title: Holocene closure of Lib Pond, Marshall Islands.
abstract: Well-preserved sediment from closed water bodies of atolls such as Lib Pond are rare opportunities to reconstruct the past regional climate, which pieced together across a latitude and longitude range identify the range of movement patterns of wider scale climate phenomena such as the Intertropical Convergence Zone (ITCZ) and El Niño Southern Oscillation (ENSO). We conducted the first physico-chemical survey of Lib Pond, a shallow, closed-water saline lake located on remote and difficult to access Lib Island in the Marshall Islands at 8° 18' 48.99″ N, 167 22' 51.90″ E in the Pacific Ocean, in July 2009. We performed a bathymetric survey, recorded salinity, dissolved oxygen, pH, and temperature profiles, monitored the tidal variability, and conducted a vegetation survey surrounding the lake. From bathymetric data we calculated the lake volume, which we used to estimate the lake's salt budget, and ultimately the residence time of water in the lake basin. We took a series of sediment cores from the lake, cores which indicate Lib Island's changing environment and climate. Radiocarbon measurements determined sediment age, and reveal significant mixing over the last 2 ka of deposition. We conclude that prior to 3 ka, Lib Island was an atoll with a central lagoon connected to the open ocean, which was then closed off from the open ocean to form the brackish system that exists today. We predict that the sediment accumulation in Lib Pond evident today will continue. As seawater is inhibited from exchanging with fresh water, Lib Pond will become a shallower lake with increasingly fresh water.
authors.affiliation: School of Oceanography, University of Washington, Seattle, Washington, United States of America.
authors.forename: Conor L
authors.initials: CL
authors.lastname: Myhrvold
authors.affiliation: School of Oceanography, University of Washington, Seattle, Washington, United States of America.
authors.forename: Fran
authors.initials: F
authors.lastname: Janny
authors.affiliation: School of Oceanography, University of Washington, Seattle, Washington, United States of America.
authors.forename: Daniel
authors.initials: D
authors.lastname: Nelson
authors.affiliation: School of Oceanography, University of Washington, Seattle, Washington, United States of America.
authors.forename: S Nemiah
authors.initials: SN
authors.lastname: Ladd
authors.affiliation: School of Oceanography, University of Washington, Seattle, Washington, United States of America.
authors.forename: Alyssa
authors.initials: A
authors.lastname: Atwood
authors.affiliation: School of Oceanography, University of Washington, Seattle, Washington, United States of America.
authors.forename: Julian P
authors.initials: JP
authors.lastname: Sachs
mesh_terms: D002980:Climate; D005618:Fresh Water / Q000737:chemistry; D005843:Geography; D019015:Geologic Sediments; D006801:Humans; D006863:Hydrogen-Ion Concentration; D060106:Lakes; D008849:Micronesia; D010100:Oxygen / Q000737:chemistry; D061005:Ponds; D054712:Salinity; D013696:Temperature
chemical_list: D010100:Oxygen