Publication: Are termites an unknown source for BVOCs?

Plants and soils, especially those in the Amazon rainforest, emit most of the biogenic volatile organic compounds (BVOCs) found in the atmosphere. There they affect many processes, such as the formation of secondary organic aerosols, which in turn influence the Earth’s radiative budget. However, few studies thus far looked into emissions from insects such as termites.

BVOCs in the Amazon

Nora Zannoni and her colleagues measured BVOC emissions at the ATTO tall tower in several heights. Specifically, they looked at one particular BVOC called α-pinene. This organic compound exists in two mirror image forms called (−)-α-pinene and (+)-α-pinene. Such chiral forms are identical in all physical properties.

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Does topography affects atmospheric turbulence?

Atmospheric turbulence

Whirling wind motions called turbulence commonly occur in the lowest 100 m of the atmosphere. Here, they play an important role in transporting energy, gases, and particles away from and toward the land surface. Accordingly, these exchanges are crucial for the interaction between the atmosphere and the biosphere. This includes processes such as:

  • transport of latent heat (energy)
  • transport of local methane emissions (gases)
  • rise of forest-produced pollen into the atmosphere, where they might function as condensation nuclei for cloud formation (particles)

Quantifying and predicting the energy available to promote this mixing is therefore critical to better understand how strong these interactions are.

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New Publication: Tree mortality in Amazonian floodplains

Floodplains in the Amazon

Recently we mentioned that drowned trees along the Uatumã River a likely the cause for enhanced methane emissions measured at ATTO. Now Angélica Resende and her co-authors investigated how changes in flooding regimes impact tree mortality in floodplains. So they compared two sites in the Amazon basin.

Along the Jaú River, the floodplain environment is still largely undisturbed. Along the Uatumã near ATTO, on the other hand, the flooding regime has been altered by the implementation of the Balbina hydroelectric plant further upstream. The construction of the dam flooded an area of 2,400 km2 of native forest.

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Understanding nighttime methane emissions

Methane in the Amazon

Methane emissions are smaller than those of CO2, and methane abundance in the atmosphere is much smaller. But methane is much more efficient in trapping heat than CO2 is, making it a very important greenhouse gas. Like CO2, methane is emitted by the burning of fossil fuels but it also has many natural sources. They include thawing permafrost and wetlands.

This is where the Amazon rainforest comes into play. The Amazon and its tributaries are bordered by wetlands of continually flooded forest. In addition, river levels swell significantly during the wet season and seasonally flood large areas of otherwise dry forest.

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Transport of black carbon-rich smoke from Africa to the Amazon

When forests burn those fires produce a lot of smoke. And that smoke usually contains soot, also called “black carbon”. Black carbon particles are aerosols that absorb radiation and as such can warm the Earth’s atmosphere and climate. But we still have much to learn about aerosols, their properties, and distribution in the atmosphere. One of those things is the question of how black carbon emitted from biomass burning in Africa (i.e. forests, grasslands, savannas etc.) is transported across the Atlantic and into the Amazon basin, and what role it plays there. Bruna Holanda and her co-authors tackled this by combining data from the northeastern Amazon collected with the HALO research aircraft during the ACRIDICON-CHUVA campaign in September 2014, with long-term data from ATTO.

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