HR: 1330h
AN: OS12A-0193    [PDF]
TI: Mapping the Extent and Rate of Overbank Deposition Using Mine-Derived Sediment Tracers Along the Strickland River, Papua New Guinea
AU: * Apte, S C
EM: Simon.Apte@csiro.au
AF: CSIRO Energy Technology, Private Mail Bag 7, Bangor, NSW 2234 Australia
AU: Dietrich, W E
AF: Deparment of Earth and Planetary Sciences, University of California, Berkeley, CA 94720-4767 United States
AU: Day, G M
AF: Lihir Management Company, PO Box 789, Port Moresby, NCD 121 Papua New Guinea
AU: Reibe, C
AF: Deparment of Earth and Planetary Sciences, University of California, Berkeley, CA 94720-4767 United States
AU: Aalto, R
AF: Department of Earth and Space Sciences, University of Washington, 63 Johnson Hall, Seattle, WA 98195 United States
AU: Sanders, J
AF: Deparment of Earth and Planetary Sciences, University of California, Berkeley, CA 94720-4767 United States
AU: Lauer, W
AF: Department of Civil Engineering, University of Minnesota, 500 Pillsbury Drive SE, Minneapolis, MN 55455-0116 United States
AU: Simpson, S L
AF: CSIRO Energy Technology, Private Mail Bag 7, Bangor, NSW 2234 Australia
AU: Marshall, A
AF: Andrew Marshall Pty Ltd., Woronora Heights, Sydney, NSW 2233 Australia
AU: Bera, M
AF: Department of Geology, Univeristy of Papua New Guinea, Private Mail Bag, Port Moresby, NCD 141 Papua New Guinea
AB: As part of collaborative investigation among an NSF sponsored Margins Source to Sink research group, University of Papua New Guinea (PNG) researchers, Porgera Joint Venture (PNG), Ok Tedi Mining Ltd (PNG) and CSIRO (Australia), a field study is being conducted to map the extent and rate of overbank deposition along the Strickland River, which is the dominant drainage to the Fly River delta, Papua New Guinea. A key question is what proportion of the river's sediment load is deposited on the lowland floodplain before the river joins the Fly. Previous studies on the Fly River above the junction with the Strickland concluded that about 40% of the lowland sediment load is lost to the floodplain. It was hypothesized that the historically much higher load on the Strickland had lead to more rapid infilling of accommodation space and consequently current rates of deposition would be proportionately smaller than on the Fly. The Strickland River receives inputs of mine tailings and waste rock from the Porgera gold mine, which is situated at an elevation of 2,500 meters in the upper catchment of the river system. While the contribution to the overall sediment load of the river is small, the mine-derived sediments contain elevated concentrations of several metals and there is both a need to understand their transport, fate and the potential release of dissolved metals as they are transported through the system and an opportunity to use these metals as tracers of sediment transport and deposition. This paper summarizes studies undertaken to examine the extent of overbank deposition of mine-derived sediments in the lower reaches of the Strickland River. Sediment cores were collected along transects at six key points on the lower Strickland River floodplain during 1997 and 2003 and analyzed for a suite of trace elements. In 2003, additional cores were collected at 5 other transects and duplicate cores were collected at all transects for analysis of 210Pb. Particulate silver and lead were used as tracers of mine-derived sediments because a previous investigation had indicated that these metals were present at elevated concentrations in mine tailings relative to pre-mining floodplain sediments. Using these relatively simple chemical tools, it was possible to obtain information on mine-derived sediment dispersion and overbank deposition rates in an extremely complex, diverse aquatic system.
DE: 1065 Trace elements (3670)
DE: 1803 Anthropogenic effects
DE: 1815 Erosion and sedimentation
DE: 1824 Geomorphology (1625)
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting