ATMOSPHERIC MEASUREMENTS OF CARBONYL SULFIDE, DIMETHYL SULFIDE, AND CARBON-DISULFIDE USING THE ELECTRON-CAPTURE SULFUR DETECTOR

Measurements of atmospheric dimethyl sulfide (DMS), carbonyl sulfide ( COS), and carbon disulfide (CS2) were conducted over the Atlantic Ocea n on board the NASA Electra aircraft during the Chemical Instrumentati on Test and Evaluation (CITE 3) project using the electron capture sul fur detector (ECD-S). The system employed cryogenic preconcentration o f air samples, gas chromatographic separation, catalytic fluorination, and electron capture detection. Samples collected for DMS analysis we re scrubbed of oxidants with NaOH impregnated glass fiber filters prio r to preconcentration. The detection limits (DL) of the system for COS , DMS, and CS2 were 5, 5, and 2 ppt, respectively. COS concentrations ranged from 404 to 603 ppt with a mean of 489 ppt for measurements ove r the North Atlantic Ocean (31-degrees-N to 41-degrees-N), and from 39 5 to 437 ppt with a mean of 419 ppt for measurements over the Tropical Atlantic Ocean (11-degrees-S to 2-degrees-N). DMS concentrations in t he lower marine boundary layer, below 600-m altitude, ranged from belo w DL to 150 ppt from flights over the North Atlantic, and from 9 to 10 4 ppt over the Tropical Atlantic. CS2 concentrations ranged from below DL to 29 ppt over the North Atlantic. Almost all CS2 measurements ove r the Tropical Atlantic were below DL.