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Anthropogenically enhanced chemical weathering and carbon evasion in the Yangtze Basin.

Guo J, Wang F, Vogt RD, Zhang Y, Liu CQ - Sci Rep (2015)

Bottom Line: Strong acids (i.e. sulfuric- and nitric acid) from anthropogenic sources have been found to influence the weathering rate and CO2 consumption, but their integrated effects remain absent in the world largest river basins.Our assessments show that anthropogenic loadings of sulfuric and nitrogen compounds accelerate chemical weathering but lower its CO2 sequestration.These findings have significant relevance to improving our contemporary global biogeochemical budgets.

View Article: PubMed Central - PubMed

Affiliation: College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.

ABSTRACT
Chemical weathering is a fundamental geochemical process regulating the atmosphere-land-ocean fluxes and earth's climate. It is under natural conditions driven primarily by weak carbonic acid that originates from atmosphere CO2 or soil respiration. Chemical weathering is therefore assumed as positively coupled with its CO2 consumption in contemporary geochemistry. Strong acids (i.e. sulfuric- and nitric acid) from anthropogenic sources have been found to influence the weathering rate and CO2 consumption, but their integrated effects remain absent in the world largest river basins. By interpreting the water chemistry and overall proton budget in the Yangtze Basin, we found that anthropogenic acidification had enhanced the chemical weathering by 40% during the past three decades, leading to an increase of 30% in solute discharged to the ocean. Moreover, substitution of carbonic acid by strong acids increased inorganic carbon evasion, offsetting 30% of the CO2 consumption by carbonic weathering. Our assessments show that anthropogenic loadings of sulfuric and nitrogen compounds accelerate chemical weathering but lower its CO2 sequestration. These findings have significant relevance to improving our contemporary global biogeochemical budgets.

No MeSH data available.


Related in: MedlinePlus

Graphical abstract illustrating the influence of anthropogenic acid loadings on chemical weathering and inorganic carbon processes.Calcite and albite exemplify carbonate and silicate minerals, respectively. This figure was drawn by software Adobe Photoshop 7.0.
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f4: Graphical abstract illustrating the influence of anthropogenic acid loadings on chemical weathering and inorganic carbon processes.Calcite and albite exemplify carbonate and silicate minerals, respectively. This figure was drawn by software Adobe Photoshop 7.0.

Mentions: Overall, anthropogenic proton loadings enhance chemical weathering but offset its CO2 consumption in the Yangtze Basin (Fig. 4). However, the mechanisms and their effects conceptually vary with rock types: (A) In regions covered by carbonate rocks the protons from atmospheric deposition, acid mining drainages and agricultural fertilizers accelerate dissolution of carbonate minerals, and increase the flux of their dissolved solutes (mainly as Ca2+ and HCO3−) to the watercourse (2, 3, 4 and 5 in Fig. 4). During their transportation to ocean, some of the bicarbonate (HCO3−) is released as CO2 due to in-river proton production by sewage nitrification (7 and 8 in Fig. 4). Part of the bicarbonate is fixated into organic carbon through photosynthesis by aquatic photosynthesis. This organic carbon is either evaded as CO2 by respiration or stored in sediments; (B) In regions devoid of carbonate rocks only a part of the anthropogenic proton loading (2, 3 and 4 in Fig. 4) is consumed by silicate weathering (6 in Fig. 4) due to their lower solubility. The remaining acidities instead protonate the bicarbonate derived from carbonic weathering (1 and 6 in Fig. 4). Furthermore, some anthropogenic acidity is leached from acid soil as H+ and acidic Al, and subsequently evades river DIC together with the acidity from nitrification (7 and 8 in Fig. 4). Since both carbonate and silicate rocks are widely distributed in the Yangtze Basin their integrated influence is in fact more convoluted than outlined by this generic description.


Anthropogenically enhanced chemical weathering and carbon evasion in the Yangtze Basin.

Guo J, Wang F, Vogt RD, Zhang Y, Liu CQ - Sci Rep (2015)

Graphical abstract illustrating the influence of anthropogenic acid loadings on chemical weathering and inorganic carbon processes.Calcite and albite exemplify carbonate and silicate minerals, respectively. This figure was drawn by software Adobe Photoshop 7.0.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493640&req=5

f4: Graphical abstract illustrating the influence of anthropogenic acid loadings on chemical weathering and inorganic carbon processes.Calcite and albite exemplify carbonate and silicate minerals, respectively. This figure was drawn by software Adobe Photoshop 7.0.
Mentions: Overall, anthropogenic proton loadings enhance chemical weathering but offset its CO2 consumption in the Yangtze Basin (Fig. 4). However, the mechanisms and their effects conceptually vary with rock types: (A) In regions covered by carbonate rocks the protons from atmospheric deposition, acid mining drainages and agricultural fertilizers accelerate dissolution of carbonate minerals, and increase the flux of their dissolved solutes (mainly as Ca2+ and HCO3−) to the watercourse (2, 3, 4 and 5 in Fig. 4). During their transportation to ocean, some of the bicarbonate (HCO3−) is released as CO2 due to in-river proton production by sewage nitrification (7 and 8 in Fig. 4). Part of the bicarbonate is fixated into organic carbon through photosynthesis by aquatic photosynthesis. This organic carbon is either evaded as CO2 by respiration or stored in sediments; (B) In regions devoid of carbonate rocks only a part of the anthropogenic proton loading (2, 3 and 4 in Fig. 4) is consumed by silicate weathering (6 in Fig. 4) due to their lower solubility. The remaining acidities instead protonate the bicarbonate derived from carbonic weathering (1 and 6 in Fig. 4). Furthermore, some anthropogenic acidity is leached from acid soil as H+ and acidic Al, and subsequently evades river DIC together with the acidity from nitrification (7 and 8 in Fig. 4). Since both carbonate and silicate rocks are widely distributed in the Yangtze Basin their integrated influence is in fact more convoluted than outlined by this generic description.

Bottom Line: Strong acids (i.e. sulfuric- and nitric acid) from anthropogenic sources have been found to influence the weathering rate and CO2 consumption, but their integrated effects remain absent in the world largest river basins.Our assessments show that anthropogenic loadings of sulfuric and nitrogen compounds accelerate chemical weathering but lower its CO2 sequestration.These findings have significant relevance to improving our contemporary global biogeochemical budgets.

View Article: PubMed Central - PubMed

Affiliation: College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.

ABSTRACT
Chemical weathering is a fundamental geochemical process regulating the atmosphere-land-ocean fluxes and earth's climate. It is under natural conditions driven primarily by weak carbonic acid that originates from atmosphere CO2 or soil respiration. Chemical weathering is therefore assumed as positively coupled with its CO2 consumption in contemporary geochemistry. Strong acids (i.e. sulfuric- and nitric acid) from anthropogenic sources have been found to influence the weathering rate and CO2 consumption, but their integrated effects remain absent in the world largest river basins. By interpreting the water chemistry and overall proton budget in the Yangtze Basin, we found that anthropogenic acidification had enhanced the chemical weathering by 40% during the past three decades, leading to an increase of 30% in solute discharged to the ocean. Moreover, substitution of carbonic acid by strong acids increased inorganic carbon evasion, offsetting 30% of the CO2 consumption by carbonic weathering. Our assessments show that anthropogenic loadings of sulfuric and nitrogen compounds accelerate chemical weathering but lower its CO2 sequestration. These findings have significant relevance to improving our contemporary global biogeochemical budgets.

No MeSH data available.


Related in: MedlinePlus