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

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.