Global Water Comparison SIBS 2014 participants provided sample from - - PowerPoint PPT Presentation
Global Water Comparison SIBS 2014 participants provided sample from many different locations. D-excess: Expresses the relationship between 18 O and D using d-excess = D - 8* 18 O Corrected 18 O Corrected D Sample ID H 2 O D
Sample ID H2O Corrected δ18O Corrected D D Excess Gugong 20476
4.5 Hepburn 20640.5
12.8 Corin Dam 19895
11.1 Eden 19928
9.7 Ljuvljana 20827.5
12.7 Beijing 19759.5
2.1 Farciones Vega 19248.5
4.0 Tidbinbilla 20752
6.4 Evian 20803.5
2.8 Cool Ridge 19788.5
14.7 Beloka 19622
12.2 Reid Rain 31 Nov 21107.5
Reid Rain 25 Nov 20951.5
9.4 Casuarina Sands 19639
Katoomba 19316
8.5 East Coast Kalnura 21210
12.9 Cotter River 20939.5
7.0 Lake District, Kendall 21045.5
9.6 Huskison 18130.5
19.2 Sydney 18192
15.1 Tuscany 20391
13.3 Brisbane 20775.5
1.7 Narellan Vale 18547.5
16.6 Cairns 20089
14.6 Edinburgh 20975.5
9.7
Corrected deuterium values.
5 10 15 20 25
Gugong Hepburn Corin Dam Eden Ljuvljana Beijing Farciones Vega Tidbinbilla Evian Cool Ridge Beloka Reid Rain (31 Nov) Reid Rain (25 Nov) Casuarina Sands Katoomba East Coast Kalnura Cotter River Edinburgh Lake District, Kendall Huskison Sydney Monteviva tuscany Brisbane Narellanvale Cairns
1 Gugong 2 Hepburn 3 Corin Dam 4 Eden 5 Ljuvljana 6 Beijing 7 Farciones Vega 8 Tidbinbilla 9 Evian 10 Cool Ridge 11 Beloka 12 Reid Rain (31 Nov) 13 Reid Rain (25 Nov) 14 Casuarina Sands 15 Katoomba 16 East Coast Kalnura 17 Cotter River 18 Edinburgh 19 Lake District, Kendall 20 Huskison 21 Sydney 22 Monteviva tuscany 23 Brisbane 24 Narellanvale 25 Cairns
Objective: To estimate effective path length in species with different venation Isotopic composition of the bulk leaf lamina reflects variation in:
Evaporative enrichment is a function of transpiration rate, modulated by the scaled effective path length → Peclet number Peclet effect accounts for the fact that diffusion of water from the sites of evaporation to the rest of the leaf is counteracted by the input of unenriched water through the transpiraitonal flow.
e L
Hydraulic conductivity of the leaf increases as the effective path length decreases
Ferrio et al. 2012
100 200 300 400 500 600 700 800 5 10 15 20 Dm Vein density (mm mm-2)
Kleaf linked to vein density via the shortening of the pathway of water movement from vein ending to evaporative sites (Dm).
Hypothesis 1: “effective path length” may reflect vein density on the basis that for a given VPD, vein density may constrain E. We predict that under optimal conditions, a species with a low vein density will have a low E rate and therefore greater leaf water enrichment, which when you solve for L would predict a larger effective path length to a plant where E rate was high. PLANTS ALL WATER STRESSED!
Hypothesis 2: Under water stress conditions causing reduced E, the fraction
the unenriched xylem, water would become important factors in the prediction of bulk leaf water enrichment. We predict that plants with high vein density would have a larger unenriched pool contributing to the leaf water 180 signal, compared with a species with low vein density.
3 species: Ginkgo biloba Dv = 1.4 Alnus glutinosa Dv = 7 Populus nigra Dv = 23.3
L = average lamina leaf water enrichment = the Péclet number E = transpiration rate L = scaled effective path length C = molar concentration of water D = diffusivity of H2
18O in water
e = evaporative site water enrichment e+ = equilibrium fractionation ek = kinetic fractionation v = enrichment of vapor outside the leaf wa = water vapor mole fraction outside leaf wi = water vapor mole fraction inside leaf
i a k v k e
e L
0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 Ginkgo Populus Alnus ΔL Istopic enrichment without Peclet effect Isotopic enrichment with Peclet (observed value)
Increasing enrichment of 18O Peclet model of leaf water enrichment predicts less enriched leaf water as observed:
y = 0.0097x + 0.0026 R² = 0.9975 0.05 0.1 0.15 0.2 0.25 5 10 15 20 25 Scaled effective path length Vein density (mm mm-2)
maximum rates of E for a given VPD)