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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

Proton loading, chemical weathering rates and discharge of Total Dissolved Salt from the Yangtze Basin during past and present periods.H+S and H+N denote the proton flux from sulfur and nitrogen processes, respectively. WCarb and WSi represent the proton flux consumed through chemical weathering of carbonate and silicate minerals, respectively. TDS donates total dissolved salt. All fluxes are statistically significant different between the two periods (p < 0.001).
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f3: Proton loading, chemical weathering rates and discharge of Total Dissolved Salt from the Yangtze Basin during past and present periods.H+S and H+N denote the proton flux from sulfur and nitrogen processes, respectively. WCarb and WSi represent the proton flux consumed through chemical weathering of carbonate and silicate minerals, respectively. TDS donates total dissolved salt. All fluxes are statistically significant different between the two periods (p < 0.001).

Mentions: Proton loadings to the Yangtze Basin were calculated for two time periods (i.e. 1964–1980 and 2000–2010) based on measured discharge fluxes of sulfate and nitrate to the ocean (Fig. 3). During the past three decades, sulfuric proton input increased by 2.2 times (p < 0.001), from 1.70 × 1011 to 5.52 × 1011 mol yr−1. Acid rain has been conceived as the major cause for this sulfate increase, since the Yangtze Basin is mainly located within the Chinese acid rain region9. However, recent studies indicate that about 60% of sulfate in the Yangtze River originates from sulfide (e.g. pyrites) oxidation1114. Sulfide oxidation is promoted by geological explorations through exposing sulfide gangue to aerobic conditions (i.e. acid mining drainage)520. The Yangtze Basin is the major production region of mining resources (e.g. coal and various metals) in China21. The increasing exploration activities are therefore partly accounting for the enhanced sulfuric acid inputs. Though nitric acid loading is less than sulfuric acid, it increased by 3.3 times (p < 0.001) during the same period. Agricultural fertilizer and urban sewage are proved as the two major sources for this increased reactive nitrogen in the Yangtze River1718.


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

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

Proton loading, chemical weathering rates and discharge of Total Dissolved Salt from the Yangtze Basin during past and present periods.H+S and H+N denote the proton flux from sulfur and nitrogen processes, respectively. WCarb and WSi represent the proton flux consumed through chemical weathering of carbonate and silicate minerals, respectively. TDS donates total dissolved salt. All fluxes are statistically significant different between the two periods (p < 0.001).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3: Proton loading, chemical weathering rates and discharge of Total Dissolved Salt from the Yangtze Basin during past and present periods.H+S and H+N denote the proton flux from sulfur and nitrogen processes, respectively. WCarb and WSi represent the proton flux consumed through chemical weathering of carbonate and silicate minerals, respectively. TDS donates total dissolved salt. All fluxes are statistically significant different between the two periods (p < 0.001).
Mentions: Proton loadings to the Yangtze Basin were calculated for two time periods (i.e. 1964–1980 and 2000–2010) based on measured discharge fluxes of sulfate and nitrate to the ocean (Fig. 3). During the past three decades, sulfuric proton input increased by 2.2 times (p < 0.001), from 1.70 × 1011 to 5.52 × 1011 mol yr−1. Acid rain has been conceived as the major cause for this sulfate increase, since the Yangtze Basin is mainly located within the Chinese acid rain region9. However, recent studies indicate that about 60% of sulfate in the Yangtze River originates from sulfide (e.g. pyrites) oxidation1114. Sulfide oxidation is promoted by geological explorations through exposing sulfide gangue to aerobic conditions (i.e. acid mining drainage)520. The Yangtze Basin is the major production region of mining resources (e.g. coal and various metals) in China21. The increasing exploration activities are therefore partly accounting for the enhanced sulfuric acid inputs. Though nitric acid loading is less than sulfuric acid, it increased by 3.3 times (p < 0.001) during the same period. Agricultural fertilizer and urban sewage are proved as the two major sources for this increased reactive nitrogen in the Yangtze River1718.

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