B. Hasholt et B. Hagedorn, Hydrology and geochemistry of river-borne material in a high arctic drainage system, Zackenberg, Northeast Greenland, ARCT ANTARC, 32(1), 2000, pp. 84-94
The roles of chemical and mechanical weathering in permafrost regions were
assessed, by measuring stream discharge and major, trace, and rare earth el
ements (REE) of suspended matter (SPM), river-bed sediments (RBS), and wate
r in two lithologically different catchments in the High Arctic at Zackenbe
rg, Northeast Greenland. The drainage basin contains sedimentary and crysta
lline rocks. In streams draining the sedimentary rock area, SPM and total d
issolved solutes (TDS) are high with maximum values of 2500 mg L-1 and 105
mu S cm(-1), respectively. Variation of both relates to changes in vegetati
on and morphology. Mineral fractionation during transport and soil-forming
processes in the sedimentary portion of the study area lead to characterist
ic chemical profiles for the SPM and RES. Streams draining the crystalline
rock area have low SPM (18 mg L-1) and TDS (14 mu S cm(-1)) as a result of
poor soil development and a lack of vegetation. Mechanical denudation excee
ds chemical denudation by an order of magnitude for the entire catchment. B
ecause the REE distributions of the crystalline differ from those in the se
dimentary SPM differ, it is possible to quantify source rock contributions
to the main outflow using a mixing calculation. A mass balance comparing th
e SPM in the main outflow with the tributaries, using the REEs as "fingerpr
ints," indicates that about 90% of the sedimentary basin suspended matter i
s redeposited before reaching the outflow, at least over the period of obse
rvation. Taking this redeposition into account, the rate of chemical denuda
tion (100 kg km(-2) d(-1)) exceeds mechanical denudation (70 kg km(-2) d(-1
)) in the sedimentary drainage basin.