Seasonal dynamics of the carbonate system in the Western English Channel

Kitidis, Vassilis; Hardman-Mountford, Nicholas J.; Litt, Emmer J.; Brown, Ian J.; Cummings, Denise; Hartman, Sue; Hydes, D.J.; Fishwick, James; Harris, Carolyn; Martinez‐Vicente, Victor; Woodward, E. Malcolm S.; Smyth, Tim

doi:10.1016/j.csr.2012.04.012

Cited by 60 publications

(96 citation statements)

References 76 publications

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“…It is not possible to re-do the flux calculations, say, based on the same gas exchange coefficient, as the original data were not provided in the papers cited. Further, there is a lack of temporal coverage as previous studies (Bozec et al, 2011;Dai et al, 2009;Kitidis et al, 2012) have demonstrated short-term changes in pCO 2 at scales of days or less. Yet, typically data on such a scale are limited to only a few cruises.…”

Section: Sea-to-air Co Fluxes In Estuariesmentioning

confidence: 99%

“…The numerical average an- nual flux per unit area, however, is not used to calculate the global release of CO 2 because small estuaries dominate the numerical average, but they contribute relatively little to the total flux. Important to note is that there is a lack of temporal coverage in most of the data sets although previous studies (Bozec et al, 2011;Dai et al, 2009;Kitidis et al, 2012) have demonstrated short-term changes in pCO 2 at scales of days or less. Yet, typically data on such a scale are limited to only a few cruises.…”

Section: Sea-to-air Co Fluxes In Estuariesmentioning

confidence: 99%

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Air–sea exchanges of CO2 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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Section: Sea-to-air Co Fluxes In Estuariesmentioning

confidence: 99%

Section: Sea-to-air Co Fluxes In Estuariesmentioning

confidence: 99%

Air–sea exchanges of CO2 in the world's coastal seas

et al. 2013

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“…pH was monitored daily to adjust the pCO 2 of the experimental media (+/−) prior to dilutions to maintain target pCO 2 levels in the incubation bottles. The seasonality in pH and total alkalinity (TA) are fairly stable at station L4 with high pH and low dissolved inorganic carbon during early summer and low pH, high DIC throughout autumn and winter (Kitidis et al, 2012). By maintaining the carbonate chemistry over the duration of the experiment, we aimed to simulate natural events at the study site.…”

Section: Perturbation Experiment Sampling and Experimental Setupmentioning

confidence: 99%

“…During October, mean seawater temperatures at 10 m decrease from 15.39 • C (±0.49 SD) to 14.37 • C (± 0.62 SD). Following a period of CO 2 oversaturation in late summer, pCO 2 returns to near-equilibrium at station L4 in October when mean pCO 2 values decrease from 455.32 µatm (± 63.92 SD) to 404.06 µatm (± 38.55 SD) (Kitidis et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Effects of elevated CO2 and temperature on phytoplankton community biomass, species composition and photosynthesis during an experimentally induced autumn bloom in the western English Channel

et al. 2018

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Abstract. The combined effects of elevated pCO2 and temperature were investigated during an experimentally induced autumn phytoplankton bloom in vitro sampled from the western English Channel (WEC). A full factorial 36-day microcosm experiment was conducted under year 2100 predicted temperature (+4.5 ∘C) and pCO2 levels (800 µatm). Over the experimental period total phytoplankton biomass was significantly influenced by elevated pCO2. At the end of the experiment, biomass increased 6.5-fold under elevated pCO2 and 4.6-fold under elevated temperature relative to the ambient control. By contrast, the combined influence of elevated pCO2 and temperature had little effect on biomass relative to the control. Throughout the experiment in all treatments and in the control, the phytoplankton community structure shifted from dinoflagellates to nanophytoplankton . At the end of the experiment, under elevated pCO2 nanophytoplankton contributed 90 % of community biomass and was dominated by Phaeocystis spp. Under elevated temperature, nanophytoplankton comprised 85 % of the community biomass and was dominated by smaller nanoflagellates. In the control, larger nanoflagellates dominated whilst the smallest nanophytoplankton contribution was observed under combined elevated pCO2 and temperature (∼ 40 %). Under elevated pCO2, temperature and in the control there was a significant decrease in dinoflagellate biomass. Under the combined effects of elevated pCO2 and temperature, dinoflagellate biomass increased and was dominated by the harmful algal bloom (HAB) species, Prorocentrum cordatum. At the end of the experiment, chlorophyll a (Chl a) normalised maximum photosynthetic rates (PmB) increased > 6-fold under elevated pCO2 and > 3-fold under elevated temperature while no effect on PmB was observed when pCO2 and temperature were elevated simultaneously. The results suggest that future increases in temperature and pCO2 simultaneously do not appear to influence coastal phytoplankton productivity but significantly influence community composition during autumn in the WEC.

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“…High nutrient inputs from land fuel intense primary production and hence stimulate atmospheric CO 2 uptake, while respiration of organic matter exported from terrestrial ecosystems stimulates the release of CO 2 in coastal areas (Bozec et al, 2006;Jönsson et al, 2011;Schiettecatte et al, 2007). In addition to these biological sinks and sources, the effect of temperature on the CO 2 solubility controls the magnitude and direction of the CO 2 exchange between coastal waters and the atmosphere (Kitidis et al, 2012;Borges and Frankignoulle, 2003). Therefore the question remains which particular drivers are governing the CO 2 dynamics in a given coastal system (Borges and Frankignoulle, 2003).…”

Section: Introductionmentioning

confidence: 99%

The impact of sedimentary alkalinity release on the water column CO2 system in the North Sea

et al. 2016

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Abstract. It has been previously proposed that alkalinity release from sediments can play an important role in the carbonate dynamics on continental shelves, lowering the pCO 2 of seawater and hence increasing the CO 2 uptake from the atmosphere. To test this hypothesis, sedimentary alkalinity generation was quantified within cohesive and permeable sediments across the North Sea during two cruises in September 2011 (basin-wide) and June 2012 (Dutch coastal zone). Benthic fluxes of oxygen (O 2 ), alkalinity (A T ) and dissolved inorganic carbon (DIC) were determined using shipboard closed sediment incubations. Our results show that sediments can form an important source of alkalinity for the overlying water, particularly in the shallow southern North Sea, where high A T and DIC fluxes were recorded in nearshore sediments of the Belgian, Dutch and German coastal zone. In contrast, fluxes of A T and DIC are substantially lower in the deeper, seasonally stratified, northern part of the North Sea. Based on the data collected, we performed a model analysis to constrain the main pathways of alkalinity generation in the sediment, and to quantify how sedimentary alkalinity drives atmospheric CO 2 uptake in the southern North Sea. Overall, our results show that sedimentary alkalinity generation should be regarded as a key component in the CO 2 dynamics of shallow coastal systems.

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Seasonal dynamics of the carbonate system in the Western English Channel

Cited by 60 publications

References 76 publications

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

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

Effects of elevated CO<sub>2</sub> and temperature on phytoplankton community biomass, species composition and photosynthesis during an experimentally induced autumn bloom in the western English Channel

The impact of sedimentary alkalinity release on the water column CO<sub>2</sub> system in the North Sea

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Seasonal dynamics of the carbonate system in the Western English Channel

Cited by 60 publications

References 76 publications

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

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

Effects of elevated CO&lt;sub&gt;2&lt;/sub&gt; and temperature on phytoplankton community biomass, species composition and photosynthesis during an experimentally induced autumn bloom in the western English Channel

The impact of sedimentary alkalinity release on the water column CO&lt;sub&gt;2&lt;/sub&gt; system in the North Sea

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Product

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

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

Effects of elevated CO<sub>2</sub> and temperature on phytoplankton community biomass, species composition and photosynthesis during an experimentally induced autumn bloom in the western English Channel

The impact of sedimentary alkalinity release on the water column CO<sub>2</sub> system in the North Sea