熱帯雨林が維持する大気酸化能力
J Lelieveld1, T M Butler, J N Crowley
1Max Planck Institute for Chemistry, 27 Becherweg, 55128 Mainz, Germany. lelieveld@mpch-mainz.mpg.de
Nature
|April 11, 2008
まとめ
熱帯雨林は,驚くほど高い大気中のヒドロキシルラジカル (OH) レベルを維持する揮発性有機化合物 (VOC) を放出します. これは,原始的な環境でも,大気の自己浄化のための自然なメカニズムを示唆しています.
科学分野:
- 大気化学 大気化学
- バイオジオケミストリー バイオジオケミストリー
- 環境科学 環境科学
背景:
- 陸上の植生,特に熱帯雨林は,大気中に大量に揮発性有機化合物 (VOC) を放出しています.
- 大気中の酸化は主にヒドロキシルラジカル (OH) によって引き起こされ,これらのVOCを除去します.
- 以前は,バイオジェニックのVOCは汚染されていない空気中のOHを枯渇させ,大気中の酸化能力を低下させると考えられていた.
研究 の 目的:
- アマゾンの熱帯雨林の上空における大気中の微量ガス濃度を調査するために.
- 予想外の高濃度のヒドロキシルラジカル (OH) を理解するために観察した.
- 低窒素酸化物 (NOx) 環境における大気酸化能力の維持における生物学的VOC酸化の役割を調査する.
主な方法:
- アマゾンの森林上空における大気中の微量ガスに関する航空機による測定.
- 大気化学モデリング.
- イソプレンの酸化機構を調査する実験室での実験.
主要な成果:
- 原始的なアマゾンの大気中に,予想外の高濃度のヒドロキシルラジカル (OH) が観察されました.
- 自然に発生するVOC,特にイソプレンの酸化が,低NOx条件下ではOHを効率的にリサイクルすることを提案した.
- モデル計算と実験室の結果は,イソプレン酸化におけるOHリサイクル効率が40~80%であることを示唆しており,観測された高いOH濃度を説明しています.
結論:
- 生物圏は,効率的なOHリサイクルを通じて大気中の酸化バランスを維持する上で重要な役割を果たしています.
- バイオジェニックのVOC酸化は,遠隔の汚染されていない地域でも,大気化学を調節する重要な要因です.
- イソプレン酸化におけるOHリサイクルの背後にある化学的メカニズムを完全に解明するために,さらなる研究が必要である.
関連する概念動画
Oxygenic Photosynthesis
Oxygenic photosynthesis is a fundamental process in which light energy is harnessed to drive the oxidation of water, leading to the production of molecular oxygen (O₂), adenosine triphosphate (ATP), and nicotinamide adenine dinucleotide phosphate (NADPH). This process is essential for sustaining aerobic life on Earth and is primarily carried out by cyanobacteria, algae, and plants. The core of oxygenic photosynthesis lies in the thylakoid membranes, where chlorophyll pigments facilitate light...
Carbon-dioxide Fixation
Carbon dioxide fixation in prokaryotes enables the assimilation of inorganic carbon into organic molecules, supporting biosynthetic pathways, sustaining ecosystems, and contributing to the global carbon cycle. It also has industrial applications in carbon capture and bioproduct synthesis. Autotrophic organisms rely on this process to utilize CO₂ as a carbon source in diverse environments.The Calvin CycleThe Calvin cycle is the most widespread carbon fixation mechanism, primarily used by...
The Carbon Cycle
Carbon is the basis of all organic matter on Earth, and is recycled through the ecosystem in two primary processes: one in which carbon is exchanged among living organisms, and one in which carbon is cycled over long periods of time through fossilized organic remains, weathering of rocks, and volcanic activity. Human activities, including increased agricultural practices and the burning of fossil fuels, has greatly affected the balance of the natural carbon cycle.
The Sulfur Cycle
Sulfur, an important element in the chemical makeup of proteins, is recycled through the atmosphere and aquatic and terrestrial environments. Found in the atmosphere as sulfur dioxide (SO2), sulfur is released by decaying organisms, weathered rocks, geothermal vents, volcanos, and burning fossil fuels. It is deposited into the ecosystem, cycled through the biotic community, and either released back into the atmosphere as gas or deposited in marine sediment for long-term storage and eventual...
Trophic Efficiency
Trophic level transfer efficiency (TLTE) is a measure of the total energy transfer from one trophic level to the next. Due to extensive energy loss as metabolic heat, an average of only 10% of the original energy obtained is passed on to the next level. This pattern of energy loss severely limits the possible number of trophic levels in a food chain.
Oxidation and Reduction of Organic Molecules
Energy production within a cell involves many coordinated chemical pathways. Most of these pathways are combinations of oxidation and reduction reactions, which occur at the same time. An oxidation reaction strips an electron from an atom in a compound, and the addition of this electron to another compound is a reduction reaction. Because oxidation and reduction usually occur together, these pairs of reactions are called redox reactions.
The removal of an electron from a molecule, results in a...
The removal of an electron from a molecule, results in a...


