A comparative overview of weathering intensity and HCO3− flux in the world's major rivers with emphasis on the Changjiang, Huanghe, Zhujiang (Pearl) and Mississippi Rivers

Cai, Wei‐Jun; Guo, Xianghui; Chen, Chen‐Tung Arthur; Dai, Minhan; Zhang, Longjun; Zhai, Weidong; Lohrenz, Steven E.; Yin, Kedong; Harrison, Paul J.; Wang, Yongchen

doi:10.1016/j.csr.2007.10.014

Cited by 220 publications

(220 citation statements)

References 76 publications

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“…It is known that nearly all of the world's large rivers have lower carbonate and calcium concentrations (and thus lower ) than receiving ocean water (Meybeck, 1987;Cai et al, 2008). The mixing of freshwater with seawater, therefore, can effectively suppress a in the nearshore area.…”

Section: The Role Of Freshwater Runoff On Variation In the Coastal Zonementioning

confidence: 99%

Carbonate mineral saturation states in the East China Sea: present conditions and future scenarios

et al. 2013

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Abstract.To assess the impact of rising atmospheric CO 2 and eutrophication on the carbonate chemistry of the East China Sea shelf waters, saturation states ( ) for two important biologically relevant carbonate minerals -calcite ( c ) and aragonite ( a ) -were calculated throughout the water column from dissolved inorganic carbon (DIC) and total alkalinity (TA) data collected in spring and summer of 2009. Results show that the highest c (∼ 9.0) and a (∼ 5.8) values were found in surface water of the Changjiang plume area in summer, whereas the lowest values ( c =∼ 2.7 and a =∼ 1.7) were concurrently observed in the bottom water of the same area. This divergent behavior of saturation states in surface and bottom waters was driven by intensive biological production and strong stratification of the water column. The high rate of phytoplankton production, stimulated by the enormous nutrient discharge from the Changjiang, acts to decrease the ratio of DIC to TA, and thereby increases values. In contrast, remineralization of organic matter in the bottom water acts to increase the DIC to TA ratio, and thus decreases values. The projected result shows that continued increases of atmospheric CO 2 under the IS92a emission scenario will decrease values by 40-50% by the end of this century, but both the surface and bottom waters will remain supersaturated with respect to calcite and aragonite. Nevertheless, superimposed on such decrease is the increasing eutrophication, which would mitigate or enhance the decline caused by anthropogenic CO 2 uptake in surface and bottom waters, respectively. Our simulation reveals that, under the combined impact of eutrophication and augmentation of atmospheric CO 2 , the bottom water of the Changjiang plume area will become undersaturated with respect to aragonite ( a =∼ 0.8) by the end of this century, which would threaten the health of the benthic ecosystem.

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Section: The Role Of Freshwater Runoff On Variation In the Coastal Zonementioning

confidence: 99%

Carbonate mineral saturation states in the East China Sea: present conditions and future scenarios

et al. 2013

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“…River end-member concentrations generally depend on river discharge. For example, TA values increase with decreasing discharge (Cai et al, 2008) in the Mississippi (Cai, 2003, Fig. 1) and Atchafalaya Rivers, e.g.…”

Section: Impacts Of River End-members and Plume Residence Time On Stomentioning

confidence: 99%

The stoichiometry of inorganic carbon and nutrient removal in the Mississippi River plume and adjacent continental shelf

et al. 2012

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Abstract. The stoichiometry of dissolved inorganic carbon (DIC) and nutrients during biological uptake is widely assumed to follow the Redfield ratios (especially the C / N ratio) in large river plume ecosystems. However, this assumption has not been systematically examined and documented, because DIC and nutrients are rarely studied simultaneously in river plume areas and interpretation of ratios can be confounded by strong river-ocean mixing as well as intense biological activity. We examined stoichiometric ratios of DIC and nutrients (NO and calculated biological removal as the difference between observed concentrations and those predicted from conservative mixing, as determined from a multi-endmember mixing model and observed salinity and total alkalinity. Despite complex physical and biogeochemical influences, relationships between DIC and nutrients were strongly dependent on salinity range and geographic location, and influenced by biological removal. Lower C / Si and N / Si ratios in one nearshore area were likely due to localized input of high Si and low NO − 3 water from adjacent wetlands or preferential removal of nitrogen in the area. When net biological uptake was separated from river-ocean mixing and corrected for preferential N removal, the stoichiometric ratio of C / N / Si was similar to the Redfield ratio, thus supporting the applicability of the Redfield-type C / N / Si ratios in river-plume biogeochemical models.

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“…during lowest discharge, owing to the dilution effect of weathering products (Cai 2003;Cai et al 2008;Chen et al 2008;Bouillon et al 2012;Guo et al 2012). High HCO 3 − content in subtropical to middle-latitude large river waters provides a high acid-base buffering capacity, comparable to that of seawater.…”

Section: Co 2 Degassing Flux In Inner Estuariesmentioning

confidence: 99%

Carbon dioxide dynamics and fluxes in coastal waters influenced by river plumes

Cai

Chen²,

Borges³

2013

Biogeochemical Dynamics at Major River-Coastal Interfaces

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A comparative overview of weathering intensity and HCO3− flux in the world's major rivers with emphasis on the Changjiang, Huanghe, Zhujiang (Pearl) and Mississippi Rivers

Cited by 220 publications

References 76 publications

Carbonate mineral saturation states in the East China Sea: present conditions and future scenarios

Carbonate mineral saturation states in the East China Sea: present conditions and future scenarios

The stoichiometry of inorganic carbon and nutrient removal in the Mississippi River plume and adjacent continental shelf

Carbon dioxide dynamics and fluxes in coastal waters influenced by river plumes

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