A 15-year record (2001–2015) of the ratio of nitrate to non-sea-salt sulfate in precipitation over East Asia

Acidifying species in precipitation can have severe impacts on ecosystems. The chemical composition of precipitation is directly related to the amount of precipitation; accordingly, it is difficult to identify long-term variation in chemical concentrations. The ratio of the nitrate (NO<sub>...

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Main Authors: S. Itahashi, K. Yumimoto, I. Uno, H. Hayami, S.-I. Fujita, Y. Pan, Y. Wang
Format: Article
Language:English
Published: Copernicus Publications 2018-02-01
Series:Atmospheric Chemistry and Physics
Online Access:https://www.atmos-chem-phys.net/18/2835/2018/acp-18-2835-2018.pdf
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author S. Itahashi
S. Itahashi
K. Yumimoto
I. Uno
H. Hayami
S.-I. Fujita
Y. Pan
Y. Wang
author_facet S. Itahashi
S. Itahashi
K. Yumimoto
I. Uno
H. Hayami
S.-I. Fujita
Y. Pan
Y. Wang
author_sort S. Itahashi
collection DOAJ
description Acidifying species in precipitation can have severe impacts on ecosystems. The chemical composition of precipitation is directly related to the amount of precipitation; accordingly, it is difficult to identify long-term variation in chemical concentrations. The ratio of the nitrate (NO<sub>3</sub><sup>−</sup>) to non-sea-salt sulfate (nss-SO<sub>4</sub><sup>2−</sup>) concentration in precipitation on an equivalent basis (hereinafter, <i>Ratio</i>) is a useful index to investigate the relative contributions of these acidifying species. To identify the long-term record of acidifying species in precipitation over East Asia, the region with the highest emissions worldwide, we compiled ground-based observations of the chemical composition of precipitation over China, Korea, and Japan from 2001 to 2015 based on the Acid Deposition Monitoring Network in East Asia (EANET). The spatial coverage was limited, but additional monitoring data for Japan, southern China, and northern China around Beijing were utilized. The period of analysis was divided into three phases: Phase I (2001–2005), Phase II (2006–2010), and Phase III (2011–2015). The behaviors of NO<sub>3</sub><sup>−</sup> and nss-SO<sub>4</sub><sup>2−</sup> concentrations and hence the <i>Ratio</i> in precipitation were related to these precursors. The anthropogenic NO<sub><i>x</i></sub> and SO<sub>2</sub> emissions and the NO<sub><i>x</i></sub> ∕ SO<sub>2</sub> emission ratio were analyzed. Further, satellite observations of the NO<sub>2</sub> and SO<sub>2</sub> column density to capture the variation in emissions were applied. We found that the long-term trend in the NO<sub>3</sub><sup>−</sup> concentration in precipitation was not related to the variation in NO<sub><i>x</i></sub> emission and the NO<sub>2</sub> column. In comparison, the nss-SO<sub>4</sub><sup>2−</sup> concentration in precipitation over China, Korea, and Japan was partially connected to the changes in SO<sub>2</sub> emissions from China, but the trends were not significant. The long-term trends of <i>Ratio</i> over China, Korea, and Japan were nearly flat during Phase I, increased significantly during Phase II, and were essentially flat again during Phase III. This variation in <i>Ratio</i> in East Asia clearly corresponded to the NO<sub><i>x</i></sub> ∕ SO<sub>2</sub> emission ratio and the NO<sub>2</sub> ∕ SO<sub>2</sub> column ratio in China. The initial flat trend during Phase I was due to increases in both NO<sub><i>x</i></sub> and SO<sub>2</sub> emissions in China, the significantly increasing trend during Phase II was triggered by the increase in NO<sub><i>x</i></sub> emissions and decrease in SO<sub>2</sub> emissions in China, and the return to a flat trend during Phase III was caused by declines in both NO<sub><i>x</i></sub> and SO<sub>2</sub> emissions in China. These results suggest that emissions in China had a significant impact not only on China but also on downwind precipitation chemistry during the 15-year period of 2001–2015. In terms of wet deposition, the NO<sub>3</sub><sup>−</sup> wet deposition over China, Korea, and Japan did not change dramatically, but the nss-SO<sub>4</sub><sup>2−</sup> wet deposition declined over China, Korea, and Japan from Phase II to III. These declines were caused by a strong decrease in the nss-SO<sub>4</sub><sup>2−</sup> concentration in precipitation accompanied by a reduction in SO<sub>2</sub> emission from China, which counteracted the increase in precipitation. These findings indicated that the acidity of precipitation shifted from sulfur to nitrogen.
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spelling doaj.art-4b975bf509f040b2978a3041b577f7652022-12-21T18:55:19ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242018-02-01182835285210.5194/acp-18-2835-2018A 15-year record (2001–2015) of the ratio of nitrate to non-sea-salt sulfate in precipitation over East AsiaS. Itahashi0S. Itahashi1K. Yumimoto2I. Uno3H. Hayami4S.-I. Fujita5Y. Pan6Y. Wang7Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Abiko, Chiba 270–1194, Japannow at: Department of Marine, Earth, and Atmospheric Sciences (MEAS), North Carolina State University (NCSU), 2800 Faucette Dr., Raleigh, North Carolina 27695, USAResearch Institute for Applied Mechanics (RIAM), Kyushu University, 6-1 Kasuga Park, Kasuga, Fukuoka 816–8580, JapanResearch Institute for Applied Mechanics (RIAM), Kyushu University, 6-1 Kasuga Park, Kasuga, Fukuoka 816–8580, JapanEnvironmental Science Research Laboratory, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Abiko, Chiba 270–1194, JapanEnvironmental Science Research Laboratory, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Abiko, Chiba 270–1194, JapanState Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences (CAS), Beijing 100029, ChinaState Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences (CAS), Beijing 100029, ChinaAcidifying species in precipitation can have severe impacts on ecosystems. The chemical composition of precipitation is directly related to the amount of precipitation; accordingly, it is difficult to identify long-term variation in chemical concentrations. The ratio of the nitrate (NO<sub>3</sub><sup>−</sup>) to non-sea-salt sulfate (nss-SO<sub>4</sub><sup>2−</sup>) concentration in precipitation on an equivalent basis (hereinafter, <i>Ratio</i>) is a useful index to investigate the relative contributions of these acidifying species. To identify the long-term record of acidifying species in precipitation over East Asia, the region with the highest emissions worldwide, we compiled ground-based observations of the chemical composition of precipitation over China, Korea, and Japan from 2001 to 2015 based on the Acid Deposition Monitoring Network in East Asia (EANET). The spatial coverage was limited, but additional monitoring data for Japan, southern China, and northern China around Beijing were utilized. The period of analysis was divided into three phases: Phase I (2001–2005), Phase II (2006–2010), and Phase III (2011–2015). The behaviors of NO<sub>3</sub><sup>−</sup> and nss-SO<sub>4</sub><sup>2−</sup> concentrations and hence the <i>Ratio</i> in precipitation were related to these precursors. The anthropogenic NO<sub><i>x</i></sub> and SO<sub>2</sub> emissions and the NO<sub><i>x</i></sub> ∕ SO<sub>2</sub> emission ratio were analyzed. Further, satellite observations of the NO<sub>2</sub> and SO<sub>2</sub> column density to capture the variation in emissions were applied. We found that the long-term trend in the NO<sub>3</sub><sup>−</sup> concentration in precipitation was not related to the variation in NO<sub><i>x</i></sub> emission and the NO<sub>2</sub> column. In comparison, the nss-SO<sub>4</sub><sup>2−</sup> concentration in precipitation over China, Korea, and Japan was partially connected to the changes in SO<sub>2</sub> emissions from China, but the trends were not significant. The long-term trends of <i>Ratio</i> over China, Korea, and Japan were nearly flat during Phase I, increased significantly during Phase II, and were essentially flat again during Phase III. This variation in <i>Ratio</i> in East Asia clearly corresponded to the NO<sub><i>x</i></sub> ∕ SO<sub>2</sub> emission ratio and the NO<sub>2</sub> ∕ SO<sub>2</sub> column ratio in China. The initial flat trend during Phase I was due to increases in both NO<sub><i>x</i></sub> and SO<sub>2</sub> emissions in China, the significantly increasing trend during Phase II was triggered by the increase in NO<sub><i>x</i></sub> emissions and decrease in SO<sub>2</sub> emissions in China, and the return to a flat trend during Phase III was caused by declines in both NO<sub><i>x</i></sub> and SO<sub>2</sub> emissions in China. These results suggest that emissions in China had a significant impact not only on China but also on downwind precipitation chemistry during the 15-year period of 2001–2015. In terms of wet deposition, the NO<sub>3</sub><sup>−</sup> wet deposition over China, Korea, and Japan did not change dramatically, but the nss-SO<sub>4</sub><sup>2−</sup> wet deposition declined over China, Korea, and Japan from Phase II to III. These declines were caused by a strong decrease in the nss-SO<sub>4</sub><sup>2−</sup> concentration in precipitation accompanied by a reduction in SO<sub>2</sub> emission from China, which counteracted the increase in precipitation. These findings indicated that the acidity of precipitation shifted from sulfur to nitrogen.https://www.atmos-chem-phys.net/18/2835/2018/acp-18-2835-2018.pdf
spellingShingle S. Itahashi
S. Itahashi
K. Yumimoto
I. Uno
H. Hayami
S.-I. Fujita
Y. Pan
Y. Wang
A 15-year record (2001–2015) of the ratio of nitrate to non-sea-salt sulfate in precipitation over East Asia
Atmospheric Chemistry and Physics
title A 15-year record (2001–2015) of the ratio of nitrate to non-sea-salt sulfate in precipitation over East Asia
title_full A 15-year record (2001–2015) of the ratio of nitrate to non-sea-salt sulfate in precipitation over East Asia
title_fullStr A 15-year record (2001–2015) of the ratio of nitrate to non-sea-salt sulfate in precipitation over East Asia
title_full_unstemmed A 15-year record (2001–2015) of the ratio of nitrate to non-sea-salt sulfate in precipitation over East Asia
title_short A 15-year record (2001–2015) of the ratio of nitrate to non-sea-salt sulfate in precipitation over East Asia
title_sort 15 year record 2001 2015 of the ratio of nitrate to non sea salt sulfate in precipitation over east asia
url https://www.atmos-chem-phys.net/18/2835/2018/acp-18-2835-2018.pdf
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