Effects of sodium dodecyl sulfate (SDS) pollution on carbon and nitrogen cycling driven by microbes in the lake-terrestrial ecotone

In recent years, the concentration of sodium dodecyl sulfate (SDS), a surfactant widely used in daily life and industrial production, has significantly increased in domestic sewage and industrial wastewater. By altering microbial activity, SDS pollution exerts a non-negligible impact on the ability of lake-terrestrial ecotones to intercept and purify pollutants. This study provides novel insights by demonstrating the concentration-dependent effects of SDS on microbial-driven carbon and nitrogen cycling in lake-terrestrial ecotones, advancing beyond previous work through large-scale simulations that link functional gene dynamics to pollutant removal. Results indicated: (1) Rising SDS concentrations stimulated growth of some soil microorganisms in lake-terrestrial ecotones (e.g., Opitutaceae and Burkholderiales ), while inhibiting SDS-sensitive microbes (e.g., Nitrospiraceae ). (2) Functional genes exhibited differential responses to SDS concentration changes. Functional genes associated with carbon fixation, methane production, nitrogen fixation, and denitrification displayed heightened sensitivity to SDS concentration changes. (3) SDS addition significantly influenced nitrogen transformation processes, manifested as enhanced nitrification and denitrification functions. This drove a dynamic equilibrium between nitrification and denitrification, thereby enhancing the coupling between carbon and nitrogen cycles. (4) At an SDS concentration of 6 mg/L, microbial activity was inhibited, but microbial community structure remained relatively unchanged. When SDS concentration increased to 10 mg/L, the microbial community shifted toward a pollution-tolerant type. This provided a carbon source for microorganisms capable of degrading SDS, thereby enhancing nitrogen cycling processes in the lake-terrestrial ecotone. • SDS exposure exhibits dose-dependent thresholds on microbial ecology in lake-terrestrial ecotones. • SDS drives microbial community shift by enriching tolerant taxa and suppressing keystone nitrifiers. • Key functional genes for C/N cycling are highly sensitive to SDS, serving as early warning indicators.