OBJECTIVE:To conduct separate factor analyses of the Three Factor Eating Questionnaire (TFEQ-R, TFEQ-D and TFEQ-H) scales and provide initial evidence of the construct validity of the obtained solutions. DESIGN: A cross-sectional survey with a 12 month retest of a subsample of subjects. SUBJECTS: A total of 553 undergraduate university women with a mean age of 25.0 y. The retest sample comprised 64 subjects with a mean age at retest of 25.7 y. MEASUREMENTS: In addition to the TFEQ, age, body mass index (BMI), satisfaction with current weight, nutrition knowledge and current exercise level were recorded. RESULTS: Three restraint (strategic dieting behaviour, attitude to self-regulation, avoidance of fattening foods), three disinhibition (habitual susceptibility, emotional susceptibility, situational susceptibility) and two hunger constructs (internal locus for hunger, external locus for hunger) were identi®ed. Initial evidence of the validity of these constructs was provided. CONCLUSION: The explanation of disordered eating behaviour is likely to be re®ned more by speci®c constructs, such as those presented, rather than by the more general constructs measured by the original TFEQ-R, TFEQ-D and TFEQ-H scales. Further examination of the factor structures presented is therefore encouraged. International Journal of Obesity (2001) 25, 900 ± 906

Methane (CH4) strongly contributes to observed global warming. As natural CH4 emissions mainly originate from wet ecosystems, it is important to unravel how climate change may affect these emissions. This is especially true for ebullition (bubble flux from sediments), a pathway that has long been underestimated but generally dominates emissions. Here we show a remarkably strong relationship between CH4 ebullition and temperature across a wide range of freshwater ecosystems on different continents using multi-seasonal CH4 ebullition data from the literature. As these temperature–ebullition relationships may have been affected by seasonal variation in organic matter availability, we also conducted a controlled year-round mesocosm experiment. Here 4 °C warming led to 51% higher total annual CH4 ebullition, while diffusion was not affected. Our combined findings suggest that global warming will strongly enhance freshwater CH4 emissions through a disproportional increase in ebullition (6–20% per 1 °C increase), contributing to global warming.

Laboratory sediment incubations and continuous ebullition monitoring over an annual cycle in the temperate Saar River, Germany confirm that impounded river zones can produce and emit methane at high rates (7 to 30 (g CH4 m(-3) d(-1)) at 25 °C and 270 to 700 (g CH4 m(-2) yr(-1)), respectively). Summer methane ebullition (ME) peaks were a factor of 4 to 10 times the winter minima, and sediment methane formation was dominated by the upper sediment (depths of 0.14 to 0.2 m). The key driver of the seasonal ME dynamics was temperature. An empirical model relating methane formation to temperature and sediment depth, derived from the laboratory incubations, reproduced the measured daily ebullition from winter to midsummer, although late summer and autumn simulated ME exceeded the observed ME. A possible explanation for this was substrate limitation. We recommend measurements of methanogenically available carbon sources to identify substrate limitation and help characterize variation in methane formation with depth and from site to site.

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