2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014)

Paper No. 325-8
Presentation Time: 2:30 PM

FROM SOURCE TO SINK: SEDIMENT ORGANIC MATTER IN FOUR LACUSTRINE WATERSHEDS, WESTFJORDS, ICELAND


HUBENY, J. Bradford1, JACQUES, Louise2, LAVOIE, Jessica J.1, PALERMO, Jennifer Ann3, PARENT, Andrew4 and STROM, John Erik1, (1)Department of Geological Sciences, Salem State University, 352 Lafayette Street, Salem, MA 01970, (2)Department of Geography, Salem State University, 352 Lafayette Street, Salem, MA 01970, (3)Department of Geological Sciences, California State University, Fullerton, 800 N. State College Blvd, Fullerton, CA 92831, (4)Department of Geological Sciences, Salem State University, 352 Lafayette St, Salem, MA 01970

Sedimentary organic matter provides valuable paleolimnologic information, and it is important to constrain the sources and potential alterations when interpreting organic proxy data. In this study we utilize a source to sink approach to quantify organic matter characteristics within four Icelandic catchments: Vatnsdalsvatn, Thidriksvallavatn, Rekavikurvatn, and Kaldbaksvatn. Organic matter was characterized using bulk stable isotopes of carbon, nitrogen, and sulfur (δ13C, δ15N, δ34S) as well as ratios or organic carbon to nitrogen (OC/N) and sulfur (OC/S) quantified on an elemental analyzer/ isotope ratio mass spectrometer (EA/IRMS). Samples include low-elevation watershed soil probes collected in 2012, particulate organic matter (POM) from lake inflows, outflows, and open water collected in 2012 and 2013, sediment traps deployed from 2011-2013, and surface sediments collected in 2012. Proxy data from the soils are very similar between watersheds, indicative of the regional soil characteristics of this region of Iceland. Patterns emerge when examining different components of the system. For instance, POM delivered to the lakes is consistently enriched in δ34S and has lower OC/N and OC/S ratios as compared to the parent soil of the watershed, suggesting preferential transport of heavy isotopic S and elemental N and S to the lakes. Lake sediments are more enriched in δ13C and have lower OC/N ratios as compared to soils, likely due to the influence of phytoplankton on the composition of lacustrine organic matter. A comparison of open water POM and sediment trap material reveals enriched δ13C of sediment in all lakes, and enriched δ15N of sediment in three of four lakes. Sedimentary OC/N is higher than POM OC/N in Vatnsdalsvatn and Thidriksvallavatn, both of which are larger and likely nutrient limited. The differences between open water POM and sediments exhibits alteration of organic matter during sedimentation and early diagenesis. Our results help to constrain sediment sources and alternations of organic matter in sub-arctic lakes, and will prove useful for the interpretation of sedimentary organic matter in similar environments.

Session No. 325

Recent Advances in Limnogeology
Wednesday, 22 October 2014: 1:00 PM-5:00 PM
213 (Vancouver Convention Centre-West)
Geological Society of America Abstracts with Programs. Vol. 46, No. 6, p.784
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