Dimethylsulfide (DMS) in the Bering Sea and Adjacent Waters:
In-situ and Satellite Observations


This project is funded by the NASA Office of Earth Science Oceanography Program and the NOAA Office of Oceanic and Atmospheric Research.

PMEL Project Description

Oceanic dimethylsulfide (DMS) is the major natural source of sulfur to the atmosphere (Bates et al., 1992). As a volatile odiferous sulfur compound, DMS serves as an olfactory attractant for sea birds (Nevitt et al., 1995). In the atmosphere DMS is oxidized to produce aerosol particles, which affect the acid-base chemistry of the atmosphere (Charlson and Rodhe, 1982) and the radiative properties of marine stratus clouds (Shaw 1983, 1987; Charlson et al., 1987; Andreae and Crutzen, 1997). An increase in the DMS flux has the potential to increase the number of atmospheric aerosol particles and the cloud drop number concentration. An increase in the number of small cloud drops suppresses precipitation leading to longer-lived clouds (Albrecht, 1989; Lohmann and Feichter, 1997). This effectively increases the cloud cover, which leads to more radiation reflected back to space.

The source of atmospheric DMS is the surface ocean. The production of DMS and its precursor, dimethylsulphoniopropionate (DMSP) is confined largely to a few classes of marine phytoplankton, specifically the Dinophyceae and the Prymnesiophycease, which include coccolithopheres (Keller et al., 1989). Blooms of the cocolithophore, Emiliania huxleyi, in the Gulf of Maine and Northeast Atlantic produced concentrations of DMS and DMSP that were as much as an order of magnitude higher than in the surrounding waters (Matrai and Keller, 1993; Malin et al., 1993). Although actively growing cells release only small quantities of DMSP and DMS, DMS is produced during cell senescence (Nguyen et al., 1988; Turner et al., 1988), zooplankton grazing (Dacey and Wakeham, 1986; Wolfe and Steinke, 1996), and the interaction of bacterioplankton (Kiene and Bates, 1990; Bates et al., 1994; Ledyard and Dacey, 1994) and viral pathogens (Malin et al., 1998; Hill et al., 1998).

Since the production and seawater consumption of DMS are highly species specific and dependent upon the bacteria, phytoplankton, and zooplankton communities, the concentration of DMS will be strongly influenced by the physical processes controlling water mass interactions and nutrient availability (Turner et al., 1996). This includes the input of atmospheric nutrients. Coccolithophore blooms have been shown to occur in seasonally stratified waters after the spring diatom bloom has depleted inorganic nutrient levels (Holligan, 1987). It has also been suggested that iron limitation might lead to coccolithophore dominated populations in regions such as the Gulf of Alaska (Martin et al., 1989).

The first true color images over the Bering Sea after the launch of SeaWiFS in August 1997 showed the presence of an extensive coccolithophore bloom. This was the first reported occurrence of a coccolithophore bloom in the Bering Sea, and it has since been associated with anomalous oceanographic and atmospheric conditions. The bloom has reoccurred annually since 1997.

Have these coccolithophore blooms in the Bering Sea affected the flux of DMS to the atmosphere? The complex interaction of physical (ocean and atmospheric circulation, temperature, salinity), chemical (availability of macro and micro nutrients), and biological (species composition and food web dynamics) factors that control the production and consumption of DMS makes it difficult to predict oceanic DMS concentrations and thus the flux to the atmosphere. It is evident that the Bering Sea ecosystem is changing and that coccolithophores have been a dominant plankton species during the past few years. There is also strong evidence from studies in the North Atlantic Ocean that these blooms lead to high concentrations of DMS.

Previous DMS measurements in the Bering Sea

DMS was measured in the Bering Sea in the spring of 1981 as part of the PROBES (Processes and Resources of the Bering Sea Shelf) program (Barnard et al., 1984). DMS concentrations in seawater were strongly correlated with the cell density of the haptophyte, Phaeocystis poucheti and ranged from 1 to 17 nM with a mean of 3 nM. DMS measurements were also made in the Bering Sea on a ship-of-opportunity in September 1985 by Bates and co-workers (1987). Concentrations ranged from 0.5 to 20 nM with a mean of 6 nM. Since DMS is biologically produced, the concentrations in the subarctic regions are very seasonally dependent (Bates et al., 1987).

Why is DMS important to the Bering Sea ecosystem?

An increase in seawater DMS concentrations in the Bering Sea could affect the ecosystem in several ways.

  1. DMS is the precursor of the background sulfate aerosol over the ocean (Bates et al., 1998 and other references in the ACE-1 Special Issue of the Journal of Geophysical Research, July 1998). An increase in atmospheric sulfur aerosol could affect the pH of precipitation falling on coastal regions around the Bering Sea.
  2. An increase in DMS emissions could increase the cloud condensation nuclei concentration and change cloud properties over the Bering Sea. This could affect precipitation frequency, cloud amount, and the regional radiation budget (Albrecht, 1989; Lohmann and Feichter, 1997).
  3. An increase in odiferous seawater sulfur compounds could be carried through the food web to higher order species. While there is evidence in studies of Baltic herring that this flavor compound may be transferred to fish from phytoplankton (Granroth and Hattula, 1976), this has never been proven.
  4. An increase in atmospheric DMS concentrations could affect the foraging behavior of Bering Sea birds. To date there has only been one such study that was carried out in the Antarctic (Nevitt et al., 1995).
Scientific Question Addressed in this Study: Has the increased abundance of coccolithophores in the Bering Sea caused an increase in the production of DMS in sea water and an increase in the flux of DMS to the atmosphere? We are addressing this question by deploying an automated underway DMS sampling/analysis system in the Bering Sea and adjacent waters. Our goal is to quantify the regional and seasonal concentrations of DMS in this region. Have the coccolithophore blooms significantly increased the concentration of DMS in the Bering Sea compared to the concentrations measured in the 1980s (Barnard et al., 1984; Bates et al., 1987)? The data are being made available to the scientific community on this web site. Our co-investigators on this project at Northwest Research Associates are monitoring the coccolithophore blooms, cloud cover and cloud reflectivity in area via satellite. With will combined our data sets in the final year of this project to address this important scientific question.
 
 

References cited

Albrecht, B.A. (1989) Aerosols, cloud microphysics, and fractional cloudiness, Science, 245, 1227-1230.

Andreae, M.O. and P.J. Crutzen (1997) Atmospheric aerosols: biogeochemical sources and role in atmospheric chemistry. Science, 276, 1052-1058.

Barnard, W.R., M.O. Andreae, and R.L. Iverson (1984) Dimethylsulfide and Phaeocystis pouchetii in the Southeastern Bering Sea. Continental Shelf Res., 3, 103-113.

Bates, T.S., J.D. Cline, R.H. Gammon, and S. Kelly-Hansen (1987) Regional and seasonal variations in the flux of oceanic dimethylsulfide to the atmosphere. J. Geophys. Res., 92, 2930-2938.

Bates, T.S., B.J. Huebert, J.L. Gras, F.B. Griffiths, and P.A. Durkee (1998) The International Global Atmospheric Chemistry (IGAC) Projectís First Aerosol Characterization Experiment (ACE-1) - Overview. J. Geophys. Res., 103, 16,297-16,318.

Bates, T.S., R.P. Kiene, G.V. Wolfe, P.A. Matrai, F.P. Chavez, K.R. Buck, B.W. Blomquist, and R.L. Cuhel (1994) The cycling of sulfur in surface seawater of the Northeast Pacific. J. Geophys. Res., 99, 7,835-7,843.

Bates, T.S., B.K. Lamb, A.B. Guenther, J. Dignon, and R.E. Stoiber (1992) Sulfur emissions to the atmosphere from natural sources. J. Atmos. Chem., 14, 315-337.

Bates, T.S. and P.K. Quinn (1997) . Dimethylsulfide (DMS) in the Equatorial Pacific Ocean (1982-1996) - Evidence of a climatic feedback? Geophys. Res. Lett., 24:861-864.

Charlson, R.J., J. Langner, H. Rodhe, C.B. Leovy, and S.G. Warren (1991) Perturbation of the northern hemisphere radiative balance by backscattering from anthropogenic sulfate aerosols, Tellus, 43AB, 152-163.

Charlson, R.J., J.E. Lovelock, M.O. Andreae, and S.G. Warren (1987) Oceanic phytoplankton, atmospheric sulfur, cloud albedo and climate, Nature. 326, 655-661.

Charlson, R.J. and H. Rodhe (1982) Factors controlling the acidity of rainwater, Nature, 295:683-685.

Charlson, R., S. Schwartz, J. Hales, R. Cess, J. Coakley, J. Hansen, D. Hoffmann (1992) Climate forcing by anthropogenic aerosols, Science, 255, 423-430.

Claud, C., K. Katsaros, G. Petty, A. Chedin, and N. Scott (1992) A cold air outbreak over the Norwegian Sea observed with the TIROS-N Operational Vertical Sounder (TOVS) and the Special Sensor Microwave/Imager (SSM/I), Tellus, 44A, 100-118.

Coakley, J., R. Bernstein, P. Durkee (1987) Effect of ship-stack effluents on cloud reflectivity, Science, 237, 1020-1022

Curran, M. and G. Jones (1998) Spatial distribution of dimethylsulfide and dimethylsulfoniopropionate in the Australasian sector of the Southern Ocean, J. Geophys. Res., 103, 16677-16689.

Dacey, J.W.H. and S.G. Wakeham (1986) Oceanic dimethylsulfide: production during zooplankton grazing on phytoplankton. Science, 233:1314-1316.

Goodberlet, M., C. Swift, J. Wilkerson (1989) Remote sensing of ocean surface winds with the Special Sensor Microwave/Imager, J. Geophys. Res., 94, 14547-14555.

Granroth, B. and T. Hattula (1976) Formation of dimethylsulfide by brackish water algae and its possible implication for the flavor of Baltic Herring. Finn. Chem. Let., 148-150.

Greenwald, T., G. Stephens, T. Vonder Haar, D. Jackson (1993) A physical retrieval of cloud liquid water over the global oceans using special sensor microwave/imager (SSM/I) observations, J. Geophys. Res., 98, 18471-18488.

Hill, R.W., B. White, M. Cottrell, and J.W.H. Dacey (1998) Virus-mediated release of demethylsulfoniopropionate from marine phytoplankton. Aquatic Microbiology and Ecology, 14, 1-6.

Holligan, P.M. (1987) The physical environment of exceptional phytoplankton blooms in the Northeast Atlantic. Rapports et Proces-Verbaux, Conseil International pour líexploration de la Mer, 187, 9-18.

Keller, M.D., W.K. Bellows, and R.R.L. Guillard (1989) Dimethylsulfide production in marine phytoplankton. In: Biogenic Sulfur in the Environment. E.S. Saltzman and W.J. Cooper, eds., American Chemical Society Symposium Series No. 393, Washington, DC, 167-182.

Kiene, R.P. and T.S. Bates (1990) Biological removal of dimethylsulfide from sea water. Nature, 345, 702-705.

Krasnopolsky, V., L. Breaker, W. Gemmil (1995) A neural network as a non-linear transfer function model for retrieving surface wind speeds from the Special Sensor Microwave Imager, J. Geophys. Res., 100, 11033-11045.

Liu, W. (1984) Estimation of latent heat flux with SEASAT-SMMR, a case study in the N. Atlantic. Large-Scale Oceanographic Experiments and Satellites. C. Gautier and M. Fieux, eds., D. Reidel, 205-221.

Liu, W. (1986) Statistical relation between monthly mean precipitable water and surface-level humidity over global oceans, Mon. Wea. Rev., 114, 1591-1602, 1986.

Lohmann, U. and J. Feichter (1997) Impact of sulfate aerosols on albedo and lifetime of clouds: a sensitivity study with the ECHAM4 GCM. J. Geophys. Res., 102, 13,685-13,700.

Ledyard, K.M. and J.W.H. Dacey (1994) Dimethylsulfide production from dimethyl-sulphoniopropionate by a marine bacterium. Mar. Ecol. Pro. Ser., 110, 95-103.

Malin, G., W.H. Wilson, G. Bratbak, P.S. Liss, and N.H. Mann (1998) Elevated production of dimethylsulfide resulting from viral infection of cultures of Phaeocystis pouchetii. Limnol. Oceanogr., 43, 1389-1393.

Malin, G., S. Turner, P. Liss, P. Holligan, and D. Harbour (1993) Dimethylsulfide and dimethylsulphoniopropionate in the Northease Atlantic during a summer coccolithophore bloom (1993). Deep Sea Res., 40, 1487-1508.

Martin, J.H., R.M. Gordon, S. Fitzwater, and W.W. Broenkow (1989) VERTEX: phytoplankton/iron studies in the Gulf of Alasksa. Deep-Sea Res., 36, 649-680.

Matrai, P.A. and M.D. Keller (1993) Dimethylsulfide in a large-scale coccolithophore bloom in the Gulf of Maine. Cont. Shelf Res., 13, 831-843.

Nevitt, G.A., R.R. Veit, and P. Kareiva (1995). Dimethylsulphide as a foraging cue for Antarctic Procellariiform seabirds. Nature, 376, 680-682.

Nguyen, B.C., S. Belviso, N. Mihalopoulos, J. Gostan and P. Nival (1988) Dimethylsulfide production during natural phytoplanktonic blooms, Mar. Chem., 24, 133-141.

Petty, G. (1990) On the response of the Special Sensor Microwave/Imager to the marine environment- Implications for atmospheric parameter retrievals, Ph.D. thesis, University of Washington, Seattle.

Radke, L., J. Coakley, M. King (1989) Direct and remote sensing observations of the effects of ships on clouds, Science, 246, 1146-1149.

Schulz, J., P. Schluessel, and H. Grassl (1993) Water vapor in the atmospheric boundary layer over the oceans from SSM/I measurements, Int J. Rem. Sensing, 14, 2773-2789.

Schluessel, P., and W. Emery (1990) Atmospheric water vapour over the oceans from SSM/I measurements, Int. J. Rem. Sensing, 11, 753-76

Schluessel, P. and H. Luthardt (1991) Surface wind speeds over the North Sea from Special Sensor Microwave Imager observations, J. Geophys. Res., 96, 4845-4853.

Shaw, G.E. (1983) Bio-controlled thermostasis involving the sulfur cycle. Climate Change 5, 297-303.

Shaw, G.E. (1987) Aerosols as climate regulators: a climate-biosphere linkage? Atmos. Environ., 21, 985-986.

Stogryn, A., C. Butler, and T. Bartolac (1995) Ocean surface wind retrievals from Special Sensor Microwave Imager data with neural networks, J. Geophys. Res., 99, 981-984.

Turner, S.M., G. Malin, P.S. Liss, D.S. Harbour, and P.M. Holligan (1988) The seasonal variation of dimethyl sulfide and dimethylsulfoniopropionate concentrations in nearshore waters. Limnol. Oceanogr., 33:364-375.

Turner, S.M., P.D. Nightingale, L.J. Spokes, M.I. Liddicoat, and P.S. Liss (1996). Increased dimethyl sulphide concentrations in sea water from in situ iron enrichment. Nature, 383, 513-517.

Walter, B., 2000: Estimating heat fluxes over the wintertime Labrador Sea using SSM/I data, submitted to J. Geophys. Res.

Weng, F., and N. Grody (1994) Retrieval of cloud liquid water using the special senor microwave imager (SSM/I), J. Geophys. Res., 99, 25535-25551.

Wentz, F. (1990) SBIR Phase II Report: West coast storm forecasting with SSM/I, RSS Tech. Report 120191, Remote Sensing Systems, Santa Rosa, CA, 69 pp.

Wentz, F. (1992) Measurement of oceanic wind vector using satellite microwave radiometers, IEEE Trans. Geosci. and Rem. Sensing, 30, 960-972

Wentz, F. (1997) A well calibrated ocean algorithm for Special Sensor Microwave Imager, J. Geophys. Res., 102, 8703-8718.

Wolfe, G.V. and M. Steinke (1996). Grazing-activated production of dimethyl sulfide (DMS) by two clones of Emiliania huxleyi. Limnol Oceanogr. 41, 1151-1160.