Dissolved oxygen variability off Eastern Luzon, Philippines during the last millennium

A change in the Dissolved Oxygen (DO) concentration was observed in the thermocline waters of Lamon Bay off Eastern Luzon for 2011 (neutral ENSO) and 2012 (La Niña). Based on optimum multiparameter analysis, a possible driver of this variability is the change in source waters of Lamon Bay. During neutral ENSO conditions, water in Lamon Bay comes mainly from the Kuroshio recirculation gyre, whereas during La Niña event there is a marked increase of North Pacific Tropical Waters, with lower DO. Variability in DO within Lamon Bay is possibly driven by the change in water mass brought about by an ENSO-influenced shift in the bifurcation latitude. To study the variability of dissolved oxygen in a longer timescale, geochemical proxies found in marine sediments was used. XRF data of a sediment core taken from a deep basin within Lamon Bay was used to reconstruct the paleodepositional redox environment in waters off Eastern Luzon. The geochemical proxies V and Mn showed possible DO fluctuations in the past 1000 years.