Lead stabilization and remediation strategy with soil amendment in situ immobilization in contaminated range lands

Abstract

In situ immobilization is a potential approach that can be used to remediate low-to-medium levels of heavy-metal in contaminated-soil. There is little known about how modifications to soil characteristics may affect Pb’s release from soil. The four different amendments, triple-superphosphate and attapulgite were combined in Ad-1; zeolite and triple-superphosphate were in Ad-2; hydroxyapatite and humus were in Ad-3; and nano-carbon. These amendments are mostly made of phyllosilicate minerals, humus, base minerals, and nano-carbon, respectively. Results revealed that the test amendments’ maximal Pb-adsorption capacity varied from 7.47 to 17.67 mg g⁻¹. Surface precipitation and ion-exchange were found to be the main mechanisms for Pb-adsorption by Ad-1 and Ad-2, while Ad-3 and Ad-4 were promising among the all, according to analysis of the modifications both before and after Pb loading. When the pH dropped (7-1) or the ion-strength rose (0–0.2 M), there was a discernible rise in the Pb-desorption percentages from the amendments. It was determined that Ad-3 and Ad-4 were more effective in situ immobilizing lead in contaminated-soils because of their high adsorption capacities (12.82 and 17.67 mg g⁻¹) and low-desorption percentages (4.46–6.23%) at ion-strengths of 0.01–0.1 mol L⁻¹ and pH levels ranging from 5 to 7.

Novelty statement

This study pioneers a comprehensive exploration into the efficacy of novel soil amendments, Ad-3 and Ad-4 crafted from phyllosilicate minerals, humus, base minerals, and nano-carbon, showcasing their unprecedented potential in mitigating lead pollution. By delving into the intricate mechanisms of lead adsorption and desorption within treated soils, this research fills a critical gap in understanding how modifications to soil characteristics can influence the secondary release of lead, thus providing essential insights for tailored in situ remediation strategies to safeguard both plant and human health in lead-endangered environments.

Keywords:

• Contamination
• lead (Pb)
• organic sources
• remediation
• strategies

Disclosure statement

No potential conflict of interest was reported by the author(s).