Ocean acidification the state of the Baltic Sea and the Skagerrak-Kattegat

Transkript

1 Miljöövervakningsdagarna, Tällberg 2-3 oktober 2013 Havets försurning - effekter och miljöövervakning Ocean acidification the state of the Baltic Sea and the Skagerrak-Kattegat Bengt Karlson 1 1 Swedish Meteorological and Hydrological Institute, Sven Källfelts gata 15, Västra Frölunda, Sweden *Corresponding author: bengt.karlson@smhi.se

2 Förbränning av fossila bränslen till 2011 ca 28 % av denna CO 2 finns i haven IPCC WGI 5th Assessment, 2013, final draft 2

3 CO 2 i luft har ökat från 280 ppm till ca 392 ppm år 2012 pco 2 i havet har ökat ph i haven har sjunkit från ca 8,2 till 8,1 IPCC WGI 5th Assessment, 2013, final draft 3

4 Samma mönster i Atlanten och Stilla havet pco 2 ökar i haven ph sjunker i haven ESTOC = Kanarieöarna BATS = Bermuda ALOHA = Hawaii 4

5 Vad säger modellerna om framtidens ph? Representative concentration pathway (RCP) scenarios IPCC WGI 5th Assessment, 2013, final draft 5

6 Har det hänt förut? Pelejero et al

7 Några organismer med kalkskelett som påverkas Turley,

8 Sannolika effekter i Östersjön och Västerhavet Hela ekosystem kommer att påverkas Växtplankton coccolithophorider Sjöborrar Ormstjärnor Larver Torsk o.s.v. 8

9 Summary of background The combustion of fossil fuels results in an increase of the carbon dioxide content of the atmosphere. This also results in effects on the carbonate system in the seas, e.g. ph is being reduced. The term ocean acidification is commonly used. Substantial effects on ecosystems and ecosystem services are expected. Accurate measurements of ph, pco 2 and total alkalinity are important to follow the changes and to understand processes. A challenge is to measure at frequencies high enough to resolve natural variability e.g. due to algal blooms Brackish waters are not well investigated 9

10 Large salinity and ph gradients 10

11 What processes impact ph and pco 2 in Swedish waters? Temperature: Cold water dissolve more CO 2 than warm Primary production: CO 2 is fixed pco 2 & ph Decay of organic matter: CO 2 is released pco 2 & ph River runoff: ph in runoff is directly coupled to the surface water pco 2, where ph gives pco 2 Organic Matter (OM) in runoff: Adds to alkalinity but can both increase and decrease ph depending on its composition Reoxidation of reduced compounds, e.g. NH 4+, Mn 2+, Fe 2+, HS -, ph 11

12 Cyanobacteria bloom in the Baltic Sea 2013 photo by Bengt Karlson Objectives Investigate variability of the carbonate system Propose methods on how to detect ocean acidification in a highly variable environment

13 Sensors and water samplers ph CO 2 13

14 TransPaper water sampling locations Sampling frequency Every two weeks Parameters 12 locations Salinity CDOM/humic substances Alkalinity 6 locations in the Kattegat- Öresund Chlorophyll a 6 locations Phytoplankton 14

15 Parameters In water, 3 m depth Flow rate Temperature, intake Salinity Temperature, salinometer Oxygen Chlorophyll fluorescence Turbidity Phycocyanin fluorescence CDOM fluorescence ph CO 2 In air Air temperature Air pressure Irradiation, PAR CO 2 Water samples Salinity Chlorophyll CDOM Alkalinity Phytoplankton Sampling frequency is every 20 seconds for most parameters

16 Fransson et al. in prep 16

17 Fransson et al. in prep 17

18 Fransson et al. in prep 18

19 Fransson et al. in prep 19

20 Fransson et al. in prep 20

21 Methods for ph measurements H+ sensitive electrode Classic, problems include Calibrations with NBS buffer don't give reliable data in seawater A reliable buffer is not stable over the period of a field cruise. Spectrophotometric method The standard in oceanic waters Useful at salinities > 20 psu Novel fluorometric method Tested in salinity range of 3-30 psu 21

22 22

23 Recommendations For OA monitoring in Swedish waters the following is recommended pco 2 and ph on continuous platforms (VOS and buoys) Total Alkalinity (TA) and ph on hydrographic cruises. Methods Total Alkalinity by potentiometric titration pco 2 by equilibrium with gas or with a buffer through membrane ph by spectrophotometry or by fluorescence 23

24 Thank you for your attention

25 FerryBox systems in the Baltic Sea area TransPaper Karlson,

26 The project participants Bengt Karlson, SMHI Elisabeth Sahlsten, SMHI (now SWAM) Agneta Fransson. GU (now Norwegian Polar Institute) Leif Andersson, GU Stefan Hulth, GU Aron Hakonen, GU and SMHI Jon Havenhand, GU Sam Dupont, GU Johan Kronsell, SMHI Sara Johansson, SMHI Anna Willstrand Wranne, SMHI Mike Thorndyke, Kristineberg Additional data processing by Christian Stranne in