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Effects of high CO2 on the fixed nitrogen inventory of the Western English Channel

Effects of high CO2 on the fixed nitrogen inventory of the Western English Channel
Effects of high CO2 on the fixed nitrogen inventory of the Western English Channel

In this study, we investigated the impact of CO2 induced seawater acidification on the concentration of inorganic nutrients, nitrate, nitrite, ammonium, soluble reactive phosphorous (SRP) and silicate at a coastal site in the Western English Channel (WEC). Samples were collected and filtered weekly during the spring to summer transition between 17th March and 21st July 2008. Ambient pH varied by 0.2 units over the study period, while purging with CO2 (380, 500, 760 and 1000 ppmv) resulted in a maximum pH decrease of 0.4 units. Surface nitrate was depleted during the spring phytoplankton bloom and nitrogen limitation was prevalent thereafter. Acidification did not change the concentrations of nitrate, nitrite, SRP or silicate. An average increase in total ammonium of 0.17 μmol L-1 (20) was observed in acidified seawater during the pre-bloom period. We suggest that this increase was not a biological interaction but due to the influx of gaseous ammonia from the atmosphere; CO2 induced acidification shifted the seawater dissolved ammonium-ammonia equilibrium towards the former and thereby decreased the sea-air concentration gradient of ammonia. Using the results from this study, a simple zero-dimensional model for the WEC was constructed which shows that this region will become a net sink for 300 mol m-2 a-1 for NH3 if atmospheric CO2 concentrations increase to 717 ppm. The increase in the total ammonium inventory of the WEC surface waters may increase phytoplankton biomass in the future.

Ammonia, Carbon dioxide, Nutrient cycles, Nutrient deficiency, PH effects
0142-7873
631-641
Wyatt, Neil J.
258d214b-9dae-4a5f-acc9-c0a55fb66efd
Kitidis, Vassilis
dcefa34f-4596-4bbf-b7f8-6b3c422e2df8
Woodward, E. Malcolm S
3a11b7bf-b110-448a-b1ee-ae1ce7d0fef5
Rees, Andrew P.
5971ea8f-f7ee-4556-b8b2-8ffc4b52d2c5
Widdicombe, Stephen
3ecf2b3e-6b3f-4f2f-86c5-baf070e8c82b
Lohan, Maeve
6ca10597-2d0f-40e8-8e4f-7619dfac5088
Wyatt, Neil J.
258d214b-9dae-4a5f-acc9-c0a55fb66efd
Kitidis, Vassilis
dcefa34f-4596-4bbf-b7f8-6b3c422e2df8
Woodward, E. Malcolm S
3a11b7bf-b110-448a-b1ee-ae1ce7d0fef5
Rees, Andrew P.
5971ea8f-f7ee-4556-b8b2-8ffc4b52d2c5
Widdicombe, Stephen
3ecf2b3e-6b3f-4f2f-86c5-baf070e8c82b
Lohan, Maeve
6ca10597-2d0f-40e8-8e4f-7619dfac5088

Wyatt, Neil J., Kitidis, Vassilis, Woodward, E. Malcolm S, Rees, Andrew P., Widdicombe, Stephen and Lohan, Maeve (2010) Effects of high CO2 on the fixed nitrogen inventory of the Western English Channel. Journal of Plankton Research, 32 (5), 631-641. (doi:10.1093/plankt/fbp140).

Record type: Article

Abstract

In this study, we investigated the impact of CO2 induced seawater acidification on the concentration of inorganic nutrients, nitrate, nitrite, ammonium, soluble reactive phosphorous (SRP) and silicate at a coastal site in the Western English Channel (WEC). Samples were collected and filtered weekly during the spring to summer transition between 17th March and 21st July 2008. Ambient pH varied by 0.2 units over the study period, while purging with CO2 (380, 500, 760 and 1000 ppmv) resulted in a maximum pH decrease of 0.4 units. Surface nitrate was depleted during the spring phytoplankton bloom and nitrogen limitation was prevalent thereafter. Acidification did not change the concentrations of nitrate, nitrite, SRP or silicate. An average increase in total ammonium of 0.17 μmol L-1 (20) was observed in acidified seawater during the pre-bloom period. We suggest that this increase was not a biological interaction but due to the influx of gaseous ammonia from the atmosphere; CO2 induced acidification shifted the seawater dissolved ammonium-ammonia equilibrium towards the former and thereby decreased the sea-air concentration gradient of ammonia. Using the results from this study, a simple zero-dimensional model for the WEC was constructed which shows that this region will become a net sink for 300 mol m-2 a-1 for NH3 if atmospheric CO2 concentrations increase to 717 ppm. The increase in the total ammonium inventory of the WEC surface waters may increase phytoplankton biomass in the future.

Full text not available from this repository.

More information

Published date: 1 May 2010
Keywords: Ammonia, Carbon dioxide, Nutrient cycles, Nutrient deficiency, PH effects
Organisations: Marine Biogeochemistry, Southampton Marine & Maritime Institute

Identifiers

Local EPrints ID: 411659
URI: http://eprints.soton.ac.uk/id/eprint/411659
ISSN: 0142-7873
PURE UUID: 881abb90-64fa-4e0e-81ad-83c64e2688fb
ORCID for Neil J. Wyatt: ORCID iD orcid.org/0000-0002-1080-7778
ORCID for Maeve Lohan: ORCID iD orcid.org/0000-0002-5340-3108

Catalogue record

Date deposited: 21 Jun 2017 16:33
Last modified: 16 May 2020 00:41

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