Physico-Chemical Speciation and Ocean Fluxes of Polycyclic Aromatic Hydrocarbons.
Abstract
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1997
- Accession Number
- ADA327841
Entities
People
- Orjan Gustafsson
Organizations
- Massachusetts Institute of Technology