- Author: UCLA News
Reposted from UCLA Samueli Engineering Newsroom
Drone sensors for deployment into a local ignition event Courtesy of Kevin Schwarm
Using new drone sensing technology, Schwarm has helped contribute to a new way of measuring the emissions of fires — carbon monoxide, carbon dioxide, particulates, volatile organic compounds, etc. — so researchers can gain a deeper understanding of the way wildfires behave.
When controlled properly, the so-called prescribed burns — fires that are intentionally set to clear out vegetation that otherwise could end up fueling larger, more catastrophic fires — can play a key role in maintaining the health of a forest. They help prevent the kinds of wildfires that have wiped out homes and caused devastating losses of lives across California in recent years.While setting fire to the forest mayseemcounterintuitive to the goal of preventing wildfires, it draws inspiration from Native American practices of setting controlled fires to improve the habitats for deer and other game animals.
Since the Gold Rush, however, the amount of plant life in forests in California has proliferated. While this growth is ostensibly good for the health of the forests, the extra vegetation actually increases the risk of extreme wildfires as it provides large amounts of fuel.
Located about 142 miles east of UC Berkeley on the western slope of the central Sierra Nevada, the 4,400-acre Blodgett Forest Research Station has been a living laboratory since 1933. In April, Rob York, an assistant Cooperative Extension specialist and adjunct associate professor of forestry at UC Berkeley, directed a field campaign involving four days of controlled burns. Scientists and forestry experts from other universities, including UCLA and UC Riverside, joined in the effort to reduce wildfire risk.
Working with engineers from OptoKnowledge, Schwarm was a part of several research teams in charge of measuring the emissions of the prescribed burns. They monitored the emissions using a drone that features on-board, optical sensors that can measure levels of airborne carbon monoxide and carbon dioxide. The team also used the data to create aerial maps that correlate the emissions with the fires, as well as other ground and air measurements.
Schwarm, whose doctoral research focuses on optical diagnostics for combustion systems and harsh environments, was responsible for monitoring the data collection, working with the optical sensor equipment and guiding the drone pilots during the tests.“The objective was to capture as much information as possible on the emissions of these fires and also to relate those to the burned vegetation that was inventoried beforehand,”saidSchwarm, who works in the lab ofMitchellSpearrin, a professor of mechanical and aerospace engineeringatUCLASamueli. “We are hoping that the results of this field campaign will help to further our understanding of wildfire combustion science, the role of wildfires in our local and global climate, and to help us develop more efficient wildfire management strategies.”
A Maine native who loves the outdoors, Schwarm was initially interested in research involving internal combustion engines when he first visited UCLA in 2017 as a prospective graduate student. After meeting Spearrin and learning about his research on laser diagnostics and combustion systems, Schwarm was intrigued and decided to join Spearrin's research group that fall.
“I found Professor Spearrin's research very compelling, with laser diagnostics providing an avenue for engine research while also remaining an elegantly simple yet powerful measurement tool with wide applicability,” Schwarm shared.
Last fall, Spearrin introduced Schwarm to the multicampus wildfire project. “I found it a very exciting opportunity to use our expertise in combustion diagnostics to play a role in enhancing our understanding of both wildfires and climate change, which could lead to better methods for managing these grave issues,” Schwarm said.
According to Schwarm, the preliminary results from emissions data collected during the field campaign indicate that the drone sensor was very effective in capturing the multi-dimensional gradients of emissions in the fire plumes.
The team has been able to create three-dimensional spatial maps of the emissions concentrations, tracking how they change over time. This finding provides the researchers with insight into how fires behave, such as where the boundaries of the fire are and where new ignition sites emerge.
“This is very exciting as a new sensor capability to provide a deeper level of information for a wide range of applications in wildfire science and management, and we are currently working with the other researchers involved in the burns to place that information into context,” Schwarm said. “This was the first full-scale, real-world test for our drone sensor, and it will serve as a strong foundation for future deployment and expansion of our methods.”
Sara Hubbard contributed to this story.
- Author: Sarah Nightingale
Reposted from University of California News
When plant matter burns, it releases a complex mixture of gases and aerosols into the atmosphere. In forests subject to air pollution, these emissions may be more toxic than in areas of good air quality, according to a new study by the University of California, Riverside and the U.S. Forest Service's Pacific Southwest Research Station.
The results suggest biomass burning of polluted forest fuels may exacerbate poor air quality—and related health concerns—in some of the world's most heavily polluted areas, among them, the Los Angeles metropolitan area, which is expected to suffer from more wildfires as drought conditions continue.
The study, which was led by Akua Asa-Awuku, a researcher at the Center for Environmental Research and Technology (CE-CERT) at UC Riverside's Bourns College of Engineering, was published online recently (March 2) in the journal Environmental Research Letters.
As people burn fuels—in cars, power plants and factories—nitrogen is released into the atmosphere and absorbed by plants. While essential for plant growth, an over-abundance of this biologically-available nitrogen can result in ‘nitrogen saturation,' a phenomenon previously reported by Forest Service scientists in Riverside. Nitrogen saturation can cause a cascade of adverse effects including a decrease in biodiversity, changes in plant species, soil acidification and water contamination.
In this paper, UCR and Forest Service researchers teamed up to explore a previously unstudied aspect of nitrogen saturation: its effect on the gases and aerosols released during burning of forest fuels from an area experiencing nitrogen saturation.
Polluted sites released up to 30 percent more nitrogen oxides than clean sites
Scientists conducted the study in the San Bernardino Mountains, a 60-mile stretch of federal and private forest land to the east of the Los Angeles metropolitan area. Since the pollution concentration decreases from west to east, as the distance from Los Angeles increases, the forests offered a rare opportunity to compare emissions from wildland fuels subjected to different levels of chronic air pollution. At sites 55 miles apart, the researchers collected recently deposited material from the forest floor, called litter, which is a primary fuel in these forests. Both sites have a similar mixture of conifer tree species, and, at the time of collection, had experienced similar temperatures and rainfall.
As shown in previous studies, the litter from the polluted site, which had endured high levels of atmospheric nitrogen oxides and ozone, had higher nitrogen content than litter from the clean site. The researchers then burned the litter in controlled lab tests, collected the emissions and analyzed them. The results showed:
- Fuel from the polluted site released more nitrogen oxides, which contribute to the formation of smog and ozone. In some cases, polluted fuels released 30 percent more nitrogen oxides than fuels from the clean site.
- Polluted fuels released more small fine particles (PM<2.5), which are known cause of respiratory health problems.
- The composition of the particles from polluted regions were different; they were less likely to evaporate but underwent similar atmospheric processing as emissions from clean fuels exposed to sunlight.
Implications for agencies in charge of controlled burns
Asa-Awuku, an associate professor of chemical and environmental engineering at the CE-CERT, said agencies that oversee prescribed burns should consider these findings when they predict the likely impact of prescribed burning of forest fuels in areas subjected to chronic air pollution.
“The environmental impact of prescribed burns has historically been based on data from clean fuels in areas of good air quality, so we have likely been under-predicting the impact of biomass emissions in polluted areas,” Asa-Awuku said.
She added that the study supports growing evidence that humans need to reduce our pollutant footprint associated with burning fossil fuels.
“This study, and specifically the concern that biomass grown and burned in polluted areas is potentially more toxic to human health, is additional evidence that human activities have consequences not yet explored and therefore not understood,” she said.
The research was conducted by Asa-Awuku and Michael Giordano, at UCR's CE-CERT, and Research Forester David Weise and Physical Science Technician Joey Chong from the Forest Service's Pacific Southwest Research Station.
Headquartered in Albany, Calif., the Pacific Southwest Research Station develops and communicates science needed to sustain forest ecosystems and other benefits to society. It has research facilities in California, Hawaii and the U.S.–affiliated Pacific Islands. For more information, visit www.fs.fed.us/psw/./h3>/h3>