Paleolimnological investigations of anthropogenic environmental change in Lake Tanganyika: VI. Geochemical indicators

C. M. O'Reilly, D. L. Dettman, A. S. Cohen

Research output: Contribution to journalArticle

21 Scopus citations

Abstract

Geochemical signals of bulk sedimentary organic matter from three cores from Lake Tanganyika provided information about both internal processes and terrestrial inputs to the lake. Indications of land use change were detected in the geochemical records of the watersheds, and the timing of these changes was consistent with historical records of population demographics. While C:N ratios suggested that the distance from shore might be important in influencing the relative amount of allochthonous vs. autochthonous material, all cores were dominated by autochthonous organic matter. In general, nitrogen isotopes were more positive at disturbed sites, indicating inputs of enriched soil nitrate that was subsequently taken up by phytoplankton. In contrast, carbon isotopes did not reflect land use patterns, and a post-1950s decline in carbon isotope ratios found in all cores may indicate a lake-wide decrease in productivity. These interpretations were consistent with pollen and climate records.

Original languageEnglish (US)
Pages (from-to)85-91
Number of pages7
JournalJournal of Paleolimnology
Volume34
Issue number1
DOIs
StatePublished - Jul 1 2005

Keywords

  • Carbon isotopes
  • Deforestation
  • Lake Tanganyika
  • Late Holocene
  • Nitrogen isotopes
  • Soil erosion

ASJC Scopus subject areas

  • Aquatic Science
  • Earth-Surface Processes

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