Seasonal and long-term changes in pH in the Dutch coastal zone

P Provoost,J J Middelburg,R W P M Laane,S Van Heuven,K Soetaert

doi:10.5194/bg-7-3869-2010

P Provoost, J J Middelburg + Show 3 more

Open Access

https://doi.org/10.5194/bg-7-3869-2010

Copy DOI

Journal: Biogeosciences (Online)	Publication Date: Nov 26, 2010
Citations: 100	License type: CC BY 3.0

Affiliation: Netherlands Institute of Ecology

Abstract

Abstract. Recent observations and modelling studies suggest that biogeochemical 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 excellent 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 pH change greatly exceed those expected from enhanced CO2 uptake, thus suggesting that other biogeochemical processes, possibly related to changes in nutrient loading, can play a dominant role in ocean acidification.

Highlights

One of the most pressing concerns facing policy makers and society as a whole is the rapid increase of atmospheric CO2 levels
The extensive dataset comprises 249 stations and covers a 31year period (1975–2006), we show the full dataset for a selection of five stations, that are representative for their respective coastal system (Fig. 2)
Our data show that ocean acidification is not exclusively linked to changes in atmospheric CO2, and could be of a much greater magnitude and less predictable than previously thought, at least in coastal systems

Summary

Introduction

One of the most pressing concerns facing policy makers and society as a whole is the rapid increase of atmospheric CO2 levels. Over the past 200 years, the anthropogenic input of CO2 to the atmosphere has accelerated, as a result of fossil fuel combustion, cement production and land use change. These anthropogenic CO2 emissions have had two global scale consequences. The second issue concerns the uptake of anthropogenic CO2 by the world oceans, causing a shift in the chemistry of seawater. This “other CO2 problem” is the topic of this paper. Projected increases in atmospheric CO2 will induce further acidification of oceanic surface waters with 0.4 pH units from circa pH 8.1 to 7.7 in 2100 (Caldeira and Wickett, 2003)

Methods

Results

Discussion

Conclusion