| Volumes and Issues Contents of Issue 6 |
www.hydrol-earth-syst-sci-discuss.net/4/4005/2007/
doi:10.5194/hessd-4-4005-2007
© Author(s) 2007. This work is licensed
under a Creative Commons License.
Assessing the biodegradability of terrestrially-derived organic matter in Scottish sea loch sediments
1UHI Millennium Institute, Scottish Association for Marine Science, Dunstaffnage Marine Laboratory, Oban PA37 1QA, Scotland, UK
2Scottish Association for Marine Science, Dunstaffnage Marine Laboratory, Oban PA37 1QA, Scotland, UK
3Environmental Systems Research Group, Geography Department, University of Dundee, Dundee DD1 4HN, Scotland, UK
*now at: Institute of Marine Geology and Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan, Republic of China
Abstract. Lignin oxidation products were used to determine the sources, transport and distribution of terrestrially-derived organic matter (OM) in two Scottish sea lochs, Loch Creran and Loch Etive. Oxygen uptake rates, molar OC/N ratios (from bulk elemental analysis) and Rp values (from loss on ignition experiments, the ratio of the refractory to total OM) were also determined for sediments along transects of the lochs. Lignin data indicate the importance of riverine inputs, contributing land-derived carbon to the lochs as total lignin (Λ, mg/100 mg organic carbon, OC) decreased from 0.69 to 0.45 and 0.70 to 0.29 from the head to outside of Lochs Creran and Etive, respectively. In addition, significant correlations for lignin content against total OM and OC (p<0.05) also suggest a distinct contribution of terrestrial OM to carbon pools in the lochs. The general trend of decreasing oxygen uptake rates from the head (20.8 mmole m−2 day−1) to mouth (9.4 mmole m−2 day−1) of Loch Creran indicates decomposition of some terrestrial OM. Biodegradability of the sediment OM was also characterized by the increase of Rp values from the head to mouth of the lochs: 0.40 to 0.80 for Etive and 0.43 to 0.63 in Creran. Further, the molar OC/N ratio decreased from 11.2 to 6.4 in Creran, and from 17.5 to 8.2 in Etive. Our results show that the relatively fresh, terrestrially-derived OM, which is still susceptible to mineralization, plays an important role in fuelling the biogeochemical cycling of carbon in both systems. This work also demonstrates that oxygen uptake rate, Rp value and molar OC/N ratio are able to serve as useful proxies to indicate sediment biodegradability.
Discussion Paper (PDF, 602 KB) Interactive Discussion (Closed, 5 Comments) Final Revised Paper (HESS)
Citation: Loh, P. S., Miller, A. E. J., Reeves, A. D., Harvey, S. M., and Overnell, J.: Assessing the biodegradability of terrestrially-derived organic matter in Scottish sea loch sediments, Hydrol. Earth Syst. Sci. Discuss., 4, 4005-4035, doi:10.5194/hessd-4-4005-2007, 2007. Bibtex EndNote Reference Manager XML
