Global and local meteoric water lines for ¹⁷O/¹⁸O and the spatiotemporal distribution of ¹⁷O in Earth's precipitation

Recently, delta O-17 and its excess (Delta ' O-17) have become increasingly significant "triple-oxygen-isotope" indicators of distinctive hydrological processes in hydrology and climatology. This situation mirrors the research regarding delta O-18 and delta H-2 in the 1960s towards a solid theoretical base and a surge in application examples and field studies worldwide. Currently, systematic global measurements for delta O-17 in precipitation are still lacking. As a result, attempts have been made to define a Global delta O-17/delta O-18 Meteoric Water Line (GMWL), often by using regional or local datasets of varying systematicity. Different definitions of the global reference slope (lambda(ref)) for determining Delta ' O-17 values have been proposed, by ongoing debate around a proposed consensus value of 0.528. This study used worldwide samples archived in the IAEA Global Network of Isotopes in Precipitation (GNIP) to (a) derive a delta O-17/delta O-18 GMWL based on four-year monthly records from 66 GNIP stations, (b) formulate local delta O-17/delta O-18 meteoric water lines (LMWL) for these stations' areas, and (c) evaluate regional and seasonal variations of Delta ' O-17 in precipitation. The GMWL for delta O-17/delta O-18 was determined to be delta ' O-17 = 0.5280 +/- 0.0002 delta ' O-18 + 0.0153 +/- 0.0013, in keeping with the consensus value. Furthermore, our results suggested that using a line-conditioned O-17-excess is a viable alternative over the global lambda(ref) in the context of regional hydrology and paleoclimatology interpretations; however, without challenging the global lambda(ref) as such.