FN Archimer Export Format
PT J
TI REE distribution and Nd isotope composition of estuarine waters and bulk sediment leachates tracing lithogenic inputs in eastern Canada
BT 
AF Casse, Marie
   Montero-Serrano, Jean-Carlos
   St-Onge, Guillaume
   Poirier, André
AS 1:1,2;2:1,2;3:1,2;4:2;
FF 1:;2:;3:;4:;
C1 Institut des sciences de la mer de Rimouski, Canada Research Chair in Marine Geology, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L 3A1, Canada
   GEOTOP Research Center, 201 Av. Président Kennedy, Montréal, Québec, Canada
C2 UNIV QUEBEC (UQAR-ISMER), CANADA
   UNIV QUEBEC (UQAM-GEOTOP), CANADA
IF 2.933
TC 24
UR https://archimer.ifremer.fr/doc/00485/59708/85379.pdf
LA English
DT Article
CR IMAGES V LEG 1-MD114
   IMAGES V LEG 4-MD114
BO Marion Dufresne
DE ;Estuary and gulf of St. Lawrence;Rare earth element;Neodymium isotopes;Strontium isotopes;Particle scavenging;Sediment provenance;Estuarine processes
AB The rare earth element (REE) concentrations and the neodymium (Nd) and strontium (Sr) isotope compositions of the detrital fraction and authigenic FeMn oxyhydroxide coatings of marine sediments may provide valuable information for better understanding the pathways of weathering inputs and estuarine and coastal exchange processes on different time scales. Here, we present the REE concentrations and 143Nd/144Nd (expressed in epsilon units, εNd) and 87Sr/86Sr ratios of detrital and authigenic (leached FeMn oxyhydroxides) fractions from sediment core-top samples and of estuarine water samples collected in the Estuary and Gulf of St. Lawrence (EGSL) and continental shelf off southeastern Canada. The REE distribution patterns, εNd values, and 87Sr/86Sr isotopic values from the detrital fraction allow for the discrimination of sediment from continental sources in the EGSL. Sediments in the Baie des Chaleurs and on the continental shelf, which have εNd values ranging from −14.3 to −16, 87Sr/86Sr values ranging from 0.72708 to 0.71475, and low La/Yb and Gd/Yb ratios, are mainly supplied by the early Paleozoic Appalachian Mountains. In contrast, sediments in the Laurentian and Esquiman channels (εNd = −18.7 to −21.8, 87Sr/86Sr = 0.72068 to 0.72607, and high La/Yb and Gd/Yb ratios) come from the Grenvillian metamorphic rocks in the Canadian Shield, and surface sediments on the southern Labrador Shelf (εNd = −28.7, 87Sr/86Sr = 0.73062, and high La/Yb and Gd/Yb ratios) mainly originate from the Hudson Strait and Baffin Bay. The εNd values obtained from estuarine water samples and bulk sediment leachates are unradiogenic, with values ranging between −18.9 and − 21.7 and between −16.1 and − 27.2, respectively. Based on these results and the dissolved REE concentrations, we speculate that salt-induced coagulation of colloidal matter, dissolution of lithogenic sediments from the adjacent continents (notably from the erosion of the Grenville Province on the North Shore), bottom scavenging within the nepheloid layer, and brine rejection during sea ice formation significantly influence the distribution of REEs and the authigenic εNd signal throughout the water column in the EGSL. Overall, our results both underscore the fact that caution must be exercised when interpreting authigenic εNd records due to bottom water-mass mixing in estuarine and coastal marine environments and highlight the potential of REE and NdSr isotope compositions in investigating changes in sediment sources and transport pathways in the EGSL. 
PY 2019
PD APR
SO Marine Chemistry
SN 0304-4203
PU Elsevier BV
VL 211
UT 000467669600010
BP 117
EP 130
DI 10.1016/j.marchem.2019.03.012
ID 59708
ER

EF