Accession Number:

ADA327841

Title:

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

Descriptive Note:

Doctoral thesis,

Corporate Author:

MASSACHUSETTS INST OF TECH CAMBRIDGE

Personal Author(s):

Report Date:

1997-02-01

Pagination or Media Count:

312.0

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 238U-234Th disequilibria, indicating a western North Atlantic pyrene sink corresponding to about 50 of emissions from the regions coastal states.

Subject Categories:

  • Organic Chemistry
  • Physical Chemistry
  • Physical and Dynamic Oceanography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE