A method was developed to determine the dimethyl sulphoxide (DMSO) reduction rate in activated sewage sludge at nearly natural conditions. Linearity of microbially produced dimethyl sulphide with incubation time and sample size was shown. Apart from a fast, sensitive and highly reproducible automatic analysis of dimethyl sulphide, simultaneous determination of mineralisation, respiration and phenol degradation rates was possible. The DMSO reduction rate of samples taken from a municipal sewage plant ranged between 2 and 3 micromol/(g dry matter per h), respiration and mineralisation rates between 30 and 80 micromol/(g per h). Added (13)C(6)-phenol was completely degradated after 96 h of incubation. A half-life of 14 h was calculated assuming first order decay. Dose response curves were obtained by incubating samples for 2, 6, 25, and 96 hours after addition of pentachlorophenol. At an incubation time of 6 h, the EC(50) values ranged from 20 mg/L (DMSO reduction) to 30 mg/L (phenol degradation) up to 180 mg/L (respiration and mineralisation). Increasing the incubation time to 96 h resulted in a lower EC(50) of 9 mg/L for DMSO reduction, whereas it increased to 500 mg/L for respiration and mineralisation.

Interpretation of the greenhouse data from the ice cores are sometimes based on rejection of analytical results, and often on assumptions disregarding gas fractionation processes. At present, our understanding of these processes in ice sheets is rather poor. There is a need for experimental studies which would provide the essential physical and chemical parameters needed. Before such studies are carried out, conclusions on low pre-industrial atmospheric levels of greenhouse gases cannot be accepted when deduced from ice core data. High contamination of the inner parts of the ice cores with lead and other metals by the drilling procedure is compelling evidence that the cores do not fulfil the absolutely essential, closed system criterion. Thus, they are not suitable for reconstruction of the composition of pre-industrial and ancient atmosphere.