Synergistic force of green-synthesized zero-valent iron nanocomposites combined with different fertilizers for inhibiting cadmium accumulation in wheat†

Abstract

The essential nutrients for healthy crop growth may affect the nanotechnology-based remediation of agricultural soils contaminated with cadmium (Cd). However, this hypothesis has not been thoroughly explored. This study investigated the Cd biotransformation and accumulation in wheat growing under a hydroponic system regulated by various nitrogen (N) and phosphate (P) fertilizers, after treatment with green-synthesized nano-zero-valent iron supported by diatomite (GnZVI@DE) composites. We found that the presence of urea–N and P with GnZVI@DE respectively inhibited Cd accumulation by 67.7% and 26.2% in wheat seedlings, alleviating further oxidative damage to wheat. This was because urea–N promoted the dispersion of GnZVI@DE particles that originated from increased steric hindrance. P induced the polyphosphate production on tea polyphenols covering GnZVI@DE, increasing Cd(II) adsorption and precipitation by 47.9% for lesser uptake by root surfaces. Conversely, nitrate-N and ammonium-N promoted Cd accumulation in wheat shoots by 86.0% and 26.3%. This was mainly attributed to reduced Cd immobilization by nanocomposites due to GnZVI@DE oxidation by nitrate and competitive adsorption by ammonium. Our study provides insights for developing a sustainable strategy for the remediation of Cd-contaminated soils and the healthy growth of wheat achieved by the synergistic force of nano-amendments combined with urea and phosphate fertilizers.