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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

Spatial correlations between annual average pH and log(NH4+).a, annual averaged values at 19 key cross sections. b, annually averaged values for 105 regular cross sections. pH and log(NH4+) were calculated based on averaged molar concentrations of H+ and NH4+, respectively.
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f2: Spatial correlations between annual average pH and log(NH4+).a, annual averaged values at 19 key cross sections. b, annually averaged values for 105 regular cross sections. pH and log(NH4+) were calculated based on averaged molar concentrations of H+ and NH4+, respectively.

Mentions: At present, there is about 6.77 × 105 ton ammonium nitrogen (NH4+-N) discharged annually into the Yangtze River18. Its nitrification releases proton directly to the water, and therefore causes acidification. However, water acidification by this large proton source is not observed directly by studying long-term pH trends (see Supplementary Information and Supplementary Figure S4 online). Instead, we document it here using two regional data sets from the Chinese Ministry of Environment Protection (MEP). Annual average pH significantly (p < 0.001) decreases with increased log of NH4+ concentration at 19 key sections (Fig. 2a). Extending the assessment to additional 105 sections, thereby covering more regional variations, confirms the similar relationship (Fig. 2b). Acidification through sewage ammonium nitrification is thus postulated to be a major factor governing regional differences in the water quality. This hypothesis is also strengthened by a separate statistical analysis (see Supplementary Information and Supplementary Figure S5 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 between annual average pH and log(NH4+).a, annual averaged values at 19 key cross sections. b, annually averaged values for 105 regular cross sections. pH and log(NH4+) were calculated based on averaged molar concentrations of H+ and NH4+, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: Spatial correlations between annual average pH and log(NH4+).a, annual averaged values at 19 key cross sections. b, annually averaged values for 105 regular cross sections. pH and log(NH4+) were calculated based on averaged molar concentrations of H+ and NH4+, respectively.
Mentions: At present, there is about 6.77 × 105 ton ammonium nitrogen (NH4+-N) discharged annually into the Yangtze River18. Its nitrification releases proton directly to the water, and therefore causes acidification. However, water acidification by this large proton source is not observed directly by studying long-term pH trends (see Supplementary Information and Supplementary Figure S4 online). Instead, we document it here using two regional data sets from the Chinese Ministry of Environment Protection (MEP). Annual average pH significantly (p < 0.001) decreases with increased log of NH4+ concentration at 19 key sections (Fig. 2a). Extending the assessment to additional 105 sections, thereby covering more regional variations, confirms the similar relationship (Fig. 2b). Acidification through sewage ammonium nitrification is thus postulated to be a major factor governing regional differences in the water quality. This hypothesis is also strengthened by a separate statistical analysis (see Supplementary Information and Supplementary Figure S5 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