1 research outputs found
Factors Affecting the Occurrence and Transport of Atmospheric Organochlorines in the China Sea and the Northern Indian and South East Atlantic Oceans
Organochlorine pesticides (OCPs) and polychlorinated
biphenyls
(PCBs) are reported in 97 air samples collected on board the RV <i>Polarstern</i> in November 2007 from the equator to Cape Town,
South Africa and the MV <i>Oceanic II</i> (The Scholar Ship)
in January-March 2008 from Shanghai, China to Cape Verde in the Central
Atlantic Ocean. The atmospheric concentrations were higher close to
the coast and lower in remote regions of the Indian and South Atlantic
Ocean. Groups of samples were selected in the South China Sea, Indian
Ocean and South Atlantic Ocean where the relative wind direction matched
the trajectory of the ship, thus all the samples had the same input
of sources upwind. In these three regions the concentrations of OCPs
and PCBs declined during atmospheric transport following first order
kinetics. These sets of measurements provided estimates of field derived
residence times (FDRTs) for individual compounds. These values were
compared with predicted atmospheric residence times (PARTs) computed
using a model of long-range atmospheric transport potential of POPs.
The FDRTs are 5–10 times longer for the more volatile PCB congeners
and TC, CC, <i>p</i>,<i>p′</i>-DDT and <i>p</i>,<i>p</i>′-DDE than the respective PARTs,
while they are similar to PARTs for the less volatile compounds. Possible
causes of discrepancies between PARTs and FDRTs are discussed, and
revolatilization from the ocean surface seems to be the main cause
for the higher values of FDRTs of the more volatile compounds in comparison
with the respective PARTs