Responses of carbonate system and CO<sub>2</sub> flux to extended drought and intense flooding in a semiarid subtropical estuary

Yao, Hongming; Hu, Xinping

doi:10.1002/lno.10646

Cited by 37 publications

(34 citation statements)

References 69 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…k). This is consistent with our previous study, which revealed that evaporating estuarine water holds less dissolved CO 2 ; and CO 2 efflux is significant under high wind speeds (Yao and Hu ). This CO 2 efflux should contribute to DIC loss (DIC estuarine < 0; Fig.…”

Section: Discussionsupporting

confidence: 93%

“…On the other hand, Chen et al () estimated that average CO 2 flux in North American estuaries is 2.2 mol·C·m −2 ·yr −1 , although their study was mostly based on U.S. east coast estuaries. Furthermore, annual CO 2 flux in MAE during these 3 years was 6.9 ± 6.5 mol·C·m −2 ·yr −1 ; our previous study estimated a much higher CO 2 flux in MAE (12.4 ± 3.3 mol·C·m −2 ·yr −1 ), although that study only spanned May 2014 to April 2015, a period of drought that preceded a large freshwater discharge event in April 2015 (Yao and Hu ). In the longer time series that we present in this study, it is likely that elevated freshwater inflow delivered nutrients and subsequently enhanced autotrophic production and reduced CO 2 emission, especially when MAE returned to an ocean‐dominated condition following the flooding.…”

Section: Discussionmentioning

confidence: 75%

“…Carbonic acid dissociation constants ( K 1 , K 2 ) from Millero () and the bisulfate dissociation constant from Dickson () were used. In our previous study (Yao and Hu ), a salinity‐dependent ∆TA (i.e., TA measured – TA calculated ) was observed. Orr et al () suggested 2.6–3.2% uncertainty in p CO 2 when pairing DIC and pH for calculations in CO2SYS, which equated to approximately an error of 8–16 μ atm in calculated p CO 2 in this study (based on the annual average p CO 2 ).…”

Section: Methodsmentioning

confidence: 77%

“…Area‐weighted annual average CO 2 flux was calculated in each estuary following the equation:

F_{avg} = \frac{\sum F_{i} \times d_{i}}{\sum d_{i}},

where F avg is annual average CO 2 flux (in mmol·m −2 ·d −1 or mol·m −2 ·yr −1 ), F i is area‐weighted CO 2 flux of sampling trip i , and d i indicates interval days in between two consecutive trips from i to i + 1 (Yao and Hu ).…”

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations

Hydrologic controls on CO₂ chemistry and flux in subtropical lagoonal estuaries of the northwestern Gulf of Mexico

Yao

McCutcheon

Staryk

et al. 2020

Limnology & Oceanography

Self Cite

View full text Add to dashboard Cite

Estuaries are generally considered a source of CO2 to the atmosphere, although with significant uncertainties in magnitude and controlling factors between and within estuaries. We studied four northwestern Gulf of Mexico estuaries that experience extreme hydrologic conditions between April 2014 and February 2017 to determine the role of dry/wet cycle on estuarine CO2 system. Annual air–water CO2 flux ranged from 2.7 to 35.9 mol·C·m−2·yr−1; CO2 flux declined by approximately an order of magnitude along with declining river discharge. Episodic flooding made CO2 flux differ between dry (−0.7 to 20.9 mmol·C·m−2·d−1) and wet (11.6–170.0 mmol·C·m–2·d–1) conditions. During wet condition, increases in dissolved inorganic carbon (DIC) and total alkalinity (TA) significantly elevated CO2 degassing. Furthermore, ventilation of river‐borne CO2 strengthened degassing when estuaries became overwhelmingly river‐dominated. During flood relaxation, all estuaries experienced heightened productivity, evidenced by DIC and TA consumption in the mid‐salinity range (10–30). When prolonged drought led to hypersalinity (>36.5), biogeochemical and evaporative effects enhanced DIC and TA consumption and CO2 degassing. Due to flooding and high wind speeds, these estuaries were a strong CO2 source during spring and summer. Then they transitioned to a weak CO2 source or sink during the fall. Low temperatures further depressed CO2 efflux during winter except when a pulse of freshwater input occurred. This study demonstrates that changes in the hydrologic condition of estuaries, such as dry/wet cycle and river discharge gradient, will greatly alter air–water CO2 flux and estuarine contribution to the global carbon budget.

show abstract

Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 75%

Section: Methodsmentioning

confidence: 77%

“…Area‐weighted annual average CO 2 flux was calculated in each estuary following the equation:

F_{avg} = \frac{\sum F_{i} \times d_{i}}{\sum d_{i}},

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Hydrologic controls on CO₂ chemistry and flux in subtropical lagoonal estuaries of the northwestern Gulf of Mexico

Yao

McCutcheon

Staryk

et al. 2020

Limnology & Oceanography

Self Cite

View full text Add to dashboard Cite

show abstract

“…Thus conceptually, higher freshwater inflow to Guadalupe, Nueces, and BB should lead to increased buffering capacity, whereas in Lavaca-Colorado the opposite occurred, with potential negative impacts on shellforming organisms in the system (Salisbury et al 2008;Mathis et al 2011). This finding highlights the important role that both watershed mineralogy and freshwater inflow play as drivers of estuarine carbonate chemistry (Yao and Hu 2017). On average, inorganic nutrient concentrations tended to be highest in upper San Antonio Bay, followed by Lavaca-Colorado, Nueces, and BB.…”

Section: Discussionmentioning

confidence: 86%

Effect of hydrological variability on the biogeochemistry of estuaries across a regional climatic gradient

Montagna

Hu²,

Palmer

et al. 2018

Limnology & Oceanography

Self Cite

View full text Add to dashboard Cite

Given projected changes in river flow to coastal regions worldwide due to climate change and increasing human freshwater demands, it is necessary to determine the role hydrology plays in regulating the biogeochemistry of estuaries. A climatic gradient exists along the Texas coast where freshwater inflow balance ranges from hydrologically positive to negative (where evaporation exceeds inflow) within a narrow latitudinal band, providing a natural experiment for examining inflow effects. Four Texas estuaries ranging from mesosaline to hypersaline were studied for 3 yr to determine how hydrological changes alter the biogeochemistry within and among the estuaries. Trends in dissolved inorganic nutrients, chlorophyll, dissolved organic matter, and carbonate chemistry indicated that these estuaries had drastically different biogeochemical signatures. Nutrients and chlorophyll patterns illustrated an emerging paradigm where phytoplankton biomass in positive estuaries is supported by “new” nitrogen from riverine input, while high concentrations of reduced nitrogen (organic, ammonium) allowed for high chlorophyll in the negative estuary. For carbonate chemistry, a positive estuary receiving river input from a limestone‐dominated watershed was well‐buffered under moderate to high freshwater inflow conditions. When weathering products were diluted during high‐flow conditions, there is carbonate undersaturation (for aragonite) and decreases in pH. However, “acidification” was not observed in the negative estuary because evaporation concentrated the dissolved species and increased buffering capacity. Hydrological changes over spatial gradients are analogous to climatic changes over time, meaning climate change forecasts of higher temperatures and decreased precipitation can make the biogeochemistry of fresher estuaries change to the patterns of saltier estuaries.

show abstract

Riverine export of water, sediment and carbon during flood events in the arid to semi‐arid Wuding River on the Chinese Loess Plateau

Ran

Yang

Tian

et al. 2020

Earth Surf Processes Landf

View full text Add to dashboard Cite

Floods have become increasingly important in fluvial export of water, sediment and carbon (C). Using high‐frequency sampling, the export of water, sediment and C was examined in the Wuding River catchment on the Chinese Loess Plateau. With groundwater as an important contributor to runoff all year round, floods were relatively less important in the export of water. However, large floods were disproportionately important in exporting sediment and inorganic C (DIC) and organic C (DOC and POC). The three largest floods in each year transported 53.6–97.3 and 41.4–77% of the annual sediment and C fluxes, respectively. An extreme flood in 2017 alone contributed 94.6 and 73.1% of the annual sediment and C fluxes, respectively, in just 7 days, which included 20.3, 92.1 and 35.7% of the annual DOC, POC and DIC fluxes, respectively. A stable carbon isotope (δ13C) analysis of POC indicated that modern soils and C3 plants were its primary source. Furthermore, floods greatly accelerated CO2 degassing due to elevated gas transfer velocity, although stream water CO2 partial pressure (pCO2) exhibited a decreasing trend with flow discharge. Although these results illustrated that increasing runoff diluted pCO2, the timing and magnitude of floods were found to be critical in determining the response of pCO2 to flow dynamics. Low‐magnitude floods in the early wet season increased pCO2 because of enhanced organic matter input, while subsequent large floods caused a lower pCO2 due to greatly reduced organic matter supply. Finally, continuous monitoring of a complete flood event showed that the CO2 efflux during the flood (2348 ± 664 mg C m–2 day–1) was three times that under low‐flow conditions (808 ± 98 mg C m–2 day–1). Our study suggests that infrequent, heavy storm events, which are predicted to increase under climate change, will greatly alter the transport regimes of sediment and C. © 2020 John Wiley & Sons, Ltd.

show abstract

Responses of carbonate system and CO₂ flux to extended drought and intense flooding in a semiarid subtropical estuary

Cited by 37 publications

References 69 publications

Hydrologic controls on CO₂ chemistry and flux in subtropical lagoonal estuaries of the northwestern Gulf of Mexico

Hydrologic controls on CO₂ chemistry and flux in subtropical lagoonal estuaries of the northwestern Gulf of Mexico

Effect of hydrological variability on the biogeochemistry of estuaries across a regional climatic gradient

Riverine export of water, sediment and carbon during flood events in the arid to semi‐arid Wuding River on the Chinese Loess Plateau

Contact Info

Product

Resources

About

Responses of carbonate system and CO2 flux to extended drought and intense flooding in a semiarid subtropical estuary

Cited by 37 publications

References 69 publications

Hydrologic controls on CO2 chemistry and flux in subtropical lagoonal estuaries of the northwestern Gulf of Mexico

Hydrologic controls on CO2 chemistry and flux in subtropical lagoonal estuaries of the northwestern Gulf of Mexico

Effect of hydrological variability on the biogeochemistry of estuaries across a regional climatic gradient

Riverine export of water, sediment and carbon during flood events in the arid to semi‐arid Wuding River on the Chinese Loess Plateau

Contact Info

Product

Resources

About

Responses of carbonate system and CO₂ flux to extended drought and intense flooding in a semiarid subtropical estuary

Hydrologic controls on CO₂ chemistry and flux in subtropical lagoonal estuaries of the northwestern Gulf of Mexico

Hydrologic controls on CO₂ chemistry and flux in subtropical lagoonal estuaries of the northwestern Gulf of Mexico