Spatiotemporal variations of dissolved inorganic carbon and controlling factors in a small karstic catchment, Southwestern China

Qin, Cai-Qing; Li, Siliang; Yue, Fu‐Jun; Xu, Sheng; Ding, Hu

doi:10.1002/esp.4672

Cited by 36 publications

(21 citation statements)

References 63 publications

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“…The result shows that the dominant anions in the Nanming River are HCO 3 – and SO 4 2– , and the dominant cations are Ca 2+ and Mg 2+ , which essentially complies with the component characteristics of major ions in the Guizhou karst rivers. A similar phenomenon has been widely discovered in karst areas with abundant carbonate sedimentary rocks, such as Houzhai Catchment, Puding Catchment, and the Xijiang River Basin . HCO 3 – , Ca 2+ , and Mg 2+ are usually considered to be produced by rock weathering rather than exogenous input .…”

Section: Resultsmentioning

confidence: 53%

Riverine Hydrochemical Characteristics of a Typical Karst Urban Watershed: Major Ion Compositions, Sources, Assessment, and Historical Evolution

Han

2022

ACS Earth Space Chem.

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Urban watersheds suffer from great pressure concerning poor water carrying capacity in the karst area with a fragile ecology system and urbanization disturbance. The hydrochemistry of karst urban rivers plays a vital role in the maintenance of water ecology. This study determined the sources of major ions (Na + , K + , Mg 2+ , Ca 2+ , F − , Cl − , NO 3 − , SO 4 2− , and HCO 3 − ) in the Nanming urban watershed. The ion concentrations were dominated by the HCO 3 − -Ca 2+ •Mg 2+ type and complied with the compoment characteristics of major ions in karst rivers with the order of Ca 2+ (mean: 83.1 mg/L) > Mg 2+ (mean: 17.6 mg/L) > Na 2+ (mean: 15.2 mg/L) > K + (mean: 6.7 mg/ L) and HCO 3 − (mean: 252.7 mg/L) > SO 4 2− (mean: 101.5 mg/L) > Cl − (mean: 17.8 mg/L) > NO 3 − (mean: 17.7 mg/L). The chemical composition of the Nanming River was possibly affected by carbonate weathering (Ca 2+ , Mg 2+ , and HCO 3 − ) and anthropogenic inputs (SO 4 2− , NO 3 − , Cl − , Na + , and K + ) through methods of principal component analysis (PCA) and ion ratios. The irrigation water quality and health risk were evaluated by the calculation of sodium adsorption ratio (SAR), soluble sodium percentage (Na%), residual sodium carbonate (RSC), and hazard quotient (HQ) and the comparison of corresponding guidelines. The results showed that the Nanming River was marginally suitable for agricultural irrigation but dangerous for direct drinking intake, and the noncarcinogenic health risk of riverine ions should also be of concern. The control of urban wastewater discharge should be paid more attention to improve the water quality in such an urban watershed.

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Section: Resultsmentioning

confidence: 53%

Riverine Hydrochemical Characteristics of a Typical Karst Urban Watershed: Major Ion Compositions, Sources, Assessment, and Historical Evolution

Han

2022

ACS Earth Space Chem.

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“…All these hydrochemical variations above are also the causes of the elevation of pH in TH relative to RA. Solutes in rivers are mostly derived from rock weathering, atmosphere, and anthropogenic inputs (Gaillardet et al, 1999;Qin et al, 2019). In this study, most solute concentrations in SU and SP are much higher than that in RA and TH (Figure 7), indicating little contributions of atmospheric sources compared with terrestrial sources.…”

Section: Dynamic Variations Of Hydrochemistry Among Different Spatialmentioning

confidence: 60%

“…The permeability of epikarst normally weakens with increasing depth (Ford and Williams, 2007). W2 is a deep confined well fed by groundwater draining a gypsum stratum and not susceptible to changes in external environment (e.g., occurrences of rainstorms and agricultural activities) (Qin et al, 2019). Therefore, its hydrological environment is stable with smaller [NO − 3 ] and lower CV of most ions.…”

Section: Discussion Dynamic Responses Of Surface Water and Groundwatmentioning

confidence: 99%

Hydrogeochemical Dynamics and Response of Karst Catchment to Rainstorms in a Critical Zone Observatory (CZO), Southwest China

Qin

Ding

et al. 2020

Front. Water

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Karst water is vital for local drinking and irrigation but is susceptible to contamination. Hydrochemistry, which is highly related to carbonate weathering in karst catchments, can affect water quality and respond rapidly to climate change. In order to explore hydrogeochemical sources, dynamics, and their responses to rainstorms, rainwater, throughfall, hillslope runoff, surface water, and groundwater were sampled synchronously during rainstorms at a karst Critical Zone Observatory (CZO), Southwest China. Results showed that the total dissolved solids (TDS) concentration in throughfall increased by 30.1 ± 8.0% relative to rainwater, but both throughfall and rainwater contributed little to TDS in surface water and groundwater compared with terrestrial sources. Hydrochemistry in surface water and groundwater was diluted by rainstorms but displayed chemostatic responses with different intensities to increasing discharge. This is possibly regulated by hydrogeological conditions, available sources of various solutes, and the difference between solute concentrations before and after rainstorms. Ca2+ and Mg2+ dynamics were mainly regulated by carbonate weathering, gypsum dissolution, and gypsum-induced dedolomitization (geological sources), which also affect Ca2+, Mg2+, and SO42- in deep confined groundwater draining a gypsum stratum. For HCO3-, CO2 from respiration and microbiologic activities is one dominant contributor, especially for spring. The chemostatic behaviors of NO3-, Cl−, and K+ were related to agricultural activities, especially in surface water. These controls on hydrochemistry may already exist as hillslope runoff occurs, which has be further demonstrated by principle component analysis (PCA). The heterogeneous permeability of epikarst can affect the mixture of groundwater from different sources and flowing pathways, enabling hydrochemistry at different hydrogeological conditions to display discrepant responses to rainstorms. The epikarst aquifer with high permeability is susceptible to changes in external environment, such as rainstorms and agricultural activities, increasing the potential risk of water environment problems (chronic pollution of nitrogen and high hardness of water) during a certain period. Drinking water safety thus deserves consideration in the agricultural karst catchment.

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“…The hydrological cycle plays a major role in controlling the carbon dynamics in the karst critical zone [129]. The stream discharge, which shows the highest variability during the year, is a key factor in relation to mineral dissolution processes (Equation (4)).…”

Section: Role Of Discharge Temperature and Vegetation On Stream Watementioning

confidence: 99%

“…China, where a decrease of rainfall between 2007 and 2013 led to an annual mean increase of dissolved element concentrations in stream water [53,129]. Moreover, in BC, during the low water flow period in summer, some tributaries dry out completely, causing particular areas to increase their relative contribution of dissolved elements to the waterbody.…”

Section: Role Of Discharge Temperature and Vegetation On Stream Watementioning

confidence: 99%

A Forty-Year Karstic Critical Zone Survey (Baget Catchment, Pyrenees-France): Lithologic and Hydroclimatic Controls on Seasonal and Inter-Annual Variations of Stream Water Chemical Composition, pCO2, and Carbonate Equilibrium

Ulloa-Cedamanos

Probst

Binet

et al. 2020

Water

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The long-term trends and seasonal patterns of stream water chemical composition in a small remote forested karst catchment, were investigated from 1978 to 2018. Calcium, magnesium, and bicarbonates, the dominant ions, increased over the period together with temperature, while sulfates decreased. Carbonate and sulfate mineral dissolution was the main source of these elements. These trends and the seasonal opposite patterns of discharge vs. temperature, calcite saturation index vs. pCO2 and bicarbonate vs. sulfates, suggested the influence of discharge, of reduced long-range atmospheric pollution, and of increasing air temperature on biological activity and carbonate dissolution. Furthermore, the hydrological regime controlled the seasonal stream water chemical composition and fluxes by: (i) a dilution during the high discharge period, (ii) a change in the contribution rate of the waters draining different lithological areas in the catchment, e.g., the increased sulfates to bicarbonates ratio during summer low flows, with a maximum alkalinity decrease of 24%, and (iii) a “piston” and a “flushing” effects of dissolved elements stored in soils and epikarst with the first autumn heavy rains. Long-term stream water hydrochemical surveys of karst system have proved to be powerful indicators of biogeochemical processes, water sources and pathways under variable natural and anthropogenic environmental pressure conditions.

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Spatiotemporal variations of dissolved inorganic carbon and controlling factors in a small karstic catchment, Southwestern China

Cited by 36 publications

References 63 publications

Riverine Hydrochemical Characteristics of a Typical Karst Urban Watershed: Major Ion Compositions, Sources, Assessment, and Historical Evolution

Riverine Hydrochemical Characteristics of a Typical Karst Urban Watershed: Major Ion Compositions, Sources, Assessment, and Historical Evolution

Hydrogeochemical Dynamics and Response of Karst Catchment to Rainstorms in a Critical Zone Observatory (CZO), Southwest China

A Forty-Year Karstic Critical Zone Survey (Baget Catchment, Pyrenees-France): Lithologic and Hydroclimatic Controls on Seasonal and Inter-Annual Variations of Stream Water Chemical Composition, pCO2, and Carbonate Equilibrium

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