Magnesium and calcium isotope systematics in a headwater catchment underlain by amphibolite: Constraints on Mg–Ca biogeochemistry in an atmospherically polluted but well-buffered spruce ecosystem (Czech Republic, Central Europe)

Novák, Martin; Holmden, Chris; Farkaš, Juraj; Krám, Pavel; Hruška, Jakub; Čuřík, Jan; Veselovský, František; Štěpánová, Markéta; Kochergina, Yulia V. Erban; Erban, Vojtěch; Andronikov, A. V.; Šebek, Ondřej; Koubová, Magdaléna; Bohdálková, Leona; Vitkova, Hyacinta

doi:10.1016/j.catena.2020.104637

Cited by 17 publications

(26 citation statements)

References 102 publications

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“…While Mg assimilation by plants is isotopically selective, plants may have little overall effect on riverine δ 26 Mg values (cf., Black et al, 2008;Bolou-Bi et al, 2012;Kimmig et al, 2018;Pogge von Strandmann et al, 2020 andSchmitt et al, 2012). In a specific area, In panel (a), data for 2019 are from this study, data for 2012 are from Novak, Holmden, et al (2020) solutions and exchange complexes, contributing to lower δ 26 Mg value of runoff (Schmitt et al, 2012). Despite the relatively old age of NAZ spruce stands ($100 years), the biomass pool size is currently increas- (Armbruster et al, 2002;Sverdrup, 1990…”

Section: Magnesium Isotopesmentioning

confidence: 88%

“…soil and vegetation (Figure1(c);Novak, Holmden, et al, 2020). Theδ 26 Mg values of bedrock amphibolite (À0.32‰), vertical soil profiles (À0.28‰), and aboveground + belowground vegetation (À0.31‰) were practically identical.…”

mentioning

confidence: 85%

“…At NAZ, mineralogical X-ray analysis of soil fractions detected only a negligible amount of clay minerals (Novak, Holmden, et al, 2020), due to high erosion rates on the relatively steep slope. The weathering profiles are dominated by Al-Fe sesquioxides, which, in principle, can also be isotope-selective when scavenging Mg 2+ from solutions.…”

Section: Magnesium Isotopesmentioning

confidence: 98%

“…In the long run, the latter Mg isotope fractionation may play a minor role at our study site because of indistinguishable mean δ 26 Mg values of bedrock and soil. The potential role of incongruent dissolution of isotopically distinct Mg-bearing rock-forming minerals has been discussed by Novak, Holmden, et al (2020). These authors documented that most Mg in amphibolite is present in common hornblende, which becomes the main source of Mg during dissolution.…”

Section: Magnesium Isotopesmentioning

confidence: 99%

“…Recently, we have reported Mg isotope systematics in a spruce‐forested catchment in the Czech Republic (Central Europe) including δ 26 Mg values of 10 pools and fluxes (Novak, Holmden, et al, 2020). Our sampling of hydrological fluxes was limited to a one‐month period in the spring of 2012.…”

Section: Introductionmentioning

confidence: 99%

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Time‐series of δ²⁶Mg values in a headwater catchment reveal decreasing magnesium isotope variability from precipitation to runoff

Novák

Andronikov

Krám

et al. 2021

Hydrological Processes

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Data on temporal variability in Mg isotope ratios of atmospheric deposition and runoff are critical for decreasing the uncertainty associated with construction of isotope mass balances in headwater catchments, and statistical evaluation of isotope differences among Mg pools and fluxes. Such evaluations, in turn, are needed to distinguish between biotic and abiotic contributions to Mg 2+ in catchment runoff. We report the first annual time-series of δ 26 Mg values simultaneously determined for rainfall, canopy throughfall, soil water and runoff. The studied 55-ha catchment, situated in western Czech Republic, is underlain by Mg-rich amphibolite and covered by mature spruce stands. Between 1970 and 1996, the site received extremely high amounts of acid deposition and fly ash form nearby coal-burning power plants. The δ 26 Mg values of open-area precipitation (median of À0.79‰) at our study site were statistically indistinguishable from the δ 26 Mg values of throughfall (À0.73‰), but significantly different from the δ 26 Mg values of soil water (À0.55‰) and runoff (À0.55‰). The range of δ 26 Mg values during the observation period decreased in the order: open-area precipitation (0.57‰) > throughfall (0.27‰) > runoff (0.21‰) > soil water (0.16‰). The decreasing variability in δ 26 Mg values of Mg 2+ from precipitation to soil water and runoff reflected an increasing homogenization of atmospheric Mg in the catchment and its mixing with geogenic Mg. In addition to atmospheric Mg, runoff also contained Mg mobilized from the three major solid Mg pools, bedrock (δ 26 Mg of À0.32‰), soil (À0.28‰), and vegetation (À0.31‰). The drought of summer 2019 did not affect the nearly constant δ 26 Mg value of runoff. Collectively, our data show that withincatchment processes buffer the Mg isotope variability of the atmospheric input.

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Section: Magnesium Isotopesmentioning

confidence: 88%

mentioning

confidence: 85%

Section: Magnesium Isotopesmentioning

confidence: 98%

Section: Magnesium Isotopesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Time‐series of δ²⁶Mg values in a headwater catchment reveal decreasing magnesium isotope variability from precipitation to runoff

Novák

Andronikov

Krám

et al. 2021

Hydrological Processes

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Time series of δ²⁶Mg variability in precipitation of north‐west Germany

Riechelmann

Spötl

Immenhauser

2021

The Depositional Record

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δ⁵³Cr values of catchment runoff exhibit seasonality regardless of bedrock Cr concentrations: Role of periodically changing chromium export fluxes

Andronikov

Novák

Krám

et al. 2021

Hydrological Processes

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One pre-requisite for the construction of a global chromium isotope mass balance is detailed understanding of Cr isotope systematics in the critical zone where redoxprocesses can modify the isotope signature of geogenic Cr input into the hydrosphere. A Cr isotope inventory of bedrock, soil, and runoff was performed in a Central European headwater catchment underlain by amphibolite, situated in the vicinity of two previously studied catchments underlain by different bedrock types (serpentinite and leucogranite). Fresh bedrock in the amphibolite catchment NAZ contained ~300 mg/kg Cr, serpentinite at PLB contained ~800 mg/kg Cr, and leucogranite at LYS contained ~2 mg/kg Cr. Monthly hydrochemical monitoring at all three sites revealed higher Cr(VI) export fluxes in winter than in summer. NAZ was characterized by a distinct seasonality in the δ 53 Cr values, with minima during winter/spring snowmelts (À0.35‰) and maxima during dry summers (0.40‰). Similar seasonality in δ 53 Cr values had been reported from PLB and LYS. Bedrock at all three sites had similar Cr isotope composition close to À0.10‰, a value indistinguishable from the δ 53 Cr value of bulk silicate Earth (BSE). Positive mean δ 53 Cr value of NAZ runoff indicated Cr-isotope fractionations during weathering of geogenic Cr(III), combined with adsorption of the resulting Cr(VI) on soil particles during pedogenesis. However, the mass-weighted mean δ 53 Cr of NAZ runoff was lower (À0.08‰), indistinguishable from the Cr isotope signature of bedrock. The same pattern of lower mass-weighted mean δ 53 Cr values of runoff, compared to arithmetic mean δ 53 Cr values of runoff, were observed also at PLB and LYS. We suggest that elevated Cr runoff fluxes in winter remove some of the residual isotopically light Cr that accumulated in the soil during summer. Seasonality in runoff δ 53 Cr values appears to be a relatively widespread phenomenon, de-coupled from Cr availability for chemical weathering.

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Magnesium and calcium isotope systematics in a headwater catchment underlain by amphibolite: Constraints on Mg–Ca biogeochemistry in an atmospherically polluted but well-buffered spruce ecosystem (Czech Republic, Central Europe)

Cited by 17 publications

References 102 publications

Time‐series of δ²⁶Mg values in a headwater catchment reveal decreasing magnesium isotope variability from precipitation to runoff

Time‐series of δ²⁶Mg values in a headwater catchment reveal decreasing magnesium isotope variability from precipitation to runoff

Time series of δ²⁶Mg variability in precipitation of north‐west Germany

δ⁵³Cr values of catchment runoff exhibit seasonality regardless of bedrock Cr concentrations: Role of periodically changing chromium export fluxes

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Magnesium and calcium isotope systematics in a headwater catchment underlain by amphibolite: Constraints on Mg–Ca biogeochemistry in an atmospherically polluted but well-buffered spruce ecosystem (Czech Republic, Central Europe)

Cited by 17 publications

References 102 publications

Time‐series of δ26Mg values in a headwater catchment reveal decreasing magnesium isotope variability from precipitation to runoff

Time‐series of δ26Mg values in a headwater catchment reveal decreasing magnesium isotope variability from precipitation to runoff

Time series of δ26Mg variability in precipitation of north‐west Germany

δ53Cr values of catchment runoff exhibit seasonality regardless of bedrock Cr concentrations: Role of periodically changing chromium export fluxes

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Time‐series of δ²⁶Mg values in a headwater catchment reveal decreasing magnesium isotope variability from precipitation to runoff

Time‐series of δ²⁶Mg values in a headwater catchment reveal decreasing magnesium isotope variability from precipitation to runoff

Time series of δ²⁶Mg variability in precipitation of north‐west Germany

δ⁵³Cr values of catchment runoff exhibit seasonality regardless of bedrock Cr concentrations: Role of periodically changing chromium export fluxes