除草剤に含まれる有害な化学物質が空気中に拡散することを示す研究結果(Study shows hazardous herbicide chemical goes airborne)

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アミン類は、人体や環境の健康に悪影響を及ぼす可能性があります。 Amines can negatively affect human, environmental health

2022-10-27 ワシントン大学セントルイス

ジカンバのドリフトとは、除草剤ジカンバが大気中を作物から移動することで、意図せず近隣の植物に被害を与える可能性がある。ジカンバのドリフトを防ぐため、ジカンバに他の化学物質(通常はアミン)を混合し、ジカンバを「固定」して、大気中を移動しやすい蒸気に変化するのを防いでいる。
アミン類は他の除草剤にも使用されており、世界で最も使用されている除草剤であるグリホサートにも使用されている。しかし、どの除草剤であっても、アミンが揮発することは確認された。

<関連情報>

除草剤塩からのアミン揮発。除草剤製剤と大気化学への影響 Amine Volatilization from Herbicide Salts: Implications for Herbicide Formulations and Atmospheric Chemistry

Stephen M. Sharkey, Anna M. Hartig, Audrey J. Dang, Anamika Chatterjee, Brent J. Williams, and Kimberly M. Parker
Environmental Science and Technology  Published:September 23, 2022
DOI:https://doi.org/10.1021/acs.est.2c03740

Abstract

Amines are frequently included in formulations of the herbicides glyphosate, 2,4-D, and dicamba to increase herbicide solubility and reduce herbicide volatilization by producing herbicide–amine salts. Amines, which typically have higher vapor pressures than the corresponding herbicides, could potentially volatilize from these salts and enter the atmosphere, where they may impact atmospheric chemistry, human health, and climate. Amine volatilization from herbicide–amine salts may additionally contribute to volatilization of dicamba and 2,4-D. In this study, we established that amines applied in herbicide–amine salt formulations undergo extensive volatilization. Both dimethylamine and isopropylamine volatilized when aqueous salt solutions were dried to a residue at ∼20 °C, while lower-vapor pressure amines like diglycolamine and n,nbis-(3-aminopropyl)methylamine did not. However, all four amines volatilized from salt residues at 40–80 °C. Because amine loss typically exceeded herbicide loss, we proposed that neutral amines dominated volatilization and that higher temperatures altered their protonation state and vapor pressure. Due to an estimated 4.0 Gg N/yr applied as amines to major U.S. crops, amine emissions from herbicide–amine salts may be important on regional scales. Further characterization of worldwide herbicide–amine use would enable this contribution to be compared to the 285 Gg N/yr of methylamines emitted globally.

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