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Communication Dans Un Congrès Année : 2006

Detection of manure-derived organic compounds in rivers draining agricultural areas of intensive manure spreading

Emilie Jardé
Gérard Gruau
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Résumé

This study presents the potentiality of organic markers to trace the impact of animal manure in soils and rivers draining agricultural watersheds. As described by Gruau et al. (in this session), the analysis of long term records of dissolved organic matter (DOM) in five watersheds in Brittany (western of France) shows divergent trends which can not be explained solely by global changes. One alternative explanation could be that long- term records of DOM in rivers are controlled by human activities, and notably by agricultural practices. In Brittany, the agricultural intensification led to an over-application of animal manures to soils. This practice can strongly increase the amount of soil-water extractable organic matter, thereby leading to an increase of organic matter fluxes in agricultural landscapes and then to a contamination of river waters. Such an hypothesis deserves consideration in view of the massive manure fluxes that are disposed on agricultural land in many parts of the world. In this goal, our study aimed at determining potential sources of organic matter and molecular markers or specific distributions in rivers draining agricultural watersheds. In this study we focused on the analysis of pig slurries because of the importance of pig production in Brittany. The analysis of pig slurry evidenced the presence of coprostanol (5ß) as a specific marker, originating from the bio- hydrogenation of cholesterol by anaerobic bacteria. The difference with other animal or human wastes has been evidenced by two ratios: 5ß/C27 and C29/C27. After the validation of the ability of coprostanol to be a molecular marker of pig slurry, our analysis has been focused on the OM of watersheds in Brittany showing divergent evolutions. The results show a systematic relation between the C29/C27 and 5ß/C27 ratios and the type of animal breeding in each watershed. This study allows us to evidence the impact of animal breeding activities in the analysed rivers. Such a study supports the view that OM export by rivers is not solely under the control of global, climatic parameters, but also under the control of local land-use factors.
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Dates et versions

insu-00165424 , version 1 (26-07-2007)

Identifiants

  • HAL Id : insu-00165424 , version 1

Citer

Emilie Jardé, Gérard Gruau. Detection of manure-derived organic compounds in rivers draining agricultural areas of intensive manure spreading. American Geophysical Union (AGU) Fall Meeting 2006, Dec 2006, San Francisco,, United States. pp.B33A-1152. ⟨insu-00165424⟩
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