大気中窒素酸化物の夜間大気化学反応による消失に関する研究
メンバー： 中嶋吉弘
分野： 環境解析学、基礎化学
所属： 農学研究院
キーワード： 大気化学、窒素化合物、オキシダント
ウェブサイト：
研究概要
大気中の窒素酸化物(NOx)は、特に光化学オキシダント生成の前駆物質として作用する重要な化学種であり、オキシダント濃度の増加傾向の原因を解明し、抑制を図るためには、窒素酸化物の生成(排出)量と消失量のより正確な把握と窒素酸化物が関与する大気化学反応過程の解明が鍵となります。NOxの生成(排出)量の推計は数多く報告されている一方で、消失量については依然として未解明な点が多く、特に夜間における窒素酸化物の消失量推計は未解明な点が多く存在します。夜間の主要な消失過程は、(1)硝酸ラジカル(NO3)とVOCs(特にアルケン類)との均一反応による有機硝酸の生成、(2)五酸化二窒素(N2O5)のエアロゾル表面との不均一反応による硝酸生成と考えられています。これらの消失過程はVOCsの種類やエアロゾルの粒径・化学組成により反応性が大きく異なります。またNO3とN2O5の存在量は地域(NO発生源が少ない都市郊外域とNO発生源に乏しい遠隔地)または季節(高温の夏季と低温の冬季)により大きく異なります。
私は主に夜間の窒素酸化物の消失に関与するNO3, N2O5の濃度測定と同時にNO3, N2O5の生成・消失過程に関与する大気微量成分(オゾン、NOx、VOCs、エアロゾル)の濃度測定を行っています。各物質の観測結果を下にNO3とN2O5の生成と消失過程を分離して検討するためのモデル計算を行ない、観測期間中の窒素酸化物の消失量の推計とその整合性を検討しています。また地理および季節要因によるNO3とN2O5の存在量の違いを考慮するために、都市郊外部と遠隔地における観測を通年で行なう予定です。
主要論文・参考事項
・Yoshihiro Nakashima, Charlotte E. Jones, Wakana Yamanobe, Yoshizumi Kajii, "Near-Surface Vertical Profiles of Urban Roadside NOx and Fine Particles", Aerosol and Air Quality Research, 14, 1763-1768, (2014)
・Yoshihiro Nakashima, Shungo Kato, Jim Greenberg, Peter Harley, Thomas Karl, Andrew Turnipseed, Eric Apel, Alex Guenther, Jim Smith, Yoshizumi Kajii, "Total OH reactivity measurements in ambient air in a southern Rocky Mountain ponderosa pine forest during BEACHON-SRM08 summer campaign", Atmospheric Environment, 85, 1-8, (2014).
・S. Kim, G. M. Wolfe, L. Mauldin, C. Cantrell, A. Guenther, T. Karl, A. Turnipseed, J. Greenberg, S. R. Hall, K. Ullmann, E. Apel, R. Hornbrook, Y. Kajii, Y. Nakashima, F. N. Keutsch, J. P. DiGangi, S. B. Henry, L. Kaser, R. Schnitzhofer, M. Graus, A. Hansel, W. Zheng, and F. F. Flocke, "Evaluation of HOx sources and cycling using measurement-constrained model calculations in a 2-methyl-3-butene-2-ol (MBO) and monoterpene (MT) dominated ecosystem", Atmos. Chem. Phys., 13, 2031-2044, (2013)
・Y. Nakashima, H. Tsurumaru, T. Imamura, I. Bejan, J. C. Wenger, Y. Kajii, "Total OH reactivity measurements in laboratory studies of the photooxidation of isoprene", Atmospheric Environment, 62, 243-247, (2012)
・J. P. DiGangi, S. B. Henry, A. Kammrath, E. S. Boyle, L. Kaser, R. Schnitzhofer, M. Graus, A. Turnipseed, J-H. Park, R. J. Weber, R. S. Hornbrook, C. A. Cantrell, R. L. Maudlin III, S. Kim, Y. Nakashima, G. M. Wolfe, Y. Kajii, E.C. Apel, A. H. Goldstein, A. Guenther, T. Karl, A. Hansel, and F. N. Keutsch, "Observations of glyoxal and formaldehyde as metrics for the anthropogenic impact on rural photochemistry", Atmos. Chem. Phys., 12, 9529-9543, (2012)
・A. Yoshino, Y. Nakashima, K. Miyazaki, S. Kato, J. Suthawaree, N. Shimo, S. Matsunaga, S. Chatani, E. Apel, J. Greenberg, A. Guenther, H. Ueno, H. Sasaki, J. Hoshi, H. Yokota, K. Ishii, Y. Kajii, "Study of air quality in urban central Tokyo - Comprehensive observations of total OH reactivity and reactive trace species", Atmospheric Environment, 49, 51-59, (2012)
・Y. Nakashima, N. Kamei, S. Kobayashi, Y. Kajii, "Total OH reactivity and VOC analyses for gasoline vehicular exhaust with a chassis dynamometer", Atmospheric Environment, 44, (2010), 468-475
お問い合わせ先
東京農工大学・先端産学連携研究推進センター
urac[at]ml.tuat.ac.jp（[at]を@に変換してください）
Studies on the chemical removal process of nitrogen oxides in troposphere in nighttime
Research members： Dr. Yoshihiro Nakashima
Research fields： Environmental analyses and evaluation, Basic chemistry
Departments： Institute of Agriculture
Keywords： atmospheric chemistry, nitrogen compounds, oxidant
Web site：
Summary
Nitrogen oxides (NOx) are one of the important species in troposphere and it acts as a precursor of the formation of photochemical oxidant. The increment of the concentration of oxidant is one of the important issues. To reduce the concentration of oxidant, it is essential to know the emission and loss amounts of NOx precisely and mechanism of the chemical reaction related with NOx. There are many reports for the output of NOx, while the loss amount of NOx has been unknown, especially loss process of NOx in nighttime. The main loss process in nighttime is (1) reaction of NO3 with volatile organic compounds (VOCs) and (2) heterogeneous reaction of N2O5 with aerosol. Loss amount of NOx by these reactions depend on the property of VOCs, diameter and component of aerosol, seasonal and geophysical conditions.
My research is the measurements of NO3 and N2O5 related with the loss process of NOx, and some trace species such as ozone, NO, NO2, VOCs and aerosol in nighttime. These measurements provide me the information about the loss amount of NOx during nighttime. I am trying to the measurements for each season and some places to know the dependence of the loss amount of NOx on the seasonal and geophysical conditions.
Reference articles and patents
・Yoshihiro Nakashima, Charlotte E. Jones, Wakana Yamanobe, Yoshizumi Kajii, "Near-Surface Vertical Profiles of Urban Roadside NOx and Fine Particles", Aerosol and Air Quality Research, 14, 1763-1768, (2014)
・Yoshihiro Nakashima, Shungo Kato, Jim Greenberg, Peter Harley, Thomas Karl, Andrew Turnipseed, Eric Apel, Alex Guenther, Jim Smith, Yoshizumi Kajii, "Total OH reactivity measurements in ambient air in a southern Rocky Mountain ponderosa pine forest during BEACHON-SRM08 summer campaign", Atmospheric Environment, 85, 1-8, (2014).
・S. Kim, G. M. Wolfe, L. Mauldin, C. Cantrell, A. Guenther, T. Karl, A. Turnipseed, J. Greenberg, S. R. Hall, K. Ullmann, E. Apel, R. Hornbrook, Y. Kajii, Y. Nakashima, F. N. Keutsch, J. P. DiGangi, S. B. Henry, L. Kaser, R. Schnitzhofer, M. Graus, A. Hansel, W. Zheng, and F. F. Flocke, "Evaluation of HOx sources and cycling using measurement-constrained model calculations in a 2-methyl-3-butene-2-ol (MBO) and monoterpene (MT) dominated ecosystem", Atmos. Chem. Phys., 13, 2031-2044, (2013)
・Y. Nakashima, H. Tsurumaru, T. Imamura, I. Bejan, J. C. Wenger, Y. Kajii, "Total OH reactivity measurements in laboratory studies of the photooxidation of isoprene", Atmospheric Environment, 62, 243-247, (2012)
・J. P. DiGangi, S. B. Henry, A. Kammrath, E. S. Boyle, L. Kaser, R. Schnitzhofer, M. Graus, A. Turnipseed, J-H. Park, R. J. Weber, R. S. Hornbrook, C. A. Cantrell, R. L. Maudlin III, S. Kim, Y. Nakashima, G. M. Wolfe, Y. Kajii, E.C. Apel, A. H. Goldstein, A. Guenther, T. Karl, A. Hansel, and F. N. Keutsch, "Observations of glyoxal and formaldehyde as metrics for the anthropogenic impact on rural photochemistry", Atmos. Chem. Phys., 12, 9529-9543, (2012)
・A. Yoshino, Y. Nakashima, K. Miyazaki, S. Kato, J. Suthawaree, N. Shimo, S. Matsunaga, S. Chatani, E. Apel, J. Greenberg, A. Guenther, H. Ueno, H. Sasaki, J. Hoshi, H. Yokota, K. Ishii, Y. Kajii, "Study of air quality in urban central Tokyo - Comprehensive observations of total OH reactivity and reactive trace species", Atmospheric Environment, 49, 51-59, (2012)
・Y. Nakashima, N. Kamei, S. Kobayashi, Y. Kajii, "Total OH reactivity and VOC analyses for gasoline vehicular exhaust with a chassis dynamometer", Atmospheric Environment, 44, (2010), 468-475
Contact
University Research Administration Center(URAC),
Tokyo University of Agriculture andTechnology
urac[at]ml.tuat.ac.jp
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