Paddy soils undergo wet-dry cycles that greatly influence the behaviour and availability of nutrients, but also of potentially toxic elements (PTEs). This study assessed the quality of paddy soils (actively cultivated and abandoned) and rice (white, brown, and wild) produced in the Baixo Vouga Lagunar (BVL) region, central-north Portugal. Surface soils were analysed for physicochemical parameters and chemical compositions, alongside sequential selective chemical extraction to evaluate metal(loid) availability. Chemical analyses were also performed on interstitial- and irrigation waters, and rice grains. The BVL soils are very strongly to moderately acidic (pH = 4.4-5.8), with organic matter contents reaching up to 34%, and exhibit a wide range of electrical conductivity values. Abandoned rice fields generally show higher values of these parameters and evidence of saline water intrusion. Several sites showed As, Cu, Pb, and U concentrations exceeding Portuguese thresholds for agricultural soils. While Cu levels were similar in both cultivated and abandoned fields, the latter had higher contents of As, Pb, and U. A geogenic origin is envisaged for these metal(loid)s, though anthropogenic contributions cannot be excluded. Sequential selective chemical extraction showed that Pb and U are strongly associated with available fractions, whereas amorphous Fe-oxyhydroxides primarily support As and Cu. Nevertheless, porewaters and irrigation waters showed low concentrations of these PTEs, suggesting minimal mobilisation to water. Furthermore, translocation to rice grains was low, with concentrations well below European Commission limits, indicating that elevated PTEs in soils do not necessarily lead to toxic levels in rice, providing reassurance regarding food safety.

The Puna region is distinguished by its extreme environmental conditions and highly valuable mining resources. However, the unregulated management of mine tailings poses a significant threat to the ecological integrity of this region. This study assesses the environmental impacts of mine tailings at La Concordia mine (Salta province, Argentina) and examines the physiological and biochemical adaptations of Parastrephia quadrangularis (Meyen) Cabrera that enable its survival under this extreme conditions. Our findings reveal that prolonged weathering of mine tailings results in the generation of acid mine drainage characterized by low pH levels (< 3.5) and elevated concentrations of As, Fe, Cu, Pb, and Zn. These levels exceed drinking water standards by 5-10 times for As, 6-13 times for Zn, 80-120 times for Pb, 20-380 times for Fe, and 4-10 times for Cu. Soil analyses highlight low pH, high salinity, and elevated concentrations of Zn (310 mg kg(-1)), Pb (153 mg kg(-1)), and Cu (128 mg kg(-1)). Despite these harsh environmental conditions, 7 plant species where identified, with Parastrephia quadrangularis being the only species present at the most polluted site. This species exhibits high heavy metal bioaccumulation and robust tolerance mechanisms against heavy metal-induced oxidative damage, as evidenced by stable total chlorophylls and malondialdehyde content, and increased levels of carotenoids, proline, and phenolic compounds. These findings emphasize Parastrephia quadrangularis as a promising candidate for revegetation and phytostabilization for sustainable mine closure programs in La Puna region.