Chen, BB;
Li, SL;
Pogge von Strandmann, PAE;
Sun, J;
Zhong, J;
Li, C;
Ma, TT;
... Liu, CQ; + view all
(2020)
Ca isotope constraints on chemical weathering processes: Evidence from headwater in the Changjiang River, China.
Chemical Geology
, 531
, Article 119341. 10.1016/j.chemgeo.2019.119341.
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Abstract
This study aims to clarify the relationship between chemical weathering of rocks and the carbon budget of rivers and better understand the weathering mechanisms of plateau watersheds. We chose to study the Jinsha River, which originates from the Tibetan Plateau and also is in the upper reaches of the Changjiang River. Analysis of hydrochemistry, radiogenic strontium isotope and stable calcium isotopes were conducted of the Jinsha River water samples, which were collected along its mainstream and main tributaries in the summer. The results show that the water chemistry of the mainstream waters is dominated by evaporite weathering, which have low 87Sr/86Sr values (0.7098–0.7108) and wide range of Sr contents (2.70–9.35 μmol/L). In contrast, tributaries of the Jinsha River have higher 87Sr/86Sr (0.7090–0.7157) and lower Sr contents (∼1 μmol/L). Moreover, the Ca isotopic compositions in the mainstream (0.87–1.11‰) are heavier than the tributaries (0.68–0.88‰) and could not be fully explained by the conventional mixing of different sources. We suggest that secondary carbonate precipitation fractionates Ca isotopes in the Jinsha River, and fractionation factors are between 0.99935 and 0.99963. At least 66% of Ca was removed in the mainstream of the Jinsha River through secondary mineral precipitation, and the average value is ∼35% in the tributaries. The results highlight that evaporite weathering results in more carbonate precipitation influencing Ca transportation and cycling in the riverine system constrained by stable Ca isotopic compositions and water chemistry.
| Type: | Article |
|---|---|
| Title: | Ca isotope constraints on chemical weathering processes: Evidence from headwater in the Changjiang River, China |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.chemgeo.2019.119341 |
| Publisher version: | https://doi.org/10.1016/j.chemgeo.2019.119341 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Ca isotopes, Chemical weathering, Secondary carbonate precipitation, Isotope fractionation. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10087308 |
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