Montmorillonite loaded with nano calcium peroxide as an effective material to mitigate methane emission in shallow lakes

Shallow lakes are significant contributors to methane (CH₄) emissions, which is a greenhouse gas that intensifies with eutrophication. Currently, geoengineering materials in lake ecosystems are mainly used for eutrophication control and pollutant removal, with limited focus on reducing CH₄ emissions. Here, a composite material, montmorillonite (MMT) loaded with nano calcium peroxide (nanoCaO₂@MMT), was developed to study its effect on mitigating CH₄ emissions and nutrient loading and to explore the potential mechanisms through a mesocosm incubation experiment. Results showed that nanoCaO₂@MMT reduced CH₄ concentration in the surface sediment by up to 69.4% and decreased total nitrogen (TN) and total phosphorus (TP) concentrations in the water column by up to 80.3% and 68.6%, respectively. The CH₄ production potential (MPP) was reduced significantly while the CH₄ oxidation potential remained stable with the addition of nanoCaO₂@MMT. High-throughput sequencing revealed substantial shifts in the prokaryotic microbial community following the addition of nanoCaO₂@MMT, while methanogenic and methanotrophic communities remained largely stable. This study verified that nanoCaO₂@MMT effectively mitigates both CH₄ emissions and nutrient loading, highlighting its potential for future applications as a multi-objective synergistic geoengineering material in shallow lake restoration.