Limits...
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

Spatial correlations of base cations and DIC with SO42βˆ’ and NO3βˆ’ in the Yangtze River.a, base cations versus SO42βˆ’; b, DIC versus SO42βˆ’; c, base cations versus NO3βˆ’; d, DIC versus NO3βˆ’. Past data (1958–1980) are average values at each hydrologic station (open circles). Recent data (filled black circles) are from a regional survey conducted in 2006. Base cations were calculated as the charge sum of Ca2+, Mg2+, K+ and Na+. DIC for past data is represented as bicarbonate (HCO3βˆ’), which is essentially equal to DIC in the pH ranges of the Yangtze River.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4493640&req=5

f1: Spatial correlations of base cations and DIC with SO42βˆ’ and NO3βˆ’ in the Yangtze River.a, base cations versus SO42βˆ’; b, DIC versus SO42βˆ’; c, base cations versus NO3βˆ’; d, DIC versus NO3βˆ’. Past data (1958–1980) are average values at each hydrologic station (open circles). Recent data (filled black circles) are from a regional survey conducted in 2006. Base cations were calculated as the charge sum of Ca2+, Mg2+, K+ and Na+. DIC for past data is represented as bicarbonate (HCO3βˆ’), which is essentially equal to DIC in the pH ranges of the Yangtze River.

Mentions: Sulfuric acid loading promotes mineral dissolution and thereby leaching of solutes to river4511121314. As shown in Fig. 1a, the concentrations of base cations (i.e. equivalence sum of Ca2+, Mg2+, K+ and Na+) are found to correlate (p < 0.001) with sulfate concentrations in both past (1958–1980) and recent data (2006), confirming the contributions of sulfuric acid to mineral dissolution. Monovalent cations (K+ + Na+) response much less than divalent cations (Ca2+ + Mg2+) to sulfate increase (see Supplementary Figure S2 online). This indicates that sulfuric weathering is principally the same on both minerals, but that the effect is stronger on the carbonates. Sedimentary paleocarbon is released when carbonate minerals are dissolved by sulfuric acid, enhancing the DIC delivery to watercourse. Since sulfuric weathering does not consume atmospheric CO2 the sulfate induced increase in flux of DIC (Fig. 1b) should be attributed entirely to the dissolution of sedimentary paleocarbon in carbonate minerals. A geochemical assessment of strontium (Sr) data, from a regional survey of the Yangtze River14, further substantiates that this DIC increase is due to enhanced carbonate rock weathering by sulfuric acid (see Supplementary Information and Supplementary Figure S3 online).


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

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

Spatial correlations of base cations and DIC with SO42βˆ’ and NO3βˆ’ in the Yangtze River.a, base cations versus SO42βˆ’; b, DIC versus SO42βˆ’; c, base cations versus NO3βˆ’; d, DIC versus NO3βˆ’. Past data (1958–1980) are average values at each hydrologic station (open circles). Recent data (filled black circles) are from a regional survey conducted in 2006. Base cations were calculated as the charge sum of Ca2+, Mg2+, K+ and Na+. DIC for past data is represented as bicarbonate (HCO3βˆ’), which is essentially equal to DIC in the pH ranges of the Yangtze River.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: Spatial correlations of base cations and DIC with SO42βˆ’ and NO3βˆ’ in the Yangtze River.a, base cations versus SO42βˆ’; b, DIC versus SO42βˆ’; c, base cations versus NO3βˆ’; d, DIC versus NO3βˆ’. Past data (1958–1980) are average values at each hydrologic station (open circles). Recent data (filled black circles) are from a regional survey conducted in 2006. Base cations were calculated as the charge sum of Ca2+, Mg2+, K+ and Na+. DIC for past data is represented as bicarbonate (HCO3βˆ’), which is essentially equal to DIC in the pH ranges of the Yangtze River.
Mentions: Sulfuric acid loading promotes mineral dissolution and thereby leaching of solutes to river4511121314. As shown in Fig. 1a, the concentrations of base cations (i.e. equivalence sum of Ca2+, Mg2+, K+ and Na+) are found to correlate (p < 0.001) with sulfate concentrations in both past (1958–1980) and recent data (2006), confirming the contributions of sulfuric acid to mineral dissolution. Monovalent cations (K+ + Na+) response much less than divalent cations (Ca2+ + Mg2+) to sulfate increase (see Supplementary Figure S2 online). This indicates that sulfuric weathering is principally the same on both minerals, but that the effect is stronger on the carbonates. Sedimentary paleocarbon is released when carbonate minerals are dissolved by sulfuric acid, enhancing the DIC delivery to watercourse. Since sulfuric weathering does not consume atmospheric CO2 the sulfate induced increase in flux of DIC (Fig. 1b) should be attributed entirely to the dissolution of sedimentary paleocarbon in carbonate minerals. A geochemical assessment of strontium (Sr) data, from a regional survey of the Yangtze River14, further substantiates that this DIC increase is due to enhanced carbonate rock weathering by sulfuric acid (see Supplementary Information and Supplementary Figure S3 online).

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