Soil air samples taken from the top one metre of the soil profile, were
measured for C02 and 02 using portable field analysers at a number of
sites of known sulphide mineralisation in South Australia. Carbon
dioxide anomalies were detected over actively oxidising sulphides during
autumn and winter following recent rainfall. Anomalies were not
detected where no oxidation was occurring, where seasonal conditions
had been very dry, or where the sulphur content of the ore was low (<2>
per cent). Plant root respiration, microbial activity and water logging
may generate false C02/02 anomalies, particularly at times of peak
rainfall and seasonal vegetative growth. Survey timing is therefore
crucial for obtaining the clearest signal to background response.