Effect of forest and savanna vegetation on the carbon-isotope composition of sediments from the Sanaga River, Cameroon
- Australian National Univ., Canberra (Australia)
- Lab de Sedimentologie et Geochimie Marine, Perpignan (France)
The carbon-isotope composition {delta}{sup 13}C values of around -22{per_thousand}. After the river passes through extensively forested regions, the {delta}{sup 13}C values of the sediments closest to the mouth of the river decrease to -25{per_thousand}. Samples collected from rivers with entirely forested catchment had low {delta}{sup 13}C values (from -27 to -29{per_thousand}) consistent with a pure C{sub 3} vegetation source. The downriver carbon-isotope trends are consistent with the hypothesis that observed variations are due to changes in the relative proportions of C{sub 3} and C{sub 4} carbon in the sediments, which are derived from terrestrial vegetation in the river catchment. Some sediments from the Mbam River, the principal tributary of the Sanaga River, have extremely high {delta}{sup 13}C values (up to -16.7{per_thousand}). These high values may be the result of severe erosion in the densely populated and intensively farmed Bamileke region in the headwaters of the Mbam. An underrepresentation of C{sub 4{minus}}derived carbon in the upper reaches of the Sanaga is possibly due to the damming of the Djerem River at Mbakaou. Since the dam was constructed <25 yr ago, this suggests that the {delta}{sup 13}C value of river sediments responds rapidly to changes in the basin. 19 refs., 5 figs., 3 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 160112
- Journal Information:
- Limnology and Oceanography, Vol. 39, Issue 8; Other Information: PBD: Dec 1994
- Country of Publication:
- United States
- Language:
- English
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