雙語：中國霧霾主要污染物源頭發(fā)現(xiàn)

Scientists said Wednesday they have solved the perplexing puzzle of how a major smog component, known as sulfate, forms during haze events in northern China, including Beijing.

周三，科學家稱已經(jīng)解決了形成包括北京在內的中國北部霧霾天氣的一種重要的被稱作硫酸鹽的霧霾成分的形成謎團。

The study, published in the US journal Science Advances, identified reactive nitrogen chemistry and water particles in the air as the two missing pieces, suggesting that reducing nitrogen oxide (NOx) emission in particular may help curb China’s air pollution.

這項發(fā)布在美國期刊《科學進展》上的研究，認定活性氮化學物質和空氣中的水分子是兩大缺失部分，這暗示著，尤其是減少氮氧化物(NOx)排放可能有助于遏制中國的空氣污染。

The findings were based on an analysis of the January 2013 winter haze event in Beijing, one of the worst atmospheric pollution events ever recorded in China, which saw the daily concentration of fine particle called PM2.5 exceed the World Health Organization guideline value by 16 times.

這項研究發(fā)現(xiàn)基于2013年1月發(fā)生在北京的冬季霧霾，這是中國史上最糟糕的大氣污染事件之一，據(jù)觀測，被稱作PM2.5的微粒日濃度超過世界健康組織指南的16倍。

At that time, researchers performed aerosol measurements on the roof of a Tsinghua University building in Beijing and analyzed data throughout the surrounding regions.

當時，研究人員在北京清華大學建筑物的屋頂進行了氣溶膠測量，并分析了周圍地區(qū)的數(shù)據(jù)。

They identified a reaction pathway that could account for the missing source of sulfate, discovering that fine water particles in the air acted as an reactor, trapping sulfur dioxide (SO2) molecules and interacting with nitrogen dioxide (NO2) to form sulfate.

他們確定了一種可以解釋硫酸鹽缺失來源的反應途徑，發(fā)現(xiàn)空氣中的微粒充當反應器，捕獲二氧化硫(SO2)分子并與二氧化氮(NO2)相互作用形成硫酸鹽。

The reaction rate was further facilitated by stagnant weather in the 2013 haze event, which trapped NO2 near the Earth’s surface, resulting in NO2 concentrations that were three fold higher than clean conditions.

2013年霧霾事件期間，由于停滯的氣候，這一過程的反應速率進一步增加了，這使得地球表面的二氧化氮被困住，造成二氧化氮濃度是清潔條件下的三倍。

This process, according to the researchers, was "self-amplifying," as increasing aerosol mass concentrations led to higher aerosol water content -- accelerating the accumulation of sulfate and causing more severe haze pollution.

據(jù)研究員，這一過程是“自我放大的”， 氣溶膠質量濃度越高，氣溶膠含水量越高，加速了硫酸鹽的積聚，造成更加嚴重的霧霾天氣。

"This study unfolds the unique sulfate formation mechanism in NCP (North China Plain) haze events, which differs from traditional scenarios," study author Guangjie Zheng of Tsinghua University said in an email to Xinhua.

研究作者清華大學鄭廣杰在給新華社的郵件中寫道：“這一研究揭露了中國北部平原地區(qū)霧霾事件獨特的硫酸鹽形成機制，這和傳統(tǒng)情景不一樣。”

"In cleaner environments such as the US or Europe, sulfate is mainly formed through the traditional OH (hydroxide) reaction pathways in atmospheric gas phase, or the H2O2 (hydrogen peroxide) and O3 (Ozon) reaction pathways in cloud chemistry. In NCP haze events, however, the dominant sulfate formation pathway shifts into the NO2 reaction pathway in aerosol water."

“在美國或者歐洲這種更加清潔的環(huán)境中，硫酸鹽主要通過傳統(tǒng)的大氣氣相中的OH(氫氧化物)反應途徑或云化學中的H 2 O 2(過氧化氫)和O 3(Ozon)反應途徑形成。然而，在中國北部霧霾事件中，主要的硫酸鹽形成途徑變成了氣溶膠水中的NO 2反應途徑。”

Zheng said results in this research reveal "the complex nature" of haze pollution events in China.

鄭說，這項研究的結果揭示了中國霧霾污染事件的“復雜本質”。

"The SO2 comes mainly from power plants, NOx is from power plants and mobile vehicles, while the NH3 (ammonia) and mineral dusts, which serve as the neutralizing substances, are from both natural and anthropogenic emissions such as industry and fugitive dusts," she said.

她說：“SO2主要來自發(fā)電廠，NOx來自發(fā)電廠和移動車輛，而作為中和物質的NH3(氨)和礦物粉塵來自自然和人為排放，如工業(yè)和揚塵。”

"These pollutants from various sources were emitted in high intensity at the same time, resulting in the unique heavy haze conditions, and thus the shifting in the dominant sulfate formation pathway. The complexity of haze pollutions in NCP further illustrated the importance of scientific emission-reduction strategies."

“這些污染物來自各種同時高濃度排放的源頭，造成獨特的重霧霾情況，因此造成主要的硫酸鹽形成途徑的轉變。中國北部平原霧霾污染的復雜性進一步表明了科學減排戰(zhàn)略的重要性。”