期刊论文详细信息
Frontiers in Digital Humanities
Arctic Deltaic Lake Sediments As Recorders of Fluvial Organic Matter Deposition
Montlucon, Daniel B.1  Hussain, Zainab A.1  Holmes, Robert M.1  Vonk, Jorien E.2  Giosan, Liviu3  Eglinton, Timothy I.4  Zipper, Samuel C.5  Galy, Valier5  Kim, Bokyung6  Dickens, Angela F.8 
[1] Chemistry Department, Mount Holyoke College, South Hadley, MA, USA;Department of Earth Sciences, Geological Institute, ETH ZüDepartment of Earth Sciences, VU University Amsterdam, Amsterdam, Netherlands;Freshwater and Marine Sciences Program, Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI, USA;Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, USA;Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA;Woods Hole Research Center, Falmouth, MA, USA;rich, Zurich, Switzerland
关键词: Lignin;    biomarkers;    leaf wax;    Mackenzie River;    Canada;    River sediment;    radiocarbon;    laminated sedimets;    stable carbon isotope;    lake sediments;   
DOI  :  10.3389/feart.2016.00077
学科分类:社会科学、人文和艺术(综合)
来源: Frontiers
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【 摘 要 】

Arctic deltas are dynamic and vulnerable regions that play a key role in land-ocean interactions and the global carbon cycle. Delta lakes may provide valuable historical records of the quality and quantity of fluvial fluxes, parameters that are challenging to investigate in these remote regions. Here we study lakes from across the Mackenzie Delta, Arctic Canada, that receive fluvial sediments from the Mackenzie River when spring flood water levels rise above natural levees. We compare downcore lake sediments with suspended sediments collected during the spring flood, using bulk (% organic carbon, % total nitrogen, 13C, 14C) and molecular organic geochemistry (lignin, leaf waxes). High-resolution age models (137Cs, 210Pb) of downcore lake sediment records (n=11) along with lamina counting on high-resolution radiographs show sediment deposition frequencies ranging between annually to every 15 years. Down-core geochemical variability in a representative delta lake sediment core is consistent with historical variability in spring flood hydrology (variability in peak discharge, ice jamming, peak water levels). Comparison with earlier published Mackenzie River depth profiles shows that (i) lake sediments reflect the riverine surface suspended load, and (ii) hydrodynamic sorting patterns related to spring flood characteristics are reflected in the lake sediments. Bulk and molecular geochemistry of suspended particulate matter from the spring flood peak and lake sediments are relatively similar showing a mixture of modern higher-plant derived material, older terrestrial permafrost material, and old rock-derived material. This suggests that deltaic lake sedimentary records hold great promise as recorders of past (century-scale) riverine fluxes and may prove instrumental in shedding light on past behaviour of arctic rivers, as well as how they respond to a changing climate.

【 授权许可】

CC BY   

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