Effects of magnesium hydroxide nanoparticles on black-odorous sediment properties and indigenous bacterial communities: Implications for remediation strategies

Magnesium hydroxide nanoparticles (Mg(OH)₂ NPs) have emerged as promising candidates for environmental remediation, owing to their effectiveness in addressing diverse pollutants within soil and water systems. In this study, the changes of sediment properties and the responses of indigenous bacteria to black-odorous sediment amended with Mg(OH)₂ NPs were investigated.

Mg(OH)₂ NPs were used to amend the black-odorous contaminated sediment, and the physicochemical properties, sulfide and heavy metal contents, enzyme activities of the sediment, and indigenous bacterial community parameters were determined.

Mg(OH)₂ NPs significantly altered the sediment physicochemical properties, enzymatic activities, and bacterial community composition of the sediment. The pH value and total phosphorus contents increased, whereas total nitrogen and total organic carbon content decreased. The sulfide content significantly decreased with injection treatment, surpassing the effect elicited by the mixed addition mode. Dehydrogenase activity was significantly enhanced, whereas urease and alkaline phosphatase activities were evidently inhibited. Bacterial 16S rRNA gene copy numbers in the surface-layer sediment treated with Mg(OH)₂ NPs increased by 267.86% (mixed) and 338.45% (injection) after a 60-day incubation period. The abundances of the dominant phyla and genera identified in the sediment increased under Mg(OH)₂ NP treatment, particularly those involved in sulfur and nitrogen metabolism.

Mg(OH)₂ nanoparticles directly or indirectly affect the indigenous bacterial community through changes in the sediment physicochemical properties, heavy metal contents, and enzyme activities. These findings contribute to the development of more targeted and effective methods for mitigating sediment pollution and restoring ecosystem health.