Atmospheric Elemental Carbon Deposition to Oak Trees and Litterfall Flux to Soil in an Urban Area

Jenna Rindy1, Alexandra G. Ponette-González2, Tate E. Barrett3 and Brett W. Luce4

Elemental Carbon (EC), a product of incomplete combustion of fossil fuels and biomass, contributes to climate warming and poor air quality. In urban areas, diesel fuel trucks are the main source of EC emissions from mobile sources. After emission, EC is deposited to receptor surfaces via two main pathways: precipitation (wet deposition) and directly as particles (dry deposition). Urban trees may play an important role in removing EC from the atmosphere by intercepting and delivering it directly to the soil. The goal of this research is to quantify the magnitude of EC retention on leaf surfaces (leaf EC) and EC fluxes to soil via leaf litterfall in the City of Denton, Texas. Denton is a rapidly growing urban area north of the Dallas-Fort Worth metropolitan Area. We are using a foliar extraction technique to determine EC retention on leaf surfaces. Foliar samples are being collected monthly, from April to November, from co-located Quercus stellata (post oak, n = 10) and Quercus virginiana (live oak, n = 10) trees. Samples are rinsed with water and chloroform in a two-step process to determine surface-deposited EC and EC retained in leaf waxes. A Sunset EC/OC carbon analyzer will be utilized to analyze EC content of extracts filtered onto quartz-fiber filters. For one year, leaf litter is being collected bi-weekly under 35 trees (20 post oak, 15 live oak), and oven dried to determine dry weight. EC retained by tree canopies will be calculated by multiplying leaf EC by canopy leaf area index, while EC flux to soil will be estimated by multiplying in-wax EC by leaf litterfall mass. Here, preliminary results of EC retention on leaf surfaces, as well as EC flux to soil for spring and summer 2017 are presented. Results of this study will assess urban tree’s ability to filter air pollution and mitigate climate change.  

 

1University of North Texas, jenna.rindy@unt.edu
2University of North Texas, alexandra.ponette@unt.edu
3University of North Texas, tate.barrett@unt.edu
4University of North Texas, BrettLuce@my.unt.edu