Helianthus annuus assessment for nickel phytoremediation

Heavy metals (HMs) are distributed in various forms within the soil, including dissolved in the soil solution, adsorbed on soil constituents, and associated with organic matter (Shuman, 1991). HMs pose serious environmental threats due to their persistence and toxicity (Gu et al., 2018; Wang et al., 2020). They accumulate in soil and organisms through natural processes and human activities like mining, pesticide use, inadequate waste management, and industrial practices contribute significantly. (Brodin et al., 2017; Ferrey et al., 2018). Therefore, it is important to develop remediation technologies for soils contaminated by heavy metals. Phytoremediation is a technique that utilizes plants to absorb, transfer, or transform pollutants and emerges as a green and effective method for environmental cleanup. It addresses soil, water, and sediment contamination caused by heavy metals, organic pollutants, and even radioactive elements. The process involves absorption, volatilization, degradation, and stabilization by plants to eliminate or immobilize pollutants, offering promise for environmental purification (Lin et al., 2021; Singh et al., 2016). This technique encompasses various approaches categorized into phytoextraction, phytostabilization, phytovolatilization, phytofiltration, and phytotransformation. Phytoextraction involves plants accumulating heavy metals in their shoots without altering soil properties, enabling the removal of pollutants from polluted environments. (Al-Baldawi et al., 2018). Several factors influence phytoremediation efficacy, including the choice of plant species, soil characteristics, rhizospheric microbial communities, climatic conditions, and heavy metal bioavailability. The bioavailability of heavy metals, affected by soil pH, moisture, organic matter, and oxygen levels, directly impacts phytoextraction efficiency. Heavy metals in soils are categorized into available, unavailable, and exchangeable fractions, with pH playing a crucial role in their dissolution. Alkaline pH reduces metal bioavailability due to low dissolution rates, highlighting the intricate interplay between soil chemistry and phytoremediation effectiveness (Ashraf et al., 2019; Javed et al., 2019; Wei et al., 2008). In this study, the evaluation of Helianthus annuus's potential in phytoremediation has been assessed, considering two polluted pots irrigated with 80 mgCu/L and 40 mgCu/L in a continuous irrigation rate of 1.644 mm/day for 12 weeks.The tolerance and phytoextraction capacity for nickel has been evaluated, and the overall phytoextraction potential has been evaluated considering bioaccumulation and translocation factors. From the results obtained, it can be stated that Helianthus annuus appears to be a good species for the remediation technology of phytoextraction in Apulian heavy metals polluted soils.