Long-term record of pH in the Dutch coastal zone: a major role for eutrophication-induced changes

Abstract

Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Biogeosciences Discuss., 7, 4127–4152, 2010 www.biogeosciences-discuss.net/7/4127/2010/ doi:10.5194/bgd-7-4127-2010 © Author(s) 2010. CC Attribution 3.0 License. Biogeosciences Discussions This discussion paper is/has been under review for the journal Biogeosciences (BG). Please refer to the corresponding final paper in BG if available. Long-term record of pH in the Dutch coastal zone: a major role for eutrophication-induced changes P. Provoost1, S. van Heuven2, K. Soetaert1, R. Laane3, and J. J. Middelburg4 1Netherlands Institute for Ecology (NIOO-KNAW), Centre for Estuarine and Marine Ecology, P.O. Box 140, 4400 AC Yerseke, The Netherlands 2Groningen University, Department of Ocean Ecosystems, P.O. Box 14, 9750 AA Haren, The Netherlands 3Deltares, P.O. Box 177, 2600 MH Delft, The Netherlands 4Faculty of Geosciences, Utrecht University, P.O. Box 80.021, 3508 TA Utrecht, The Netherlands Received: 20 May 2010 – Accepted: 20 May 2010 – Published: 4 June 2010 Correspondence to: P. Provoost (p.provoost@nioo.knaw.nl) Published by Copernicus Publications on behalf of the European Geosciences Union. 4127 Abstract Recent observations and modelling studies suggest that eutrophication-related biogeo- chemical changes can mask atmospheric CO2-induced pH decreases. Data collected by the Dutch monitoring authorities in different coastal systems (North Sea, Wadden Sea, Ems-Dollard, Eastern Scheldt and Scheldt estuary) since 1975 provide an ex- cellent opportunity to test whether this is the case in the Dutch coastal zone. The time-series were analysed using Multi-Resolution Analysis (MRA) which resulted in the identification of system-dependent patterns on both seasonal and intra-annual time scales. The observed rates of change greatly exceed those expected from enhanced CO2 uptake, thus confirming that eutrophication can play a dominant role in ocean acidification.