Cars may produce more climate-warming particles than previously thought

February 24, 2012 | Latest News

Black Carbon Belchers?

Pollution Monitoring: Cars may produce more climate-warming particles than previously thought
Department: Science & Technology
Keywords: black carbonsootmonitoringlaser spectral detectiondiesel enginesclimate change
Start Your Engines
Gasoline-burning cars produce more black carbon than suspected, according to a new study
Credit: Shutterstock
Tiny particles known as black carbon can pack a heavy punch when it comes to climate change, by trapping heat in the atmosphere and by alighting atop, and melting, Arctic ice. With an eye toward controlling these emissions, researchers have tracked black carbon production from fossil fuel combustion in gasoline-burning cars and diesel-burning trucks. Once thought to be minor players, gasoline-burning engines could put out twice as much black carbon as was previously measured, according to new field methods (Environ. Sci. Technol., DOI: 10.1021/es2033845).
Black carbon particles, which come from many combustion processes, have become a focus this month of an international agreement to control climate impacts from short-lived but powerful actors such as methane, hydrofluorocarbons, and black carbon (C&EN, Feb. 20, page 8). The new findings could lead to controls on gas-burning vehicles, long considered to produce less black carbon than diesel-burning trucks and cars.
A team of Canadian government scientists stumbled upon the hidden black carbon emissions after deploying a new laser-based method to monitor soot and other tiny particles in the chaos of traffic. In 2010, John Liggio and his colleagues fromEnvironment Canada and the National Research Council Canada deployed the new device along highways around Toronto.
The instrument’s pulsed laser beam heats black carbon particles up to thousands of degrees Celsius, making them light up like “red-hot glowing charcoal,” says project leader Jeffrey Brook. A photometer measures the brightness of the particles to estimate their mass in real time. The team compared their device to a commonly used single-particle analyzer, known as SP2, which they set out at the same time.
The researchers followed 30 heavy-duty, diesel-burning vehicles and collected samples of their exhaust. They found that the trucks belched out levels of black carbon similar to those documented by prior studies.
While the scientists were chasing trucks, stationary monitors measured particles moving downwind of the same multi-lane highways. Video monitoring helped the team track the number and types of vehicles passing by. After measuring the mass of black carbon as it fluctuated over 17 days, the scientists compared those data with estimates of total black carbon based on expected black carbon emissions of diesel- and gasoline-burning vehicles. But their estimates always fell short of the actual black carbon measurements.
Gasoline-burning vehicles would have to emit more to take up the slack, the researchers concluded. They calculated that such vehicles must emit about 75 mg of black carbon per kilogram of fuel, about twice the amount that other scientists have reported and that the SP2 measured. They surmised that, unlike the new device, other methods miss tiny black carbon particles as small as 7 nm.
Researchers should be aware of the limitations of SP2, an instrument that is growing in popularity despite its lower sensitivity, says Dan Lack of the National Oceanic and Atmospheric Administration. However, other monitoring techniques such as absorption filters can track smaller particles, he says. For now, the discovery of a hidden well of black carbon holds true only for the team’s Toronto sites, he points out.
Mark Jacobson of Stanford University comments that if the results hold true elsewhere, they “imply an even greater urgency for taking measures to reduce particle emissions from vehicles.”

Chemical & Engineering News
ISSN 0009-2347
Copyright © 2012 American Chemical Society

No comments:

Carbon Footprint Calculator

Notes to ponder

NASA claims that the government could slow down worldwide global warming by cutting down on soot emissions. Studies by NASA show that cutting down on soot would not only have an immediate cooling effect, but would also put a stop to many of the deaths caused by air pollution. When soot is formed, it typically travels through the air absorbing and releasing solar radiation which in turn begins to warm the atmosphere. Cutting soot emissions would be an immediate help against global warming, as the soot would quickly fall out of the atmosphere and begin to cool it down.

Cutting back on soot emissions would buy us time in our fight against global warming. Soot is caused by the partial burning of fossil fuels, wood and vegetation. Soot is known to contain over forty different cancer causing chemicals, and a complete cut would offer untold health benefits worldwide.

Environmental conservation has always been a topic for lengthy discussions, but up until recent times, global warming and climate changes were vague subjects, with no hard proof. Not surprisingly, the previous lack of attention to these issues have created a very gloomy outlook on our future. So, considering all this, what could be the biggest contributor to climate changes through global warming? Transportation - the man-made iron horses, flying machines and sea monsters, so to speak.

The question we have now is how green is our transportation? The majority of the worlds' vehicles are fueled by oil (petrol, diesel and kerosene). Even if they rely on electricity, the stations used to generate this electricity use fossil fuels for power! Excluding vehicle manufacture, transportation is responsible for 14% of the artificially created greenhouse emissions, mostly carbondioxide.

Automobiles, trains and planes are all responsible for this problem, but cars are the highest impact-makers. They release approximately six times more carbondioxide than a plane and seven times more than sea vessels.

What is Air Pollution?

Air pollution is somewhat difficult to define because many air pollutants, at low concentrations, are essential nutrients for the sustainable development of ecosystems. So, air pollution could be defined as:A state of the atmosphere, which leads to the exposure of human beings and/or ecosystems to such high levels or loads of specific compounds or mixtures thereof, that damage is caused. With very few exceptions, all compounds that are considered air pollutants have both natural as well as human-made origins.

Air pollution is not a new phenomenon; in Medieval times, the burning of coal was forbidden in London while Parliament was in session. Air pollution problems have dramatically increased in intensity as well as scale due to the increase in emissions since the Industrial Revolution.