Abstract. 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.

Abstract. During three measurement campaigns on the Baltic and North Seas, atmospheric and dissolved methane was determined with an automated gas chromatographic system. Areaweighted mean saturation values in the sea surface waters were 113 + 5% and 395 + 82% (Baltic Sea, February and July 1992) and 126 + 8% (south central North Sea, September 1992). On the bases of our data and a compilation of literature data the global oceanic emissions of methane were reassessed by introducing a concept of regional gas transfer coefficients. Our estimates computed with two different air-sea exchange models lie in the range of 11-18 Tg CH 4 yr -•.Despite the fact that shelf areas and estuaries only represent a small part of the world's ocean they contribute about 75% to the global oceanic emissions. We applied a simple, coupled, threelayer model to evaluate the time dependent variation of the oceanic flux to the atmosphere. The model calculations indicate that even with increasing tropospheric methane concentration, the ocean will remain a source of atmospheric methane.

We determined atmospheric and dissolved nitrous oxide (N2O) in the surface waters of the central North Sea, the German Bight, and the Gironde estuary. The mean saturations were 104 ± 1% (central North Sea, September 1991), 101 ± 2% (German Bight, September 1991), 99 ± 1% (German Bight September 1992), and 132% (Gironde estuary, November 1991). To evaluate the contribution of coastal areas and estuaries to the oceanic emissions we assembled a compilation of literature data. We conclude that the mean saturations in coastal regions (with the exception of estuaries and regions with upwelling phenomena) are only slightly higher than in the open ocean. However, when estuarine and coastal upwelling regions are included, a computation of the global oceanic N2O flux indicates that a considerable portion (approximately 60%) of this flux is from coastal regions, mainly due to high emissions from estuaries. We estimate, using two different parameterizations of the air‐sea exchange process, an annual global sea‐to‐air flux of 11–17 Tg N2O. Our results suggest a serious underestimation of the flux from coastal regions in widely used previous estimates.

Abstract. Spectral measurements of the aerosol optical depth (AOD) and the Angstrom coefficient were conducted at Thessaloniki, Greece (40.5° N, 22.9° E) between January 1997 and December 2005 with a Brewer MKIII double-monochromator spectroradiometer. The dataset was compared with collocated measurements of a second spectroradiometer (Brewer MKII) and a CIMEL sun-photometer, showing correlations of 0.93 and 0.98 respectively. A seasonal variation of the AOD was observed at Thessaloniki, with AOD values at 340 nm of 0.52 and 0.28 for August and December respectively. Back trajectories of air masses for up to 4 days were used to assess the influence of long-range transport from various regions to the aerosol load over Thessaloniki. It is shown that part of the observed seasonality can be attributed to air masses with high AOD originating from North-Eastern and Eastern directions during summertime. The analysis of the long-term record (9 years) of AOD showed a downward tendency. A similar decreasing tendency was found in the record of the PM-10 aerosol measurements, which are conducted near the surface at 4 air-quality monitoring stations in the area of the city of Thessaloniki.

A simple technique is described for the rapid determination of methylmercury in fish tissue. Following simple dissolution in methanolic KOH solution, aqueous phase ethylation by derivatization with NaB(C2H5)4, cryogenic trapping on a packed chromatographic column, and GC separation, volatile mercury species are detected by atomic absorption spectrometry. Absolute detection limits are 4 pg of Hg for CH3Hg+ and 75 pg of Hg for labile Hg2+. Concentration detection limits for this optimized procedure are 4 ng of Hg for CH3Hg+ and 75 ng of Hg for labile Hg2+ per gram of pulverized dried fish tissue. Analysis of standard reference materials demonstrates the accuracy, precision, and reproducibility of the analytical method.