The intensification of anthropogenic nitrogen (N) and phosphorus (P) inputs profoundly affects water environmental quality. Hence it is pivotal to clarify the response relationship between riverine TN/TP export and anthropogenic N/P inputs to provide strategies guidance in N/P management. Based on the variation of net anthropogenic N and P inputs (NANI/NAPI) in the Raohe basin from 1990 to 2018, we constructed the response relationship between NANI/NAPI and total nitrogen and phosphorus (TN/TP) export fluxes in the riverine, which successfully predicted N and P export at the basin scale management. We found N export ratio (ratio of TN export to NANI) increased with slight fluctuation and was mainly affected by the combined effects of Nfer (fertilizer N inputs) and Ndep (atmospheric N deposition) etc., while the decrease of P export ratio (ratio of TP export to NAPI) was mainly due to intensive retention effect of the soil and sediment induced by anthropogenic influence to P transportation process. These results indicate that the downstream aquatic systems take a high risk of increasing N load pressure and the basin systems suffer a danger from rising P load pressure. Therefore, it is recommended to concentrate more on downstream aquatic systems during the N management strategy implementation and pay closer attention to the whereabouts of P in the basin system.
Keywords: Net anthropogenic nitrogen and phosphorus inputs; Nitrogen and phosphorus export fluxes; Nitrogen and phosphorus export ratio; Raohe basin; Response model.
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