The vertical evolution of volatile organic compounds vary between winter and summer

February 15, 2021

Scientists have discovered that pollution concentration varies between seasons. A new study, conducted in the North China Plain, determined where volatile organic compounds (VOCs) are distributed within the vertical layers of the atmosphere, and found notable changes from winter to summer.

"The concentration of VOCs in the vertical direction was much higher in winter than that in summer and their emission sources showed different contributions in both seasons," said Guiqian Tang, associate professor in the Institute of Atmospheric Physics, Chinese Academy of Sciences, and the corresponding author of a study just published in Advances in Atmospheric Sciences .

The researchers conducted a field campaign from June 8 to July 3, 2019. They focused on VOCs, which react with nitrogen oxides and carbon monoxide to produce excess ozone (O3), a notable greenhouse gas. The most serious photochemical and VOC pollution in the North China Plain is concentrated near the city of Shijiazhuang, where the team chose to conduct their research.

"Photochemical pollution in summer over the North China Plain is a serious problem, but the mechanisms are not fully understood," said Dr. Tang. He also cited the importance of analyzing the vertical layers of the atmosphere to understand how VOCs evolve vertically and contribute to O3 formation.

Researchers used a tethered balloon, which was better suited than tower, aircraft, and unmanned aerial vehicles for low altitude observations below 1000 m. The balloon explored the vertical evolution of VOCs in the atmospheric boundary layer near the surface.

"Our findings in this campaign were compared with the results of our winter observations from January 2019. It showed that the VOC concentrations and proportions in winter and summer exhibited significant differences vertically," Dr. Tang said.

The total VOC concentration was relatively uniform through the year below 600 m, slightly increasing from 600 m to 1000 m through summer. Alkanes were the largest chemical species in both winter and summer, according to the researchers. These VOCs result from gasoline combustion in vehicles and industrial sources, and accounted for the largest proportion of VOCs that gradually increased at each sampling height.

"We should take measures to improve oil quality to limit exhaust emissions of motor vehicles to reduce VOC pollution," said Dr. Tang. He and his collaborators showed that gasoline emissions from vehicles should be controlled at the surface. Meanwhile, the effects of reducing VOC-based industrial pollution is most impactful at high altitudes.

Soon, researchers also plan to observe the vertical evolution of nitrogen oxides to further explore the formation mechanisms of O3. Nitrogen oxides and carbon monoxide present in the atmosphere are critical components in the reaction that produces ozone in the lower atmosphere.

Institute of Atmospheric Physics, Chinese Academy of Sciences

Related Nitrogen Articles from Brightsurf:

Chemistry: How nitrogen is transferred by a catalyst
Catalysts with a metal-nitrogen bond can transfer nitrogen to organic molecules.

Illinois research links soil nitrogen levels to corn yield and nitrogen losses
What exactly is the relationship between soil nitrogen, corn yield, and nitrogen loss?

Reducing nitrogen with boron and beer
The industrial conversion of nitrogen to ammonium provides fertiliser for agriculture.

New nitrogen products are in the air
A nifty move with nitrogen has brought the world one step closer to creating a range of useful products -- from dyes to pharmaceuticals -- out of thin air.

'Black nitrogen'
In the periodic table of elements there is one golden rule for carbon, oxygen, and other light elements.

A deep dive into better understanding nitrogen impacts
This special issue presents a selection of 13 papers that advance our understanding of cascading consequences of reactive nitrogen species along their emission, transport, deposition, and the impacts in the atmosphere.

How does an increase in nitrogen application affect grasslands?
The 'PaNDiv' experiment, established by researchers of the University of Bern on a 3000 m2 field site, is the largest biodiversity-ecosystem functioning experiment in Switzerland and aims to better understand how increases in nitrogen affect grasslands.

Reducing reliance on nitrogen fertilizers with biological nitrogen fixation
Crop yields have increased substantially over the past decades, occurring alongside the increasing use of nitrogen fertilizer.

Flushing nitrogen from seawater-based toilets
With about half the world's population living close to the coast, using seawater to flush toilets could be possible with a salt-tolerant bacterium.

We must wake up to devastating impact of nitrogen, say scientists
More than 150 top international scientists are calling on the world to take urgent action on nitrogen pollution, to tackle the widespread harm it is causing to humans, wildlife and the planet.

Read More: Nitrogen News and Nitrogen Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to