scholarly journals African volcanic emissions influencing atmospheric aerosol particles over the Amazon rain forest

2017 ◽  
Author(s):  
Jorge Saturno ◽  
Florian Ditas ◽  
Marloes Penning de Vries ◽  
Bruna A. Holanda ◽  
Mira L. Pöhlker ◽  
...  
Keyword(s):  
Rain Forest ◽  
Amazon Basin ◽  
Dimethyl Sulfide ◽  
Aerosol Particles ◽  
Amazon Region ◽  
Volcanic Emissions ◽  
Airborne Measurements ◽  
Amazon Rain Forest ◽  
Sulfur Emissions

Abstract. Long-range transport (LRT) plays an important role in the Amazon rain forest by bringing in different primary and secondary aerosol particles from distant sources. The atmospheric oxidation of dimethyl sulfide (DMS), emitted from marine plankton, is considered an important sulfate source over the Amazon rain forest, with a lesser contribution from terrestrial soil and vegetation sulfur emissions. Volcanic sulfur emissions from Africa could be a source of particulate sulfate to the Amazonian atmosphere upon transatlantic transport but no observations have been published. By using satellite observations, together with ground‑based and airborne aerosol particle observations, this paper provides evidence of the influence that volcanic emissions have on the aerosol properties that have been observed in central Amazonia. Under the volcanic influence, sulfate mass concentrations reached up to 3.6 µg m−3 (hourly mean) at ground level, the highest value ever reported in the Amazon region. The hygroscopicity parameter was higher than the characteristic dry-season average, reaching a maximum of 0.36 for accumulation mode aerosol particles. Airborne measurements and satellite data indicated the transport of two different volcanic plumes reaching the Amazon Basin in September 2014 with a sulfate-enhanced layer at an altitude between 4 and 5 km. These observations show that remote volcanic sources can episodically affect the aerosol cycling over the Amazon rain forest and perturb the background conditions. Further studies should address the long-term effect of volcanogenic aerosol particles over the Amazon Basin by running long-term and intensive field measurements in the Amazon region and by monitoring African emissions and their transatlantic transport.

scholarly journals African volcanic emissions influencing atmospheric aerosols over the Amazon rain forest

2018 ◽  
Vol 18 (14) ◽  
pp. 10391-10405 ◽  
Author(s):  
Jorge Saturno ◽  
Florian Ditas ◽  
Marloes Penning de Vries ◽  
Bruna A. Holanda ◽  
Mira L. Pöhlker ◽  
...  
Keyword(s):  
Atmospheric Aerosols ◽  
Rain Forest ◽  
Cloud Condensation Nuclei ◽  
Atmospheric Composition ◽  
Volcanic Emissions ◽  
Volcanic Event ◽  
Airborne Measurements ◽  
Amazon Rain Forest ◽  
Aerosol Cloud Interactions ◽  
Sulfur Emissions

Abstract. The long-range transport (LRT) of trace gases and aerosol particles plays an important role for the composition of the Amazonian rain forest atmosphere. Sulfate aerosols originate to a substantial extent from LRT sources and play an important role in the Amazonian atmosphere as strongly light-scattering particles and effective cloud condensation nuclei. The transatlantic transport of volcanic sulfur emissions from Africa has been considered as a source of particulate sulfate in the Amazon; however, direct observations have been lacking so far. This study provides observational evidence for the influence of emissions from the Nyamuragira–Nyiragongo volcanoes in Africa on Amazonian aerosol properties and atmospheric composition during September 2014. Comprehensive ground-based and airborne aerosol measurements together with satellite observations are used to investigate the volcanic event. Under the volcanic influence, hourly mean sulfate mass concentrations in the submicron size range reached up to 3.6 µg m−3 at the Amazon Tall Tower Observatory, the highest value ever reported in the Amazon region. The substantial sulfate injection increased the aerosol hygroscopicity with κ values up to 0.36, thus altering aerosol–cloud interactions over the rain forest. Airborne measurements and satellite data indicate that the transatlantic transport of volcanogenic aerosols occurred in two major volcanic plumes with a sulfate-enhanced layer between 4 and 5 km of altitude. This study demonstrates how African aerosol sources, such as volcanic sulfur emissions, can substantially affect the aerosol cycling and atmospheric processes in Amazonia.

scholarly journals Dimethyl sulfide in the Amazon rain forest

2015 ◽  
Vol 29 (1) ◽  
pp. 19-32 ◽  
Author(s):  
K. Jardine ◽  
A. M. Yañez-Serrano ◽  
J. Williams ◽  
N. Kunert ◽  
A. Jardine ◽  
...  
Keyword(s):  
Rain Forest ◽  
Dimethyl Sulfide ◽  
Amazon Rain Forest

scholarly journals Aerosol number fluxes over the Amazon rain forest during the wet season

2009 ◽  
Vol 9 (24) ◽  
pp. 9381-9400 ◽  
Author(s):  
L. Ahlm ◽  
E. D. Nilsson ◽  
R. Krejci ◽  
E. M. Mårtensson ◽  
M. Vogt ◽  
...  
Keyword(s):  
Rain Forest ◽  
Large Scale ◽  
Friction Velocity ◽  
Aerosol Particles ◽  
Deposition Flux ◽  
Wet Season ◽  
Transfer Velocity ◽  
Aerosol Emission ◽  
Amazon Rain Forest ◽  
Particle Fluxes

Abstract. Number fluxes of particles with diameter larger than 10 nm were measured with the eddy covariance method over the Amazon rain forest during the wet season as part of the LBA (The Large Scale Biosphere Atmosphere Experiment in Amazonia) campaign 2008. The primary goal was to investigate whether sources or sinks dominate the aerosol number flux in the tropical rain forest-atmosphere system. During the measurement campaign, from 12 March to 18 May, 60% of the particle fluxes pointed downward, which is a similar fraction to what has been observed over boreal forests. The net deposition flux prevailed even in the absolute cleanest atmospheric conditions during the campaign and therefore cannot be explained only by deposition of anthropogenic particles. The particle transfer velocity vt increased with increasing friction velocity and the relation is described by the equation vt = 2.4×10−3×u* where u* is the friction velocity. Upward particle fluxes often appeared in the morning hours and seem to a large extent to be an effect of entrainment fluxes into a growing mixed layer rather than primary aerosol emission. In general, the number source of primary aerosol particles within the footprint area of the measurements was small, possibly because the measured particle number fluxes reflect mostly particles less than approximately 200 nm. This is an indication that the contribution of primary biogenic aerosol particles to the aerosol population in the Amazon boundary layer may be low in terms of number concentrations. However, the possibility of horizontal variations in primary aerosol emission over the Amazon rain forest cannot be ruled out.

scholarly journals Black and brown carbon over central Amazonia: Long-term aerosol measurements at the ATTO site

2017 ◽  
Author(s):  
Jorge Saturno ◽  
Bruna A. Holanda ◽  
Christopher Pöhlker ◽  
Florian Ditas ◽  
Qiaoqiao Wang ◽  
...  
Keyword(s):  
El Niño ◽  
Light Absorption ◽  
Rain Forest ◽  
El Nino ◽  
Aerosol Particles ◽  
Wavelength Dependence ◽  
Brown Carbon ◽  
Amazon Rain Forest ◽  
Central Amazonia ◽  
Measurement Period

Abstract. The Amazon rain forest is considered a very sensitive ecosystem that could be significantly affected by a changing climate. It is still one of the few places on Earth where the atmosphere in the continent approaches near-pristine conditions for some periods of the year. The Amazon Tall Tower Observatory (ATTO) has been built in central Amazonia to monitor the atmospheric and forest ecosystem conditions. The atmospheric conditions at the ATTO site oscillate between biogenic and biomass burning (BB) dominated states. By using a comprehensive ground-based aerosol measurement setup, we studied the physical and chemical properties of aerosol particles at the ATTO site. This paper presents results from 2012 to 2017, with special focus on light absorbing aerosol particles. The aerosol absorption wavelength dependence (expressed as the absorption Ångström exponent, åabs) was usually below 1.0 and increased during the presence of smoke transported from fires in the southern and eastern regions of the Amazon or advected from savanna fires in Africa. In this study, the brown carbon (BrC) contribution to light absorption at 370 nm was obtained by calculating the theoretical wavelength dependence of åabs (WDA). Our calculations resulted in BrC contributions of 17–29 % (25th and 75th percentiles) to total light absorption at 370 nm (σap 370) during the measurement period (2012–2017). The BrC contribution increased up to 27–47 % during fire events occurring under the influence of El Niño, between September and November 2015. An extended time series of ATTO and ZF2 (another Amazon rain forest sampling site) data showed enhanced light scattering and absorption coefficients during El Niño periods in 2009 and 2015. Long-range transport (LRT) aerosol particles that reached the central Amazon Basin from Africa or from southern Amazon exhibited a wide range of black carbon (BC) to carbon monoxide (CO) enhancement ratios (ERBC) (between 4 and 15 ng m−3 ppb−1) reflecting the variability of fuels, combustion phase, and removal processes in the atmosphere. Higher ERBC were measured during the dry season when we observed values up to 15 ng m−3 ppb−1, which were related to the lowest single scattering albedo (ω0) measured during the studied period, (0.86–0.93). A parameterization of åabs as a function of the BC to OA mass ratio was investigated and was found applicable to tropical forest emissions but further investigation is required, especially by segregating fuel types. Additionally, important enhancements of the BC mass absorption cross‑section (αabs) were found over the measurement period. This enhancement could be linked to heavy coating of the BC aerosol particles. In the future, the BC mixing state should be systematically investigated by using different instrumental approaches.

The Relevance of Biogeochemistry to Amazon Development and Conservation

2001 ◽  
Author(s):  
Michael McClain
Keyword(s):  
Rain Forest ◽  
Amazon Basin ◽  
Biological Diversity ◽  
Regional Climate ◽  
Ecological Integrity ◽  
The Public ◽  
Amazon Rain Forest ◽  
News Service ◽  
Gold Miners ◽  
Earth’S Climate

To read the press of recent years, one might imagine that the fate of the world rests in the hands of those who would develop the Amazon basin. Waves of incoming colonists are blamed for the bulk of the deforestation and development (Schomberg 1998), but Asian logging firms, multinational oil companies, and gold miners are also portrayed as destructive agents hacking down the forest, systematically undermining its biodiversity, and severely contaminating its myriad ecosystems (Althaus 1996, Ferreira 1996, James 1998). The effects of these varied threats are regularly broadcast in alarming tones. Rueters News Service warned in January 1998 that “Brazil’s Amazon rain forest, the world’s richest trove of biological diversity and source of much of the Earth’s oxygen, continues to be ravaged” (Craig 1998). And, in April 1999, a writer for the Associated Press communicated the “fear” of unspecified scientists that “damage to the rain forest... could throw the Earth’s climate out of balance” (Donn 1999). Clearly, the fate of the Amazon and the implications of its fate to the overall Earth system are topics of enormous scientific and popular interest. While there is little disagreement that the complete destruction of Amazon forests would be catastrophic, what about partial deforestation of the region? How much, and which parts, of the Amazon can be converted to sustainable human land uses without compromising the ecological integrity of the conserved areas? How might this development impact regional climate, adjoining coastal systems, and overall global processes? Answers to these volatile questions remain elusive and seemingly endless strands of controversy swirl about them. At the heart of the matter, yet largely beyond the public discussion, are biogeochemical cycles that support and regulate the functioning of the Amazonia’s biological systems. Moreover, it is the incomplete understanding of these cycles that promotes uncertainty and feeds the controversy. The purpose of this book is to present a coherent assessment of our current understanding of the biogeochemical functioning of the Amazon basin. Although it is surely presumptuous to assume that this presentation will shed sufficient light on the uncertainties to eliminate the current controversies, we hope that it will provide a basis for lifting the discussion to a higher level.

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