Modelling the chemical weathering fluxes at the watershed scale in the Tropics (Mule Hole, South India): Relative contribution of the smectite/kaolinite assemblage versus primary minerals

Violette, Aurélie; Goddéris, Yves; Maréchal, Jean-Christophe; Riotte, Jean; Oliva, Priscia; Kumar, M. S. Mohan; Sekhar, M.; Braun, Jean‐Jacques

doi:10.1016/j.chemgeo.2010.07.009

Cited by 56 publications

(19 citation statements)

References 48 publications

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“…For Na, different processes can lead to non-conservative behaviour, and must be checked for specific sites. In our study site, previous studies demonstrated that Na is not recycled in any secondary mineral during weathering processes 23 and only marginally adsorbed onto clays contrary to the other major cations Ca, Mg, K 73 . It was also recently demonstrated in the case of Mule Hole that Na was not significantly cycled through the vegetation 47,51 .…”

Section: Validity Assessment Of Deconvolution Method the Deconvolutimentioning

confidence: 70%

Potash fertilizer promotes incipient salinization in groundwater irrigated semi-arid agriculture

Buvaneshwari

Riotte

Sekhar

et al. 2020

Sci Rep

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Incipient groundwater salinization has been identified in many arid and semi-arid regions where groundwater is increasingly used for irrigation, but the dominant processes at stake in such context are yet uncertain. Groundwater solutes originates from various sources such as atmospheric inputs, rock dissolution and fertilizer residues, and their concentration is controlled by hydrological processes, in particular evapotranspiration. Here, we propose a deconvolution method to identify the sources and processes governing the groundwater Chloride concentration in agricultural catchments, using the relative variations of Sodium and chloride and using a neighbouring pristine catchment as a reference for the release rate of Na by weathering. We applied the deconvolution method to the case of the Kabini Critical Zone Observatory, South India, where groundwater was sampled in 188 farm tubewells in the semi-arid catchment of Berambadi and in 5 piezometers in the pristine catchment of Mule Hole. In Berambadi, groundwater composition displayed a large spatial variability with Cl contents spanning 3 orders of magnitude. The results showed that the concentration factor due to evapotranspiration was on average about 3 times more than in the natural system, with higher values in the valley bottoms with deep Vertisols. Linked with this process, large concentration of Chloride originating from rain was found only in these areas. At the catchment scale, about 60 percent of the Chloride found in groundwater originates from fertilizer inputs. These results show that Potassium fertilization as KCl is an important source of groundwater salinization in semi-arid context, and stress that identifying dominant drivers is crucial for designing efficient mitigation policies.

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Section: Validity Assessment Of Deconvolution Method the Deconvolutimentioning

confidence: 70%

Potash fertilizer promotes incipient salinization in groundwater irrigated semi-arid agriculture

Buvaneshwari

Riotte

Sekhar

et al. 2020

Sci Rep

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“…In addition, precipitation and weathering of secondary mineral phases of primary rocks may contribute to the estimated low specific bicarbonate fluxes per runoff from VB+ (e.g. Roelandt et al, 2010;Violette et al, 2010). Nevertheless, a comparison with previous studies (i.e.…”

Section: Runoff and Lithologymentioning

confidence: 92%

Atmospheric CO2 consumption by chemical weathering in North America

Moosdorf

Hartmann

Lauerwald

et al. 2011

Geochimica et Cosmochimica Acta

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“…Assuming an average CaCO 3 content of 1 g/kg within vertisol and ferralsol profiles, the LREE‐Ce reservoir contained in pedogenic carbonates is about 1%, meaning that these authigenic minerals do not exert a significant control on LREE‐Ce dynamic in the soil cover. Subsequently, simplified calculation carried out to allocate the LREE‐Ce reservoir between the iron phases and phosphate minerals assuming that (i) all P is in rhabdophane [(La)PO 4 ·(H 2 O), Molecular Weight = 252 g, 12.3% of P and 55.1% of La], (ii) an average P content of 140 ± 30 µg/g (0.032% of P 2 O 5 ; Violette et al, , Appendix A) in soil, and (iii) an average La content of 26 ± 9 µg/g in soil, tell that a maximum of roughly 25% of La (less if we take into account La‐florencite) is likely incorporated in rhabdophane and the remaining 75% are likely to be adsorbed/occluded on/in poorly crystallized iron oxides and oxyhydroxides. These secondary phases can incorporate Ce(III) as the other LREE.…”

Section: Discussionmentioning

confidence: 99%

“…The regolith architecture and composition have been thoroughly investigated (Braun et al, ; Maréchal et al, ; Riotte et al, a, b, ; Ruiz et al, ; Violette et al, ). The parent rocks consist of Peninsular gneiss of the >2.8 Ga West Dharwar craton (Naqvi & Rogers, ) mainly composed of quartz and Na‐plagioclase as major minerals and amphibole, sericite, biotite, and epidote as minor minerals.…”

Section: Settingsmentioning

confidence: 99%

REY‐Th‐U Dynamics in the Critical Zone: Combined Influence of Reactive Bedrock Accessory Minerals, Authigenic Phases, and Hydrological Sorting (Mule Hole Watershed, South India)

Braun

Riotte²,

Battacharya

et al. 2018

Geochem Geophys Geosyst

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The sources of REY‐Th‐U and long‐term mass balance were assessed in the gneissic tropical forested Critical Zone Observatory of Mule Hole, India. The study relies on the characterization of the solid compartments (bedrock, soils, streambed and suspended sediments), on batch leaching experiments of the parent gneiss and on extractions of cation‐exchangeable and iron‐related pools of selected soil samples. The REY‐Th‐U primary reservoir is controlled by monazite, xenotime, thorite, allanite, bastnesite, titanite, apatite, and, to a lesser extent, by zircon. This accessory mineral assemblage was profoundly modified by episodes of metamorphism and hydrothermal activity. Allanite, bastnesite, titanite, and apatite are prone to break down at incipient weathering stage while monazite, xenotime and zircon are resistant minerals. On a long‐term basis, REY are roughly inert in the immature saprolite and depleted in the soil cover and are strongly redistributed among secondary phases. LREE and HREY are mainly controlled by poorly crystallized secondary iron oxides and oxyhydroxides, and, to a lesser extent, by secondary phosphates (e.g., rhabdophane). Th, inert in the saprolite, is controlled by well‐crystallized secondary iron oxides and oxyhydroxides and likely by secondary thorianite (ThO2). REY and Th are not easily mobilized during surface processes such as chelation by organic matter and uptake by plants. REY and Th are, by far, exported as suspended sediments associated with iron oxides. The U export by groundwater and suspended sediments dominates over those of streambed sediments and stream.

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Modelling the chemical weathering fluxes at the watershed scale in the Tropics (Mule Hole, South India): Relative contribution of the smectite/kaolinite assemblage versus primary minerals

Cited by 56 publications

References 48 publications

Potash fertilizer promotes incipient salinization in groundwater irrigated semi-arid agriculture

Potash fertilizer promotes incipient salinization in groundwater irrigated semi-arid agriculture

Atmospheric CO2 consumption by chemical weathering in North America

REY‐Th‐U Dynamics in the Critical Zone: Combined Influence of Reactive Bedrock Accessory Minerals, Authigenic Phases, and Hydrological Sorting (Mule Hole Watershed, South India)

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