Features of bioaccumulation and translocation of heavy metals in the soil–plant system: factors and mechanisms

Abstract

Soil contamination by heavy metals represents one of the most persistent forms of agroecosystem degradation, since metals are not biodegradable and gradually accumulate in the soil profile, subsequently entering plants and the food chain. The aim of this review is to systematise recent findings on bioaccumulation and translocation of heavy metals in the soil–plant system and to assess the role of key physical-chemical and biological factors that regulate metal mobility. The objectives include analysing anthropogenic and natural inputs of metals into soils, examining their speciation and bioavailability, describing the molecular mechanisms of root uptake and xylem transport, and summarising quantitative indices of bioaccumulation and translocation. The methodology was based on a critical synthesis of scientific publications indexed in Scopus, Web of Science, PubMed and eLibrary, predominantly published between 2011 and 2025. The principal results demonstrate that the efficiency of accumulation and transport depends on metal type, soil pH, organic matter content, redox conditions of the rhizosphere, and the activity of specific transporter proteins of the HMA, NRAMP, ZIP, ABC and YSL families. Cadmium exhibits the highest bioaccumulation factor, while nickel shows the highest root-to-shoot mobility. The practical value of the review lies in generalising the principles of plant selection for phytoremediation of contaminated soils and ensuring the safety of agricultural production for human consumption