Assessing the Potential of Persistent Organic Chemicals for Long-Range Transport and Accumulation in Polar Regions

Abstract

A zonally averaged global distribution model is used to identify chemical partitioning properties and emission scenarios that favor enrichment in Arctic ecosystems. An immediate and a long-term Arctic Contamination Potential (ACP) are defined as the fraction of the total amount in global surface media that is in the Arctic after 1 and 10 years of steady emissions with a generic zonal distribution. Simulations for a two-dimensional "space" of hypothetical chemical property combinations indicate that the ACP of a perfectly persistent organic chemical is determined by a complex set of processes but tends to be higher for two combinations of partitioning properties: relatively volatile (log K OA < 9) and water soluble (4 > log K AW > -0.5) substances and substances which are semivolatile (log K OA 6.5-10) and relatively hydrophobic (log K AW > -3). Very volatile chemicals with log K OA < 6.5 and log K AW > -0.5 remain in the atmosphere even under Arctic temperature conditions, whereas very involatile chemical with a log K OA > 10 are efficiently and irreversibly deposited with atmospheric particles before reaching the Arctic. The two sets of partitioning characteristics with elevated ACP overlap in the range 6.5 < log K OA < 10 and -0.5 > log K AW > -3, which also corresponds to a log K OW range of 5 to 8, i.e., comprises substances with a potential for bioaccumulation. Organic contaminants known to accumulate in the Arctic, such as hexachlorobenzene and the lighter PCBs, indeed have such partitioning properties. Marine currents contribute significantly to the long-range transport of chemicals with log K AW < -2. Emissions to surface media greatly reduce the ACP, except for chemicals with octanol/water partition coefficients log K OW < 5. The ACP of chemicals with different partitioning properties is sensitive to different sets of environmental parameters, reflecting the different pathways which determine their global transport behavior. The ACP of most chemicals is sensitive to the temperature dependence of the partition coefficients, temperature, atmospheric mixing coefficients, and sea ice cover.

Gas/particle partitioning and global distribution of polycyclic aromatic hydrocarbons – A modelling approach

“…This potentially strong influence of the mode of entry on the LRT potential had been emphasized before (e.g. Wania, 2003;Lammel et al, 2007). The ranking of substances according to their LRT potential differs between the Arctic and the Antarctic, this can be explained by substance interactions with different patterns of land/ocean, oxidants, precipitation, etc.…”

Atmospheric Emission of PCDD/Fs, PCBs, Hexachlorobenzene, and Pentachlorobenzene from the Coking Industry

“…Once released into the environment, they can be transported and distributed on a global scale by the grasshopper effect and global fractionation (1,2). Minimizing environmental exposure to POPs is an important public goal for environmental protection, also with respect to sustainable development.…”

Current-Use and Legacy Pesticide History in the Austfonna Ice Cap, Svalbard, Norway

“…Under conditions of low oxidation, the presence of CUPs and other organic compounds in the gas phase is a function of high vapor pressure (vp) and low water solubility (Sw). A lack of atmospheric moisture may influence the effect of Sw (19). The ratio of vp and Sw, when adjusted to common units, becomes KAW, the air-water partition coefficient, which, when high, indicates a tendency to remain in the gas phase (20).…”