Ge Isotopes Research Articles

β decay of the very neutron-deficient Ge60 and Ge62 nuclei

We report here the results of a study of the $\beta$ decay of the proton-rich Ge isotopes, $^{60}$Ge and $^{62}$Ge, produced in an experiment at the RIKEN Nishina Center. We have improved our knowledge of the half-lives of $^{62}$Ge (73.5(1) ms), $^{60}$Ge (25.0(3) ms) and its daughter nucleus, $^{60}$Ga (69.4(2) ms). We measured individual $\beta$-delayed proton and $\gamma$ emissions and their related branching ratios. Decay schemes and absolute Fermi and Gamow-Teller transition strengths have been determined. The mass excesses of the nuclei under study have been deduced. A total $\beta$-delayed proton-emission branching ratio of 67(3)% has been obtained for $^{60}$Ge. New information has been obtained on the energy levels populated in $^{60}$Ga and on the 1/2$^-$ excited state in the $\beta p$ daughter $^{59}$Zn. We extracted a ground state to ground state feeding of 85.3(3)% for the decay of $^{62}$Ge. Eight new $\gamma$ lines have been added to the de-excitation of levels populated in the $^{62}$Ga daughter.

Possible triaxial deformation in <i>N</i> = <i>Z</i> nucleus germanium-64

Evidence for nonaxial <i>γ</i> deformations has been widely found in collective rotational states. The <i>γ</i> deformation has led to very interesting characteristics of nuclear motions, such as wobbling, chiral band, and signature inversion in rotational states. There is an interesting question; why the nonaxial <i>γ</i> deformation is not favored in the ground states of even-even (e-e) nuclei. The quest for stable triaxial shapes in the ground states of e-e nuclei, with a maximum triaxial deformation of <inline-formula><tex-math id="M2">\begin{document}$ \left| \gamma \right| $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210187_M2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210187_M2.png"/></alternatives></inline-formula> ≈ 30°, is still a major theme in nuclear structure. In the present work, we use the cranked Woods-Saxon (WS) shell model to investigate possible triaxial shapes in ground and collective rotational states. Total-Routhian-surface calculations by means of the pairing-deformation-frequency self-consistent cranked shell model are carried out for even-even germanium and selenium isotopes, in order to search for possible triaxial deformations of nuclear states. Calculations are performed in the lattice of quadrupole (<i>β</i><sub>2</sub>, <i>γ</i>) deformations with the hexadecapole <i>β</i><sub>4</sub> variation. In fact, at each grid point of the quadrupole deformation (<i>β</i><sub>2</sub>, <i>γ</i>) lattice, the calculated energy is minimized with respect to the hexadecapole deformation <i>β</i><sub>4</sub>. The shape phase transition from triaxial shape in <sup>64</sup>Ge, oblate shape in <sup>66</sup>Ge, again through triaxiality, to prolate deformations is found in germanium isotopes. In general, the Ge and Se isotopes have <i>γ</i>-soft shapes, resulting in significant dynamical triaxial effect. There is no evidence in the calculations pointing toward rigid triaxiality in ground states. The triaxiality of <inline-formula><tex-math id="M3">\begin{document}$ \gamma = - 30^\circ $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210187_M3.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210187_M3.png"/></alternatives></inline-formula> for the ground and collective rotational states, that is the limit of triaxial shape, is found in <sup>64, 74</sup>Ge. One should also note that the depth of the triaxial minimum increases with rotational frequency increasing in these two nuclei. The present work focuses on the possible triaxial deformation of <i>N</i> = <i>Z</i> nucleus <sup>64</sup>Ge. Single-particle level diagrams can give a further understanding of the origin of the triaxiality. Based on the information about single-particle levels obtained with the phenomenological Woods-Saxon (WS) potential, the mechanism of triaxial deformation in <i>N</i> = <i>Z</i> nucleus <sup>64</sup>Ge is discussed, and caused surely by a deformed <i>γ</i>≈30° shell gap at <i>Z</i>(<i>N</i>) = 32. At <i>N</i> = 34, however, an oblate shell gap appears, which results in an oblate shape in <sup>66</sup>Ge (<i>N</i> = 34). With neutron number increasing, the effect from the <i>N</i> = 34 oblate gap decreases, and hence the deformations of heavier Ge isotopes change toward the triaxiality (or prolate).

Nuclear moments of germanium isotopes near N=40

Collinear laser spectroscopy measurements were performed on $^{69,71,73}$Ge isotopes ($Z = 32$) at ISOLDE-CERN. The hyperfine structure of the $4s^2 4p^2 \, ^3P_1 \rightarrow 4s^2 4p 5s \, ^3P_1^o$ transition of the germanium atom was probed with laser light of 269 nm, produced by combining the frequency-mixing and frequency-doubling techniques. The hyperfine fields for both atomic levels were calculated using state-of-the-art atomic relativistic Fock-space coupled-cluster calculations. A new $^{73}$Ge quadrupole moment was determined from these calculations and previously measured precision hyperfine parameters, yielding $Q_{\rm s}$ = $-$0.198(4) b, in excellent agreement with the literature value from molecular calculations. The moments of $^{69}$Ge have been revised: $\mu$ = +0.920(5) $\mu_{N}$ and $Q_{\rm s}$= +0.114(8) b, and those of $^{71}$Ge have been confirmed. The experimental moments around $N = 40$ are interpreted with large-scale shell-model calculations using the JUN45 interaction, revealing rather mixed wave function configurations, although their $g$-factors are lying close to the effective single-particle values. Through a comparison with neighboring isotones, the structural change from the single-particle nature of nickel to deformation in germanium is further investigated around $N = 40$.

A multi-isotope study (Fe, Ge, O) of hydrothermal alteration in the Limousin ophiolite (French Massif Central)

Geochemical studies using non-traditional stable isotopes can help tracing processes of hydrothermal alteration (or hydrothermal metamorphism) of ancient oceanic lithosphere. In this study, we have measured non-traditional Ge and Fe isotopes and traditional O isotopes in a series of ultrabasic and basic rocks from the Limousin ophiolite (French Massif Central) to decipher the different signatures of hydrothermal vs. magmatic processes. Serpentinites are strongly oxidised rocks (Fe3+/ΣFe: 0.58–0.71) and display δ18O values (+5.0 to +6.1‰) typical of hydrothermally altered ultrabasic rocks. They display δ56Fe (+0.15 to +0.18‰) and δ74Ge values (+0.48 to +0.93‰) similar to heavier than ultrabasic rocks. The negative correlation between δ18O and δ74Ge and between δ18O and δ56Fe, suggests that Ge and Fe isotopes have fractionated during hydrothermal alteration. The δ74Ge shows a slight positive correlation with the δ56Fe, indicating concomittant Ge and Fe isotope fractionation towards heavier values during hydrothermal alteration. However, δ56Fe values display a larger deviation from ultrabasic rocks than δ74Ge and δ18O values, suggesting that oxidising conditions have enhanced Fe isotope fractionation to a larger extent than Ge isotopes. Amphibolites display Fe3+/ΣFe ratios (0.11–0.14) and δ56Fe values (+0.03 to +0.17‰) typical of mid-ocean ridge basalts (MORB). δ18O values are typical of high-T hydrothermally altered MORB (+6.2 to +6.6‰). δ74Ge values show a small range (+0.72 to +0.77‰) and are heavier than most basalts and gabbros. The δ18O slightly decreases with the increase of the δ56Fe, indicating that Fe isotopes may have fractionated towards lighter values during hydrothermal alteration. However, the lack of correlation between δ74Ge and δ56Fe values indicates that Ge isotope fractionation has prevailed over Fe isotope fractionation during hydrothermal alteration of basic rocks in the absence of oxidising conditions.

A way forward towards the improvement of tensor force in pf-shell

In many shell model interactions, the tensor force monopole matrix elements are observed to retain systematic trends originating in the bare tensor force. In this work, however, we note for GX-interactions of pf-shell that the seven out of ten T = 1 tensor force monopole matrix elements do not share these systematic. We ameliorate this disparity making use of Yukawa-type tensor force and spin-tensor decomposition. Furthermore, we have modified the single-particle energy of 1p3/2 orbit and two TBMEs of 0f-orbit, and the revised interaction has been tested from Ca to Ge isotopes with various physics viewpoints. The results are found to be satisfactory with respect to the experimental data.

Shape phase changes with N in 72−84Kr isotopes

The Kr isotopes lying in between the lighter isotopes of (Zn, Ge and Se) and the heavier isotopes of (Sr and Zr) in the [Formula: see text]–80 region exhibit very interesting spectral features. The spectra of [Formula: see text]Kr isotopes display a striking contrast from those of Zn, Ge and Se isotopes. The role of spherical and oblate and prolate deformed subshell gaps at specific [Formula: see text] and [Formula: see text] and the resulting re-inforcement are strikingly evident in these contrasting features, with variation in [Formula: see text] or [Formula: see text]. The evolution of the spectral features in Kr isotopes with [Formula: see text] as reflected in the quadrupole deformation, [Formula: see text]-band structures, [Formula: see text]0 decay, [Formula: see text]2) values, [Formula: see text]-softness of the nuclear core and odd–even staggering in [Formula: see text]-bands is studied to explore the role of the under lying nuclear interactions. The correlations with odd–[Formula: see text] isotopes are explored. The shape co-existence displayed in some Kr isotopes is studied. The large deformation observed in the ground bands of [Formula: see text]Kr, as exhibited in the [Formula: see text]2) values, is especially interesting.

Ground state properties of Zn, Ge, and Se isotopic chains in covariant density functional theory

A systematic investigation of the ground state deformation, the physical properties (two-neutron separation energy and neutron, proton, and charge radii), and the possibility of nuclear shape coexistence in Zn, Ge, and Se isotopes was performed using the relativistic Hartree-Bogoliubov formalism using density-dependent zero- and finite-range $NN$ interactions. Shape coexistence does not show up clearly in Zn isotopes. However, it is clear in most of the Ge and Se isotopes; the two coexistence minima are axial and triaxial in the case of Ge, while both are axial in the case of Se. Along all these chains one can see the existence of several transition points, where the ground state shape suddenly changes. This sudden change affects the evolution of the physical properties. The density of states near the Fermi level is a key factor in determining the ground state minima. Both point-coupling and meson-exchange models give similar results with few exceptions. A very good agreement is found with the available experimental data. The SU(3) proxy provides a reasonable prediction of the deformation value in the middle of the isotopic chain.

Cross Section Measurements of (n,p) Reactions on Ge Isotopes

The 72,73Ge(n,p)72,73Ga reaction cross sections were measured at the 5.5MV HV Tandem accelerator of NCSR “Demokritos”, at neutron energies 17.7 and 19.3 MeV by using the activation method. The contamination from the (n,d) and (n,np) reactions on 73Ge and 74 Ge, leading to the 72Ge and 73Ge residual nuclei, respectively, has been taken into account, implementing the corresponding cross sections from TENDL-2017. A systematic investigation of the isotopic effect on all Ge isotopes is also presented, from threshold up to 20MeV, using the present data along with existing data in literature

Isomeric Cross Section Study of Neutron Induced Reactions on Ge Isotopes

In the present work, natural Ge targets have been irradiated by neutron beams of 17.7 and 19.3 MeV, at the 5MV tandem accelerator of NCSR "Demokritos". The cross section of the 72,74Ge(n,α)69,71Zn and 76Ge(n,2n)75Ge reactions, leading to the population of isomeric states, has been deduced with respect to the 27Al(n,α)24Na and 93Nb(n,2n)92mNb reference reactions. After the neutron irradiations, the induced γ-ray activity of the Ge target and reference foils, was measured with high-resolution HPGe detectors.

Primary study of germanium isotope composition in sphalerite from the Fule Pb–Zn deposit, Yunnan province

The Sichuan–Yunnan–Guizhou metallogenic province in southwest China is one of the most important low-temperature metallogenic domains in the country, and more than 400 Pb–Zn deposits and/or mineralization points are located in this area. The Fule deposit is better known that the other Pb–Zn deposits in the region because it is extremely highly enriched with dispersed elements, including Ge, Ga, and Cd. Based on information obtained from our previous studies, the contents of Ge and its isotopic compositions in sphalerite are investigated herein. Results show that the Ge content ranges from 60 ppm to 141.5 ppm, and δ74/70Ge values vary from −6.57‰ to 0.97‰. In this respect, −6.57‰ is the most negative Ge isotope composition value reported in any sphalerite or seafloor sulfides to date. The Cd and Ge contents in sphalerite have a good negative relationship, and it is suggested that the mechanisms of Cd and Zn substitution are responsible for the low incorporation of Ge and relate to the high Cd content (up to 3%) of the sphalerite. In addition, there is a good positive correlation between the Ge contents and δ34S values, which was likely triggered by variations of fluid temperature. In the same hand specimen, light Ge isotope is more likely to be enriched in dark sphalerite rather than light sphalerite, similarly to Cd isotope distribution in dark and light-colored sphalerite. In addition, Cd and Ge isotope compositions, measured in an ore profile from SBFL22 to SBFL26, show a good positive relationship, suggesting that the fractionation mechanisms between Cd and Ge isotopes may be similar and they were controlled by kinetic fractionation during sphalerite precipitation. Based upon previous limited studies, we conclude that Ge in the Fule deposit is derived from mixing sources and sediment is likely the dominant one.

Shell model calculations in the A=80-100 mass region and study of double β transitions

The structure of the Ζ,Ν < 50 nuclei is examined in a model space consisting of the 0g9/2, 1p1/2, 1p3/2 and the 0f5/2 hole orbitals outside the doubly closed 100Sn core. The effective interaction for this model space is derived by introducing second order corrections to the Sussex matrix elements, while the one-hole energies are deduced by a least square fit to the observed levels. The results of the calculation are found to be in very satisfactory agreement with experiment for all nuclei with 38<Ζ<46 but for Ζ<38 this agreement begins to deteriorate. Such a feature possibly indicates the appearance of deformation and the breaking of the Ν=50 core. The wavefunctions of the calculation are used to determine double β matrix elements in the Ge, Se, Sr and Kr isotopes.

Isomeric cross section study of neutron induced reactions on Ge isotopes

Cross sections for the70,76Ge(n,2n),72,73Ge(n,p) and72,74Ge(n,α) reactions have been measured at the 5.5 MV tandem T11/25 Accelerator Laboratory of NCSR Demokritos, using the activation technique. Neutron beams have been produced in the ~16-20 MeV energy region, by means of the3H(d,n)4He reaction. The maximum flux has been determined to be of the order of 105n/cm2s, while the flux variation of the neutron beam was monitored by using a BF3 detector. The cross section has been deduced with respect to the27Al(n,α)24Na and93Nb(n,2n)92mNb reference reactions. The contaminations from reactions induced on neighboring Ge isotopes and leading to the same residual nucleus, have been taken into account. After the end of the irradiations, the activity induced by the neutron beams at the targets and reference foils, has been measured by HPGe detectors. Statistical model calculations using the EMPIRE code were performed on the data measured in this work as well as on data reported in literature.

Cross Section Measurements on Isotopes of Ge and Hf Using the Activation Technique

Cross section measurements of neutron induced reactions on isotopes of Ge and Hf have been determined at energies 8.8, 9.6, 10.6, 11.1, 11.4 MeV using the activation technique. Neutrons produced by the 2H(d,n)3He reaction were used to irradiate pellets of natural Ge and Hf02- The neutron flux at the target position was determined using the 27Al(n,a)24Na, 93Nb(n,2n)92mNb and 197Au(n,2n)196Au reference reactions. HPGe detectors of relative efficiency εΓ=80% and 55% were used to determine the decay of the produced unstable nuclei. The cross section values were compared with those taken from the literature.

Cross sections of deuteron-induced reactions on medium-mass nuclei

Cross section measurements of deuteron-induced reactions on Ni and Ge isotopes have been carried out at energies well below the Coulomb barrier. The preliminary results are compared with statistical model calculations

Neutron induced reactions at the Athens Tandem accelerator NCSR "Demokritos"

The neutron facility at the 5.5 MV Tandem Tll/25 accelerator of NCSR "Demokritos" has been used to produce monoenergetic neutron beams in the energy range 120-650 keV and 4-11.5 MeV via the 7Li(p,n) and 2H(d,n) reactions, respectively. The flux variation of the neutron beam was monitored by using a BF3 detector, while an investigation of the energy dependence of the neutron fluence has been carried out with a liquid scintillator BC501A detector as well as with the multiple foil activation technique. The 232Th(n,2n)231Th and 241Am(n,2n)240Am as well as (n,2n), (n,p) and (η,α) reactions on natural Ge and Hf isotopes, have been investigated from threshold up to 11.5 MeV, by using the activation method.

First-excited state g factors in the stable, even Ge and Se isotopes

Transient-field $g$-factor measurements in inverse kinematics were performed for the first-excited states of the stable, even isotopes of Ge and Se. The $g$ factors of $^{74}\mathrm{Ge}$ and $^{74}\mathrm{Se}$ were measured simultaneously using a cocktail beam, which eliminates most possible sources of systematic error in a relative $g$-factor measurement. The results are $g(^{74}\mathrm{Se})/g(^{74}\mathrm{Ge})=1.34(7), g(^{70}\mathrm{Ge})/g(^{74}\mathrm{Ge})=1.16(15), g(^{72}\mathrm{Ge})/g(^{74}\mathrm{Ge})=0.92(13), g(^{76}\mathrm{Ge})/g(^{74}\mathrm{Ge})=0.88(5), g(^{76}\mathrm{Se})/g(^{74}\mathrm{Se})=0.96(7), g(^{78}\mathrm{Se})/g(^{74}\mathrm{Se})=0.82(5), g(^{80}\mathrm{Se})/g(^{74}\mathrm{Se})=0.99(7)$, and $g(^{82}\mathrm{Se})/g(^{74}\mathrm{Se})=1.19(6)$. The measured $g$-factor ratios are in agreement with ratios from previous measurements, despite considerable variation in previous reported absolute values. The absolute values of the $g$ factors remain uncertain, however, the Rutgers parametrization was used to set the transient-field strength and then compare the experimental $g$ factors with shell-model calculations based on the JUN45 and jj44b interactions. Modest agreement was found between experiment and theory for both interactions. The shell-model calculations indicate that the $g({2}_{1}^{+})$ values and trends are determined largely by the balance of the spin carried by orbital motion of the protons.

A First Look at Dissolved Ge Isotopes in Marine Sediments

The removal of chemical species from seawater during the precipitation of authigenic minerals is difficult to constrain but may play a major role in the global biogeochemical cycles of some elements, including silicon (Si) and germanium (Ge). Here, we present Ge/Si, δ74Ge, and supporting chemical data of pore waters and core incubations at three continental margin sites in California and the Gulf of Mexico. We used these data to partition Ge release and uptake by the various allogenic (delivered via sedimentation) and authigenic (formed in situ) phases in these sediments. About half of the pore water Ge (δ74Gepw = 1.3-2.4‰) is supplied by biogenic silica dissolution (δ74Ge ~3‰), with the other half contributed by lithogenic particulates (δ74Ge ~0.6‰). The highest Ge/Si (~ 3µmol/mol) and lowest δ74Ge (1.3-1.9‰) are observed at the Fe redox horizon, suggesting a supply from detrital Ge-rich Fe oxides. The precipitation of authigenic phases (most likely aluminosilicate clays) in deeper sediments preferentially incorporates Ge over Si, resulting in low pore water Ge/Si (~ 0.3µmol/mol). The lack of corresponding δ74Gepw trend indicates negligible Ge isotope fractionation during this process. Ge fluxes measured via core incubations were variable and appeared strongly controlled by Fe redox behavior near the sediment-water interface. In some cases, reductive Fe oxide dissolution appeared to enhance the benthic Ge flux by over 100% and released fractionated low δ74Ge of ~–0.7‰, resulting in overall benthic δ74Geinc between -0.2 and 3.6‰, depending on Fe oxide contribution to Ge flux. We estimate that detrital inputs supply 19±15% of total dissolved Ge to continental margin pore fluids globally, resulting in an average dissolved δ74Ge of 2.5±0.4‰. Assuming 10-60% of pore water Ge is captured by the authigenic aluminosilicate sink, the dissolved Ge flux to the ocean derived from terrigenous inputs should be roughly 2.4-6.4 Mmol/y, much higher than previously estimated. Our results imply that authigenic Si burial in continental margins should be in the range of 0.9-8.1Tmol/y (best estimate 3.1 Tmol/y), sufficient to close the global marine Si budget.

Feasibility study of the production of bulk stable Ge isotopes by the hydrogen plasma chemical reduction of fluorides

A «fluoride» method for preparation of germanium isotopes was developed and tested, including two main stages: 1) germanium deposition in the process of plasma chemical hydrogen reduction of germanium tetrafluoride with the subsequent compaction of the deposited polycrystalline germanium; 2) zone refining and single grystal growth of germanium if required. Degree of conversion of germanium tetrafluoride of 90–95% was achieved with a productivity of up to 10 g/h. The total yield of about 38% was attained for 72Ge n-type single crystal with a purity of >7 N. The method suggested has been compared with methods described in literature. Its advantage is the high yield production of germanium isotopes directly from enriched tetrafluoride without optional reagents. Plasma-chemical reduction of germanium tetrafluoride does not require sophisticated equipment. Thus, the “fluoride” method could be promising for production of germanium isotopes on industrial scale.

Search for trinucleon decay in the Majorana Demonstrator

The Majorana Demonstrator is an ultra low-background experiment searching for neutrinoless double-beta decay in $^{76}$Ge. The heavily shielded array of germanium detectors, placed nearly a mile underground at the Sanford Underground Research Facility in Lead, South Dakota, also allows searches for new exotic physics. We present the first limits for tri-nucleon decay-specific modes and invisible decay modes for Ge isotopes. We find a half-life limit of $4.9 \times 10^{25}$ yr for the decay $^{76}{\rm Ge(ppn)} \to {}^{73}{\rm Zn}\ e^+\pi^+$ and $4.7\times10^{25}$ yr for the decay $^{76}{\rm Ge(ppp)} \to ^{73}{\rm Cu}\ e^+\pi^+\pi^+$. The half-life limit for the invisible tri-proton decay mode of $^{76}$Ge was found to be $7.5\times10^{24}$ yr.

Germanium isotopes and Ge/Si fractionation under extreme tropical weathering of basalts from the Hainan Island, South China

Abstract Chemical weathering of silicate rocks controls the fluvial input of dissolved Ge and Si into the ocean, and has substantial influence on the global Ge and Si geochemical cycles. The heavier dissolved Ge isotope compositions in the rivers (relative to the bulk silicate earth) suggest preferential incorporation of light isotopes into secondary weathering products during rock weathering (Baronas et al., 2017a). In this paper, we present the Ge isotope and Ge/Si ratio variations in the solid weathering products (soil and saprolite) from a well-developed basalt weathering profile (>15 m thick, including soil, saprolite, semi-weathered rock and fresh basalt) on the tropical island of Hainan (South China). We discussed the elemental/isotopic fractionation mechanism and the possible influence of major oxide composition on Ge isotope fractionation during extreme weathering of basalts in tropical climate. The Ge content ([Ge] = 2.19–4.12 ppm, 2.93 ppm on average, n = 52) and Ge/Si ratios (5.55–13.7 μmol/mol, 7.42 μmol/mol on average, n = 52) of solid weathering products are distinctly higher than those of the fresh basalts (avg. [Ge] = 1.64 ppm, Ge/Si = 2.66 μmol/mol, n = 5). The δ74Ge values of solid weathering products range from −0.02 ± 0.10‰ (2σ) to 0.63 ± 0.10‰ (2σ), and exhibits complex stratigraphic variation across the weathering profile. There are no distinct correlations between the concentrations of Ge (or the Ge/Si ratio and δ74Ge values) and SiO2, Al2O3, Fe2O3 and MnO for most of the soil and saprolite samples. The distinct positive δ74Ge vs. Ge (or τGe value and Ge/Si ratio) correlations for most soil and saprolite samples indicate that the enrichment (or depletion) of Ge content, Ge isotopes and Ge/Si fractionation are controlled by a common sorption process of solid weathering products. The predicted opposite relationships between Ge/Si ratios and δ74Ge values for pore water and that for solid weathering products can be evidenced by the positive Ge/Si vs. δ74Ge correlation in the Wenchang basalt weathering profile and a negative one in the river water (Baronas et al., 2017a). Moreover, the estimated negative Δ74Gesolid-dissolved (1000 * Ln(α)) value (−1.38 ± 0.28‰ (2σ)) indicates that solid weathering products are a sink for light Ge isotopes, possibly balancing the isotopic budget with heavy Ge isotope compositions in global rivers and oceans.