Assessing nutrient fate from terrestrial to freshwater systems using a semi-distributed model for the Fuxian Lake Basin, China

Jinhui Zhou; José M Mogollón; Peter M van Bodegom

doi:10.1016/j.scitotenv.2024.171068

Assessing nutrient fate from terrestrial to freshwater systems using a semi-distributed model for the Fuxian Lake Basin, China

Sci Total Environ. 2024 Apr 15:921:171068. doi: 10.1016/j.scitotenv.2024.171068. Epub 2024 Feb 17.

Authors

Jinhui Zhou¹, José M Mogollón², Peter M van Bodegom²

Affiliations

¹ Institute of Environmental Sciences (CML), Leiden University, Leiden, the Netherlands. Electronic address: j.zhou.12@cml.leidenuniv.nl.
² Institute of Environmental Sciences (CML), Leiden University, Leiden, the Netherlands.

PMID: 38373457
DOI: 10.1016/j.scitotenv.2024.171068

Abstract

The growing and increasingly intensified agricultural sector exerts major pressures on the environment. Specifically, nitrogen (N) and phosphorus (P) runoff can induce eutrophication in freshwater ecosystems. To formulate environmental strategies for controlling eutrophication, decision-makers commonly consider the importance of pollutant contributors before developing sector-specific environmental policies. These types of science-based decisions benefit from nutrient models that quantify nutrient transport and fate. However, due to a lack of fertilizer application data, distributed models are generally not suitable for most rural regions with extensive agriculture, while lumped models cannot properly characterize the spatial variation of nutrient fate in these regions. To assess the nutrient contributions from different emission sources to freshwater, we developed a localized semi-distributed model to simulate total nitrogen (TN) and total phosphorus (TP) in 52 inflow rivers of Fuxian Lake Basin in China. The results show that diffuse sources contributed 82 % TN and 92 % TP loading to the inflow rivers. The highest eutrophication potentials (i.e., loading per area) is from the built environment, which is more than 10 times that of forests, but the contribution of the built environment to total diffuse loading is only the second-highest as it occupies 8.7 % of the surface area. Farmland is the main contributor, generating 49 % of diffuse TN and 57 % TP, respectively. Our results show that promoting a 10 % increase in nutrient use efficiency would reduce 5 % of N and 30 % of P diffuse loadings to the rivers. Through examining the impact of nutrient use efficiency, we emphasize the potential trade-offs between food productivity and environmental effects. This analysis workflow can be applied to other agricultural regions.

Keywords: Agricultural emissions; Freshwater eutrophication; Nitrogen use efficiency; Phosphorus use efficiency; Semi-distributed model; Strategic Environmental Assessment.