| Summary: | Detailed records of methanesulphonic acid (MSA) and non-sea-salt sulpha te (nss So/- ) have been obtained from ice cores drilled on Dolleman Island on the east coast of the Antarctic Peninsula (i0°35 .2' S, 60°55.5' W). Annual average concentrations of MSA arc presented for the period I 652- 1992. Over this Lime span, the mean ann ual concen tration of MSA is 0.69 μeq 1-1 (cr = 0.33, n = 340), the range is 0. 13- 2.35μeq 1- 1 , a nd the MSA/ nss-S04 2 - ratio is 0.22. The high MSA concentration reflects the proximity of the Weddell Sea, believed . to be a region of high marine phyt0plankton production. T he overa ll mean nss-SO/-concentration is about 66% of the total sulphate d eposited in the snowfall. Low-frequency variations of MSA and oxygen -isoLOpe signals correla te closely, indicat ing that they may be modulated by similar atmospheric processes. Positive correlations are observed between the oxygenisotope signature and both l\'1SA (r =0.4·1) and nss S04 2 - (r = 0.50), signilicant at the 99% level. A small negative correlation can be seen between both species and the annual duration or sea ice a t Scoria Bay, Laurie Island in the South Orkneys, since 1902 (MSA r = - 0.23, and nss so/- r = - 0.29; significant at 95% confidence). No significant link between high MSA concentrations and El Nino even ts is observed at this location.
|
|---|