Lake Challa, East Africa 25KYr Leaf Wax Deuterium Data Tierney, J.E.; Russell, J.M.; Sinninghe Damsté, J.S.; Huang, Y.; Verschuren, D. Tierney, J.E. Russell, J.M. Sinninghe Damsté, J.S. Huang, Y. Verschuren, D. Monsoon earth science/paleoclimate/paleolimnology (delta 2H,C28 n-alkanoic acid,null,per mil VSMOW,null,paleolimnology,corrected,null,N,ice volume corrected) earth science/paleoclimate/paleolimnology (depth,null,null,centimeter,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (delta 2H,C28 n-alkanoic acid,null,per mil VSMOW,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (age,null,null,calendar year before present,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (Lake Challa>LATITUDE -3.3167>LONGITUDE 37.7) Both Atlantic and Indian Ocean climate dynamics exert influence over tropical African hydroclimate, producing complex patterns of convergence and precipitation. To isolate the Indian Ocean influence on African paleohydrology, we analyzed the deuterium/ hydrogen ratio of higher plant leaf waxes (dDwax) in a 25 000-year sediment record from Lake Challa (3°S, 38° E) in the easternmost area of the African tropics. Whereas both the seismic record of inferred lake level fluctuations and the Branched and Isoprenoidal Tetraether (BIT) index proxy record changes in hydrology within the Challa basin, dDwax, as a proxy for the isotopic composition of precipitation (dDP) is interpreted as a tracer of large-scale atmospheric circulation that integrates the history of the moisture transported to the Lake Challa area. Specifically, based on modern- day isotope-rainfall relationships, we argue that Lake Challa dDwax reflects the intensity of East African monsoon circulation. The three hydrological proxy records show generally similar trends for the last 25 000 years, but there are important differences between them, primarily during the middle Holocene. We interpret this deviation of dDwax from local hydrological history as a decoupling of East African monsoon intensity - which heavily influences the isotopes of precipitation in East Africa today - from rainfall amount in the Challa basin. In combination, the hydrological proxy data from Lake Challa singularly highlight zonal gradients in tropical African climate that occur over a variety of timescales, suggesting that the Congo Air Boundary plays a fundamental role in controlling hydroclimate in the African tropics. STUDY NOTES: Deuterium/hydrogen ratio of higher plant leaf waxes (dDwax) from Lake Challa, Kenya, covering the last 25,000 years. The chronology for the Lake Challa composite sediment sequence is based on a combination of 210Pb and AMS 14C dating as previously described by Verschuren et al. (2009). The composite sedimentary sequence was sampled every 4 cm down to a depth of 200 cm to generate a high-resolution (30-50 year) record for the past two millennia, and then was sampled every 16 cm (~300 years) thereafter. Higher sampling resolution (~100 year) was also applied during the Younger Dryas interval. D/H composition of the C28 fatty acid samples (dDwax) was determined via gas chromatography-isotope-ratio mass spectrometry. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Tierney, J.E. Investigator : Russell, J.M. Investigator : Sinninghe Damsté, J.S. Investigator : Huang, Y. Investigator : Verschuren, D. 2011-04-22 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/10889 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/eastafrica/challa2011.xls https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/eastafrica/challa2011.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/eastafrica/challa2011.xls https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/eastafrica/challa2011.txt English https://www.ncdc.noaa.gov/paleo/study/10889 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/eastafrica/challa2011.xls https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/eastafrica/challa2011.txt Tierney, J.E., J.M. Russell, J.S. Sinninghe Damsté, Y. Huang, and D. Verschuren. 2011. Late Quaternary behavior of the East African monsoon and the importance of the Congo Air Boundary. Quaternary Science Reviews, Vol. 30 (7-8), pp. 798-807. doi:10.1016/j.quascirev.2011.01.017 START YEAR: 24922 cal yr BP * END YEAR: -30 cal yr BP 37.7 -3.3167 37.7 -3.3167