Unravelling Coupled Hydrological and Geochemical Controls on Long-Term Nitrogen Enrichment in a Large River Basin

• DOI: 10.1021/acs.est.4c05015
• Publication Date: 2024-10-31T06:10:24Z
• Authors: Ying Liang; Rui Ma; Henning Prommer; Qing-Long Fu; Xue Jiang; Yiqun Gan; Yanxin Wang

Many groundwater and surface water bodies around the world show a puzzling often steady increase in nitrogen (N) concentrations, despite significant decline of agricultural N inputs. This study uses combination long-term hydrogeochemical hydraulic monitoring, molecular characterization dissolved organic matter (DOM), column experiment, reactive transport modeling to unravel processes controlling N-reactive mass budgets under impacts dynamic hydrologic conditions at field site central Yangtze River Basin. Our analysis shows that desorption ammonium (NH4+) from sediments via cation exchange reactions dominates mobilization aqueous while mineralization compounds plays only minor role. The results illustrate important role are induced by temporary NH4+ input concentration changes impact both seasonal variations. Historically, exchangers have acted as efficient storage devices mitigated high levels input. residing on exchanger sites later acts source waters with delayed sediment-bound change conditions. highlight complex linkages between highly variable partitioning near-surface, river-derived sediments.