Sea-to-air emissions of bromocarbon gases are known to play an important role in atmospheric ozon... more Sea-to-air emissions of bromocarbon gases are known to play an important role in atmospheric ozone depletion. In this study, seawater concentrations of bromoform (CHBr3) and dibromomethane (CH2Br2) were measured regularly between February 2005 and March 2007 at the Rothera Oceanographic and Biological Time Series (RaTS) site located in Marguerite Bay on the Antarctic Peninsula. Strong seasonality in CHBr3 and CH2Br2 concentrations was observed. The highest bromocarbon concentrations (up to 276.4 ± 13.0 pmol CHBr3 L-1 and 30.0 ± 0.4 pmol CH2Br2 L-1) were found to coincide with the annual microalgal bloom during the austral summer, with lower concentrations (up to 39.5 pmol CHBr3 L-1 and 9.6 ± 0.6 pmol CH2Br2 L-1) measured under the winter fast ice. The timing of the initial increase in bromocarbon concentrations was related to the sea-ice retreat and onset of the microalgal bloom. Observed seasonal variability in CH2Br2/CHBr3 suggests that this relationship may be of use in resolving bromocarbon source regions. Mainly positive saturation anomalies calculated for both the 2005/2006 and 2006/2007 summers suggest that the bay was a source of CHBr3 and CH2Br2 to the atmosphere. Estimates of bromocarbon sea-to-air flux rates from Marguerite Bay during ice-free periods are 84 (-13 to 275) CHBr3 nmol m-2 d-1 and 21 (2 to 70) nmol CH2Br2 m-2 d-1. If these flux rates are representative of the seasonal ice edge zone bloom which occurs each year over large areas of the Southern Ocean during the austral summer, sea-to-air bromocarbon emissions could have an important impact on the chemistry of the Antarctic atmosphere.
During June and early July of 1996, we measured concentrations of dimethylsulfide, DMS, and dimet... more During June and early July of 1996, we measured concentrations of dimethylsulfide, DMS, and dimethylsulfoniopropionate, DMSP, in surface waters on the continental shelf and slope off the western coast of Ireland. We examined the distribution of DMS, DMSP, and the calculated flux of DMS to the atmosphere during four time series. A band of water with high DMS concentrations (>5nM)
A B S T R A C T It is well known that iron fertilization can increase primary production and henc... more A B S T R A C T It is well known that iron fertilization can increase primary production and hence CO 2 drawdown over a significant fraction of the oceans. What is less well established is the extent to which this leads to long-term sequestration of carbon to the deep oceans, and to feedbacks to the atmosphere arising from increased biological activity. In this note results for changes in trace gas concentrations during an iron addition experiment in the Southern Ocean are presented. They demonstrate that a complex situation exists; some gases (DMS, CH 3 I, CHBr 2 Cl) show increases in concentration following fertilization with iron while others show no change (CH 3 ONO 2 , CH 2 ClI) or even a decrease (CHBr 3 ). The concomitant effects on air-sea fluxes of these gases are potentially important for climate and atmospheric composition.
Proceedings of the National Academy of Sciences, 2010
The oceanic uptake of man-made CO 2 emissions is resulting in a measureable decrease in the pH of... more The oceanic uptake of man-made CO 2 emissions is resulting in a measureable decrease in the pH of the surface oceans, a process which is predicted to have severe consequences for marine biological and biogeochemical processes [Caldeira K, Wickett ME (2003) Nature 425:365; The Royal Society (2005) Policy Document 12 /05 (Royal Society, London)]. Here, we describe results showing how a doubling of current atmospheric CO 2 affects the production of a suite of atmospherically important marine trace gases. Two CO 2 treatments were used during a mesocosm CO 2 perturbation experiment in a Norwegian fjord (present day: ∼380 ppmv and year 2100: ∼750 ppmv), and phytoplankton blooms were stimulated by the addition of nutrients. Seawater trace gas concentrations were monitored over the growth and decline of the blooms, revealing that concentrations of methyl iodide and dimethylsulfide were significantly reduced under high CO 2. Additionally, large reductions in concentrations of other iodocarbons were observed. The response of bromocarbons to high CO 2 was less clear cut. Further research is now required to understand how ocean acidification might impact on global marine trace gas fluxes and how these impacts might feed through to changes in the earth's future climate and atmospheric chemistry. dimethylsulfide | halocarbons | atmospheric chemistry | climate
Philosophical Transactions of the Royal Society B: Biological Sciences, 1997
The principal volatile sulphur species found in seawater are dimethyl sulphide (DMS), carbonyl su... more The principal volatile sulphur species found in seawater are dimethyl sulphide (DMS), carbonyl sulphide (COS) and carbon disulphide (CS # ). Of these, DMS is the most abundant and widespread in its distribution. The predominant oceanic source of DMS is dimethylsulphoniopropionate (DMSP), a compatible solute synthesized by phytoplankton for osmoregulation and\or cryoprotection. Not all species have the same ability to form DMSP ; for example, diatoms generally produce little, whereas prymnesiophytes and some dinoflagellates make significantly larger amounts. Much of the release of DMSP and DMS to the water occurs on death or through predation of the plankton. Our recent field data strongly suggest that oxidation of DMS to dimethyl sulphoxide (DMSO) is an important process in the water column, and it is clear that considerable internal cycling in the DMSP\DMS\DMSO system occurs in the euphotic zone. A fraction of the DMS crosses the sea surface and enters the atmosphere where it is oxidized by radicals such as OH and NO $ to form products such as methanesulphonate (MSA), DMSO and non-sea salt sulphate (NSSS) particles. These particles are the main source of cloud condensation nuclei (CCN) over oceanic areas remote from land.
The first generation of open-ocean iron enrichments (1993 to 2005) have all had broadly the same ... more The first generation of open-ocean iron enrichments (1993 to 2005) have all had broadly the same design. Enrichment of patches of ocean was typically on a 10 km length-scale, and experiments were of a duration of weeks. These scales were dictated by what could conveniently be achieved from research vessels, using tracers to track Lagrangian patches. The extrapolation of experimental findings to the larger scales required for carbon sequestration by ocean iron fertilization (OIF) leaves many uncertainties, to answer which, longer duration (i.e. months) and larger scale observations (100 to 200 km length-scale) are required. However, to extrapolate to a timescale of decades and to the scale of ocean basins, such observations must be conducted in parallel (and where possible assimilated into) detailed models of the physics and biogeochemistry of the fertilized waters. Our present understanding suggests that any carbon sequestration will occur as the net result of changes in the air-sea flux integrated over millions km 2 and many years, and can only realistically be assessed by modelling. A central role of the observational studies will be to make such models as accurate as possible in their simulations and predictions. We present a scheme for the design of a second generation of ocean iron-enrichments and discuss the challenges that are evident in linking the modelling and observational components of such studies.
A model for dimethylsulphlde (DMS) production in the southern North Sea is presented. This model ... more A model for dimethylsulphlde (DMS) production in the southern North Sea is presented. This model is coupled to the phytoplankton model FYFY, which calculates the biomass of different phytoplankton groups with their specific contents of dimethylsulphoniopropionate (DMSP), the precursor of DMS. The combined models provide a synoptic view of the seasonal distribution of DMS and its sea-to-air exchange rates. Results are in close agreement with field data, showing a spring peak and high concentrations in the coastal area off continental Europe. Model analysis shows high sensitivity to phytoplankton DMSP-lyase, particularly in the description of the spring peak of DMS. Omission of this pathway for DMS production leads to an underestimation of the annual sea-to-air flux of up to 25%. Model output also suggests that anthropogenic eutrophication of the southern North Sea may have caused a 2.5-fold increase between the beginning of this century and the 1980s in the mean annual emission of DMS to the atmosphere. KEY WORDS: Dimethylsulphide (DMS) . Dimethylsulphoniopropionate (DMSP) . Phytoplankton DMSP-lyase . DMSP content. DMS model 0 Inter-Research 1996 Resale of full article not permitted
Turner, S.M., Malin, G., B~gander, L.E. and Leck, C., 1990. Interlaboratory calibration and sampl... more Turner, S.M., Malin, G., B~gander, L.E. and Leck, C., 1990. Interlaboratory calibration and sample analysis of dimethyl sulphide in water. Mar. Chem., 29: 47-62.
The distribution of DMS concentrations in surface waters of the southern North Sea is described f... more The distribution of DMS concentrations in surface waters of the southern North Sea is described for nine months (February–October) in 1989. Minimum concentrations in winter were 0.13 nM and the maximum, monthly mean concentration was 25 nM, in May, coincident with large blooms of Phaeocystis pouchetii, off the continental coast. Comparison with other North Sea data suggests that the interannual
of biogenic dimethyl sulfide (DMS) in seawater around mainland Britain in winter and summer (1985... more of biogenic dimethyl sulfide (DMS) in seawater around mainland Britain in winter and summer (1985) ranged from 1 to 1,100 ng S (DMS) liter-'. The mean winter DMS concentration was 4 ng S (DMS) liter-' compared with the mean summer concentration of 220. Analyses of phytoplankton species composition in summer indicate that the main sources of DMS were coccolithophores, various dinoflagellates including the bloom species Gyrodinium aureolum, and certain unidentified taxa of small flagellates. Concentrations of dimethylsulfoniopropionate (DMSP), the precursor of DMS, were measured in 53 of the summer samples, and its mean concentration was about an order of magnitude greater than that of DMS. Particulate (>0.2 pm) and dissolved fractions of DMSP were operationally resolved, with the latter showing the stronger correlation with DMS.
The osmolyte dimethylsulphoniopropionate (DMSP) can be enzymatically cleaved to dimethylsulphide ... more The osmolyte dimethylsulphoniopropionate (DMSP) can be enzymatically cleaved to dimethylsulphide (DMS), acrylate and a proton. The enzyme involved in this reaction is dimethylpropiothetin dethiomethylase (DMSP lyase; enzyme classification number 4.4. 1.3.). Although the importance of this reaction for the global sulphur cycle, the influence of DMS on atmospheric acidity and the possible effect on climate regulation have been widely recognised, our knowledge of DMSP lyases is limited to just a few studies. Activity ...
... Over the past decade orso thousands of anal-yses have been made covering coastal, shelf, and ... more ... Over the past decade orso thousands of anal-yses have been made covering coastal, shelf, and open ocean environments, which show that DMS is ubiquitous in seawater but that considerable spatial and temporal variability occurs (see Cooper and Ma-lfai 1989). ...
1] Climate change and human activities are expected to have a major impact on the structure and f... more 1] Climate change and human activities are expected to have a major impact on the structure and functioning of marine ecosystems and the biogeochemical cycles they mediate in the coming years. Here we describe time series measurements of biogenic bromocarbons (CHBr 3 and CH 2 Br 2 ) collected in coastal waters of the western Antarctic Peninsula which is one of the world's most rapidly changing marine environments. Our measurements spanned a period of changing sea-ice dynamics and phytoplankton community structure driven by climatic forcing. Specifically, the occurrence of high chlorophyll a concentrations (≥5 mg L À1 ) and dominance of the largest phytoplankton size fraction (≥20 mm) indicating diatom bloom conditions was reduced following winter periods with a relatively short winter sea-ice duration (<50 days). While large inter-annual variability in seawater CHBr 3 concentrations was observed alongside these changes the same was not found for CH 2 Br 2 which is surprising given their proposed common source. Seawater CHBr 3 concentrations were found to be significantly higher (122 [14.7-580] pmol L À1 , P < 0.0001, Mann-Whitney) in samples collected in diatom bloom compared to non-bloom waters (42.9 [12.0-126] pmol L À1 ). A comparison of sea-to-air flux rates suggests that a switch from diatom bloom to non-bloom conditions results in a factor of 3-4 decrease in average CHBr 3 sea-to-air emission rates which will reduce the supply of biogenic bromine to the atmosphere. Our calculations suggest that this will drive a decrease in inorganic bromine levels in the troposphere by a factor of 2-3 outside of ozone depletion events with potentially important implications for ozone cycling and dimethyl sulphide oxidation. This work has captured and crucially quantified the impact of a climate-induced change in a marine ecosystem on ocean-atmosphere biogeochemistry. Citation: Hughes, C., et al. (2012), Climate-induced change in biogenic bromine emissions from the Antarctic marine biosphere, Global Biogeochem. Cycles, 26, GB3019,
A database of 15,617 point measurements of dimethylsulfide (DMS) in surface waters along with les... more A database of 15,617 point measurements of dimethylsulfide (DMS) in surface waters along with lesser amounts of data for aqueous and particulate dirhethylsulfoniopropionate concentration, chlorophyll concentration, sea surface salinity and temperature, and wind speed has been assembled. The database was processed to create a series of climatological annual and monthly 1øxl ø latitude-longitude squares of data. The results were compared to published fields of geophysical and biological parameters. No significant correlation was found between DMS and these parameters, and no simple algorithm could be found to create monthly fields of sea surface DMS concentration based on these parameters. Instead, an annual map of sea surface DMS was produced using an algorithm similar to that employed by Conkright et al. [1994]. In this approach, a first-guess field of DMS sea surface concentration measurements is created and then a correction to this field is generated based on actual measurements. Monthly sea surface grids of DMS were obtained using a similar scheme, but the sparsity of DMS measurements made the method difficult to implement. A scheme was used which projected actual data into months of the year where no data were otherwise present.
Sea-to-air emissions of bromocarbon gases are known to play an important role in atmospheric ozon... more Sea-to-air emissions of bromocarbon gases are known to play an important role in atmospheric ozone depletion. In this study, seawater concentrations of bromoform (CHBr3) and dibromomethane (CH2Br2) were measured regularly between February 2005 and March 2007 at the Rothera Oceanographic and Biological Time Series (RaTS) site located in Marguerite Bay on the Antarctic Peninsula. Strong seasonality in CHBr3 and CH2Br2 concentrations was observed. The highest bromocarbon concentrations (up to 276.4 ± 13.0 pmol CHBr3 L-1 and 30.0 ± 0.4 pmol CH2Br2 L-1) were found to coincide with the annual microalgal bloom during the austral summer, with lower concentrations (up to 39.5 pmol CHBr3 L-1 and 9.6 ± 0.6 pmol CH2Br2 L-1) measured under the winter fast ice. The timing of the initial increase in bromocarbon concentrations was related to the sea-ice retreat and onset of the microalgal bloom. Observed seasonal variability in CH2Br2/CHBr3 suggests that this relationship may be of use in resolving bromocarbon source regions. Mainly positive saturation anomalies calculated for both the 2005/2006 and 2006/2007 summers suggest that the bay was a source of CHBr3 and CH2Br2 to the atmosphere. Estimates of bromocarbon sea-to-air flux rates from Marguerite Bay during ice-free periods are 84 (-13 to 275) CHBr3 nmol m-2 d-1 and 21 (2 to 70) nmol CH2Br2 m-2 d-1. If these flux rates are representative of the seasonal ice edge zone bloom which occurs each year over large areas of the Southern Ocean during the austral summer, sea-to-air bromocarbon emissions could have an important impact on the chemistry of the Antarctic atmosphere.
During June and early July of 1996, we measured concentrations of dimethylsulfide, DMS, and dimet... more During June and early July of 1996, we measured concentrations of dimethylsulfide, DMS, and dimethylsulfoniopropionate, DMSP, in surface waters on the continental shelf and slope off the western coast of Ireland. We examined the distribution of DMS, DMSP, and the calculated flux of DMS to the atmosphere during four time series. A band of water with high DMS concentrations (>5nM)
A B S T R A C T It is well known that iron fertilization can increase primary production and henc... more A B S T R A C T It is well known that iron fertilization can increase primary production and hence CO 2 drawdown over a significant fraction of the oceans. What is less well established is the extent to which this leads to long-term sequestration of carbon to the deep oceans, and to feedbacks to the atmosphere arising from increased biological activity. In this note results for changes in trace gas concentrations during an iron addition experiment in the Southern Ocean are presented. They demonstrate that a complex situation exists; some gases (DMS, CH 3 I, CHBr 2 Cl) show increases in concentration following fertilization with iron while others show no change (CH 3 ONO 2 , CH 2 ClI) or even a decrease (CHBr 3 ). The concomitant effects on air-sea fluxes of these gases are potentially important for climate and atmospheric composition.
Proceedings of the National Academy of Sciences, 2010
The oceanic uptake of man-made CO 2 emissions is resulting in a measureable decrease in the pH of... more The oceanic uptake of man-made CO 2 emissions is resulting in a measureable decrease in the pH of the surface oceans, a process which is predicted to have severe consequences for marine biological and biogeochemical processes [Caldeira K, Wickett ME (2003) Nature 425:365; The Royal Society (2005) Policy Document 12 /05 (Royal Society, London)]. Here, we describe results showing how a doubling of current atmospheric CO 2 affects the production of a suite of atmospherically important marine trace gases. Two CO 2 treatments were used during a mesocosm CO 2 perturbation experiment in a Norwegian fjord (present day: ∼380 ppmv and year 2100: ∼750 ppmv), and phytoplankton blooms were stimulated by the addition of nutrients. Seawater trace gas concentrations were monitored over the growth and decline of the blooms, revealing that concentrations of methyl iodide and dimethylsulfide were significantly reduced under high CO 2. Additionally, large reductions in concentrations of other iodocarbons were observed. The response of bromocarbons to high CO 2 was less clear cut. Further research is now required to understand how ocean acidification might impact on global marine trace gas fluxes and how these impacts might feed through to changes in the earth's future climate and atmospheric chemistry. dimethylsulfide | halocarbons | atmospheric chemistry | climate
Philosophical Transactions of the Royal Society B: Biological Sciences, 1997
The principal volatile sulphur species found in seawater are dimethyl sulphide (DMS), carbonyl su... more The principal volatile sulphur species found in seawater are dimethyl sulphide (DMS), carbonyl sulphide (COS) and carbon disulphide (CS # ). Of these, DMS is the most abundant and widespread in its distribution. The predominant oceanic source of DMS is dimethylsulphoniopropionate (DMSP), a compatible solute synthesized by phytoplankton for osmoregulation and\or cryoprotection. Not all species have the same ability to form DMSP ; for example, diatoms generally produce little, whereas prymnesiophytes and some dinoflagellates make significantly larger amounts. Much of the release of DMSP and DMS to the water occurs on death or through predation of the plankton. Our recent field data strongly suggest that oxidation of DMS to dimethyl sulphoxide (DMSO) is an important process in the water column, and it is clear that considerable internal cycling in the DMSP\DMS\DMSO system occurs in the euphotic zone. A fraction of the DMS crosses the sea surface and enters the atmosphere where it is oxidized by radicals such as OH and NO $ to form products such as methanesulphonate (MSA), DMSO and non-sea salt sulphate (NSSS) particles. These particles are the main source of cloud condensation nuclei (CCN) over oceanic areas remote from land.
The first generation of open-ocean iron enrichments (1993 to 2005) have all had broadly the same ... more The first generation of open-ocean iron enrichments (1993 to 2005) have all had broadly the same design. Enrichment of patches of ocean was typically on a 10 km length-scale, and experiments were of a duration of weeks. These scales were dictated by what could conveniently be achieved from research vessels, using tracers to track Lagrangian patches. The extrapolation of experimental findings to the larger scales required for carbon sequestration by ocean iron fertilization (OIF) leaves many uncertainties, to answer which, longer duration (i.e. months) and larger scale observations (100 to 200 km length-scale) are required. However, to extrapolate to a timescale of decades and to the scale of ocean basins, such observations must be conducted in parallel (and where possible assimilated into) detailed models of the physics and biogeochemistry of the fertilized waters. Our present understanding suggests that any carbon sequestration will occur as the net result of changes in the air-sea flux integrated over millions km 2 and many years, and can only realistically be assessed by modelling. A central role of the observational studies will be to make such models as accurate as possible in their simulations and predictions. We present a scheme for the design of a second generation of ocean iron-enrichments and discuss the challenges that are evident in linking the modelling and observational components of such studies.
A model for dimethylsulphlde (DMS) production in the southern North Sea is presented. This model ... more A model for dimethylsulphlde (DMS) production in the southern North Sea is presented. This model is coupled to the phytoplankton model FYFY, which calculates the biomass of different phytoplankton groups with their specific contents of dimethylsulphoniopropionate (DMSP), the precursor of DMS. The combined models provide a synoptic view of the seasonal distribution of DMS and its sea-to-air exchange rates. Results are in close agreement with field data, showing a spring peak and high concentrations in the coastal area off continental Europe. Model analysis shows high sensitivity to phytoplankton DMSP-lyase, particularly in the description of the spring peak of DMS. Omission of this pathway for DMS production leads to an underestimation of the annual sea-to-air flux of up to 25%. Model output also suggests that anthropogenic eutrophication of the southern North Sea may have caused a 2.5-fold increase between the beginning of this century and the 1980s in the mean annual emission of DMS to the atmosphere. KEY WORDS: Dimethylsulphide (DMS) . Dimethylsulphoniopropionate (DMSP) . Phytoplankton DMSP-lyase . DMSP content. DMS model 0 Inter-Research 1996 Resale of full article not permitted
Turner, S.M., Malin, G., B~gander, L.E. and Leck, C., 1990. Interlaboratory calibration and sampl... more Turner, S.M., Malin, G., B~gander, L.E. and Leck, C., 1990. Interlaboratory calibration and sample analysis of dimethyl sulphide in water. Mar. Chem., 29: 47-62.
The distribution of DMS concentrations in surface waters of the southern North Sea is described f... more The distribution of DMS concentrations in surface waters of the southern North Sea is described for nine months (February–October) in 1989. Minimum concentrations in winter were 0.13 nM and the maximum, monthly mean concentration was 25 nM, in May, coincident with large blooms of Phaeocystis pouchetii, off the continental coast. Comparison with other North Sea data suggests that the interannual
of biogenic dimethyl sulfide (DMS) in seawater around mainland Britain in winter and summer (1985... more of biogenic dimethyl sulfide (DMS) in seawater around mainland Britain in winter and summer (1985) ranged from 1 to 1,100 ng S (DMS) liter-'. The mean winter DMS concentration was 4 ng S (DMS) liter-' compared with the mean summer concentration of 220. Analyses of phytoplankton species composition in summer indicate that the main sources of DMS were coccolithophores, various dinoflagellates including the bloom species Gyrodinium aureolum, and certain unidentified taxa of small flagellates. Concentrations of dimethylsulfoniopropionate (DMSP), the precursor of DMS, were measured in 53 of the summer samples, and its mean concentration was about an order of magnitude greater than that of DMS. Particulate (>0.2 pm) and dissolved fractions of DMSP were operationally resolved, with the latter showing the stronger correlation with DMS.
The osmolyte dimethylsulphoniopropionate (DMSP) can be enzymatically cleaved to dimethylsulphide ... more The osmolyte dimethylsulphoniopropionate (DMSP) can be enzymatically cleaved to dimethylsulphide (DMS), acrylate and a proton. The enzyme involved in this reaction is dimethylpropiothetin dethiomethylase (DMSP lyase; enzyme classification number 4.4. 1.3.). Although the importance of this reaction for the global sulphur cycle, the influence of DMS on atmospheric acidity and the possible effect on climate regulation have been widely recognised, our knowledge of DMSP lyases is limited to just a few studies. Activity ...
... Over the past decade orso thousands of anal-yses have been made covering coastal, shelf, and ... more ... Over the past decade orso thousands of anal-yses have been made covering coastal, shelf, and open ocean environments, which show that DMS is ubiquitous in seawater but that considerable spatial and temporal variability occurs (see Cooper and Ma-lfai 1989). ...
1] Climate change and human activities are expected to have a major impact on the structure and f... more 1] Climate change and human activities are expected to have a major impact on the structure and functioning of marine ecosystems and the biogeochemical cycles they mediate in the coming years. Here we describe time series measurements of biogenic bromocarbons (CHBr 3 and CH 2 Br 2 ) collected in coastal waters of the western Antarctic Peninsula which is one of the world's most rapidly changing marine environments. Our measurements spanned a period of changing sea-ice dynamics and phytoplankton community structure driven by climatic forcing. Specifically, the occurrence of high chlorophyll a concentrations (≥5 mg L À1 ) and dominance of the largest phytoplankton size fraction (≥20 mm) indicating diatom bloom conditions was reduced following winter periods with a relatively short winter sea-ice duration (<50 days). While large inter-annual variability in seawater CHBr 3 concentrations was observed alongside these changes the same was not found for CH 2 Br 2 which is surprising given their proposed common source. Seawater CHBr 3 concentrations were found to be significantly higher (122 [14.7-580] pmol L À1 , P < 0.0001, Mann-Whitney) in samples collected in diatom bloom compared to non-bloom waters (42.9 [12.0-126] pmol L À1 ). A comparison of sea-to-air flux rates suggests that a switch from diatom bloom to non-bloom conditions results in a factor of 3-4 decrease in average CHBr 3 sea-to-air emission rates which will reduce the supply of biogenic bromine to the atmosphere. Our calculations suggest that this will drive a decrease in inorganic bromine levels in the troposphere by a factor of 2-3 outside of ozone depletion events with potentially important implications for ozone cycling and dimethyl sulphide oxidation. This work has captured and crucially quantified the impact of a climate-induced change in a marine ecosystem on ocean-atmosphere biogeochemistry. Citation: Hughes, C., et al. (2012), Climate-induced change in biogenic bromine emissions from the Antarctic marine biosphere, Global Biogeochem. Cycles, 26, GB3019,
A database of 15,617 point measurements of dimethylsulfide (DMS) in surface waters along with les... more A database of 15,617 point measurements of dimethylsulfide (DMS) in surface waters along with lesser amounts of data for aqueous and particulate dirhethylsulfoniopropionate concentration, chlorophyll concentration, sea surface salinity and temperature, and wind speed has been assembled. The database was processed to create a series of climatological annual and monthly 1øxl ø latitude-longitude squares of data. The results were compared to published fields of geophysical and biological parameters. No significant correlation was found between DMS and these parameters, and no simple algorithm could be found to create monthly fields of sea surface DMS concentration based on these parameters. Instead, an annual map of sea surface DMS was produced using an algorithm similar to that employed by Conkright et al. [1994]. In this approach, a first-guess field of DMS sea surface concentration measurements is created and then a correction to this field is generated based on actual measurements. Monthly sea surface grids of DMS were obtained using a similar scheme, but the sparsity of DMS measurements made the method difficult to implement. A scheme was used which projected actual data into months of the year where no data were otherwise present.
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