Estimativa do fluxo de metano e dióxido de carbono em áreas de manguezais do município de São Caetano de Odivelas - PA.

Abstract

Mangroves are considered environmentally and socioeconomically productive ecosystems because of their contribution to mitigating climate change, capturing and storing CO2 in the aerial and underground biomass, and a large fraction of carbon is escaped from soil and water into the atmosphere. The mangrove areas are important contributors to greenhouse gases (GHG). The study highlights the monthly measurements of fluxes methane (FCH4) and carbon dioxide (FCO2) flows in mangrove forest at the soil-atmosphere interface (Macaca Island), and water-atmosphere interface (Mojuim Estuary). The measurements included the temporal (dry period: July to December 2017 and rainy: January to June 2018) and spatial, (high topography: 2.5 m and low: 2.0 m) scale. Flows are measured by the dynamic chamber method associated with an infrared gas analyser. Additionally, parameters were recorded. A) environmental, air temperature, relative humidity, wind speed. B) physical and chemical water, water temperature, dissolved oxygen and pH. C) soil physical and chemical, soil temperature, soil moisture, organic matter, pH, organic total carbon, total nitrogen, and C/N ratio, microbial carbon, microbial nitrogen. The FCH4 in the soil varied in means of 0.1874 g m-2 d-1 and 0.0711 g m-2 d-1 between dry and rainy season. The FCO2 varied in means of 6.3607 g m-2 d-1, and 7.0542 g m-2 d-1 between dry and rainy season. The FCH4 ranged from 0.2360 g m-2 d-1 to 0.0271 g m-2 d-1 between low and high topography. The FCO2 ranged from 5.4383 g m-2 d-1, and 7.079 g m-2 d-1 between low and high topography. This could be related to the lower amount of organic matter, oxidized environment and good soil aeration in the high topography favoring FCH4 anoxia. The FCH4 in the estuary varied between season dry and rainy from 0.039 to 0.050 g m-2 d-1. The FCO2 varied between season dry and rainy from 10.474 g m-2 d-1 to 28.985 g m-2 d-1. The FCO2 present difference (p < 0.05) between the dry and rainy season, and may be influenced by the salubrious sea water in the tide and fresh water from the Mojuim River into the ebb. In this study it was observed that the highest FCH4 and FCO2 occur in the rainy season, and minimal variation of FCO2 in the soil.