Equilibrium isotherms for the simultaneous uptake of binary nonionic organic compounds from water on soil indicated no competitive effect between the two solutes.This observation supports the hypothesis that partition to the soil organic phase is the primary process for sorption of nonionic organic compounds from water on soil. The partition process between soil organic matter and water was analyzed by using the conventional solution concept for solutes in water and the Flory-Huggins treatment for solutes in the polymeric humic phase. Sorption determined for 12 aromatic compounds on a Woodburn soil shows that the extent of solute insolubility in water (S) is the primary factor affecting the soil organic matterwater partition coefficient (Kom) and that the effect of solute incompatibility with soil organic matter is significant but secondary. This explains the commonly observed correlations of log Kom vs. log S and log Kom vs. log Kow (octanol-water).
To estimate the emissions of anthropogenic semivolatile organic compounds (SOCs) from East Asia and to identify unique SOC molecular markers in Asian air masses, high-volume air samples were collected on the island of Okinawa, Japan between 22 March and 2 May 2004. Contributions from different source regions (China, Japan, the Koreas, Russia, and ocean/local) were estimated by use of source region impact factors (SRIFs). Elevated concentrations of hexachlorobenzene (HCB), hexachlorcyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), and particulate-phase polycyclic aromatic hydrocarbons (PAHs) were attributed to air masses from China. A large proportion of the variation in the current-use pesticides, gas-phase PAHs, and polychlorinated biphenyl (PCB) concentrations was explained by meteorology. Chlordanes showed a technical mixture profile and similar concentrations regardless of source region. alpha/gamma HCH and trans/cis chlordane ratios did not vary significantly with different source regions and had regional averages of 2.5 +/- 1.0 and 1.2 +/- 0.3, respectively. Particulate-phase PAH concentrations were significantly correlated (p value < 0.05) with other incomplete combustion byproduct concentrations, including elemental mercury (Hg0), CO, NOx, black carbon, submicrometer aerosols, and SO2. By use of measured PAH, CO, and black carbon concentrations and estimated CO and black carbon emission inventories, the emission of six carcinogenic particulate-phase PAHs was estimated to be 1518-4179 metric tons/year for Asia and 778-1728 metric tons/year for China, respectively. These results confirm that East Asian outflow contains significant emissions of carcinogenic particulate-phase PAHs.
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