scholarly journals Long-term spatial and temporal variation of CO<sub>2</sub> partial pressure in the Yellow River, China

2015 ◽  
Vol 12 (4) ◽  
pp. 921-932 ◽  
Author(s):  
L. Ran ◽  
X. X. Lu ◽  
J. E. Richey ◽  
H. Sun ◽  
J. Han ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Temporal Variation ◽  
Yellow River ◽  
Dilution Effect ◽  
High Pco2 ◽  
Spatial And Temporal Variation ◽  
The Yellow River ◽  
Wet Season ◽  
Co2 Partial Pressure ◽  
River Waters

Abstract. Carbon transport in river systems is an important component of the global carbon cycle. Most rivers of the world act as atmospheric CO2 sources due to high riverine CO2 partial pressure (pCO2). By determining the pCO2 from alkalinity and pH, we investigated its spatial and temporal variation in the Yellow River watershed using historical water chemistry records (1950s–1984) and recent sampling along the mainstem (2011–2012). Except the headwater region where the pCO2 was lower than the atmospheric equilibrium (i.e. 380 μatm), river waters in the remaining watershed were supersaturated with CO2. The average pCO2 for the watershed was estimated at 2810 ± 1985 μatm, which is 7-fold the atmospheric equilibrium. As a result of severe soil erosion and dry climate, waters from the Loess Plateau in the middle reaches had higher pCO2 than that from the upper and lower reaches. From a seasonal perspective, the pCO2 varied from about 200 μatm to > 30 000 μatm with higher pCO2 usually occurring in the dry season and lower pCO2 in the wet season (at 73% of the sampling sites), suggesting the dilution effect of water. While the pCO2 responded exponentially to total suspended solids (TSS) export when the TSS concentration was less than 100 kg m−3, it decreased slightly and remained stable if the TSS concentration exceeded 100 kg m−3. This stable pCO2 is largely due to gully erosion that mobilizes subsoils characterized by low organic carbon for decomposition. In addition, human activities have changed the pCO2 dynamics. Particularly, flow regulation by dams can diversely affect the temporal changes of pCO2, depending on the physiochemical properties of the regulated waters and adopted operation scheme. Given the high pCO2 in the Yellow River waters, large potential for CO2 evasion is expected and warrants further investigation.

scholarly journals Spatial and temporal dynamics of CO<sub>2</sub> partial pressure in the Yellow River, China

2014 ◽  
Vol 11 (10) ◽  
pp. 14063-14096
Author(s):  
L. Ran ◽  
X. X. Lu ◽  
J. E. Richey ◽  
H. Sun ◽  
J. Han ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Temporal Dynamics ◽  
Yellow River ◽  
Dilution Effect ◽  
High Pco2 ◽  
The Yellow River ◽  
Wet Season ◽  
Co2 Partial Pressure ◽  
River Waters ◽  
Air Interface

Abstract. Carbon transport in river systems is an important component of the global carbon cycle. Most rivers of the world act as atmospheric CO2 sources due to high riverine CO2 partial pressure (pCO2). We investigated the pCO2 dynamics in the Yellow River watershed by using historical water chemistry records (1950s–1984) and recent sampling along the mainstem (2011–2012). Except the headwater region where the pCO2 was lower than the atmospheric equilibrium (i.e., 380 μatm), river waters in the remaining watershed were supersaturated with CO2. The average pCO2 for the watershed was estimated at 2810 ± 1985 μatm, which is 7-fold the atmospheric equilibrium. This indicates a strong CO2 outgassing across the water-air interface. As a result of severe soil erosion and dry climate, waters from the Loess Plateau in the middle reaches had higher pCO2 than that from the upper and lower reaches. From a seasonal perspective, the pCO2 varied from about 200 μatm to >30 000 μatm with higher pCO2 usually occurring in the dry season and low pCO2 in the wet season (at 73% of the sampling sites), suggesting the dilution effect of water. While the pCO2 responded positively to total suspended solids (TSS) transport when the TSS was less than 100 kg m−3, it slightly decreased and remained stable when the TSS exceeded 100 kg m−3. This stable pCO2 is largely due to gully erosion that mobilizes subsoils characterized by low organic matter for decomposition. In addition, human activities have changed the pCO2 dynamics. Particularly, flow regulation by dams can diversely affect the temporal changes of pCO2, depending on the physiochemical properties of the regulated waters and adopted operation scheme. Given the high pCO2 in the Yellow River waters, the resultant CO2 outgassing is expected to be substantial and warrants further investigation.

scholarly journals Study on the hydro-chemistry process after mixing between water and rocks

2018 ◽  
Vol 54 (2) ◽  
pp. 104-114
Author(s):  
Xiuyan Jing ◽  
Hongbin Yang ◽  
Na Wang
Keyword(s):  
River Water ◽  
Arid Regions ◽  
Yellow River ◽  
Dilution Effect ◽  
Northwest China ◽  
Experimental Simulation ◽  
The Yellow River ◽  
Mixing Ratio ◽  
Close Attention ◽  
Semi Arid

Abstract The chemical evolution of groundwater has received close attention from hydro-geologists. Northwest China largely consists of arid and semi-arid regions, where surface water and groundwater frequently exchange with each other, and where the mixing and water–rock interactions significantly affect the direction of water quality evolution. Based on experimental simulation, this paper investigates the interactions among the Yellow River water, groundwater and rocks in Yinchuan. The study found that when groundwater is mixed with the Yellow River water, the Yellow River water has a certain dilution effect on the hydro-chemical composition of groundwater; however, this effect is not simply diluted by proportion for no reaction between irons, but a portion of calcium, sulfur, and carbonate form precipitates. After mixing of the Yellow River water, groundwater and rocks, the pH increased, and the carbon dioxide system reached equilibrium again. In addition, CO32− was produced. While Na+ increase was mainly due to dissolution, SO42− decrease was because of precipitation. The precipitation or dissolution of Ca2+, Mg2+, and CO32− mainly depended on the mixing ratio between groundwater and river water, which suggested the reversible behavior of the dissolution-precipitation of carbonate minerals.

scholarly journals CO<sub>2</sub> partial pressure and CO<sub>2</sub> emission along the lower Red River (Vietnam)

2018 ◽  
Vol 15 (15) ◽  
pp. 4799-4814 ◽  
Author(s):  
Thi Phuong Quynh Le ◽  
Cyril Marchand ◽  
Cuong Tu Ho ◽  
Nhu Da Le ◽  
Thi Thuy Duong ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Co2 Flux ◽  
River System ◽  
Water Quality Monitoring ◽  
Red River ◽  
Wet Season ◽  
Night Time ◽  
Co2 Partial Pressure ◽  
The Difference ◽  
Hoa Binh

Abstract. The Red River (Vietnam) is representative of a south-east Asian river system, strongly affected by climate and human activities. This study aims to quantify the spatial and seasonal variability of CO2 partial pressure and CO2 emissions of the lower Red River system. Water quality monitoring and riverine pCO2 measurements were carried out for 24 h at five stations distributed along the lower Red River system during the dry and the wet seasons. The riverine pCO2 was supersaturated relative to the atmospheric equilibrium (400 ppm), averaging about 1589±43 ppm and resulting in a water–air CO2 flux of 530.3±16.9 mmol m−2 d−1 for the lower Red River. pCO2 and CO2 outgassing rates were characterized by significant spatial variation along this system, with the highest values measured at Hoa Binh station, located downstream of the Hoa Binh Dam, on the Da River. Seasonal pCO2 and CO2 outgassing rate variations were also observed, with higher values measured during the wet season at almost all sites. The higher river discharges, enhanced external inputs of organic matter from watersheds and direct inputs of CO2 from soils or wetland were responsible for higher pCO2 and CO2 outgassing rates. The difference in pCO2 between the daytime and the night-time was not significant, suggesting weak photosynthesis processes in the water column of the Red River due to its high sediment load.

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