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

• Published in: Atmospheric pollution research 2019-03, Vol.10 (2), p.564-570
• Main Authors: da Silva, Cleyton M., da Silva, Luane L., Souza, Thainá de C., Dantas, Taisa C., Corrêa, Sergio M., Arbilla, Graciela
• Format: Article
• Language: English
• Subjects: Carbon capture; Carbon dioxide; Greenhouse gases determination; Urban forest; Urban pollution
• ISSN: 1309-1042; 1309-1042
• DOI: 10.1016/j.apr.2018.10.009

The increase in Greenhouse Gases (GHGs) clearly shows the impact of humankind on Earth's equilibrium and is one of the parameters that led to the concept of a new geological epoch, the Anthropocene. The levels of the three main GHGs (CO2, CH4 and N2O) were determined in Tijuca Forest, the largest urban secondary Atlantic forest in the world, and in an urban and suburban area of the Rio de Janeiro Metropolitan Region, using a low-cost method. Samples were collected using polypropylene syringes and analyzed by gas chromatography with multiple detectors. Concentrations of CO2, CH4 and N2O were in the range of 407–444 ppmV, 1.77–2.74 ppmV and 257–284 ppbV, respectively, in August 2016. In February and March, values were in the range of 350–419 ppmV, 1.61–2.07 ppmV and 283–335 ppbV, for CO2, CH4 and N2O, respectively. The CO2 levels determined in the forest and in the urbanized area showed no significant differences, suggesting the rapid transport of air masses and the role of the forest in the offsetting of CO2 in the urbanized area. In the suburban area, values were approximately 5% lower due to its relatively low population density and anthropogenic emissions. The CO2 concentrations obtained in this work are approximately 10% lower than values previously determined in other Brazilian cities using the same method, stressing the positive impact of dense urban forests on air quality and urban metabolism. •CO2, CH4 and N2O concentrations were determined using a low-cost method.•The method is a good alternative in cities where global monitoring is not performed.•The dense urban rainforest contributes to CO2 concentration mitigation.•CO2 concentrations in Rio de Janeiro are 10–15% lower than in other Brazilian cities.