Seasonal variation of gaseous HNO3 and NH3 at a Tropical Savannah site

Rondôn, Alberto; Sanhueza, Eugenio

doi:10.1007/bf00118351

Cited by 14 publications

(6 citation statements)

References 51 publications

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“…These results differed from those reported by Adon et al (2010) in the equatorial African forests of Zoetele and Bomasa, where no significant difference of NH 3 and NO 2 concentration was observed between the wet and the dry season; furthermore, the reported concentrations of NH 3 were higher than those reported in Ankasa. The latter were also lower than those measured by Rondon and Sanhueza (1990) with active sampling in a woodland savannah in Venezuela (between the Amazon rainforest and the Caribbean Sea) following a biomass burning; however, the opposite is true for NO − 3 , which was three times higher in the Ankasa site. This difference might also be explained in terms of distance of the fires from the sampling site, since in the Venezuelan study fires were closer to the sampling station, which probably favored higher NH 3 depositions, while NO − 3 in aerosol, which is considered to be a significant component of long-range transported Nr in the atmosphere (Hertel et al, 2006), might have deposited further from the sampling station in Venezuela.…”

Section: Discussioncontrasting

confidence: 55%

Seasonal trends of dry and bulk concentration of nitrogen compounds over a rain forest in Ghana

Fattore¹,

Bertolini

Materia

et al. 2014

Biogeosciences

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Abstract. African tropical forests of the equatorial belt might receive significant input of extra nitrogen derived from biomass burning occurring in the north savanna belt and transported equatorward by northeastern winds. In order to test this hypothesis an experiment was set up in a tropical rain forest in the Ankasa Game Reserve and Nini-Suhien National Park (Ghana) aimed at quantifying magnitude and seasonal variability of concentrations of N compounds, present as gas and aerosol (dry nitrogen) or in the rainfall (bulk nitrogen), over the studied forest; and relating their seasonal variability to trends of local and regional winds and rainfall and to variations of fire events in the region. Three DELTA systems, implemented for monthly measurements of NO 2 , were mounted over a tower at 45 m height, 20 m above forest canopy to sample gas (NH 3 , NO 2 , HNO 3 , HCl, SO 2 ) and aerosol (NH

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Section: Discussioncontrasting

confidence: 55%

Seasonal trends of dry and bulk concentration of nitrogen compounds over a rain forest in Ghana

Fattore¹,

Bertolini

Materia

et al. 2014

Biogeosciences

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“…In wet savannas and forested ecosystems, lower HNO 3 concentrations are directly correlated with lower levels of measured NO 2 concentrations (Serça et al, 1998;Jaegle et al, 2004), and can also be attributed to the very high HNO 3 solubility in water which is thus easily scavenged by clouds and rain Yoboue et al, 2005). At a tropical forested savanna site of South America, very low concentrations of HNO 3 (0.04 ppb) were reported by Rondon and Sanhueza (1990).…”

Section: Nitric Acid (Hno 3 )mentioning

confidence: 95%

Long term measurements of sulfur dioxide, nitrogen dioxide, ammonia, nitric acid and ozone in Africa using passive samplers

et al. 2010

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Abstract. In this paper we present the long term monitoring of ambient gaseous concentrations within the framework of the IDAF (IGAC-DEBITS-AFRICA) program. This study proposes for the first time an analysis of long-term inorganic gas concentrations (1998 to 2007) of SO 2 , NO 2 , HNO 3 , NH 3 and O 3 , determined using passive samplers at seven remote sites in West and Central Africa. Sites are representative of several African ecosystems and are located along a transect from dry savannas-wet savannas-forests with sites at Banizoumbou (Niger), Katibougou and Agoufou (Mali), Djougou (Benin), Lamto (Cote d'Ivoire), Zoetele (Cameroon) and Bomassa (Congo). The strict control of measurement techniques as well as the validation and inter-comparison studies conducted with the IDAF passive samplers assure the quality and accuracy of the measurements. For each type of African ecosystem, the long term data series have been studied to document the levels of surface gaseous concentrations. The seasonal and interannual variability have also been analyzed as a function of emission source variations. We compared the measured West and Central African gas Correspondence to: M. Adon (adonatma@yahoo.fr) concentrations to results obtained in other parts of the world. Results show that the annual mean concentrations of NO 2 , NH 3 , HNO 3 measured in dry savannas are higher than those measured in wet savannas and forests that have quite similar concentrations. Annual mean NO 2 concentrations vary from 0.9±0.2 in forests to 2.4±0.4 ppb in the dry savannas, NH 3 from 3.9±1.4 to 7.4±0.8 ppb and HNO 3 from 0.2±0.1 to 0.5±0.2 ppb. Annual mean O 3 and SO 2 concentrations are lower for all ecosystems and range from 4.0±0.4 to 14.0±2.8 and from 0.3±0.1 to 1.0±0.2 ppb, respectively. A focus on the processes involved in gas emissions from dry savannas is presented in this work, providing explanations for the high concentrations of all gases measured at the three dry savannas sites. At these sites, seasonal concentrations of all gases are higher in the wet season. Conversely, concentrations are higher in the dry season in the wet savannas. In forested regions, we measure no significant difference between wet and dry seasons. This unique database of long term gases concentrations monitoring is available at:

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“…Also, it is important to note that the atmospheric concentration of NH 3 used in the calculations corresponds to measurements made at only one site [Rond6n and Sanhueza, 1990], and the likely spatial variability could increase the NH 3 deposition range given in Table 5 •Values include fluxes estimated from budget considerations. …”

Section: Ammonia-ammonium Cyclingmentioning

confidence: 99%

Budgets of fixed nitrogen in the Orinoco Savannah Region: Role of pyrodenitrification

Sanhueza¹,

Crutzen²

1998

Global Biogeochemical Cycles

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Seasonal variation of gaseous HNO3 and NH3 at a Tropical Savannah site

Cited by 14 publications

References 51 publications

Seasonal trends of dry and bulk concentration of nitrogen compounds over a rain forest in Ghana

Seasonal trends of dry and bulk concentration of nitrogen compounds over a rain forest in Ghana

Long term measurements of sulfur dioxide, nitrogen dioxide, ammonia, nitric acid and ozone in Africa using passive samplers

Budgets of fixed nitrogen in the Orinoco Savannah Region: Role of pyrodenitrification

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