Identifying the functional groups and the influence of synthetic chelators on Cd availability and microbial biomass...

Synthetic chelators play an important role in boosting the microbial biomass carbon (MBC), dissolved organic carbon (DOC), and heavy metal solubility in a contaminated soil toward a sustainability of environment for agricultural crops. Castor plant was grown under different levels of Cd contaminated soil (-Cd and +Cd) following adding three chelating agents, ethylenediaminetetraacetic acid (H₄EDTA), nitriloacetic acid (H₃ NTA), and NH₄ citrate (ammonium citrate) to the soil at rates of 10, 15, and 25 mmol in 5 kg of soil per pot. The highest bioavailable Cd concentrations in soil and castor plant were obtained from NH₄ citrate and H₄EDTA treatments in the contaminated soil. Fourier transform infrared (FTIR) analysis showed that NH₄ citrate was the most effective chelator in Cd-contaminated soil. MBC and DOC contents were significantly increased and reached at 81.98-80.37 and 1.96-1.90 mg kg^-1 respectively, in the (H₃ NTA) and NH₄ citrate treatments in Cd-contaminated soil. Further research is needed to investigate the use of chelators in the phytoextraction of Cd-contaminated soils under field conditions and whether it may be beneficial in accelerating the phytoextraction of Cd through hyperaccumulating plants.