and arsenic?

Abstract

This study aimed to determine the transfer of metals (Cd, Pb and Zn) and As to a Mediterranean forest close to five tailings ponds in Cartagena-La Union mining district (SE Spain). In addition, the effect of the rhizosphere of two native plant species, Olea europaea (OE) and Pistacia lentiscus (PL), on soil properties and chemical speciation of metal(oid)s was evaluated. Results showed there was no influence of the rhizosphere in the total concentration of metal(loid)s in soil, decreasing as Pb [ Zn [ As [ Cd. Chemical partitioning revealed that only Cd and As can be considered hazardous, with a high percentage of these elements in the soil-labile fractions (20-40%). The accumulation in vegetal tissues was only high for Pb in PL roots, which makes it a suitable species for phytostabilization. Additionally, translocation factors showed transfer of Pb and Zn in OE, and Zn in PL to aerial parts, although no toxicity evidences for plants or animals were found. Finally, soil properties affected metal(loid)s accumulation in plants. The OE species was related to soil-labile metal(loid) fractions and pH, total N, organic carbon and silt content. The PL species were associated with immobilized metal(loid) fractions, sand content, electrical conductivity and total concentrations of As, Cd and Pb. Hence, mining activity has affected native adjacent soils, with accumulation of metals in plant species, although translocation was low, likely due to physiological strategies of the studied species to protect themselves against hazardous elements, and to the high soil pH, which limits metals' mobility.

Phytoremediation Potential of Native Plant Species in Mine Soils Polluted by Metal(loid)s and Rare Earth Elements

“…Sahoo et al [ 55 ], by the review of a total of 117 relevant reports from 19 different countries such as India, Iran, Slovakia, Brazil, China, and Morocco, reported that in soil plus overburden samples taken near mining sites, maximum CF values for Fe, Zn, Cd, Pb, and As were 10.5, 28.8, 320, 34, 754, respectively. Martinez-Carlos et al [ 21 ] reported that As, Pb, Cd, and Zn exceed more than 10, 600, 40, and 80-fold the background level for natural soils in the study area located in the Cartagena-La Union mining district, Murcia Region (SE Spain), near the tailings ponds with a high concentration of Pb, Zn, Fe, Mn, or As.…”

“…Additionally, plants used for phytoremediation need to effectively tolerate high concentrations of metal(loid)s, grow rapidly, and their root systems must be vigorous and show proper adaptability against a specific area [ 16 ]. Native plants, which can be found in wide geographical locations, are of particular interest in this perspective, since these spontaneous plant species are genetically adapted to the contaminant and, as such, can remove or retain it, reducing its toxicity in soil [ 15 , 21 ]. They could belong to a group known as hyperaccumulators, which can tolerate, absorb, accumulate, and translocate high levels of metal(loid)s, or excluder plants that can maintain relatively low levels in their shoot while still containing large amounts of metal(loid)s in their roots [ 22 ].…”

Use of aided phytostabilization facilitate the production of aromatic plants in mining wastes as an environmental and socieconomic rehabilitation strategy

“…En general, una de las características de los depósitos mineros localizados en el Distrito Minero de Cartagena-La Unión es la acumulación de concentraciones elevadas de metal(oide)s (Azizi et al, 2023;Martínez-Carlos et al, 2022;Shahrokh et al, 2023b), Concretamente, los metal(oide)s que presentaron mayor concentración en el conjunto de las parcelas analizadas en este estudio fueron el Zn y el Pb, seguidos de As y Cd (Figuras 4.3.1. y 4.3.2).…”

“…Hay que destacar que, aunque los NGR utilizados en este estudio son de uso general y excluyen los suelos mineros, la comparación con los mismos es de utilidad para estimar el grado de enriquecimiento en metales que sufren estos suelos respecto de los naturales no mineros próximos a la zona de estudio. Concretamente, algunos estudios realizados por otros investigadores en la Sierra Minera de Cartagena-La Unión corroboran el importante enriquecimiento en metal/oides que sufren estos suelos (Gabarrón et al, 2018;Khademi et al, 2018;Martínez-Carlos et al, 2022).…”

“…• Beltrá, J. C., Gabarrón, M., Faz, Á., Zornoza, R., Acosta, J. A., & Martínez-Martínez, S. (2022) Anexo 2.…”