Paleo-precipitation and water isotopes10/14/10 Archives of interest : 1)ice cores 2)deep-sea sediments 3)lake sediments 4)corals 5)speleothems 6)groundwaters 7)tree rings? Primary goal: 1)To reconstruct (and hopefully quantify) environmental changes in the past Secondary goal: 2)To use isotopes as tracers to study transport mechanisms and processes The Eastern Meditteranean and the Red Sea are both semi-enclosed, evaporative basins

growing glaciers deep-sea foraminifera Water isotopes in deep-sea cores The “Ice Volume” effect- Light isotope removed from ocean, locked into large ice sheets. Ocean  18 O shift (+1.5‰) recorded in marine carbonates that grew during glacial. SPECMAP – standard benthic δ 18 O record, used to date marine sediments of unknown age

Ex: EPICA – a new LONG Antarctic ice core Augustin, L. et al Water isotopes in ice cores Also applied to: Greenland  18 O – GISP, Jouzel et al., Andes  18 O, Lonnie Thompson Alaska  18 O, Ken Moore and others

Pore fluids – glacial ocean water  18 O glacial enrichment advection drives water out of compacting sediments diffusion works to erase pulse signal & Need to model pore fluid profiles because: Goal: to quantify the glacial-interglacial change in seawater  18 O; Result = ‰

Red Sea  18 O – high-resolution sea level history Theory: when sea level is high, Red Sea well-mixed with light ocean water when sea level is low, Red Sea dominated by evaporation, heavy  18 O Siddall et al., Nature, 2003 red and black = Red Sea benthic foraminfera  18 O green = corals from ocean islands (Cutler et al., 2003) blue = Chappell (2002) scaling deep-sea benthic foram  18 O to sea level

Coral records of paleo-precipitation Theory: 1) more rain = lighter  18 O “amount” effect 2) surface seawater  18 O will become lighter 3) coral  18 O lighter Cole and Fairbanks, 1990

Water isotopes in speleothems (cave stalagmites) Theory: 1)  18 O of speleothem =  18 O of precipitation 2)  18 O of precipitation fxn of temperature (mid- to high-latitudes) and/or amount of rainfall (low latitudes) Wang et al., Science, 2001

Water isotopes in tree rings temperate tree ring tropical tree ring Theory:  18 O of cellulose will track the seasonal cycle from dry to wet seasons (monsoon)

Water isotopes in tree rings: promising but still potential seasonal signal ENSO signal Evans et al., 2005

and White, 1989 Water isotopes in ecology Goal: to use isotopes to understand how water is cycled through a biotic system Ex:  D in trees -photosynthesis occurs in leaf -leaf experiences evaporative enrichment -photosynthetic reactions cause large depletion in products -by careful mass balance you can study the movement of water through this system For more information see: Stable Isotopes in Ecological Systems, ed. by P. Rundel, J.R. Ehleringer and K.A. Nagy, Springer-Verlag, 1989

Bender, 1994 Water isotopes in ecology

The future of water isotopes: satellite retrievals of water vapor Worden et al, 2007

TES retrievals of water vapor content (q) and isotopes (δD) key observations: 1)tropics are moist and enriched 2)largest enrichments over large tropical continents

TES retrievals of q and δD: obs versus modeled blue = Raleigh distillation orange = pure evaporation black = vapor in equil w/ ocean water red = clear sky (dry) blue = cloudy sky (wet) key results: 1)tropical oceans characterized by recycled moisture (high q, low δD) 2) tropical continents characterized by more enriched moisture (evapotrans?)