中国治霾有救了?伦敦雾霾之谜终于揭晓

2016-11-22 能源圈 能源圈 能源圈

最近看到了一篇国外的媒体报道,是一篇研究者揭示1952年伦敦”毒雾”成因的文章,以下为原文:

(文章下方有中文哦!)

In 1952, a mysterious fog swept through London, blanketing the city in a dense layer of pollutants that killed thousands of people and animals and made it difficult to breathe for days.


While the exact cause has long remained unknown, an international team of researchers now says its solved the mystery – and the same air chemistry can be seen today in China and other areas.


In a new analysis, the researchers have pinpointed the chemical processes that combined with natural fog as a result of coal burning, eventually creating a deadly acidic haze that turned the sky completely dark.

 

Researchers have pinpointed the chemical processes that combined with natural fog as a result of coal burning, eventually creating a deadly acidic haze that turned the sky completely dark


THE KILLER FOG REVEALED


Using data from modern pollution in China, researchers have determined that the catastrophic event was the result of sulfuric acid particles mixing with natural fog to cover the entire city.


According to the researcher, a similar chemistry frequently occurs in modern China, which hosts 16 of the world’s most polluted cities.


When the fog first rolled through in December of 1952, residents took little notice; fogs have long enveloped the city.


But in the days to follow, visibility was reduced to just three feet in some areas, transportation was shut down, and thousands of people suffered from breathing problems.


After the devastating event, it was thought that at least 4,000 people had died, along with thousands of animals, and more than 150,000 people were hospitalized.


Later studies, however, estimate that the death count may actually have exceeded 12,000.


Now, using data from modern pollution in China, researchers have determined that the catastrophic event was the result of sulfuric acid particles mixing with natural fog to cover the entire city.


‘People have known that sulfate was a big contributor to the fog, and sulfuric acid particles were formed from sulfur dioxide released by coal burning for residential use and power plants, and other means,’ says Renyi Zhang, University Distinguished Professor and the Harold J. Haynes Chair of Atmospheric Sciences and Professor of Chemistry at Texas A&M University.


‘But how sulfur dioxide was turned into sulfuric acid was unclear.


The deadly fog first rolled in during December of 1952.


It enveloped London in a thick blanket of pollutants, reducing visibility to just three feet in some areas and causing transportation to shut down.


According to researchers, the sky during this time turned completely dark and thousands of people suffered from breathing problems.


The fog finally lifted on December 9, but at the time, it was thought that at least 4,000 people had died, along with thousands of animals, and more than 150,000 people were hospitalized.


Later studies, however, estimate that the death count may actually have exceeded 12,000.


While it’s long been known that coal burning was the cause, researchers have struggled to identify the exact chemical processes that made this event, also known as the Great Smog of 1952, so deadly.

 

When the fog first rolled through in December of 1952, residents took little notice; fogs have long enveloped the city. The image reveals heavy smog in Piccadilly Circus, London, 6th December 1952


'Our results showed that this process was facilitated by nitrogen dioxide, another co-product of coal burning, and occurred initially on natural fog.

‘Another key aspect in the conversion of sulfur dioxide to sulfate is that it produces acidic particles, which subsequently inhibits this process.


'Natural fog contained larger particles of several tens of micrometers in size, and the acid formed was sufficiently diluted.


‘Evaporation of those fog particles, then left smaller acidic haze particles that covered the city.’


According to the researcher, a similar chemistry frequently occurs in modern China, which hosts 16 of the world’s most polluted cities.

 

A man feels his way cautiously from the pavement to the Underground in Westminster in 1952, battling through the haze that enveloped the city.

But, China’s pollution problem is not exactly the same.


The country has experienced massive industrial and manufacturing growth over the past few decades, and the emissions largely come from power plants, automobiles, and fertilizers.


‘The difference in China is that the haze starts from much smaller nanoparticles, and the sulfate formation process is only possible with ammonia to neutralize the particles,’ Zhang said.


‘In China, sulfur dioxide is mainly emitted by power plants, nitrogen dioxide is from power plants and automobiles, and ammonia comes from fertilizer use and automobiles.

 

Charles Chaplin (Charlie Chaplin, 1889-1977) pictured with his wife Oona (1926-1991) on the roof of the London hotel (unnamed) where they were staying in 1952.Behind them, the haze is clearly visible


‘Again, the right chemical processes have to interplay for the deadly haze to occur in China. Interestingly, while the London fog was highly acidic, contemporary Chinese haze is basically neutral.’


The 1952 event is considered to be the deadliest air pollution event in European history, and spurred the passage of the Clean Air Act in 1956 by British Parliament.


And, while China has been making attempts in recent years to cut back on its emissions, the researchers note that the poor air quality still often necessitates breathing masks during much of the day.


Tourists wearing masks in Temple of Heaven in haze-covered Beijing, China. Studies show pollution is causing the deaths of up to 500,000 people in the country a year.


By solving the mystery of the London fog, they say they may also have uncovered insight that could help in China.


‘A better understanding of the air chemistry holds the key for development of effective regulatory actions in China,’ Zhang said.


‘The government has pledged to do all it can to reduce emissions going forward, but it will take time.


‘We think we have helped solve the 1952 London fog mystery and also have given China some ideas of how to improve its air quality.


‘Reduction in emissions for nitrogen oxides and ammonia is likely effective in disrupting this sulfate formation process.’


 看不懂英文没关系


 以下为能源圈结合上述文章以及中国雾霾情况论述观点


1952年伦敦曾出现严重雾霾天气,最终导致1.2万人死于空气污染。当时的媒体是这样描写持续5天的伦敦雾霾事件:浓重的雾霾吞噬了汽车,车速甚至不如秉烛前进的行人;电影院被迫关门,因为能见度还不到前几排;歌唱家因为突发咽喉不适而无法登台演出;肮脏的雾霾钻入室内,也钻入伦敦人的肺里,大批心脏病、哮喘和支气管疾病患者因得不到及时治疗而死去。伦敦雾霾事件被视为欧洲历史上最严重的污染事件之一。




如今,一个国际科研组终于揭开了伦敦雾霾事件之谜。


西班牙《阿贝赛报》11月17日报道,虽然众所周知,导致死亡的罪魁祸首是碳排放,但60年来产生致命雾霾的具体化学反应过程尚不清楚。


美国得克萨斯农业与机械大学张人一教授率领来自中国、美国、以色列和英国等国的国际研究组在美国《国家科学院学报》发表报告,指出了导致这一事件的具体化学反应过程。




1952年12月5日当雾霾笼罩伦敦时,起初市民并未感到意外,因为对于厚重的雾霾他们早已习以为常。然而随着时间推移,情况愈发严重,伦敦在接下来的日子一直暗无天日。凛冽的寒风迫使人们烧很多煤炭取暖,来自工厂、汽车和家庭的浓烟聚集在城市上空。加之缺少大风的帮助,雾霾久久不散。


查理·卓别林(Charlie Chaplin,1889-1977)图为他与妻子Oona(1926-1991)在伦敦酒店的屋顶,在他们身后,烟雾清晰可见。


在伦敦的很多地方能见度都降低到1米以下,交通陷入瘫痪,上万人出现呼吸问题。12月9日当雾霾消散时,死亡人数达到4000人,还有超过15万人入院治疗。英国最新调查显示,当时死亡人数将近1.2万人。此外,还有大量牲畜死亡。  此次伦敦雾霾事件迫使英国政府于1956年出台了世界上首部治理空气污染的《清洁空气法案》。



伦敦的公共汽车行驶在充满烟雾的舰队街


得益于在中国进行的实验和数据测量,张人一教授领导的国际研究组成功发现了其中奥秘。张教授指出,过去已知的是,硫酸盐是导致雾霾的罪魁祸首之一,而碳废气当中的二氧化硫具有酸性,可与空气中的其他物质反应,会生成微小的亚硫酸盐和硫酸盐颗粒。但二氧化硫如何形成亚硫酸盐和硫酸盐颗粒的过程并不清楚。国际研究组的研究结果显示,碳废气当中的另一种物质——二氧化氮为这一过程提供了条件。普通的雾颗粒直径约为几十微米。但雾接下来的蒸发过程会留下更小的颗粒,于是就形成了笼罩城市上空的雾霾。


研究显示,中国也经常发生类似情况。虽然中国一直在努力治理污染,但在全世界20座污染最严重的城市当中依然有16座位于中国。北京经常打破美国环境保护署制定的空气标准。实际上,11月17日北京刚刚拉响首个重污染“橙色预警”。当局建议老人、儿童和患有呼吸疾病的患者减少外出。由于供暖已经开始,而且近日少风,北京已经陷入一片雾霾之中。




在中国,二氧化硫主要来自工厂,二氧化氮主要来自发电站和汽车尾气,氨气则来自肥料和汽车尾气。可能生成致命雾霾的化学反应过程再次在中国出现。


不同的是,半个世纪前伦敦雾霾的酸性很高,但中国现在的雾霾却偏中性。许多中国城市如今正在经历与伦敦雾霾事件类似的情况,唯一的区别是,中国尚未出现当年那么惨痛的后果。


最近10年来中国当局一直致力于解决空气污染问题,但是糟糕的空气依然迫使很多人戴上防霾口罩。25年间工业、制造业以及城市化的飞速发展导致中国出现严重的污染问题。


张人一教授表示,深入理解空气化学过程有助于中国采取有效的治理污染行动。他还相信,随着伦敦雾霾事件之谜被揭开,中国将获得如何改善空气质量的灵感。减少二氧化氮和氨气的排放或许能够中断生成硫酸盐颗粒的反应过程。


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