Decadal to Centennial History of Lena River Discharge to the Arctic Ocean

1. Decadal to Centennial History of Lena River Discharge to the Arctic Ocean Principal Investigators: Eugeny B. Karabanov, Douglas F. Williams PhD. Candidates: Janiel Rivera Pinet Straud Armstrong Department of Geological Sciences University of South Carolina Photo of USGS: LANDSAT Program

2. Variations of sea-ice flux from the Arctic to the North Atlantic Ocean are known to cause major changes in thermohaline circulation. Via this mechanism, the influx of freshwater from Siberian rivers plays an important role in ventilation of the Arctic and North Atlantic Oceans and global climate processes (SEARCH, 2001). From this point of view, understanding the history of freshwater discharge to the Arctic is a critical component of water exchange between the Arctic, North Atlantic (PARCS, 1999; ASOF, 2001). Variations of sea-ice flux from the Arctic to the North Atlantic Ocean are known to cause major changes in thermohaline circulation. Via this mechanism, the influx of freshwater from Siberian rivers plays an important role in ventilation of the Arctic and North Atlantic Oceans and global climate processes (SEARCH, 2001). Understanding the history of freshwater discharge to the Arctic is a critical component of water exchange between the Arctic and North Atlantic (PARCS, 1999; ASOF, 2001). Photo of USGS: LANDSAT Program

3. Synthesis of river-monitoring data reveals that the average annual discharge of fresh water from the six largest Eurasian rivers to the Arctic Ocean appears to have increased by 7% from 1936 to 1999 (Peterson et al., 2002). These changes in river discharge are potentially important to NADW formation and global climate processes. From Aaagard, Carmack, 1989 From Peterson et al., 2002

4. Our goals are: • The Lena River delivers approximately 525 km3yr-1 of freshwater. The average sediment supply from the Lena to the Laptev Sea is about 21 x106 tons of suspended material per year and annually the Lena River delivers to the Laptev Sea ~5.3 t6 of total organic carbon (4.5 t6dissolved and 0.8 t6 particulate organic carbon). • to recover high-resolution records of freshwater discharge variability and terrestrial organic carbon flux to the Arctic Ocean via the Lena River for the last 50-150 years • to extend this record into the Late Holocene ( the last 2,000 years)

5. Research Objectives • determine present-day fluxes of freshwater-sediments-organic carbon to the Laptev Sea • parameterize historical records of Lena River discharge with sedimentary records • obtain decadal to centennial scale resolution Photo of USGS: LANDSAT Program

6. About the Study Area

7. First Year Planon Lena Rivercollect water and sediment samples, major elements, nutrients and organic components of Lena River system. • Major ions, nutrients, dissolved and particulate organic carbon • C, N stable isotopes • Sediment and suspended matter samples for rare and heavy metals • Sediment and suspended matter samples for radionuclides • Samples for present day pollen rain

8. First year planon Lena River delta - study of modern processes and proxies of the Lena River water-sediment-carbon discharge- collect sediment cores from peat deposits, river floodplain, lagoons and shallow bays Photo of USGS: LANDSAT Program

9. Second and Third Year Plans Lena Delta Tiksi • Extend our work on Lena River delta to Laptev Sea shelf SIBERIA RUSSIA Yakutsk Bathymetric units: Jakobsson, M., et al.