The Response of Nitrogen Deposition in China to Recent and Future Changes in Anthropogenic Emissions

Abstract

We present a model analysis that quantifies the influence of anthropogenic emission variations on the recent (2005–2015) and future (2030) changes in national scale nitrogen deposition in China and the interacting relationships between their emissions and depositions. We find that the 0.39 Tg N yr−1 increase in the dry deposition of reduced nitrogen (NHx) during 2007–2015 is dominated by the decrease in sulfur dioxides (SO2) emissions, which reduces the formation of ammonium (NH4+) aerosols from gas‐phase ammonia (NH3). Although the decrease in SO2 emissions led to conversion from wet to dry deposition of NHx, the NH4+ wet deposition increased by 0.75 Tg N yr−1 with large interannual variations driven by precipitation. Different from NHx, the oxidized nitrogen (NOy) deposition increased by 1.6 Tg N yr−1 from 2005 to 2011 and decreased by 1.1 Tg N yr−1 from 2011 to 2015, following the changes in nitrogen oxides (NOx) emissions. Based on the national scale emission‐deposition relationship estimated from model sensitivity experiments, we find that future emission control would reduce the NOy deposition by 2.4 ± 0.08 to 3.4 ± 0.12 Tg N yr−1 (49%–73%), but only lead to small decreases of 0.93 ± 0.05 to 1.2 ± 0.06 Tg N yr−1 (9%–14%) in NHx deposition in China from 2015 to 2030. The decrease in NOx and SO2 emissions under future scenarios would enhance the NHx dry deposition over domestic China, diminishing the effectiveness of the NH3 emission control. The results emphasize that stricter strategies for controlling agricultural NH3 emissions should be taken to alleviate the adverse environmental impacts from atmospheric nitrogen deposition.

Combined short-term and long-term emission controls improve air quality sustainably in China

“…In contrast, the gaseous fraction of NH 3 increased from 0.39 to 0.52 over the 10 years. Ambient mean NH 3 concentrations and NH 3 deposition in 2020 were 34% and 27% higher than in 2011, counteracting the decrease in p NH 4 + concentrations, confirming the stability of NH 3 emissions and indicating that more NH 3 is present as a gas in the atmosphere due to the reductions in acid gas emissions 24 , 25 . The decrease in NH 4 + bulk deposition (from 10.3 to 7.80 kg N ha − 1 yr − 1 , p = 0.01) offset the increase in gaseous NH 3 so that total reduced N deposition presented a small decrease, which was generally consistent with the change in NH 3 emissions (NH X deposition decreased by 13% vs NH 3 emission by 14%, Fig.…”

Atmospheric Nitrogen Pollution Control Benefits the Coastal Environment

“…This reduction in NO x emissions can be attributed to a series of air pollution control policies, such as the implementation of the "Clean Air Act" and rigorous environmental protection inspections. 49 Surface runoff nitrogen loss displayed an initially increasing trend, followed by a subsequent decrease, resulting in an overall reduction of 5.94 Tg (−36%) throughout the study period. This decline can be attributed to China's substantial investments in surface pollution treatment and municipal industrial wastewater management over the past decade.…”

“…And NO x emission experienced a substantial increase of 55% (+2.78 Tg) from 2000 to 2011, followed by a decrease of 3.37 Tg (−66%) from 2012 to 2017. This reduction in NO x emissions can be attributed to a series of air pollution control policies, such as the implementation of the “Clean Air Act” and rigorous environmental protection inspections . Surface runoff nitrogen loss displayed an initially increasing trend, followed by a subsequent decrease, resulting in an overall reduction of 5.94 Tg (−36%) throughout the study period.…”

A Decadal Change in Atmospheric Nitrogen Deposition at a Rural Site in Southern China

“…China is a world hotspot for atmospheric N deposition due to its rapid industrialization and intensive agricultural production [29]. The country's overall level of N deposition increased from the 1980s to the 2000s [2] but stabilized after the 2000s [30], mainly due to high emissions of NH 3 and NO x [14].…”