Phosphorus-based soil prophylactics for managing Pb contamination in soil: Slow-release kinetics and microbiological effects

Abstract

Soil remediation poses significant challenges due to its spatial heterogeneity, surpassing the complexities of atmospheric and water remediation. This study introduces an innovative approach to prevent soil heavy metal pollution by developing three phosphorus slow-release heavy metal soil prophylactic agents (SLPs) — Sap-11, Sap-12, and Sap-21. At a liquid-to-solid ratio of 1:20, the three types of SLPs achieve phosphorus sustained slow release amounts of 1.586 g/L, 4.259 g/L, and 1.444 g/L within 30 days, respectively. Over a cultivation period of 120 days, after amendment with the three SLPs, the surface soil demonstrates stabilization capacities for Pb of 29.56 mg/g, 46.24 mg/g, and 25.77 mg/g, respectively, representing enhancements of 283.64 %, 500.12 %, and 250.74 % compared to the control. Firstly, the direct contribution of P (up to 3.778 mg/g) released from SLPs chemically binding with Pb, and secondly, a significant proportion of the indirect contribution originating from the microbial activity and soil organic matter. In summary, SLP emerges as an effective strategy for soil heavy metal management, stabilizing heavy metals by stimulating the soil's inherent physiological and biochemical reactions. This approach provides a practical solution for the application of P-containing materials and introduces novel perspectives for soil heavy metal management strategies.