210Pb and 210Po distributions and disequilibrium in the water column of the Gaoping Submarine Canyon

Gwo-Wei Hung, National Penghu University of Science and Technology, General Education Center, Magong, Taiwan
Abstract:
Water samples were collected at five stations along the axis of the Gaoping Submarine Canyon(GPSC) off southwest Taiwan in early January 2007, after the Fang-Liao submarine earthquake. Concentration profiles of 210Pb and 210Po were measured to reveal the scavenging processes in this study. The dissolved 210Po activities in the water column of below 75 m display obvious deficit relative to 210Pb, indicating significant biological uptake or organic particular scavenging of 210Po. However, the excess of 210Po in dissolved form observed in the surface water suggests an additional flux of 210Po from the coastal sediment. Both the particular and total(dissolved+ particulate) 210Po relative to 210Pb are in near equilibrium or excess below the surface mixed layer. In contrast, the results measured from the same five stations, but before Fang-Liao submarine earthquake, indicate a variable deficiency of 210Po relative to 210Pb, In addition, the total 210Pb and 210Po observed after submarine earthquake are both generally higher than those obtained before earthquake, suggesting the strong resuspension and substantial transport of sediment particles caused by submarine earthquake has resulted in significant inputs of 210Pb and 210Po to these waters and affected the particulate scavenging process in this study.