The influence of environmental and soil-related variables on the spatial distribution of PCBs in Norwegian and UK soils: implications for global cycling.

This paper reports the influence of environmental variables on soil concentrations of polychlorinated biphenyls (PCBs) and their global fractionation. Soils were sampled from remote woodland (coniferous and deciduous) and grassland locations on a latitudinal transect through the United Kingdom and Norway. Different processes control PCB concentrations and burdens in coniferous, deciduous, and grassland soil systems; these are discussed, with emphasis on the influence of canopy scavenging and soil organic matter (OM) content. In general, concentration differences between sites were 1−2 orders of magnitude for lighter PCBs and 2−3 orders of magnitude for heavier PCBs, when expressed on a pg g-1 dry weight basis. These differences decreased by up to an order of magnitude when expressed as pg g-1 OM. The dataset suggests that the more volatile PCBs are moving toward equilibrium with the OM burden of the soil compartment on a European regional scale, while the distribution of the “stickier”, heavier homologues appears to still be primarily influenced by their preferential deposition closer to source areas. The relative concentration of the tri- and tetra-PCBs increases with latitude, while that of the hepta- and octa-PCBs decreases, consistent with the global fractionation theory. However, the regression slopes are quite shallow, with high scatter, implying that many environmental and soil-related factors (such as precipitation, organic carbon content and type, other soil properties, local sources, etc.) are also influencing the observed congener patterns. Temperature-driven fractionation, while clearly operating and detectable, needs to be considered in this broader context

Assessing the contribution of diffuse domestic burning as a source of PCDD/Fs, PCBs, and PAHs to the UK atmosphere.

Ambient air samples were taken concurrently at four sites in northwest England to assess the role of domestic burning of coal/wood on ambient levels of PCDD/Fs, PCBs (including co-PCBs), and PAHs. Fifty-six samples (ca. 800 m3 each) were taken in January and February 1998 at an urban site, a rural reference site, and two village sites, which relied on domestic burning for space heating. Correlations with meteorological parameters found the urban site to be a source area of all POPs investigated, while the village sites had a local impact of PAHs and, to a lesser extent, PCDD/Fs. PCDD/F-levels changed simultaneously at all sites, pointing toward a combination of regional meteorological effects and increased domestic burning. Two sampling events, marked by low ambient temperatures and wind speeds, showed substantial increases in PCDD/F and PAH concentrations (by factors of 2−5). We estimate that local sources at the villages accounted for 25% of the ΣTEQ (with 75% stemming from advective transport) and 75% of the ΣPAHs in the ambient air at those sites (25% advective transport) during our winter sampling events. This study singled out PCDFs, notably the lower chlorinated ones, as good indicators of domestic burning, together with a range of PAHs. The co-PCBs #126 and 169 were found to behave like PCDD/Fs and PAHs rather than the more abundant “regular” PCBs, confirming that they have different sources to the environment

Proteomic analysis of arginine adducts on glyoxal-modified ribonuclease

Accumulation of advanced glycation end-products (AGEs) on proteins is associated with the development of diabetic complications. Although the overall extent of modification of protein by AGEs is limited, localization of these modifications at a few critical sites might have a significant effect on protein structure and function. In the present study, we describe the sites of modification of RNase by glyoxal under physiological conditions. Arg(39) and Arg(85), which are closest to the active site of the enzyme, were identified as the primary sites of formation of the glyoxal-derived dihydroxyimidazolidine and hydroimidazolone adducts. Lower amounts of modification were detected at Arg(10), while Arg(33) appeared to be unmodified. We conclude that dihydroxyimidazolidine adducts are the primary products of modification of protein by glyoxal, that Arg(39) and Arg(85) are the primary sites of modification of RNase by glyoxal, and that modification of arginine residues during Maillard reactions of proteins is a highly selective process