Reported data on the temperature dependence of atmospheric concentrations of semivolatile organic compounds (SOCs) are compiled and expressed as linear regressions of the logarithm of the partial pressure in air versus reciprocal temperature:  ln p A = m/T + b. Two simple models are introduced to explain the dependence of these air concentrations on temperature. The first assumes equilibrium between the atmosphere and the earth's surface. In the second, air concentrations are established as a result of chemical inflow and outflow in advected air and reversible exchange with a soil or water surface. The model equations are rearranged to express the partial pressure of the chemical as a function of temperature. On the basis of these models, it is shown that only under selected circumstances, namely, if surface contamination is high and atmospheric background concentration low, does the slope m of the ln p vs 1/T relationship reflect the thermodynamics of air−surface partitioning. Generally, however, m is a measure of the extent to which air concentrations are controlled by evaporation from surfaces close to the sampling location and by advection of air masses with global background concentrations. A shallow slope or low temperature dependence indicates that long-range transport controls atmospheric levels at a sampling site. Steeper slopes indicate high surface concentrations in the vicinity of the site. This hypothesis is applied to the observed tem perature dependence of the compiled atmospheric concentration data and is found to be capable of explaining differences in slope m (i) between chemicals, (ii) between sampling sites, and (iii) at different seasons. Research efforts should be directed toward quantifying by measure ments and predicting by models the kinetics of exchange of SOCs between the atmosphere and various surfaces.

The influence of seasonal changes and long-range transport on levels of selected polychlorinated compounds was studied by taking ambient air samples at Ny-Ålesund (78°55‘ N, 11°56‘ E), Svalbard, Norway, once a week from March to October 1993 and with 48-h sampling intervals from November to December 1993. Polychlorinated pesticides such as chlordanes, hexachlorocyclohexanes (HCH), and DDT compounds as well as polychlorinated biphenyl (PCB) congeners were quantified by high-resolution gas chromatography combined with high- or low-resolution mass spectrometry. Due to levels being often in the subpicogram per cubic meter range, a comprehensive quality control program was applied. This first continuous measurement campaign in the Norwegian Arctic showed a clear seasonal variation of trans-chlordane and cis-nonachlor. Circumpolar trajectories allowed identification of long-range transport from different source regions. The temporal concentration profiles of compounds with different industrial and agricultural sources allowed us to confirm such transport episodes and to differentiate between the influence of industrial and agricultural areas. A significant correlation was found between concentrations of some chlordane congeners, α- and γ-HCH isomers, and the most volatile PCB congeners. No seasonal change of the PCB concentrations was found, indicating that a weekly average temperature of 5−8 °C during summer is not large enough for a measurable revolatilization of already deposited material.

Red meat high in heme iron may promote the formation of potentially genotoxic aldehydes during lipid peroxidation in the gastrointestinal tract. In this study, the formation of malondialdehyde (MDA) equivalents measured by the thiobarbituric acid reactive substances (TBARS) method was determined during in vitro digestion of cooked red meat (beef and pork), as well as white meat (chicken) and fish (salmon), whereas analysis of 4-hydroxyhexenal (HHE) and 4-hydroxynonenal (HNE) was performed during in vitro digestion of cooked beef and salmon. Comparing products with similar fat contents indicated that the amount of unsaturated fat and not total iron content was the dominating factor influencing the formation of aldehydes. It was also shown that increasing fat content in beef products caused increasing concentrations of MDA equivalents. The highest levels, however, were found in minced beef with added fish oil high in unsaturated fat. This study indicates that when ingested alone, red meat products low in unsaturated fat and low in total fat content contribute to relatively low levels of potentially genotoxic aldehydes in the gastrointestinal tract.