AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Airborne Soil Organic Particles Generated by Precipitation
Bingbing Wang, Tristan Harder, Stephen Kelly, Dominique Piens, Swarup China, Libor Kovarik, Keiluweit Marco, Arey Bruce, Mary Gilles, ALEXANDER LASKIN, Pacific Northwest National Laboratory
Abstract Number: 409 Working Group: Remote and Regional Atmospheric Aerosols
Abstract Airborne organic particles play a critical role in Earth’s climate, public health, air quality, and hydrological and carbon cycles. However, sources and formation mechanisms for semi-solid and solid organic particles are poorly understood and typically neglected in atmospheric models. Laboratory evidence suggests that fine particles can be formed from impaction of mineral surfaces by droplets (Joung & Buie, 2015). Here, we use chemical imaging of particles collected following rain events in the Southern Great Plains, Oklahoma, USA and after experimental irrigation to show that raindrop impaction of soils generates solid organic particles. We find that after rain events, sub-micrometre solid particles, with a chemical composition consistentwith soil organicmatter, contributed up to 60% of atmospheric particles. Our irrigation experiments indicate that intensive water impaction is su cient to cause ejection of airborne soil organic particles fromthe soil surface. Chemical imaging and micro-spectroscopy analysis of particle physico-chemical properties suggest that these particles may have important impacts on cloud formation and e efficiently absorb solar radiation. We suggest that raindrop-induced formation of solid organic particles from soils may be a widespread phenomenon in ecosystems such as agricultural systems and grasslands where soils are exposed to strong, episodic precipitation events.