Long-term decline of the Amazon carbon sink

Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades1, 2, with a substantial fraction of this sink probably located in the tropics3, particularly in the Amazon4. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity5. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale1, 2, and is contrary to expectations based on models6

Exercise inhibits the effects of smoke-induced COPD involving modulation of STAT3

Purpose . Evaluate the participation of STAT3 in the e ff ects of aerobic exercise (AE) in a model of smoke-induced COPD. Methods . C57Bl/6 male mice were divided into control, Exe, COPD, and COPD+Exe groups. Smoke were administered during 90 days. Treadmill aerobic training begun on day 61 until day 90. Pulmonary in fl ammation, systemic in fl ammation, the level of lung emphysema, and the airway remodeling were evaluated. Analysis of integral and phosphorylated expression of STAT3 by airway epithelial cells, peribronchial leukocytes, and parenchymal leukocytes was performed. Results . AE inhibited smoke-induced accumulation of total cells ( p <0 001 ), lymphocytes ( p <0 001 ), and neutrophils ( p <0 001 ) in BAL, as well as BAL levels of IL- 1 β ( p <0 001 ), CXCL1 ( p <0 001 ), IL-17 ( p <0 001 ), and TNF- α ( p <0 05 ), while increased the levels of IL-10 ( p <0 001 ). AE also inhibited smoke-induced increases in total leukocytes ( p <0 001 ), neutrophils ( p <0 05 ), lymphocytes ( p <0 001 ), and monocytes ( p <0 01 ) in blood, as well as serum levels of IL-1 β ( p <0 01 ), CXCL1 ( p <0 01 ), IL-17 ( p <0 05 ), and TNF- α ( p <0 01 ), while increased the levels of IL-10 ( p <0 001 ). AE reduced smoke-induced emphysema ( p <0 001 ) and collagen fi ber accumulation in the airways ( p <0 001 ). AE reduced smoke-induced STAT3 and phospho-STAT3 expression in airway epithelial cells ( p <0 001 ), peribronchial leukocytes ( p <0 001 ), and parenchymal leukocytes ( p <0 001 ). Conclusions .AE reduces smoke-induced COPD phenotype involving STAT3

Physical, chemical and microbiological aspects during the dry and rainy seasons in a pond covered by macrophyte used in aquaculture water supply

AIM: The water quality of a pond covered by macrophytes and used as a water supply for aquaculture was evaluated during the dry and rainy seasons; METHODS: Six points were established for water sampling, at water inflow and outflow. Samplings were carried out monthly between June 2008 and May 2009; RESULTS: Inflow points P1, P2 and P3 in the pond had higher nutrient concentrations and high trophic rates. Moreover, capybaras in the area caused sediment suspension and an increase in fecal coliforms. There was significant difference (p < 0.05) in the concentrations of nutrients in water between the dry and rainy seasons. The outflow of water caused by rain carried the material around the pond directly into the water; CONCLUSIONS: The system studied was influenced by rain and lack of adequate management of the surrounding area. Water quality was deteriorated by increase in nutrient concentrations, fecal coliforms and reduction of dissolved oxygen in the water during the rainy season. This was due to allochthonous material from the area surrounding the pond that affected negatively the supply system