On the contribution of atmospheric reactive nitrogen deposition to nitrogen burden in a eutrophic Lake in eastern China

Weikun Li; Xia Wang; Wei Song; Zhongyi Zhang; Xueying Wang; Xiaodong Liu; Tianming Ma; Qi Wang; Yanli Zhang; Xinming Wang; Lei Geng

doi:10.1016/j.watres.2024.122597

On the contribution of atmospheric reactive nitrogen deposition to nitrogen burden in a eutrophic Lake in eastern China

Water Res. 2024 Oct 9;268(Pt A):122597. doi: 10.1016/j.watres.2024.122597. Online ahead of print.

Authors

Weikun Li¹, Xia Wang¹, Wei Song², Zhongyi Zhang¹, Xueying Wang³, Xiaodong Liu¹, Tianming Ma⁴, Qi Wang², Yanli Zhang², Xinming Wang², Lei Geng⁵

Affiliations

¹ School of Earth and Space Sciences, University of Science and Technology of China, Hefei, 230026, China.
² Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.
³ Lake Chaohu Research Institute, Lake Chaohu Administration Bureau in Anhui Province, Hefei, China.
⁴ Operational Oceanography Institution (OOI)/School of Marine Science and Environment Engineering, Dalian Ocean University, Dalian, 116023, China.
⁵ School of Earth and Space Sciences, University of Science and Technology of China, Hefei, 230026, China; CAS Center for Excellence in Comparative Planetology, University of Science and Technology of China, Hefei, 230026, Anhui, China; Deep Space Exploration Laboratory, Hefei, China. Electronic address: genglei@ustc.edu.cn.

PMID: 39405628
DOI: 10.1016/j.watres.2024.122597

Abstract

Although it has been demonstrated that atmospheric reactive nitrogen (i.e., Nr mainly including NH₃, NH₄⁺, NO_x, NO₃^- and etc.) deposition has substantial impacts on nitrogen pools in remote and/or sensitive lakes, there is a scarcity of systematic evaluations regarding the impact on nitrogen burden in eutrophic lakes with riverine input as primary nitrogen source. Utilizing a regional atmospheric chemical transport model, combined with observation-based estimates of atmospheric nitrogen deposition fluxes and riverine nitrogen inputs, we investigate the contribution of atmospheric Nr deposition to the fifth largest freshwater lake located in eastern China, i.e., the Chaohu Lake which is facing frequent outbreaks of algal bloom. The results indicate that in the studied year of 2022, riverine total nitrogen (TN) input to the lake was 11553.3 t N yr^-1 and atmospheric TN deposition was 2326.0 t N yr^-1. For Nr species which are directly available for the biosphere supporting algae and plant growth, riverine NH₄⁺ input was 1856.1 t N yr^-1 and atmospheric NH_x (NH₃ and NH₄⁺) deposition was 824.5 t N yr^-1. The latter accounts for 30.8% of total NH_x input to the lake. For NO_y (HNO₃ and NO₃^-), riverine NO₃^- input was estimated as 2621.7 t N yr^-1, while atmospheric NO_y deposition was 629.3 t N yr^-1, accounting for 19.4%. In all, atmospheric Nr deposition accounts for 24.5 % of total Nr input to the lake. Our results suggest that even in regions with dense human activities with primary riverine N input, atmospheric deposition of Nr could also contribute significantly to the bio-available nitrogen in lake systems, and addressing eutrophication in Lake Chaohu and other eutrophic lakes will also need to consider the influence of atmospheric Nr deposition which is related to NH₃ and NO_x (i.e., NO + NO₂, the precursor of NO_y) emissions, in addition to the mitigation of riverine N input.

Keywords: Atmospheric chemical transport model; Atmospheric reactive nitrogen deposition; Eutrophic lakes; Lake nitrogen burden.