**: China Science Daily.
Oil sands in Alberta, Canada. A new study led by Drew Gentner, an environmental engineer at Yale University in the United States, and John Liggio, a chemist at Canada's Federal Agency for Environment and Climate Change (ECCC), shows that according to aircraft measurements, Canada's controversial oil-producing oil sands emit a large amount of polluting gases, affecting air quality, and releasing more polluting gases than large cities such as Los Angeles, about the same as the sum of other anthropogenic emission sources in Canada. Including automotive traffic and other industrial emissions. The data shows that the pollution detected this time is 20 64 times higher than reported by the standard monitoring technology industry. The study was published Jan. 25 in Science.
The study used a new method to measure all carbon-based molecules in the air above the oil sands in Alberta. The researchers excluded greenhouse gases such as carbon dioxide and tracked only molecules that had an important impact on air quality, many of which had never been monitored in the oil sands before. These carbon-based gases can sow particulate-polluted seeds in the air and react with other chemicals to form ground-level ozone.
Liggio said the ECCC is working with partners to determine how the findings will improve the approach to oil sands use. Mark Cameron, spokesperson for the Calgary Alliance, Canada's largest oil sands company, said: "The oil sands industry uses the standards set by the ECCC to measure emissions, and we look forward to working together to explore opportunities to further improve measurement practices. ”
Canada's oil sands contain a lot of oil, making Canada the third largest oil reserve country after Saudi Arabia and Venezuela. Since the 60s of the 20th century, many companies have been extracting this oil, but it is locked in viscous tar sands, so the process is energy and water intensive. Oil production has surged to more than 3 million barrels per day, or about 3% of Canada's gross domestic product.
The environmental impact of large-scale oil extraction operations has made it an international target. Global Forest Watch Canada, a nonprofit organization, estimates that 770,000 hectares of forest have been cut down or degraded by the industry since 2000. Extracting oil requires additional energy, which means that each barrel of oil sands produces more greenhouse gases than conventional oil. The huge tailings pond where the residues from the refining process are stored has leaked, which has raised concerns, especially for local residents living downstream.
Air quality is not usually considered one of the main issues in tar sands mining. Researchers have previously noted high concentrations of particulate pollutants known as secondary organic aerosols in the air downwind of the tar sands, similar to those found downwind in major cities such as Mexico City. As a result, they began to identify and measure the carbon-based gas emissions that lead to aerosol formation.
Most reports on organic emissions focus on only a subclass of volatile organic compounds, which evaporate easily and are often thought to be responsible for much of the air pollution, according to the research team. The latest study uses a more commonly used method and also looks at semi-volatile and low-volatile compounds that do not evaporate easily. The research team noted that the entire collection could include thousands of compounds, ranging from small molecules like acetone to heavy carbon-based molecules that may be found in diesel fuel.
The research team collected data from 30 flights across 17 oil sands operations in 2018. Specific organic compounds are also measured and identified, both to understand what makes up the emission mixture and to remove background levels of carbon dioxide, methane and carbon monoxide from the measurement. The researchers say this approach can also be used for more comprehensive emissions monitoring in other industries.
These findings help paint a broader picture of oil sands pollution, complementing previous studies that have highlighted higher-than-expected methane emissions. Previously, the Liggio team reported that the greenhouse gas emissions of tar sands were about 30% higher than those measured by the industry using standard techniques. Liggio noted that Canada is working with industry and other partners to understand this difference. Xin Yu).
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