Study of CO, isoprene, and anthropogenic non-methane hydrocarbons (C2-C7) as photochemical sinks for hydroxyl radical at a northern Michigan forested site.

Abstract

On a global scale CO is considered to be a main sink for the hydroxyl radical (OH). However, in areas with high concentrations of biogenic VOC's, specifically isoprene (2-methyl-1,3-butadiene) isoprene may limit the OH concentration in summertime. PROPHET is located in ""mixed"" forest in northern Michigan, rich in species that emit summertime isoprene. PROPHET 2000 and 2001 intensive study periods show that isoprene provided the dominant OH sink in this area, more than CO or anthropogenic hydrocarbons. Isoprene accounts for 85%-90% of the OH sink during both summers, regardless of whether transport was from north or south, (north generally meaning lower in anthropogenic pollutants, and south meaning more anthropogenic sources). This dominance of isoprene shows its importance to tropospheric chemistry in isoprene rich sites.