日前,，最新一期雜志Nature Geoscience刊登了法國和比利時(shí)研究人員的一項(xiàng)最新研究成果"Satellite evidence for a large source of formic acid from boreal and tropical forests"，研究人員發(fā)現(xiàn)北方森林和熱帶森林會產(chǎn)生大量甲酸,，從而降低這些地區(qū)降雨的PH值,，帶來酸雨污染。
硝酸和硫酸是造成酸雨污染的“元兇”,，但偏遠(yuǎn)地區(qū)的酸雨主要由甲酸造成,。根據(jù)科學(xué)家早先的認(rèn)識，人類活動(dòng),、森林火災(zāi)以及植物的葉子可直接向大氣中釋放甲酸,，此外,，有機(jī)物的光化學(xué)降解也會產(chǎn)生這種物質(zhì)。
法國和比利時(shí)研究人員發(fā)現(xiàn),，全球森林每年可制造近1億噸甲酸,，比已知的甲酸產(chǎn)生途徑多出兩到三倍。研究人員根據(jù)歐洲航天局和歐洲氣象衛(wèi)星組織的衛(wèi)星所攜紅外線大氣探測干涉儀發(fā)回的數(shù)據(jù)建立模型,，發(fā)現(xiàn)全球每年可產(chǎn)生1億至1.2億噸甲酸,，其中90%經(jīng)由生物途徑產(chǎn)生，而且大部分集中在北方森林和熱帶森林地區(qū),。
該報(bào)告說,，森林中的松柏植物會釋放出一些不穩(wěn)定的萜類有機(jī)化合物，這些有機(jī)物在氧化過程中會釋放甲酸,，從而降低相應(yīng)地區(qū)降雨的PH值,。（生物谷Bioon.com）
doi:10.1038/ngeo1354
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Satellite evidence for a large source of formic acid from boreal and tropical forests
T. Stavrakou,J-F. Müller,J. Peeters,A. Razavi,L. Clarisse,C. Clerbaux,P-F. Coheur,D. Hurtmans,M. De Mazière,C. Vigouroux,N. M. Deutscher,D. W. T. Griffith,N. Jones& C. Paton-Walsh
Formic acid contributes significantly to acid rain in remote environments1, 2. Direct sources of formic acid include human activities, biomass burning and plant leaves. Aside from these direct sources, sunlight-induced oxidation of non-methane hydrocarbons (largely of biogenic origin) is probably the largest source3, 4. However, model simulations substantially underpredict atmospheric formic acid levels5, 6, 7, indicating that not all sources have been included in the models. Here, we use satellite measurements of formic acid concentrations to constrain model simulations of the global formic acid budget. According to our simulations, 100–120?Tg of formic acid is produced annually, which is two to three times more than that estimated from known sources. We show that 90% of the formic acid produced is biogenic in origin, and largely sourced from tropical and boreal forests. We suggest that terpenoids—volatile organic compounds released by plants—are the predominant precursors. Model comparisons with independent observations of formic acid strengthen our conclusions, and provide indirect validation for the satellite measurements. Finally, we show that the larger formic acid emissions have a substantial impact on rainwater acidity, especially over boreal forests in the summer, where formic acid reduces pH by 0.25–0.5.
