CFC-11 (CCl3F), CFC-12 (CCl2F2), CFC-113 (CCl2FCClF2), methyl chloroform (CH3CCl3), carbon tetrachloride (CCl4), nitrous oxide (N2O) and HCFC-22 (CHClF2) were measured in the air and surface waters of the Pacific Ocean between 55°N and 22°S during the late summer and early fall of 1992. Atmospheric measurements of all gases agreed well with results from NOAA fixed stations at similar latitudes. CFC-11, CFC-12, and CFC-113, which have long atmospheric lifetimes and are essentially inert in seawater, responded mainly to physical processes in the air and water. The first two gases were supersaturated by 2-6% at higher, northern latitudes, reflecting the effects of radiative warming. Their saturation anomalies declined southward through the tropics and ultimately became slightly negative in the southern hemisphere. HCFC-22 showed signs of small losses in the tropics and subtropics, a sink that may account for 2% of the losses of this gas from the atmosphere. CH3CCl3 showed a similar pattern, with only a tropical sink. This is consistent with hydrolysis and, together with data from an earlier expedition, implies that about 6% of atmospheric CH3CCl3 is lost to the ocean. The net saturation anomaly for CCl3 was virtually negative everywhere and only slightly dependent upon latitude. This would be expected for a sink that was not particularly temperature dependent and it is consistent with evidence from deepwater profiles that indicate a sink at depth. Fluxes calculated from CCl4 saturation anomalies indicate that 15-35% of atmospheric CCl4 is lost to the ocean.
|Gas chromatograph / electron capture detector (surface water):
(also at depth)
From left to right: Tom, John Wayne, Jürgen, and Jim (just arriving at John Wayne Airport in Long Beach, CA) .
The John V. Vickers is about 67 m long and fast. Formerly a tuna-fish boat, the Vickers was converted to a scientific vessel in the late 80s. It served several major missions (WOCE, TOGA/COARE) carrying a crew of about 14 with a capacity of 24 scientists, before it was retired in 1993.
OAXTC 92 is shown in dark green through the Pacific Ocean, out of Long Beach, California into Noumea, New Caledonia.