Geological regulation of nitrous oxide emission risks in rivers globally
摘要
Fertilizer application has been recognized as the major driver of nitrous oxide (N2O) emissions in rivers. However, the intrinsic risk of N2O emissions in responding to nitrogen discharge (i.e., ratios between N2O emissions and dissolved inorganic nitrogen or fertilizer) may vary across rivers but remains unclear. Here we uncover the hidden yet substantial control of riverine N2O emissions by bedrock geology through field observations and global data analyses. We discover lower denitrification but higher N2O production rates in rivers with silicate-dominated bedrocks compared to those with carbonate-dominated bedrocks. On one hand, the larger sediment grain size found in the silicate-dominated rivers shortens porewater residence time for reaction, which diminishes the likelihood of complete denitrification (NO3−