Iron isotope composition of the bulk waters and sediments from the Amazon River Basin

Iron isotopes reveal distinct dissolved iron sources and pathways in the intermediate versus deep Southern Ocean

“…The isotopic fractionations associated with organic matter remineralization processes have not yet been extensively constrained. However, remineralization could potentially release light iron through kinetic fractionation, or from an initially light signature of the remineralized matter [two studies suggest a preferential uptake of light Fe isotopes by phytoplankton (10,14), although adsorption experiments on phytoplankton lead to the opposite conclusion (30)], or from reduction steps involved in several remineralization mechanisms [e.g., grazing (31), microbial reduction in aggregates (32)]. These light signatures could then be redistributed meridionally across the ACC as explained above.…”

Isotope Fractionation Processes of Selected Elements

“…Because of its very low concentration, the Fe isotope composition of ocean water is not easily determined. Radic et al (2011) and John and Adkins (2012) Rivers rich in clastic suspended detrital material, like the white waters of the Amazon have a Fe isotope composition close to the continental crust (Poitrasson et al 2014). Rivers rich in organic material contain a large portion in dissolved Fe form and are depleted in heavy Fe isotopes with significant annual variations (Dos Santos Pinheiro et al 2014).…”

Fe Isotopic Compositions of Modern Seafloor Hydrothermal Systems and Their Influence Factors

“…The chemical property differences of the fluids are significantly affected by phase separation [87]. The oxidization-reduction reaction during the mixing of the vent fluids enriched in H 2 S and seawater enriched in SO 4 2− causes the S isotope differences of the hydrothermal fluids [87]. The ranges of 34 S values of the vent fluids at the Bio9 vent (3.1 to 3.2‰) and the Lucky Strike hydrothermal field (1.5 to 4.5‰) at the East Pacific Rise also indicate the differences in the vent fluid properties in hydrothermal fields.…”

“…The range of 56 Fe values in loess/dust is from −0.15‰ to 0.33‰, with an average 56 Fe of 0.05±0.10‰ ( = 40). Fe in marine systems is derived primarily from rivers [3,4], atmospheric dust [5], and seafloor hydrothermal fluids [6,7]. The removal of Fe from oceans is primarily in the form of marine sediments, carbonates, and Fe-Mn nodules and crusts [8].…”

“…The range of Fe isotope compositions of seawater is from −0.64‰ to 0.80‰, with an average 56 ; the black rectangle shows the average value of 56 Fe. All data from the literatures: river [3,4,11,12]; ocean water [13][14][15][16]; oceanic sediment [6,7,12,17]; hydrothermal sulfide [6,[18][19][20]; hydrothermal fluid [6,7,[19][20][21]; Fe-Mn noddle and crust [8,[22][23][24]; deposit [25][26][27][28][29][30][31]; banded Fe formations [32][33][34][35][36][37][38][39][40][41][42]; carbonate rock [36,43,44]; loess/dust [6,…”