Inferring atmospheric sources of gaseous organophosphate esters from spatial patterns

Organophosphate esters (OPEs) have emerged as pervasive environmental contaminants, with concentrations often exceeding those of traditional flame retardants and plasticizers by orders of magnitude. Here, we present concentrations of OPEs in the atmospheric gas phase collected using passive air samplers deployed in the coastal regions of Quebec and British Columbia in southern Canada. Four OPEs, i.e., tri-n-butyl phosphate (TBP), tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), and tris (phenyl) phosphate (TPhP) were reliably and ubiquitously detected, with TCPP showing the highest level, followed by TBP. Concentration levels of TCPP and TCEP are correlated with each other and with population, possibly indicating emission from consumer products. Spatial patterns of TBP and TPhP are more indicative of industrial usage, with airports possibly being a major source for TBP. The positive relationships between atmospheric OPEs and population are influenced by ambient temperature, whereby the size of the populated area around a sampling site influencing the air concentration appears to be decreasing at higher temperatures.