Shiftwork is associated with adverse metabolic pathophysiology, and the rising incidence of shiftwork in modern societies is thought to contribute to the worldwide increase in obesity and metabolic syndrome. The underlying mechanisms are largely unknown, but may involve direct physiological effects of nocturnal light exposure, or indirect consequences of perturbed endogenous circadian clocks. This study employs a two-week paradigm in mice to model the early molecular and physiological effects of shiftwork. Two weeks of timed sleep restriction has moderate effects on diurnal activity patterns, feeding behavior, and clock gene regulation in the circadian pacemaker of the suprachiasmatic nucleus. In contrast, microarray analyses reveal global disruption of diurnal liver transcriptome rhythms, enriched for pathways involved in glucose and lipid metabolism and correlating with first indications of altered metabolism. Although altered food timing itself is not sufficient to provoke these effects, stabilizing peripheral clocks by timed food access can restore molecular rhythms and metabolic function under sleep restriction conditions. This study suggests that peripheral circadian desynchrony marks an early event in the metabolic disruption associated with chronic shiftwork. Thus, strengthening the peripheral circadian system by minimizing food intake during night shifts may counteract the adverse physiological consequences frequently observed in human shift workers.

CFCs are useful tracers for age dating young water. Two critical assumptions are typically invoked: (1) the initial concentration needs to be known, and (2) the tracer must be stable. A series of 8000 CFC air data from four sites on the west European continent (from high‐alpine clean air down to urban sites) show site‐specific CFC excesses relative to the global background ranging from 125% at an urban site (Heidelberg) to only 30% at a rural site (Wachenheim). In both cases we find regular diurnal, weekly, and annual variations but also episodic variations due to changing air mass and sporadic local emission as well as a decrease of the CFC excess due to decreasing emissions in Europe. However, in soil air above the groundwater table the CFC excess variation is low‐pass filtered, allowing reconstruction of the site‐specific CFC input anomaly in relation to the global background. Thus local CFC soil air measurements can provide a valuable local correction factor for CFC dating and extend the applicability of CFC studies in specific environments. To investigate the chemical stability assumption, five field sites and two laboratory experiments show CFC 11 and CFC 12 degradation under anoxic conditions with degradation rates ranging from 0.05 up to 3×105 pmol L−1 yr−1. However, the CFC 12/CFC 11 degradation ratio is found to be constant over six orders of magnitude, with CFC 12 always being less reactive by a factor of about 10.

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