Journal information: Proceedings of the National Academy of Sciences © 2014 Phys.org China censors US embassy pollution data during APEC More information: Elucidating severe urban haze formation in China, PNAS, by Song Guo, DOI: 10.1073/pnas.1419604111AbstractAs the world’s second largest economy, China has experienced severe haze pollution, with fine particulate matter (PM) recently reaching unprecedentedly high levels across many cities, and an understanding of the PM formation mechanism is critical in the development of efficient mediation policies to minimize its regional to global impacts. We demonstrate a periodic cycle of PM episodes in Beijing that is governed by meteorological conditions and characterized by two distinct aerosol formation processes of nucleation and growth, but with a small contribution from primary emissions and regional transport of particles. Nucleation consistently precedes a polluted period, producing a high number concentration of nano-sized particles under clean conditions. Accumulation of the particle mass concentration exceeding several hundred micrograms per cubic meter is accompanied by a continuous size growth from the nucleation-mode particles over multiple days to yield numerous larger particles, distinctive from the aerosol formation typically observed in other regions worldwide. The particle compositions in Beijing, on the other hand, exhibit a similarity to those commonly measured in many global areas, consistent with the chemical constituents dominated by secondary aerosol formation. Our results highlight that regulatory controls of gaseous emissions for volatile organic compounds and nitrogen oxides from local transportation and sulfur dioxide from regional industrial sources represent the key steps to reduce the urban PM level in China. (Phys.org) —A combined team of researchers from the U.S. and China has found a direct link between gaseous pollutants from motorized vehicles and industrial emissions and the thick haze that often covers the Chinese capital. In their paper published in the Proceedings of the National Academy of Sciences, the team describes their study which included taking air samples over a long period of time and what they found in analyzing the data. Citation: Study shows Beijing haze linked directly to gaseous pollutants from traffic, industrial emissions (2014, November 25) retrieved 18 August 2019 from https://phys.org/news/2014-11-beijing-haze-linked-gaseous-pollutants.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Most people have heard of the air pollution problems going on in China—the country is home to 16 of the 20 most polluted cities in the world. Getting the most attention, has been Beijing, the country’s capital and host of the 2008 summer Olympics. In this new effort the joint research team sought to better understand why Beijing, and perhaps other Chinese cities have such serious air pollution problems.It doesn’t take much looking to find that the pollution in Beijing comes mostly from cars, coal fired utility plants and other manufacturing and industrial operations. But, the team noted, taken together, they didn’t appear to account for the level of haze that covers the city on a periodic basis. To learn more, they used new state-of-the-art equipment to take air samples from October to December of last year.In studying the data, they found that the amount of fine particulate matter (the basis of haze) was more than was produced by the primary sources. Further study revealed that photochemical oxidation of gaseous pollutants was resulting in the formation of fine particulates, adding to the overall amount. Furthermore, they found that atmospheric conditions played a larger role in the development of heavy haze days than was previously thought. Wind, they noted, carried pollution from the south, where there are many coal fired plants, to the city, causing higher levels of haze. It also accounted for the cyclic nature of haze days in the city. Also, the team noted that there were fewer heavy hazy days in the summer because the city gets more rain then which tends to clean the air.The researchers believe their findings are likely applicable to other cities in China and suggest that the only way to solve the air pollution problems in that country is to reduce the amount of pollutants emitted into the air. Explore further Campus view of Peking University on clean and polluted days. Credit: Song Guo and Min Hu, Peking University.
Tag Archives: 儋州桑拿
Go back to the e-newsletter >Book the Victoria Palace Hotel in Paris for four nights or more and receive 15% commission. In addition, your clients will receive reduced rates. Promotional rates start at €263.00 per night in a Superior Room and €280.00 per night in a Deluxe Room. These rates include tax, Wi-Fi and breakfast.Other exclusive extras include:Ask for the ‘Foodies Discovery Trail’ for a chance to experience and taste the wonderful local produce.TAPER welcome: advise us of your booking and we will place a personal welcome note from YOU and a small dish of chocolates in your client’s room on arrival.All children aged four-12 staying at least two nights will receive a special gift: a ‘Cornet Surprise’ full of sweets and small toys and a welcome picture book introducing them to the French language signed by the hotel owner.Rollaway beds confirmed at time of booking. Cots are complimentary for children up to two years old. An extra bed for a third person from three years to adult is 51 Euros per night.Interconnecting rooms can be confirmed and guaranteed at time of booking.*Rates are inclusive of daily buffet breakfast and government taxes (excluding city tax of 3.30 EUR per person, per day). Please note the four night promotion is not valid for stays during high season including 9 May – 13 July and 5 Sept – 28 October 2016. Blackout dates apply.Go back to the e-newsletter >