Laurence Monin’s research while affiliated with Catholic University of Louvain and other places

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Publications (4)


The Lena River catchment
Sampling location (Samoylov Island; red star) at the outlet of the Lena River catchment comprising four major sub-catchments, with contribution to annual streamflow for the Upper Lena (42%), the Aldan (30%), the Vilui (9%), and the Lower Lena (19%) catchments²⁰ with digital elevation model of the Lena catchment (GEBCO Grid).
One-year chemical monitoring of the Lena River water
Between 20th April 2018 and 28th March 2019 (A, M, J, J, A, S, O, N, D, J, F, M: months from April until March) at Samoylov station including the open water period (blue area) and the ice-covered period: (a) Discharge close to Samoylov station for the Lena catchment (Roshydromet⁴²); (b) Ge/Si ratio ( ± SD); (c) Si isotope composition ( ± SD); (d) SUVA values (Y-axis reverted) and dissolved NH4 concentrations¹⁵.
Winter chemical monitoring of the Lena River water
Between 15th October 2018 and 31th March 2019 (O, N, D, J, F, M: months from October until March): (a) Air temperature for the whole Lena catchment, with shaded areas for the colder winter phases with air temperature < −30 °C (ERA5-Land⁴¹); (b) Discharge (dashed line; Roshydromet⁴²) and water temperature (dotted line) at Samoylov station¹⁵; (c) Ice thickness measurement (dots; Roshydromet⁴²) and modeled ice growth rate (full line) at Samoylov station (see Methods); (d) Dissolved Si isotope composition ( ± SD) and Ge/Si ratio ( ± SD) at Samoylov station, (e) SUVA values (Y-axis reverted) and NH4 concentration at Samoylov station¹⁵.
Processes leading to the formation of microzones in river ice
Longer reaction time for solutes in the water column under river ice cover (red arrows). A: Flow; B: Stable ice cover; C: Frazil produced in supercooled water (T < 0 °C); D: Turbulent flow entrains frazil in flow; E: Frazil agglomerates; F: Frazil tends to accumulate at slope transitions; G: Frazil sticks to bed matter to form anchor ice; H: Microzones with longer reaction time for winter biogeochemical processes in the water column; I: Water with longer time in the water column (heavy Si isotope composition, high Ge/Si) and amorphous silica precipitates (light Si isotope composition, low Ge/Si). Graphical design by Y. Nowak.
Frazil ice changes winter biogeochemical processes in the Lena River
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November 2024

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41 Reads

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2 Citations

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Pier Paul Overduin

The ice-covered period of large Arctic rivers is shortening. To what extent will this affect biogeochemical processing of nutrients? Here we reveal, with silicon isotopes (δ³⁰Si), a key winter pathway for nutrients under river ice. During colder winter phases in the Lena River catchment, conditions are met for frazil ice accumulation, which creates microzones. These are conducive to a lengthened reaction time for biogeochemical processes under ice. The heavier δ³⁰Si values (3.5 ± 0.5 ‰) in river water reflect that 39 ± 11% of the Lena River discharge went through these microzones. Freezing-driven amorphous silica precipitation concomitant to increased ammonium concentration and changes in dissolved organic carbon aromaticity in Lena River water support microbially mediated processing of nutrients in the microzones. Upon warming, suppressing loci for winter intra-river nitrogen processing is likely to modify the balance between N2O production and consumption, a greenhouse gas with a large global warming potential.

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Rare earth elements in an intercropping cover crop to evaluate the trace element transfer from soil to plant

November 2022

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144 Reads

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7 Citations

Biogeochemistry

Transfer of trace elements, such as toxic metals, from soil to plant is a corner stone for risk assessment. Rare earth elements (REE) are frequently used as environmental tracers to understand biogeochemical processes in the soil–plant system. In this study, we combined trace element and REE measurements in the soil–plant continuum to evaluate the element transfer between different compartments. We specifically aimed at: (1) assessing the geochemical relevance and representativeness of intermediate compartments (soil solution and soil water-extract as a proxy of the bioavailable soil fraction) by comparing the REE normalized patterns; and (2) characterizing the environmental conditions that control the trace element transfer by quantifying the REE indices. For that purpose, we compared geochemical signatures in an intercropping cover crop (bean, Persian clover, and spelt) in Belgium, including soil, root, shoot, soil solution, soil water-extract, earthworm, and snow samples. Evaluation of the element mobility was performed using both soil extractability and transfer factors. The main result showed dissimilar REE patterns between soil/plant samples and soil solution/soil water-extract samples, indicating that the intermediate compartments (i.e., soil solutions or soil water-extracts) do not chemically represent the bioavailable fraction of elements without obvious propensity to biological accumulation (unlike Cd, Cu, or Zn). Compared to light REE, heavy REE were more extractable and thus transferred to plants unlike what is observed in the literature. According to their different extractabilities, Ce and Eu allowed to highlight distinct transfer from soil to plant due to possible adsorption or organic matter complexation that should be further confirmed by studying contrasted soils.


The origin of early continental crust: New clues from coupling Ge/Si ratios with silicon isotopes

March 2022

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207 Reads

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19 Citations

Earth and Planetary Science Letters

The recent discovery of heavy Si isotopic compositions in both high-Na Tonalite-Trondhjemite-Granodiorite (TTG) and High-K Granite-Monzonite-Syenite (GMS) suites of early continental crust requires that a notable seawater-derived silica-rich component had been added to their respective protoliths prior to melting. Here we use the Ge/Si ratio as a complementary tracer to δ30Si in order to delineate the exact role of modal quartz and silicified basalts from the Archean seafloor among the primary controls of the early appearance of felsic melts on Earth. We have approached the question by (1) specifying the Ge/Si signatures of various Archean and post-Archean rock types by compiling the Ge-SiO2 data stored within the GEOROC database; (2) coupling Ge/Si investigation to silicon isotopes on a large selection of silicified and unsilicified altered mafic and ultramafic greenstones, felsic volcanics, TTG and GMS granitoids and mineral separates from TTGs of the Barberton Greenstone Belt (BGB) of South Africa. The GEOROC compilation demonstrates that Archean TTGs and granites display much lower Ge/Si (1.15±0.10 and 1.13±0.11 μmol/mol, respectively) than post-Archean adakites, granites, tonalites and granodiorites (with average Ge/Si in the range of 1.64 to 1.85 μmol/mol). This result is corroborated by the Ge/Si ratios we report from BGB rocks that formed prior to Kaapvaal craton stabilisation, including 3.5 Ga Theespruit Formation felsic volcanic rocks, 3.5-3.2 Ga TTGs and 3.2-3.1 Ga GMSs, all of which exhibit low ratios (0.68±0.23; 0.92±0.17; 1.05±0.19 μmol/mol, respectively). Based on their low TTG-like Ge/Si, pre-cratonic GMSs are dismissed as being derived from melting of both TTG and metasedimentary sources. Instead, TTGs and GMSs originated from similar Ge-depleted sources. Low Ge/Si ratios, coupled to heavy Si isotopic signatures (−0.14‰<δ30Si<+0.27‰) are also a characteristic feature of mafic and ultramafic BGB greenstones subjected to low-temperature hydrothermal seafloor alteration, especially at the interface between silicified (0.2<Ge/Si<1.2 μmol/mol) and unsilicified (1.8<Ge/Si<3.1 μmol/mol) portions of the altered Archean seafloor. We infer that both Na-rich and K-rich Archean felsic melts are derived from a unique class of protoliths: Ge-depleted metabasalts containing a significant modal proportion of supracrustal quartz generated by the silicification of the Eo-Paleoarchean basaltic seafloors. The transition from Na-rich to K-rich felsic melts in the BGB is assumed to be connected to a gradual increase of potassium as a key element associated with seafloor silicification. In contrast, younger (3.07-2.69 Ga), post-cratonic BGB granites have higher Ge/Si (1.93±0.23 μmol/mol) and were generated through the reworking of a TTG-like basement, by incongruent melting of biotite and hornblende (1.79<Ge/Si<2.97 μmol/mol) leaving an oligoclase-rich (0.64<Ge/Si<0.72) residue. The Earth changed from a prevalent Ge-depleted felsic crust in early-middle Archean times to a widespread Ge-enriched post-Archean crust, which emphasizes the importance of late Archean changes in the Earth dynamics. In particular, our data suggest the likelihood of generating primitive felsic continents by rather shallow melting processes, without the need for inducing high pressures by subduction, as long as Archean ocean floors were silicified.

Citations (2)


... The bioconcentration factor (BCF) reflects root ability to accumulate HMs from the soil (Arbalestrie et al. 2022). It was estimated using the following formula: ...

Reference:

Screening for Heavy Metal-Resistant Clones in the Xero-Halophyte Atriplex halimus L.: A Prerequisite for Phytoremediation of Polymetallic Mining Pollution in Arid Areas
Rare earth elements in an intercropping cover crop to evaluate the trace element transfer from soil to plant

Biogeochemistry

... Germanium is an economically critical and geochemically intriguing element with distinct chalcophile, lithophile, organophile, and siderophile affinities in different geological environments (Bernstein, 1985;Capobianco et al., 1999;Ernst et al., 2022;Fernandez et al., 2021;Le Roux et al., 2015;Mare et al., 2020;Pokrovski and Schott, 1998a;Van Hoof et al., 2020). Recent advances in high-precision analytical techniques coupled with the emergence of new experimental data have rekindled the Ge/Si systematics as a promising biogeochemical tracer for diverse applications from paleo-climatic reconstructions to discrimination of the source rocks of magmas and elucidation of Earth's origin and early evolution (André et al., 2022;Bau et al., 2022;Ernst et al., 2022;Fernandez et al., 2021;He et al., 2019;Mare et al., 2021;Mare et al., 2020;Phillips et al., 2023;Yang et al., 2020). ...

The origin of early continental crust: New clues from coupling Ge/Si ratios with silicon isotopes
  • Citing Article
  • March 2022

Earth and Planetary Science Letters