@article{fdi:010085253,
  title = {{S}easonal, weathering and water use controls of silicon cycling along the river flow in two contrasting basins of {S}outh {I}ndia},
  author = {{S}arath, {P}. {K}. and {M}angalaa, {K}. {R}. and {C}ardinal, {D}. and {G}urumurthy, {G}. {P}. and {D}apoigny, {A}. and {S}arma, {V}vss and {R}iotte, {J}ean},
  editor = {},
  language = {{ENG}},
  abstract = {{W}e present the first study of river water silicon isotopic composition from two contrasting basins in {S}outh {I}ndia, the east flowing {K}averi river and the west flowing {N}etravathi river. {B}oth rivers originate from the {W}estern {G}hats. {R}iver water samples were collected from mainstream, tributaries and reservoirs at different locations along the river flow during dry and wet (monsoon) seasons, with an additional post-monsoon sampling in {N}etravathi. {H}igh rainfall in {N}etravathi basin and upper reaches of {K}averi induce intense weathering in the region, with superposing contribution from anthropogenic controls in downstream {K}averi. {T}he delta {S}i-30({DS}i) values range from +0.42 to +1.65 parts per thousand for {N}etravathi river basin and + 0.32 to +2.85 parts per thousand for {K}averi river basin. {S}ilicate weathering index ({R}-e) shows intense weathering associated with monosiallitization (kaolinite-gibbsite formation) in {N}etravathi basin and relatively moderate weathering with bisiallitization (smectite-kaolinite formation) in {K}averi basin. {T}he seasonal changes in delta {S}i-30({DS}i) and {R}-e in each basin shows similar patterns, with a likely higher and heavier contribution of soil water from deeper soil profiles closer to weathering front and bedrock, associated with significant secondary mineral formation during dry season and leaching of superficial soil profiles during the high discharge periods of monsoon. {W}e provide a theoretical framework to estimate relative contribution of silicate weathering vs. anthropogenic processes on riverine delta {S}i-30({DS}i). {R}-e is broadly correlated with delta {S}i-30({DS}i) and an isotopic mass balance involving the whole rock composition (excluding the stable quartz and sericite) shows that the delta {S}i-30 in river water are well explained by silicate weathering and gibbsite-kaolinite formation in the {N}etravathi and upper upper reaches of {K}averi. {H}owever, silicate weathering explains only partially the heavier delta {S}i-30({DS}i) signatures in the middle and lower reaches of the {K}averi, and the additional enrichment of about +1.06 parts per thousand can be attributed to uptake of silicon and {S}i-depleted return flow through irrigated agriculture in the basin. {T}his study confirms the major control of pedoclimatic conditions on the delta {S}i-30 of rivers and provides for the first time an estimation of the impact of human activities on the silicon isotopic signature of rivers.},
  keywords = {{S}ilicon isotopes ; {T}ropical rivers ; {D}issolved silicon ; {K}averi ; {N}etravathi ; {INDE} ; {KAVERI} {COURS} {D}'{EAU} ; {NETRAVATHI} {COURS} {D}'{EAU}},
  booktitle = {},
  journal = {{C}hemical {G}eology},
  volume = {604},
  numero = {},
  pages = {120883 [13 p.]},
  ISSN = {0009-2541},
  year = {2022},
  DOI = {10.1016/j.chemgeo.2022.120883},
  URL = {https://www.documentation.ird.fr/hor/fdi:010085253},
}