1

Global Water Cycle(Water fluxes in 1000 km3/yr)

2

Latitudinal Trends in Global P and E

3

Equilibrium Fractionation between Water Vapor and Liquid

4

Temperature Dependence of Equilibrium

Fractionationfor Water

Phases

(‰)

18O

(‰)

Dα = R(liq) / R(gas)

5

Rayleigh Distillation Prediction18O vs Temp

d18O = -2 ‰

dD = -7 ‰

d18O = -5 ‰

dD = -32 ‰

6

18O vs Temperature

for Precipitation

18O

(

‰)

7D

(‰

)

18O (‰)

D vs 18O for Global Precipitation

8

D of Precipitation Globally

D of Precipitation in N. America

9

18O Precipitation vs Altitude

10

18O of Precip vs Distance

from Coast

11

Seasonality of 18O of

Precipitation

12

Deviations from MWL

• Although global pattern of 18O and D of precipitation follows MWL, there can be significant deviations.

• Mainly in arid regions, where evaporation is important.

• Use Deuterium Excess to quantify departure from MWL.

• Implication is that evaporation can play a significant role in the isotopic composition of precipitation by imposing kinetic, rather than equilibrium, isotope effects.

13

D vs 18O in Arid Regions

Rio Grande (Southwest US)

and Darling (Central

Australia)

In arid regions, D vs 18O slope is significantly less than 8 of MWL.

14

18O of Precip at Tropical Sites with Seasonal Cycle in Humidity

15

Deuterium Excessd-excess (‰) = D (‰) – 8* 18O (‰)

d-excess of MWL = 10 (‰)

Prediction: d-excess depends

on Relative Humidity

16

Effect of humidity on D vs 18O slope

Lakes E. Washington

Lakes W. Washington

MWL

17

Isotopic Signatures of the Global Water Cycle

18

Air-Sea Transfer of Water Vapor

19

18O versus Borehole Paleothermometrya controversy in Greenland Ice Cores

emp/18O= 1.5 ºC / ‰)

Current Precipitation emp/18O= 3 ºC / ‰

Borehole Temps

Climate scientists favor the borehole temperature changes.

20

Greenland Ice Core 18O and Temperature Record

Using borehole temperature vs 18O calibration

21

Antarctic Ice Core Record of D and Implied Temperature

22

SeasonalRecords of 18O and D in

PrecipitationD

18O

Temp

23

18O and D as a Water

Source Tracer in Steams and

Rivers

D (‰)

18O

(

‰)

Five European Rivers

22 = Rhine River

24

18O and D in US

Rivers

Missouri R.

Mississippi R.

Meramac R.?L

25

18O and D as a Water

Source Tracer in

Rivers

26

d-excess of US Rivers

27

18O in Ground Waters

28

18O and D as Groundwater

Tracers in Arid Regions

29

Surface Ocean 18O

(‰ vs SMOW)

(LeGrande, GRL 2006)

30

Surface Salinity

31

18O vs Salinity

32

18O in the Deep Atlantic Ocean

33

D of Seawater in the Deep Sea