Anthropogenic perturbation of the carbon fluxes from land to ocean

A substantial amount of the atmospheric carbon taken up on land through photosynthesis and chemical weathering is transported laterally along the aquatic continuum from upland terrestrial ecosystems to the ocean. So far, global carbon budget estimates have implicitly assumed that the transformation and lateral transport of carbon along this aquatic continuum has remained unchanged since pre-industrial times. A synthesis of published work reveals the magnitude of present-day lateral carbon fluxes from land to ocean, and the extent to which human activities have altered these fluxes. We show that anthropogenic perturbation may have increased the flux of carbon to inland waters by as much as 1.0 Pg C yr-1 since pre-industrial times, mainly owing to enhanced carbon export from soils. Most of this additional carbon input to upstream rivers is either emitted back to the atmosphere as carbon dioxide (~0.4 Pg C yr-1) or sequestered in sediments (~0.5 Pg C yr-1) along the continuum of freshwater bodies, estuaries and coastal waters, leaving only a perturbation carbon input of ~0.1 Pg C yr-1 to the open ocean. According to our analysis, terrestrial ecosystems store ~0.9 Pg C yr-1 at present, which is in agreement with results from forest inventories but significantly differs from the figure of 1.5 Pg C yr-1 previously estimated when ignoring changes in lateral carbon fluxes. We suggest that carbon fluxes along the land–ocean aquatic continuum need to be included in global carbon dioxide budgets.Peer reviewe

Effects of progressive strength training on muscle mass in type 2 diabetes mellitus patients determined by computed tomography

Objective: To examine the effect of a 4-month progressive strength training program on muscle and fat mass assessed by computed tomography (CT) in type 2 diabetes mellitus (T2DM) patients, and to assess the relationships of changes in muscle cross-section area (CSA) with glycaemic control. Methods: Twenty adults (mean age ± SE: 56.4 ± 0.9 a) with T2DM participated in a supervised strength training program for 4 months 3 days/week. Muscle and fat areas of the quadriceps muscle were estimated by CT volumetry before and immediately after the training. Glycaemic (HbA1c) and anthropometric (BMI, skinfolds) measurements were assessed at 0 and 4 months, respectively. Results: After strength training, muscle strength increased significantly in all measured muscle groups. Quadriceps size (CSA of the muscle) was increased by 2.4% (from 7.99 ± 0.3 cm to 8.18 ± 0.3 cm, p = 0.003) for the right extremity, 3.9% (from 8.1 ± 0.4 cm to 8.41 ± 0.5 cm, p = 0.04) for the left side. Fat tissue CSA reduced from 0.66 ± 0.1 cm to 0.56 ± 0.12 cm for the right leg (15.3% reduction) and from 0.58 ± 0.12 cm to 0.37 ± 0.13 cm for the left leg (35.8% reduction), resulting in a mean fat CSA reduction of 24.8%. Fat mass assessed by skin folds was significantly reduced and lean body mass was significantly increased. The change in muscle CSA was not correlated with the changes in HbA1c or muscle strength. Conclusions: Strength training significantly improves both muscle mass and the muscle to fat ratio in T2DM. However, changes in muscle observed with computed tomography were not related to changes observed in HbA1c with training