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| Titel |
Hydrological controls on Chemical weathering in the Jinsha River draining the southeastern Qinghai-Tibet Plateau |
| VerfasserIn |
Jun Zhong, Siliang Li, Fujun Yue, Hu Ding |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250131496
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| Publikation (Nr.) |
 EGU/EGU2016-11914.pdf |
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| Zusammenfassung |
| The geochemistry of the riverine waters could provide an insight in understanding the surface
processes, such as chemical weathering and carbon cycle. As the headwater of Chanjiang
(Yangtze) River, Jinsha River flows on the southestern Qinhai-Tibet Plateau at high altitute
(from 1000m to 4600m) above the major areas of human impact and carries important
information on this erosive region. In spite of being impacted by monsoonal climate and with
significant variations of discharge, the temporal variations of compositions of main ions and
chemical weathering of Jinsha River are rarely documented. In this study, a systematic
investigation on the seasonal and episodic water geochemistry (major ions and
δ13CDIC) of the outlet of Jinsha River basin were carried out with the purpose of 1)
characterizing temporal variations of aqueous geochemistry and its controlling factors, 2)
quantifying rock weathering and associated CO2 consumption rates, and 3) exploring
the impact of hydrological controls on chemical weathering of the Jinsha River
Basin.
The results show that the concentrations of Ca, Mg, HCO3 and NO3 are generally
decreased during monsoon season, while that of Cl, Na, SO4, K are relative higher in
monsoon season than in dry season, which may be mainly caused by hydrological condition,
i.e., with increased runoff, more surficial evaporate dissolved water and salt lake water of the
Basin flow into the river. Moreover, due to increased contribution of soil CO2and fast
decomposition of organic matters, δ13CDIC in the high-flow period has more negative values
than in low-flow period, and shows a negative relation with the concentration of DOC.
An increasing of Ca concentrations was found with shift of the δ13CDIC values,
positively, indicating the precipitation might be occured. Meanwhile, the dissolution of
gypsum and anhydrite might enhance the calcium precipition. The forward model
results show that the weathering rates of silicate and carbonate as well as that of
related CO2 consumption have a positive relation with water discharge, highlighting
the hydrological controls on chemical weathering and CO2 consumption rates,
which should be considered in the future study in river basins impacted by monsoon
climate.
This work was supported by The China National Science Fund for Outstanding Young
Scholars (Grant No. 41422303). |
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