Seasonal variations in greenhouse gas production in coastal sandy sediments.

Understanding the greenhouse gas (GHG) production rates and ecological effects of sandy coastal sediments is critical for refining global carbon cycle assessments. Despite their extensive distribution and potential role in climate regulation, sandy sediments remain understudied compared to muddy counterparts, particularly regarding seasonal dynamics and redox-controlled biogeochemical processes. This study investigates seasonal GHG dynamics in sandy coastal sediments of the Guangdong Province, China. Results revealed that temperature as the primary seasonal driver, directly regulating microbial kinetics governing GHG production. Meanwhile, Pearson correlation analysis revealed a significant positive association between Fe2+ and GHG production, while NO3- was negatively correlated with CO2 production (p < 0.05). Additionally, annual net GHG flux from China's coastal sandy sediments (top 5 cm) is estimated at -1.27 × 106 t CO2e, representing 0.0026 % of global fluxes (4.94 × 1010 t CO2e). Our findings highlighted the critical necessity of integrating seasonal variability parameters and sediment compositional heterogeneity into methodological frameworks for global GHG inventories.