TRAKER-Mobile road dust measurement systemIn order to better understand the pollutant sources that are affecting Lake’s Tahoe’s water quality, Research Professor Hampden Kuhns, began studying Lake Tahoe in 2003 when he assembled the areas first emissions inventory. The inventory included local measurements using his TRAKER road dust measurement system, a mobile platform for measuring dust emissions from paved and unpaved roads.

“The concept for the TRAKER was to get real-time data measurements from the road dust so that we can better understand when and where dust is emitted that can ultimately deposit into the Lake and affect water clarity,” Kuhns said. Preliminary results showed that winter time dust emissions were very high due to the application of sand to snowy road. It was then up to Dr. Dongzi “Davis” Zhu, as graduate student, to collect the data that would resolve many of the knowledge gaps that existed at the time.

“In 2006-2007 year I made 23 trips around the lake collecting measurements,” Zhu, currently a postdoctoral researcher, said. Now that’s dedication. It’s that drive that brought Kuhns and Zhu together this time to hone in on the processes that transport emissions from the road source over the lake.

Dr. Hampden Kuhns (left) and Dr. Dongzi “Davis” Zhu“We use computer models calibrated with local data to determine how much dust deposits to the vegetation or ground before reaching the lake,” Kuhns added.

Previous DRI emissions studies indicate that nearly 300 metric tons of fine particulates are contributed annually to the atmosphere by cars driving on paved roads in the basin. Other sources of particulate emissions include wind-blown dust, unpaved road dust and fires. The current study will provide a more accurate measure of how these sources end up in the lake.

This time the pair developed the portable deposition monitoring platform. The strategically placed equipment, near Stateline, Tahoe City and Incline Village will account for a previously unaccounted for process of deposition within 100 meters of the source.

“We are measuring the effect of on and off shore breezes in the transport of dust into the lake,” Zhu said.

Air quality and emissions inventories have provided basin managers with an estimate of particulate deposition into Lake Tahoe, but with these new real-time monitoring devices DRI researchers have found that the problem may not be a severe as previously thought.

“Studies have estimated the amount of PM10 deposition at 210 tons per year and our preliminary data shows this number may be closer to seven tons,” Zhu said.

Hampden Kuhns, right, and Davis Zhu with several of their portable deposition monitoring platformsThe amount of dust on the roadways does follow a season pattern, the sand and brine needed to help control the ice buildup on the roadways during the winter does have an effect, but the amount of traffic is also an issue.

“This data will help managers decided which roads get priority for street sweeping. We want to help them get the most bang for their buck,” Kuhns said.

The models and portable deposition monitoring platforms are being used by other DRI researchers in studies around the world, including use by the military to monitor dust emissions by transport vehicles near major cities.

Kuhns also has extensive experience in ambient air pollutant and emissions data analysis and validation. He’s worked closely with officials in local and state governments to ensure that results from air quality studies can be directly applied to air pollution mitigation, state implementation plan preparation (SIP), and compliance with U.S. EPA air quality standards.