1 research outputs found
PAHs on a West-to-East Transect Across the Tropical Atlantic Ocean
Surface
water and atmospheric samples were collected across the
tropical Atlantic Ocean on a transect of the R/V <i>Endeavor</i> in summer 2009 and analyzed for polycyclic aromatic hydrocarbons
(PAHs). Across the entire tropical Atlantic Ocean, phenanthrene displayed
on average highest dissolved concentrations (170 pg L<sup>–1</sup>), followed by pyrene (70 pg L<sup>–1</sup>) and fluoranthene
(30 pg L<sup>–1</sup>). The Amazon plume was characterized
by elevated dissolved concentrations of phenanthrene and benzoÂ(g,h,i)Âfluoranthene.
The warm eddy that we accidentally sampled at 66° W displayed
highest concentrations of PAHs across the entire cruise, with phenanthrene,
pyrene, and fluoranthrene all >1 ng L<sup>–1</sup>. After
having
crossed the warm core, concentrations decreased back to previous levels.
Samples taken in the Gulf Stream were below detection limit for all
parent PAHs, implying very efficient removal processes. Dissolved
dimethylphenanthrenes were frequently detected in the samples from
the southern hemisphere, the Amazon plume, and in samples characteristic
of the Gulf Stream and the U.S. East Coast. Atmospheric concentrations
were dominated by gas-phase fluoranthene, pyrene, phenanthrene, and
retene. Air–water gradients indicated that PAHs are mostly
undergoing net deposition across the tropical Atlantic Ocean, with
conditions closer to equilibrium off the U.S. East Coast and in Rhode
Island Sound