Main Greenhouse Gases levels in the largest secondary urban forest in the world

Özet

The increase in Greenhouse Gases (GHGs) clearly shows the impact of humankind on Earth's equilibrium and isone of the parameters that led to the concept of a new geological epoch, the Anthropocene. The levels of thethree main GHGs ($CO_2$, $CH_4$ and $2O$) were determined in Tijuca Forest, the largest urban secondary Atlanticforest in the world, and in an urban and suburban area of the Rio de Janeiro Metropolitan Region, using a lowcost method. Samples were collected using polypropylene syringes and analyzed by gas chromatography withmultiple detectors. Concentrations of $CO_2$, $CH_4$ and $2O$ were in the range of 407–444 ppmV, 1.77–2.74 ppmVand 257–284 ppbV, respectively, in August 2016. In February and March, values were in the range of 350–419ppmV, 1.61–2.07 ppmV and 283–335 ppbV, for $CO_2$, $CH_4$ and $2O$, respectively. The $CO_2$ levels determined inthe forest and in the urbanized area showed no significant differences, suggesting the rapid transport of airmasses and the role of the forest in the offsetting of $CO_2$ in the urbanized area. In the suburban area, values wereapproximately 5% lower due to its relatively low population density and anthropogenic emissions. The $CO_2$concentrations obtained in this work are approximately 10% lower than values previously determined in otherBrazilian cities using the same method, stressing the positive impact of dense urban forests on air quality andurban metabolism.