SULFITE RADICALS IN BANDED CORAL

We compare records of stable oxygen isotope ratio (delta(18)O) and SO3 -/CO2- ratio in an 8 yr long modern coral skeleton from a small volcan ic island in the Banda Islands, eastern Indonesia. The SO3-/CO2- ratio in ESR signal intensity reflects the skeletal SO32-/CO32- ratio, whic h is the degree of sulfite incorporation. The resulting delta(18)O and SO3-/CO2- records correlate well for the most recent years of growth. We speculate that water mass effect and possibly sea surface temperat ure (SST) control the sulfite incorporation in the coral. The rainfall in Banda Islands and the SO3-/CO2- record correlate negatively. This indicates that the source of sulfites in this coral is seawater and ra infall dilutes this sulfite loading to an inverse relationship between the SO3-/CO2- and rainfall. A weaker negative correlation with SST ex ists which may represent an additional factor affecting SO3-/CO2- rati os. We also analyzed ESR of a coral from Manado, Sulawesi Island which was affected by river discharge. The SO3-/CO2- ratio of the coral is about twice as large as that of the Banda Islands in average, indicati ng there is additional sulfite source from terrestrial waters. The SO3 -/CO2- record also correlates negatively with rainfall. Rainfall seems to dilute both the oceanic sulfite and the sulfite being delivered by Manado River. Copyright (C) 1996 Elsevier Science Ltd