Increasing shallow groundwater CO2 and limestone weathering, Konza Prairie, USA

Macpherson, G.L.; Roberts, J. A. Fraser; Blair, John M.; Townsend, Margaret; Fowle, David A.; Beisner, Kimberly R.

doi:10.1016/j.gca.2008.09.004

Cited by 96 publications

(88 citation statements)

References 68 publications

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“…River A T originates from erosion and is correlated with bedrock composition (e.g., McGrath et al, 2016). Positive trends in river A T have been documented in North America and occur via a number of processes including (1) the interplay of rainfall and land use (Raymond and Cole, 2003), (2) anthropogenic limestone addition used to enhance agricultural soil pH (Oh and Raymond, 2006;Stets et al, 2014) and freshwater pH (Clair and Hindar, 2005), and (3) potentially indirect effects of anthropogenic CO 2 on groundwater CO 2 acidification and weathering (Macpherson et al, 2008). These and other processes were hypothesized to have driven A T changes in the Baltic Sea (Müller et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

Coastal ocean acidification and increasing total alkalinity in the northwestern Mediterranean Sea

et al. 2017

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Abstract. Coastal time series of ocean carbonate chemistry are critical for understanding how global anthropogenic change manifests in near-shore ecosystems. Yet, they are few and have low temporal resolution. At the time series station Point B in the northwestern Mediterranean Sea, seawater was sampled weekly from 2007 through 2015, at 1 and 50 m, and analyzed for total dissolved inorganic carbon (C T ) and total alkalinity (A T ). Parameters of the carbonate system such as pH (pH T , total hydrogen ion scale) were calculated and a deconvolution analysis was performed to identify drivers of change. The rate of surface ocean acidification was −0.0028 ± 0.0003 units pH T yr −1 . This rate is larger than previously identified open-ocean trends due to rapid warming that occurred over the study period (0.072 ± 0.022 • C yr −1 ). The total pH T change over the study period was of similar magnitude as the diel pH T variability at this site. The acidification trend can be attributed to atmospheric carbon dioxide (CO 2 ) forcing (59 %, 2.08 ± 0.01 ppm CO 2 yr −1 ) and warming (41 %). Similar trends were observed at 50 m but rates were generally slower. At 1 m depth, the increase in atmospheric CO 2 accounted for approximately 40 % of the observed increase in C T (2.97 ± 0.20 µmol kg −1 yr −1 ). The remaining increase in C T may have been driven by the same unidentified process that caused an increase in A T (2.08 ± 0.19 µmol kg −1 yr −1 ). Based on the analysis of monthly trends, synchronous increases in C T and A T were fastest in the spring-summer transition. The driving process of the interannual increase in A T has a seasonal and shallow component, which may indicate riverine or groundwater influence. This study exemplifies the importance of understanding changes in coastal carbonate chemistry through the lens of biogeochemical cycling at the land-sea interface. This is the first coastal acidification time series providing multiyear data at high temporal resolution. The data confirm rapid warming in the Mediterranean Sea and demonstrate coastal acidification with a synchronous increase in total alkalinity.

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Section: Discussionmentioning

confidence: 99%

Coastal ocean acidification and increasing total alkalinity in the northwestern Mediterranean Sea

et al. 2017

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“…Although efforts have been made to evaluate the parameters that affect the carbon cycle and to model past and future 6534 C.-T. A. Chen et al: Air-sea exchanges of CO 2 in the world's coastal seas changes in carbon fluxes (Friederich et al, 2002;Fransson et al, 2006;Macpherson et al, 2008;Ver et al, 1999b, a;Mackenzie et al, 2000Mackenzie et al, , 2004Thomas et al, 2007;Borges, 2011), whether the size of the estuarine source and the continental shelf sink for CO 2 changes with time has not been determined because too few data are available. As stated above, the fact that the shelves are a sink rather than a source of CO 2 has only been established in the last few years.…”

Section: Temporal Changesmentioning

confidence: 99%

Air–sea exchanges of CO<sub>2</sub> in the world's coastal seas

et al. 2013

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Abstract. The air-sea exchanges of CO 2 in the world's 165 estuaries and 87 continental shelves are evaluated. Generally and in all seasons, upper estuaries with salinities of less than two are strong sources of CO 2 (39 ± 56 mol C m −2 yr −1 , positive flux indicates that the water is losing CO 2 to the atmosphere); mid-estuaries with salinities of between 2 and 25 are moderate sources (17.5 ± 34 mol C m −2 yr −1 ) and lower estuaries with salinities of more than 25 are weak sources . Mixing with low-pCO 2 shelf waters, water temperature, residence time and the complexity of the biogeochemistry are major factors that govern the pCO 2 in estuaries, but wind speed, seldom discussed, is critical to controlling the air-water exchanges of CO 2 . The total annual release of CO 2 from the world's estuaries is now estimated to be 0.10 Pg C yr −1 , which is much lower than published values mainly because of the contribution of a considerable amount of heretofore unpublished or new data from Asia and the Arctic. The Asian data, although indicating high pCO 2 , are low in sea-to-air fluxes because of low wind speeds. Previously determined flux values rely heavily on data from Europe and North America, where pCO 2 is lower but wind speeds are much higher, such that the CO 2 fluxes are higher than in Asia. Newly emerged CO 2 flux data in the Arctic reveal that estuaries there mostly absorb rather than release CO 2 .Most continental shelves, and especially those at high latitude, are undersaturated in terms of CO 2 and absorb CO 2 from the atmosphere in all seasons. Shelves between 0 and 23.5 • S are on average a weak source and have a small flux per unit area of CO 2 to the atmosphere. Water temperature, the spreading of river plumes, upwelling, and biological production seem to be the main factors in determining pCO 2 in the shelves. Wind speed, again, is critical because at high latitudes, the winds tend to be strong. Since the surface water pCO 2 values are low, the air-to-sea fluxes are high in regions above 50 • N and below 50 • S. At low latitudes, the winds tend to be weak, so the sea-to-air CO 2 flux is small. Overall, the world's continental shelves absorb 0.4 Pg C yr −1 from the atmosphere.

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“…At this site, periodic vertical chemical stratification in the water alternated with periods of chemical homogeneity. Macpherson et al (2008) quantified the increasing alkalinity and dissolved CO 2 in a thin, shallow limestone aquifer in a mid-continental temperate-climate setting. Their results suggest that shallow groundwater, unaffected by urbanization or other changes in land use or surface-water engineering, is associated with an increase in net chemical weathering driven by increasing subsurface CO 2 .…”

Section: Baselines: Natural Groundwater Chemistry and Natural Variabimentioning

confidence: 99%

Developments since 2005 in understanding potential environmental impacts of CO2 leakage from geological storage

Jones

Beaubien

Blackford

et al. 2015

International Journal of Greenhouse Gas Control

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This paper reviews research into the potential environmental impacts of leakage from geological storage of CO 2 since the publication of the IPCC Special Report on Carbon Dioxide Capture and Storage in 2005. Possible impacts are considered on onshore (including drinking water aquifers) and offshore ecosystems. The review does not consider direct impacts on man or other land animals from elevated atmospheric CO 2 levels. Improvements in our understanding of the potential impacts have come directly from CO 2 storage research but have also benefitted from studies of ocean acidification and other impacts on aquifers and onshore near surface ecosystems. Research has included observations at natural CO 2 sites, laboratory and field experiments and modelling. Studies to date suggest that the impacts from many lower level fault-or well-related leakage scenarios are likely to be limited spatially and temporarily and recovery may be rapid. The effects are often ameliorated by mixing and dispersion of the leakage and by buffering and other reactions; potentially harmful elements have rarely breached drinking water guidelines. Larger releases, with potentially higher impact, would be possible from open wells or major pipeline leaks but these are of lower probability and should be easier and quicker to detect and remediate.

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Increasing shallow groundwater CO2 and limestone weathering, Konza Prairie, USA

Cited by 96 publications

References 68 publications

Coastal ocean acidification and increasing total alkalinity in the northwestern Mediterranean Sea

Coastal ocean acidification and increasing total alkalinity in the northwestern Mediterranean Sea

Air–sea exchanges of CO<sub>2</sub> in the world's coastal seas

Developments since 2005 in understanding potential environmental impacts of CO2 leakage from geological storage

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Increasing shallow groundwater CO2 and limestone weathering, Konza Prairie, USA

Cited by 96 publications

References 68 publications

Coastal ocean acidification and increasing total alkalinity in the northwestern Mediterranean Sea

Coastal ocean acidification and increasing total alkalinity in the northwestern Mediterranean Sea

Air–sea exchanges of CO&lt;sub&gt;2&lt;/sub&gt; in the world's coastal seas

Developments since 2005 in understanding potential environmental impacts of CO2 leakage from geological storage

Contact Info

Product

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Air–sea exchanges of CO<sub>2</sub> in the world's coastal seas