Hopkins FE, Turner SM, Nightingale PD, Steinke M, Bakker D, Liss P
Dimethylsulfide, DMS, halocarbons, atmospheric chemistry, climate change, mesocosm, Espegrend, Bergen, Norway, 11 m3
The oceanic uptake of man-made CO2 emissions is resulting in ameasureable decrease in the pH of the surface oceans, a processwhich is predicted to have severe consequences formarine biologicaland biogeochemical processes [Caldeira K,WickettME(2003) Nature425:365; The Royal Society (2005) Policy Document 12/05 (Royal Society,London)]. Here, we describe results showing how a doubling ofcurrent atmospheric CO2 affects the production of a suite of atmosphericallyimportant marine trace gases. Two CO2 treatments wereused during a mesocosm CO2 perturbation experiment in a Norwegianfjord (present day: ?380 ppmv and year 2100: ?750 ppmv), andphytoplankton bloomswere stimulated by the addition of nutrients.Seawater trace gas concentrations were monitored over the growthand decline of the blooms, revealing that concentrations of methyliodide and dimethylsulfide were significantly reduced under highCO2. Additionally, large reductions in concentrations of other iodocarbonswere observed. The response of bromocarbons to high CO2was less clear cut. Further research is now required to understandhow ocean acidification might impact on global marine trace gasfluxes and how these impacts might feed through to changes inthe earth’s future climate and atmospheric chemistry.