Our investigation has demonstrated the need to make interannual observations of high spatial resolution to deduce coastal sediment dynamics and OC transport and distribution processes on the East Siberian Arctic shelf. Two types of sedimentation regimes have been revealed: erosion-accumulation, and accumulation. The erosion-accumulation conditions were observed during the short ice-free period of the year (expeditions in late August of 1999-2007). This is believed to be the most common and quantitatively most important mechanism for suspended particulate matter (SPM) and terrestrial particulate organic carbon (POC) delivery to these coastal systems. In this mechanism, terrigenous sources of SPM and POC prevail, originating from thermoabrasion of shores (coastal ice-complex), river sedimentary material and remobilized material from the bottom (Fig.1). Based on multi-year investigations features of suspended particulate matter formation were revealed, depending of synoptic processes and river water discharge. It was found that the variability in the content and distribution structure of the suspended particulate matter during the ice-free period caused changes in the conditions of mobilization and supply of terrigenous material. Under the influence of northerly winds and storm the erosion of shore ice complex and coastal slope are activated, as result to the coastal shelf waters enters abnormal volume of sedimentary material. Different sedimentary regime is formed with minor disturbances and predominant of weak southerly winds. This work was supported by the Government of the Russian Federation (megagrant # 14.Z50.31.0012).
Fig.1. Delivery scheme of sedimentary material from coastal ice-complex and mouths of the Lena River flow channels for two sedimentation regimes. Black points show concentration of sedimentary material, blue arrows show force and direction of movement of water, red arrows show intensity and direction of movement of flows of sedimentary material. Picture snapshots show northern coast of Muostakh Island at different sedimentation regimes. Satellite snapshots feature flows of SPM under various regimes of sedimentation.