Exploring the potential of green-synthesized hydroxyapatite for cadmium remediation in paddy soils

The Cadmium contamination in paddy soils significantly threatens soil health and food safety. This study addresses the urgent need for cost-effective and sustainable remediation methods by evaluating the efficacy of green-synthesized hydroxyapatite (GHAP) in immobilizing Cd in paddy soils. The investigation focused on the effects of applying GHAP, commercial hydroxyapatite (CHAP), and pure hydroxyapatite (CK) on soil physicochemical properties, as well as Cd mobility and transfer within the soil-rice system. Our results demonstrate that GHAP significantly enhanced Cd adsorption and reduced bioavailable Cd content by up to 48.47 %, with the most effective results observed at a 1 % amendment rate. Additionally, GHAP application elevated soil pH and available phosphorus, contributing to better soil structure, fertility, and rice growth. Correlation and principal component analyses revealed that the GHAP dosage was a key factor in modifying soil properties and influencing Cd speciation and mobility. These findings suggest that a 1 % GHAP dosage achieves an optimal balance between improving soil quality and effectively passivating Cd, making GHAP a promising amendment for remediating Cd-contaminated soils.