09 Nov 2022
 | 09 Nov 2022
Status: a revised version of this preprint is currently under review for the journal BG.

Long-term changes of nitrogen leaching and their contributions to lake eutrophication dynamics on the Yangtze Plain of China

Qi Guan, Jing Tang, Lian Feng, Stefan Olin, and Guy Schurgers

Abstract. Over the past half century, drastically increased chemical fertilizer have entered agricultural ecosystems to promote the crop production on the Yangtze Plain, potentially enhancing agricultural nutrient sources for eutrophication in freshwater ecosystems. However, long-term trends of nitrogen dynamics in terrestrial ecosystems and their impacts on eutrophication changes in this region remain poorly studied. Using a process-based ecosystem model, we investigated the temporal and spatial patterns of nitrogen use efficiency (NUE) and nitrogen leaching on the Yangtze Plain from 1979 to 2018. The agricultural NUE for the Yangtze Plain significantly decreased from 50 % in 1979 to 25 % in 2018, with the largest decline of NUE in soybean, rice and rapeseed. Simultaneously, the leached nitrogen from cropland and natural land increased with annual rates of 4.5 kg N ha-1 yr-2 and 0.22 kg N ha-1 yr-2, respectively, leading to an overall increase of nitrogen inputs to the fifty large lakes. We further examined the correlations between terrestrial nutrient sources (i.e., the leached nitrogen, total phosphorus sources, and industrial wastewater discharge) and the satellite-observed probability of eutrophication occurrence (PEO) at an annual scale, and showed that PEO was positively correlated with the changes in terrestrial nutrient sources for most lakes. Agricultural nitrogen and phosphorus sources were found to explain the PEO trends in lakes in the western and central part of Yangtze Plain, and industrial wastewater discharge was associated with the PEO trends in eastern lakes. Our results revealed the importance of terrestrial nutrient sources for long-term changes in eutrophic status over the fifty lakes of the Yangtze Plain. This calls for sustainable nitrogen applications in agriculture systems to improve water quality of local lake ecosystems.

Qi Guan et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on bg-2022-197', Anonymous Referee #1, 16 Dec 2022
  • RC2: 'Comment on bg-2022-197', Anonymous Referee #2, 20 Jan 2023
  • EC1: 'Comment on bg-2022-197', Sébastien Fontaine, 13 Feb 2023

Qi Guan et al.


Total article views: 444 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
306 119 19 444 31 3 6
  • HTML: 306
  • PDF: 119
  • XML: 19
  • Total: 444
  • Supplement: 31
  • BibTeX: 3
  • EndNote: 6
Views and downloads (calculated since 09 Nov 2022)
Cumulative views and downloads (calculated since 09 Nov 2022)

Viewed (geographical distribution)

Total article views: 446 (including HTML, PDF, and XML) Thereof 446 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
Latest update: 21 Mar 2023
Short summary
Understanding terrestrial sources of nitrogen is vital to examine lake eutrophication changes. Combining process-based ecosystem modeling and satellite observations, we found that land-leached nitrogen in the Yangtze Plain significantly increased from 1979 to 2018 and terrestrial nutrient sources were positively correlated with eutrophication trends observed in most lakes, demonstrating the necessity of sustainable nitrogen management to control eutrophication.