Effects of tropical deforestation on global and regional atmospheric chemistry

Keller, Michael; Jacob, Daniel J.; Wofsy, Steven C.; Harriss, Robert C.

doi:10.1007/bf00142221

Cited by 69 publications

(18 citation statements)

References 54 publications

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“…Organic emissions of formic and acetic acids that could not be detected in the laboratory of the University of Münster are suggested to have caused the apparent anion deficit in the fog samples analyses. The change of land use from native forest to pasture associated with biomass burning account for an elevated ion deposition in the tropics (Keller et al, 1991). Particularly during the dry period from October through March, local emissions are transported on a regional scale and deposit on the receptor surface before they get washed out (Lanfer, 2003).…”

Section: Discussionmentioning

confidence: 99%

Chemical characterization of fog and rain water collected at the eastern Andes cordillera

Beiderwieden¹,

Wrzesinsky²,

Klemm³

2005

Hydrol. Earth Syst. Sci.

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Abstract. During a three month period in 2003 and 2004, the chemistry of fog and rainwater were studied at the "El Tiro" site in a tropical mountain forest ecosystem in Ecuador, South America. The fogwater samples were collected using a passive fog collector, and for the rain water, a standard rain sampler was employed. For all samples, electric conductivity, pH, and the concentrations of NH We found considerably higher ion concentrations in fogwater samples than in rain samples. Median pH values are 4.58 for fog water, and 5.26 for the rain samples, respectively. The median electric conductivity was 23 µS cm −1 for the fog and 6 µS cm −1 for the rain. The continent samples exhibit higher concentrations of most ions as compared to the pacific samples, but these differences could not be detected statistically.

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Section: Discussionmentioning

confidence: 99%

Chemical characterization of fog and rain water collected at the eastern Andes cordillera

Beiderwieden¹,

Wrzesinsky²,

Klemm³

2005

Hydrol. Earth Syst. Sci.

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“…Methane consumption was lower in soil cropped to wheat than in a fallow field (Mosier et al 1991). Methane uptake in cultivated soils were one quarter that in corresponding semideciduous tropical forest soils in Panama (Keller et al 1991). Methane uptake was undetectable in a cultivated soil adjacent to a mixed forest that was a weak methane sink in Ottawa, Canada (Lessard et al 1994).…”

Section: Anthropogenic Effects On Soil Methane Uptake and Productionmentioning

confidence: 98%

Soils as sources and sinks for atmospheric methane

Topp¹,

Pattey²

1997

Can. J. Soil. Sci.

194

115

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1997. Soils as sources and sinks for atmospheric methane. Can. J. Soil Sci. 77: 167-178. Methane is considered to be a significant greenhouse gas. Methane is produced in soils as the end product of the anaerobic decomposition of organic matter. In the absence of oxygen, methane is very stable, but under aerobic conditions it is mineralized to carbon dioxide by methanotrophic bacteria. Soil methane emissions, primarily from natural wetlands, landfills and rice paddies, are estimated to represent about half of the annual global methane production. Oxidation of atmospheric methane by well-drained soils accounts for about 10% of the global methane sink. Whether a soil is a net source or sink for methane depends on the relative rates of methanogenic and methanotrophic activity. A number of factors including pH, Eh, temperature and moisture content influence methane transforming bacterial populations and soil fluxes. Several techniques are available for measuring methane fluxes. Flux estimation is complicated by spatial and temporal variability. Soil management can impact methane transformations. For example, landfilling of organic matter can result in significant methane emissions, whereas some cultural practices such as nitrogen fertilization inhibit methane oxidation by agricultural soils.Key words: Methane, methanogenesis, methane oxidation, soil, flux measurement Topp, E. et Pattey, E. 1997. Le sol considéré comme source d'émission de méthane dans l'atmosphère. Can. J. Soil Sci. 77: 167-178. Le méthane est considéré comme gaz à effet de serre important : c'est le produit terminal de la décomposition de la matière organique en conditions anaérobies. En l'absence d'oxygène, il est très stable, mais en aérobiose, il est minéralisé en gaz carbonique par les bactéries méthanotrophes. Les émissions de méthane provenant surtout des terres humides naturelles, des décharges et des rizières représenteraient environ la moitié de la production annuelle de méthane dans la planète. Par ailleurs l'oxydation de méthane de l'atmosphère par les sols bien drainés compteraient pour environ 10 % du méthane stocké. Que le sol soit une source ou un puits d'accumulation nette de méthane, dépend des taux relatifs des activités méthanogéniques et méthan-otrophiques. Un certain nombre de facteurs, notamment, pH, Eh, la température et le niveau hydrique du sol, influent sur les populations bactériennes qui transforment le méthane ainsi que sur le flux de méthane dans le sol. On dispose de plusieurs techniques pour mesurer le flux de méthane, mais l'estimation de ces flux est compliquée par leur variabilité dans le temps et dans l'espace. Il y a aussi le mode de conduite du sol : ainsi par exemple, la mise en décharge des matières organiques peut provoquer d'importantes émissions de méthane, mais l'inverse quelques pratiques culturales comme le fumier et la fumure azotée entravent l'oxydation du méthane par les terres agricoles.

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“…Moreover, land use change is the most important cause of increases in atmospheric concentrations of the greenhouse gases methane and nitrous oxide (Matson and Vitousek 1990, Watson et al 1990, Fung et al 1991. Fires associated with land use change add nitric oxide and carbon monoxide to the atmosphere (Logan 1985, Keller et al 1991, altering its reactive chemistry and bringing episodes of urban-like oxidant air pollution to extensive areas of the tropics ( Crutzen and Zimmermann 1 991 , Fishman et al 1991 ). Fires also produce aerosols that can affect energy balance and climate regionally and globally (Penner et al 1992).…”

Section: Land Use/land Cover Changementioning

confidence: 99%