Use of Sr isotopes as a tool to decipher the soil weathering processes in a tropical river catchment, southwestern India

G. P. Gurumurthy, K. Balakrishna, M. Tripti, Jean Riotte, Stéphane Audry, Jean Jacques Braun, H. N. Udaya Shankar

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3 Citations (Scopus)

Abstract

River water composition (major ion and 87Sr/86Sr ratio) was monitored on a monthly basis over a period of three years from a mountainous river (Nethravati River) of southwestern India. The total dissolved solid (TDS) concentration is relatively low (46mgL-1) with silica being the dominant contributor. The basin is characterised by lower dissolved Sr concentration (avg. 150nmolL-1), with radiogenic 87Sr/86Sr isotopic ratios (avg. 0.72041 at outlet). The composition of Sr and 87Sr/86Sr and their correlation with silicate derived cations in the river basin reveal that their dominant source is from the radiogenic silicate rock minerals. Their composition in the stream is controlled by a combination of physical and chemical weathering occurring in the basin. The molar ratio of SiO2/Ca and 87Sr/86Sr isotopic ratio show strong seasonal variation in the river water, i.e., low SiO2/Ca ratio with radiogenic isotopes during non-monsoon and higher SiO2/Ca with less radiogenic isotopes during monsoon season. Whereas, the seasonal variation of Rb/Sr ratio in the stream water is not significant suggesting that change in the mineral phase being involved in the weathering reaction could be unlikely for the observed molar SiO2/Ca and 87Sr/86Sr isotope variation in river water. Therefore, the shift in the stream water chemical composition could be attributed to contribution of ground water which is in contact with the bedrock (weathering front) during non-monsoon and weathering of secondary soil minerals in the regolith layer during monsoon. The secondary soil mineral weathering leads to limited silicate cation and enhanced silica fluxes in the Nethravati river basin.

Original languageEnglish
Pages (from-to)498-506
Number of pages9
JournalApplied Geochemistry
Volume63
DOIs
Publication statusPublished - 01-12-2015

Fingerprint

Weathering
Isotopes
Catchments
weathering
Rivers
isotope
catchment
Soils
river water
silicate
Silicates
mineral
Minerals
isotopic ratio
river
Water
monsoon
soil
seasonal variation
river basin

All Science Journal Classification (ASJC) codes

  • Environmental Chemistry
  • Pollution
  • Geochemistry and Petrology

Cite this

Gurumurthy, G. P. ; Balakrishna, K. ; Tripti, M. ; Riotte, Jean ; Audry, Stéphane ; Braun, Jean Jacques ; Udaya Shankar, H. N. / Use of Sr isotopes as a tool to decipher the soil weathering processes in a tropical river catchment, southwestern India. In: Applied Geochemistry. 2015 ; Vol. 63. pp. 498-506.
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Use of Sr isotopes as a tool to decipher the soil weathering processes in a tropical river catchment, southwestern India. / Gurumurthy, G. P.; Balakrishna, K.; Tripti, M.; Riotte, Jean; Audry, Stéphane; Braun, Jean Jacques; Udaya Shankar, H. N.

In: Applied Geochemistry, Vol. 63, 01.12.2015, p. 498-506.

Research output: Contribution to journalArticle

TY - JOUR

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AU - Gurumurthy, G. P.

AU - Balakrishna, K.

AU - Tripti, M.

AU - Riotte, Jean

AU - Audry, Stéphane

AU - Braun, Jean Jacques

AU - Udaya Shankar, H. N.

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