Table 3 Existing conversion equations.

VPDB/VSMOW

Coplen⁵⁵

δ¹⁸O_x/VSMOW = 1.03091 δ¹⁸O_x/VPDB + 30.91

δ¹⁸O_x/VPDB = 0.97001 δ¹⁸O_x/VSMOW – 29.99

δ¹⁸O_p/δ¹⁸O_c

Iacumin et al.³¹

δ¹⁸O_p(SMOW) = 0.98 δ¹⁸O_c(SMOW) – 8.5

31

Bryant et al.³⁰

δ¹⁸O_c (± 1.3) = 1.02 (± 0.04) δ¹⁸O_p + 8.3 (± 0.7)

42

Wright et al.³²

δ¹⁸O_p(SMOW) = 0.899 δ¹⁸O_c(PDB) + 21.397

Chenery et al.²⁴ (cold, temperate and warm humid climates)

δ¹⁸O_p = 1.0322 (± 0.008) δ¹⁸O_c – 9.6849 (± 0.187)

51

Chenery et al.²⁴ (hot-arid climates)

δ¹⁸O_p = 1.122 δ¹⁸O_c – 13.73

38

δ¹⁸O_p/δ¹⁸O_dw

Longinelli⁶

δ¹⁸O_p = 0.64 δ¹⁸O_w + 22.37

10

Luz et al.⁷

δ¹⁸O_p = 0.78 δ¹⁸O_dw + 22.7

6

Levinson et al.⁸

δ¹⁸O_p = 0.46 δ¹⁸O_dw + 19.4

40

Daux et al.¹⁶ (Eq. 4)

δ¹⁸O_dw = 1.73 (± 0.21) δ¹⁸O_p – 37.25 (± 3.55)

12

Daux et al.¹⁶ (Eq. 5)

δ¹⁸O_dw = 1.70 (± 0.22) δ¹⁸O_p – 39.28 (± 3.68)

12

Daux et al.¹⁶ (Eq. 6) *combined equation

δ¹⁸O_dw = 1.54 (± 0.09) δ¹⁸O_p – 33.72 (± 1.51)

42

Chenery et al.¹⁸ *corrected Levinson et al.⁸

δ¹⁸O_p = 0.46 δ¹⁸O_dw + 20.8

40

Pollard et al.²¹ *superset

δ¹⁸O_p = 0.531 δ¹⁸O_dw + 20.52

94

Herrmann et al.¹⁹

δ¹⁸O_p = 0.62 δ¹⁸O_dw + 21.74

45

Warner et al.²³

δ¹⁸O_dw = 1.64 δ¹⁸O_p – 31.35

27

δ¹⁸O_c/δ¹⁸O_dw

Ehleringer et al. ¹⁴

δ¹⁸O_c(VSMOW) = 0.350 δ¹⁸O_dw + 27.6

5

Posey²²

δ¹⁸O_c(VSMOW) = 0.77 δ¹⁸O_dw + 28.1

58

Keller et al.²⁰

δ¹⁸O_c(VSMOW) = 0.396 δ¹⁸O_dw + 26.9

156

Dotsika¹⁷

δ¹⁸O_dw = 1.020 δ¹⁸O_c – 32.941

16