Ge/Si ratios indicating hydrothermal and sulfide weathering input to rivers of the Eastern Tibetan Plateau and Mt. Baekdu

Han, Yeongcheol; Huh, Youngsook; Derry, Louis A.

doi:10.1016/j.chemgeo.2015.06.001

Cited by 11 publications

(9 citation statements)

References 43 publications

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“…On this basis, the mean Ge fluxweighted δ 74 Ge riv value is calculated to be 2.62 ± 0.16 ‰ (flux-weighted uncertainty, including 10% error on water discharge and analytical errors of Ge and δ 74 Ge measurements), significantly lower than the previous preliminary estimate of 3.5±1.5 ‰ (Baronas et al, 2017a). The Mississippi, Changjiang, and Mekong rivers included here are know to be significantly affected by hydrothermal or anthropogenic inputs Han et al, 2015). Excluding these rivers has no effect on global δ 74 Ge riv (2.56 ± 0.15 ‰) but strongly impacts Ge/Si riv which is reduced from 0.90 ± 0.06 μmol/mol to 0.68 ± 0.05 μmol/mol, bringing it to closer agreement with the previous estimate of 0.54 μmol/mol that was primarily based on small pristine streams (Froelich et al, 1992).…”

Section: Global Riverine Ge Isotope and Ge/si Compositionmentioning

confidence: 54%

Ge and Si isotope signatures in rivers: A quantitative multi-proxy approach

Baronas

Torres

West

et al. 2018

Earth and Planetary Science Letters

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Solutes derived from the dissolution of silicate minerals play a key role in Earth's climate via the carbon and other biogeochemical cycles. Silicon (Si) is a unique constituent of silicate minerals and a biologically important nutrient, so tracing its behavior in near-surface environments may provide important insights into weathering processes. However, Si released by weathering is variably incorporated into secondary mineral phases and biota, obscuring signals derived from primary weathering processes. Due to chemical similarities, Germanium (Ge) may help better understand the Si cycle and its relationship to chemical weathering. With this aim, we report new measurements of the concentration and isotopic composition of Ge for both the dissolved and particulate phases of a variety of global rivers. These measurements are combined with analyses of concentration and isotopic ratio of Si on the exact same sample set in order to make direct comparisons of the behavior of these two elements in natural river systems. With this dataset, we develop a new modeling framework describing the full elemental and isotopic systems of these solutes in rivers (i.e., Ge/Si, δ74Ge, and δ30Si). This multi-proxy approach allows us to ascertain the relative importance of biological versus mineral uptake in modulating the fluxes of these elements delivered to the modern ocean. Dissolved δ74Ge composition of rivers studied thus far range from 0.9 to 5.5 ‰ with a discharge-weighted global average of 2.6±0.5 ‰. The Ge isotope composition of riverine suspended and bedload sediments is indistinguishable from silicate source rocks, which is consistent with mass balance expectations. The multi-proxy modeling suggests that, among the watersheds studied here, the isotopic fractionation of Si during secondary mineral phase precipitation (∆30Sisec) ranges from-2.7 to-0.2 ‰, which removes between 19-79% of the initial dissolved Si sequestration, while between 12-54% is incorporated by biota. For Ge, modeling indicates that 79-98% of the dissolved load is incorporated into secondary mineral phases with a ∆74Gesec ranging from-4.9 to-0.3 ‰. The fractionation induced by biological uptake is calculated to range from-2.6 to-1.3 ‰ for ∆30Sibio and-0.7±0.7 ‰ for ∆74Gebio. In addition to improving our understanding of the coupled Ge and Si cycles, our study provides a framework for Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site. using multiple isotopic tracers to elucidate the chemical behavior of solutes in natural waters Highlights ► Ge and Si isotope composition of water and sediments in various rivers is presented. ► Dissolved δ 74 Ge range 0.9-5.5‰, river sediment δ 74 Ge range 0.5-0.7‰. ► Dissolved δ 74 Ge is strongly fractionated due to low chemical Ge mobility. ► Ge/Si-isotope multi-proxy provides quantitative constraints on secondary vs biological fractionation.

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Section: Global Riverine Ge Isotope and Ge/si Compositionmentioning

confidence: 54%

Ge and Si isotope signatures in rivers: A quantitative multi-proxy approach

Baronas

Torres

West

et al. 2018

Earth and Planetary Science Letters

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“…Coal is an important raw material for Ge [39]. Germanium is easily hydrolyzed and generally exists in the form of Ge(OH) 4 in fluid, thus preferentially enriched in river water compared with other trace elements such as Cu and Zn derived from fly ash [31]. Rivers that drain industrial areas present relatively high Ge/Si ratios resulting from coal combustion [40].…”

Section: Resultsmentioning

confidence: 99%

“…Previous studies have reported the Ge/Si ratio in river water on the Tibetan Plateau, generally higher than the global average [23,30,31]. The elevated riverine Ge/Si ratio in the three river regions (Yangtze, Salween, and Mekong) is due to high hydrothermal activity, while in the Huang He and Hong Rivers, it may reflect the weathering of sulfide and coal-bearing minerals [23,31]. The Narayani River rises in the Great Himalaya Range in Nepal, where the Ge/Si ratio of river water is increased due to the input of the Ge-enriched hydrothermal water.…”

Section: Introductionmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

“…For rivers on the Tibetan Plateau, the controls of the Ge/Si ratio in river water are much more complex and could be affected by multiple factors such as silicate weathering, hydrothermal water discharge, sulfide weathering, and fly coal ash [30,31]. Previous studies have reported the Ge/Si ratio in river water on the Tibetan Plateau, generally higher than the global average [23,30,31]. The elevated riverine Ge/Si ratio in the three river regions (Yangtze, Salween, and Mekong) is due to high hydrothermal activity, while in the Huang He and Hong Rivers, it may reflect the weathering of sulfide and coal-bearing minerals [23,31].…”

Section: Introductionmentioning

confidence: 99%

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Ge/Si Ratio of River Water in the Yarlung Tsangpo: Implications for Hydrothermal Input and Chemical Weathering

Wang

Жао

et al. 2022

Water

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Germanium/Silicon (Ge/Si) ratio is a common proxy for primary mineral dissolution and secondary clay formation yet could be affected by hydrothermal and anthropogenic activities. To decipher the main controls of riverine Ge/Si ratios and evaluate the validity of the Ge/Si ratio as a weathering proxy in the Tibetan Plateau, a detailed study was presented on Ge/Si ratios in the Yarlung Tsangpo River, southern Tibetan Plateau. River water and hydrothermal water were collected across different climatic and tectonic zones, with altitudes ranging from 800 m to 5000 m. The correlations between TDS (total dissolved solids) and the Ge/Si ratio and Si and Ge concentrations of river water, combined with the spatial and temporal variations of the Ge/Si ratio, indicate that the contribution of hydrothermal water significantly affects the Ge/Si ratio of the Yarlung Tsangpo River water, especially in the upper and middle reaches. Based on the mass balance calculation, a significant amount of Ge (11–88%) has been lost during its transportation from hydrothermal water to the river system; these could result from the incorporation of Ge on/into clays, iron hydroxide, and sulfate mineral. In comparison, due to the hydrothermal input, the average Ge/Si ratio in the Yarlung Tsangpo River is a magnitude order higher than the majority of rivers over the world. Therefore, evaluation of the contribution of hydrothermal sources should be considered when using the Ge/Si ratio to trace silicate weathering in rivers around the Tibetan Plateau.

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Metamorphic fluxes of water and carbon in rivers of the eastern Qinghai-Tibetan Plateau

Zhong

et al. 2022

Sci. China Earth Sci.

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Ge/Si ratios indicating hydrothermal and sulfide weathering input to rivers of the Eastern Tibetan Plateau and Mt. Baekdu

Cited by 11 publications

References 43 publications

Ge and Si isotope signatures in rivers: A quantitative multi-proxy approach

Ge and Si isotope signatures in rivers: A quantitative multi-proxy approach

Ge/Si Ratio of River Water in the Yarlung Tsangpo: Implications for Hydrothermal Input and Chemical Weathering

Metamorphic fluxes of water and carbon in rivers of the eastern Qinghai-Tibetan Plateau

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