Spatial and Temporal Trends of Particle Phase Organophosphate Ester Concentrations in the Atmosphere of the Great Lakes.

The concentrations of six organophosphate esters (OPEs) in atmospheric particle phase samples collected once every 12 days at five sites in the North American Great Lakes basin over the period of March 2012 to December 2014, inclusive, are reported. These OPEs include tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP), and tris(1,3-dichloroisopropyl) phosphate (TDCIPP), tri-n-butyl phosphate (TNBP), triphenyl phosphate (TPHP), and 2-ethylhexyl diphenyl phosphate (EHDP). Median total OPE concentrations (∑OPE) ranged from 93 pg/m at Sleeping Bear Dunes to 1046 pg/m at Chicago. The ∑OPE levels were significantly (P < 0.05) higher at Chicago and Cleveland, our urban sites, than at our rural and remote sites. The composition profiles were dominated by chlorinated OPEs at the urban and rural sites and by nonchlorinated OPEs at the remote sites. The concentrations of all OPEs were significantly (P < 0.001) correlated to one another, suggesting that these compounds share similar sources. Most atmospheric ∑OPE concentrations were significantly (P < 0.05) decreasing over time, with halving times of about 3.5 years at the urban sites and about 1.5 years at the rural and remote sites. Interestingly, TCEP and EHDP concentrations were increasing over time at the rural and remote sites with doubling times of 2.2 and 3.7 years, respectively.