FN Archimer Export Format
PT J
TI Constraints on the source of reactive phases in sediment from a major Arctic river using neodymium isotopes
BT 
AF LARKIN, Christina S.
   PIOTROWSKI, Alexander M.
   HINDSHAW, Ruth S.
   BAYON, Germain
   HILTON, Robert G.
   BARONAS, J. Jotautas
   DELLINGER, Mathieu
   WANG, Ruixue
   TIPPER, Edward T.
AS 1:1;2:1;3:1;4:2;5:3;6:1;7:3;8:1;9:1;
FF 1:;2:;3:;4:PDG-REM-GM-LGS;5:;6:;7:;8:;9:;
C1 Univ Cambridge, Dept Earth Sci, Cambridge, England.
   IFREMER, Marine Geosci Unit, Brest, France.
   Univ Durham, Dept Geog, Durham, England.
C2 UNIV CAMBRIDGE, UK
   IFREMER, FRANCE
   UNIV DURHAM, UK
SI BREST
SE PDG-REM-GM-LGS
IN WOS Ifremer UPR
   copubli-europe
IF 5.785
TC 8
UR https://archimer.ifremer.fr/doc/00697/80901/88251.pdf
LA English
DT Article
DE ;iron oxides;bioavailable;neodymium isotopes;Arctic
AB Riverine suspended particulate matter (SPM) is essential for the delivery of micronutrients such as iron (Fe) to the oceans. SPM is known to consist of multiple phases with differing reactivity, but their role in the delivery of elements to the oceans is poorly constrained. Here we provide new constraints on the source and composition of reactive phases in SPM from the Mackenzie River, the largest sediment source to the Arctic Ocean. Sequential leaching of SPM shows that river sediments contain labile Fe phases. We estimate the labile Fe flux is substantial (0.21(+0.06,-0.05) Tg/yr) by quantifying Fe concentrations in weak leaches of the SPM. The labile Fe phase hosts a considerable amount of rare earth elements (REE), including neodymium (Nd). We demonstrate that the labile Fe phase and dissolved load have radiogenic Nd isotope ratios that are identical within uncertainty, but up to 8 epsilon units distinct from the silicate phase. We interpret this as evidence for dynamic cycling between Fe-oxide phases in SPM and the river water, demonstrating the high reactivity of the labile Fe phase. Nd isotope and elemental molar ratios suggest that a significant amount of labile Fe- and Nd-bearing phases are derived from Fe-oxides within the sedimentary source rock rather than silicate mineral dissolution. Thus, sedimentary rock erosion and weathering provides an important source of labile Fe, manganese (Mn) and by extension potentially other trace metals. Our results imply that both past and future environmental change in the Arctic, such as permafrost thaw, may trigger changes to the supply of reactive trace metals. These results demonstrate that a re-evaluation of sediment reactivity within rivers is required where uplifted sedimentary rocks are present. 
PY 2021
PD JUN
SO Earth And Planetary Science Letters
SN 0012-821X
PU Elsevier
VL 565
UT 000649176900006
DI 10.1016/j.epsl.2021.116933
ID 80901
ER

EF