Mf. Simcik et al., Temperature dependence and temporal trends of polychlorinated biphenyl congeners in the Great Lakes atmosphere, ENV SCI TEC, 33(12), 1999, pp. 1991-1995
Citations number
16
Categorie Soggetti
Environment/Ecology,"Environmental Engineering & Energy
As part of the Integrated Atmospheric Deposition Network (IADN), we have me
asured gas-phase polychlorinated biphenyl (PCB) concentrations in the atmos
phere around the Great Lakes since November of 1990. In this paper, we use
these data to explore the temperature and time dependencies of gas-phase PC
B concentrations near Lakes Superior, Michigan, and Erie and in Chicago. Co
ncentrations of individual PCB congeners were well correlated to temperatur
e for the three remote sites using the Clausius-Clapeyron equation, but the
calculated heats of surface-air exchange did not correlate (on a congener
basis) with laboratory-measured heats of vaporization. On the other hand, t
he heats of surface-air exchange for PCB congeners measured in Chicago are
well correlated with laboratory-measured heats of vaporization. We conclude
that the gas-phase PCB concentrations measured at Chicago are controlled b
y short-range transport, but at the three remote sites, these concentration
s are controlled by long-range transport. Gasphase PCBs also exhibited decr
easing concentrations over the period 1991-1997 near Lakes Michigan and Eri
e and in Chicago. Significant half-lives ranged from 0.5 to 7.5 years for i
ndividual congeners and 2.8 to 3.3 years for total PCBs. Gas-phase PCBs nea
r Lake Superior showed no general trend in gas-phase concentration over thi
s same time period.