Physico-Chemical Speciation and Ocean Fluxes of Polycyclic Aromatic Hydrocarbons.

• Main Author: Gustafsson, Orjan
• Other Authors: MASSACHUSETTS INST OF TECH CAMBRIDGE
• Format: Text
• Language: English
• Published: 1997
• Subjects: Organic Chemistry; Physical Chemistry; Physical and Dynamic Oceanography; *FLUX(RATE); *AROMATIC HYDROCARBONS; *OCEANS; *PHYSICOCHEMICAL PROPERTIES; *POLYCYCLIC COMPOUNDS; SOOT; COASTAL REGIONS; DISPERSING; FLUORESCENCE; OCEAN SURFACE; MODELS; THESES; CARBON; QUENCHING; SURFACES; CONTINENTAL SHELVES; VERTICAL ORIENTATION; ABSORBERS(MATERIALS); ORGANIC MATERIALS; MACROMOLECULES; HORIZONTAL ORIENTATION; COLLOIDS; SEDIMENTS; BAYS; ULTRAFILTRATION; *SPECIATION; ECOTOXICOLOGY; BIOAVAILABILITY; SORBENTS; PARTION COEFFICIENTS; AQUEOUS SOLUTIONS; North Atlantic
• Online Access: http://www.dtic.mil/docs/citations/ADA327841; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA327841

Partitioning of ecotoxicologically significant polycyclic aromatic hydrocarbons (PAHs) to non-aqueous, particularly colloidal and soot, phases results in a decrease in their, directly bioavailable, dissolved fractions. Functionally distinguishing colloidal sorbents from dissolved entities as constituents that provide a molecular milieu into and onto which chemicals can escape from the aqueous solution, implies that non all macromolecules can act as sorbents. Thus, instead of ultrafiltration, less invasive time-resolved fluorescence quenching experiments revealed that coastal colloids exhibit a factor of five-to-ten lower sorbent efficiencies, on an organic-carbon basis, than sedimentary organic matter. PAH concentrations in continental shelf surface sediments could be explained with the soot carbon concentrations (r2-0.97-0.99) while they were not correlated with non-soot organic carbon at the 95% confidence level. Theoretically estimated soot-water partion coefficients, assuming sorbate-soot interaction is thermodynamically similar to sorbate fusion, are suggesting a soot sorption strength 100 times greater than for non-soot organic matter (carbon basis). Exponentially decreasing surface ocean fluxes of PAHs away from northeastern USA was demonstrated using (238)U-234Th disequilibria, indicating a western North Atlantic pyrene sink corresponding to about 50% of emissions from the region's coastal states.