Seasonal and Spatial Variations of Chemical Weathering in the Mekong Basin: From the Headwaters to the Lower Reaches

Kajita, Hiroto; Ota, Yutaka; Yoshimura, Toshihiro; Araoka, Daisuke; Manaka, Takuya; Ziyu, Ouyang; Iwasaki, Shinya; Yanase, Takuya; Inamura, Akihiko; Uchida, Etsuo; Zheng, Hongbo; Yang, Qingshu; Wang, Ke; Suzuki, Atsushi; Kawahata, Hodaka

doi:10.1007/s10498-020-09374-y

Cited by 10 publications

(5 citation statements)

References 59 publications

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“…During the low-water period, a portion of the exposed surface in the basin may be out of contact with river water and therefore be unavailable for water–rock interaction. In contrast, during the high-water period, more surface area is in contact with river water, and chemical weathering is enhanced [ 8 , 28 , 29 ]. The TDS concentrations decreased downstream along the main trunk ( Figure 2 ).…”

Section: Resultsmentioning

confidence: 99%

“…The TZ + of most samples was slightly higher than the TZ − for the normalized ionic charge balance values [NICB = (TZ + − TZ − )/(TZ + + TZ − ) × 100%] within ±5%. The slight imbalance may be attributed to unanalysed organic complex matter [ 8 , 30 ].…”

Section: Resultsmentioning

confidence: 99%

“…The DWR values in the high-water period were 1.10- to 4.07-fold greater than the values in the low-water period. Seasonal variations in chemical weathering rates were controlled by multiple parameters, including climate (temperature, water discharge, and precipitation) and so on [ 8 , 10 , 20 , 31 , 47 ]. During the high-water period, the warm and humid climate conditions associated with the Asian monsoon enhanced chemical weathering.…”

Section: Discussionmentioning

confidence: 99%

“…The chemical weathering of terrestrial silicate rocks constitutes a significant carbon sink in global biogeochemical cycles on geological time scales [ 1 , 2 , 3 , 4 , 5 , 6 ]. The CO 2 consumption flux by silicate rock weathering controls the long-term global carbon cycle time scales of millions of years [ 7 , 8 , 9 , 10 ]. This consumed CO 2 is chemically locked in marine sediments and cannot be easily released back into the atmosphere on short timescales.…”

Section: Introductionmentioning

confidence: 99%

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Chemical Weathering and CO2 Consumption Inferred from Riverine Water Chemistry in the Xi River Drainage, South China

Zhao

Wijbrans

Wang

et al. 2023

IJERPH

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Hydrochemistry and strontium isotope data were analysed in water samples from the Xi River Drainage system to reveal the spatial and seasonal variations in chemical weathering, associated CO2 consumption fluxes, and their control factors. The main ions were Ca2+, Mg2+, and HCO3−, which are characteristic of a drainage system on carbonate-dominated bedrock. The dissolved loads were derived from four major end-member reservoirs: silicate, limestone, dolomite, and atmosphere. The silicate weathering rates (SWRs) increased downstream from 0.03 t/km2/year to 2.37 t/km2/year. The carbonate weathering rates (CWRs) increased from 2.14 t/km2/year in the upper reaches, to 32.65 t/km2/year in the middle reaches, and then decreased to 23.20 t/km2/year in the lower reaches. The SWR values were 281.38 and 113.65 kg/km2/month during the high- and low-water periods, respectively. The CWR values were 2456.72 and 1409.32 kg/km2/month, respectively. The limestone weathering rates were 2042.74 and 1222.38 kg/km2/month, respectively. The dolomite weathering rates were 413.98 and 186.94 kg/km2/month, respectively. Spatial and seasonal variations in chemical weathering were controlled mainly by lithology, vegetation, and climate (temperature, water discharge, and precipitation). The CO2 consumption flux by chemical weathering was estimated at 189.79 × 109 mol/year, with 156.37 × 109 and 33.42 × 109 mol/year for carbonate and silicate weathering, respectively. The CO2 fluxes by chemical weathering are substantially influenced by sulfuric acid in the system. The CO2 flux produced by sulfuric acid weathering was estimated at 30.00 × 109 mol/year in the basin. Therefore, the Xi River Basin is a CO2 sink with a net consumption of CO2 flux of 3.42 × 109 mol/year.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Chemical Weathering and CO2 Consumption Inferred from Riverine Water Chemistry in the Xi River Drainage, South China

Zhao

Wijbrans

Wang

et al. 2023

IJERPH

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show abstract

“…Secondary minerals such as pedogenic carbonates precipitate in soils following previous flood events and can then be washed into rivers and re-dissolved during the wet season (Huth et al, 2019;Kajita et al, 2020;Meyer et al, 2014). Unlike the almost constant radiogenic Sr isotopes, the δ 44/40 Ca values in the Jinsha River system decrease with increasing discharge during the high-runoff period (Fig.…”

Section: Dissolution Of Secondary Soil Mineralsmentioning

confidence: 99%

Behaviour of Sr, Ca, and Mg isotopes under variable hydrological conditions in high-relief large river systems

Chen

Strandmann

et al. 2023

Geochimica et Cosmochimica Acta

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Spatio-temporal assessing rainfall and dam impacts on surface runoff in the Sanaga river basin (transition tropical zone in central part of Cameroon)

Kpoumié

Ngouh

Mfonka

et al. 2022

Sustain. Water Resour. Manag.

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Seasonal and Spatial Variations of Chemical Weathering in the Mekong Basin: From the Headwaters to the Lower Reaches

Cited by 10 publications

References 59 publications

Chemical Weathering and CO2 Consumption Inferred from Riverine Water Chemistry in the Xi River Drainage, South China

Chemical Weathering and CO2 Consumption Inferred from Riverine Water Chemistry in the Xi River Drainage, South China

Behaviour of Sr, Ca, and Mg isotopes under variable hydrological conditions in high-relief large river systems

Spatio-temporal assessing rainfall and dam impacts on surface runoff in the Sanaga river basin (transition tropical zone in central part of Cameroon)

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