Chlorinated biphenyls and p,p'-DDE in Mediterranean surface waters

Individual chlorobiphenyls (CBs) and p,p'-DDE were determined in solution and suspension in surface transects of the open Mediterranean Sea in 1987. Large volumes of sea water (1400—1700 dm3) were analyzed. Concentrations of CBs were low in solution (<5 pg/dm3) and in suspension (<60 pg/dm3). Values for their sum (XCB) were 1.7-43.9 and 190-615 pg/dm3, respectively. Compositions of the CB mixtures in solution as well as those in suspension were very similar in the various transects, but considerable differences were present between solution and suspension in each transect. It was attempted to interpret these differences in terms of molecular characteristics (octanol-water distribution coefficients, Kaw). The resulting plots of log Kovl vs. the apparent distribution coefficient (log K&) gave evidence for the uptake of CBs by suspended particles, followed by sedimentation out of the surface layer. Concentrations in solution were much lower (1-2 orders of magnitude) than those reported before. This may result from improvements in the sampling and analytical techniques. No clear evidence for significant local sources of these compounds was detected in the surface waters, as the levels in solution were very similar to the very low concentrations in the adjacent open Atlantic

Bilanzierung und Quantifizierung des Chlorbiphenyl-Eintrages in das Oderhaff

Under the EC sponsored research project ODER (Oder Discharge-Environmental Response) first investigations have been carried out to estimate the chlorinated biphenyls (CB) input into Oderhaff via the Oder river. For this purpose, vertical profiles of CB content and composition were analysed on samples of three sediment cores. In two water samples, the content of suspended particulate material as weil as the particulate CB content and congener-specific composition were measured. In the Oderhaff the CB concentrations of particulate material were between 700 to 800 pg/dm3. Significant differences in the composition of the components were not observed. In sediments, CB contents were as high as 17 to 24 ngig dry weight in near surface sediment layers. They decreased with increasing sediment depth and were below detection limits at 15 to 21 cm depth. Based on the size of the 49 accumulation area and related hydrographic conditions, we estimated an input of 95 kg into the Oderhaff for the last 65 years since the onset of CB production. Applying the present prevailing conditions, we calculated an average transport of about 825 kg CB by the Oder river during this period. Comparing these two estimates, we observed that at least 15 % of the CB transported by the Oder river was deposited in the Oderhaff. The remaining 85 % (-730 kg), have been further transported into the South Pomeranian Bight and Southern Baltic Sea

A time series of incubation experiments to examine the production and loss of CH3I in surface seawater

In order to investigate production pathways of methyl iodide and controls on emissions from the surface ocean, a set of repeated in vitro incubation experiments were performed over an annual cycle in the context of a time series of in situ measurements in Kiel Fjord (54.3°N, 10.1°E). The incubation experiments revealed a diurnal variation of methyl iodide in samples exposed to natural light, with maxima during day time and losses during night hours. The amplitude of the daily accumulation varied seasonally and was not affected by filtration (0.2 µm), consistent with a photochemical pathway for CH3I production. The methyl iodide loss rate at nighttime correlates with the concentration accumulated during daytime suggesting a first-order loss mechanism (R2 = 0.29, p << 0.01). Daily (24 h) net production (Pnet) was similar in magnitude between in vitro and in situ mass balances. However, the estimated gross production (Pgross) of methyl iodide ranged from −0.07 to 2.24 pmol L−1 d−1 and was up to 5 times higher in summer than Pnet calculated from the in situ study. The large excess of Pgross over Pnet in summer revealed by the incubation experiments is a consequence of large losses of CH3I by as-yet uncharacterized processes (e.g., biological degradation or chemical pathways other than Cl− substitution)

Chlorinated Biphenyls and p,p\u27-DDE in Mediterranean Surface Waters

Individual chlorobiphenyls (CBs) and p,p\u27-DDE were determined in solution and suspension in surface transects of the open Mediterranean Sea in 1987. Large volumes of sea water (1400—1700 dm3) were analyzed. Concentrations of CBs were low in solution (<5 pg/dm3) and in suspension (<60 pg/dm3). Values for their sum (XCB) were 1.7-43.9 and 190-615 pg/dm3, respectively. Compositions of the CB mixtures in solution as well as those in suspension were very similar in the various transects, but considerable differences were present between solution and suspension in each transect. It was attempted to interpret these differences in terms of molecular characteristics (octanol-water distribution coefficients, Kaw). The resulting plots of log Kovl vs. the apparent distribution coefficient (log K&) gave evidence for the uptake of CBs by suspended particles, followed by sedimentation out of the surface layer. Concentrations in solution were much lower (1-2 orders of magnitude) than those reported before. This may result from improvements in the sampling and analytical techniques. No clear evidence for significant local sources of these compounds was detected in the surface waters, as the levels in solution were very similar to the very low concentrations in the adjacent open Atlantic

Toxokinetik und -dynamik ausgewahlter individueller chlorierter Biphenyle

SchluBbericht zum Forschungsvorhaben 03F0551

Evidence for dissolution of fatty acids in sediment traps: impact on flux estimates

The effect of dissolution from particulates into the supernatant solution in sediment trap sample cups has been measured for fatty acids. A mooring array with time series sediment traps was deployed in the northeast Atlantic Ocean (59°N, 21°W) for 14 months. Selected representative samples from the trap at 2200 m (poisoned with NaN3) were analyzed for total and free fatty acids in both the solution and particulate phase by means of gas chromatography‐mass spectrometry with an ion trap detector. The flux contribution of the dissolved total fatty acids (∑ DTFA) was found to be between 15 and 75% of the total flux (∑ TTFA, sum of the fluxes of total fatty acids in both particles and supernatants). Dissolved free fatty acids (∑ DFFA) represented 25–88% of the total flux of free fatty acids (∑ TFFA). Absolute concentrations of total and free fatty acids in both compartments are discussed in terms of the processes controlling the distribution between the two phases, for example, readsorption. Sample handling, poisoning, bacterial activity, and swimmers may also affect fatty acid distribution. Flux data (sum of particulate and dissolved fluxes) are presented for individual fatty acids. Also, the degree of dissolution of individual fatty acids is shown for one sample (dissolved fraction ranging between 16 and 98% of total flux)

Seasonal variability of methyl iodide in the Kiel Fjord

From October 2008 to November 2010, CH3I concentrations were measured in the Kiel Fjord together with potentially related biogeochemical and physical parameters. A repeating seasonal cycle of CH3I was observed with highest concentrations in summer (ca. 8.3 pmol L−1; June and July) and lowest concentrations in winter (ca. 1.5 pmol L−1; December to February). A strong positive correlation at zero lag between [CH3I] and solar radiation (R2 = 0.93) was observed, whereas correlations with other variables (SST, Chlorophyll a) were weaker, and they lagged CH3I by ca. 1 month. These results appear consistent with the hypothesis that SSR is the primary forcing of CH3I production in surface seawater, possibly through a photochemical pathway. A mass balance of the monthly averaged data was used to infer mean rates of daily net production (Pnet) and losses for CH3I over the year. The sea-to-air flux of CH3I in the Kiel Fjord averaged 3.1 nmol m−2 d−1, the mean chemical loss rate was 0.047 pmol L−1 d−1, and Pnet varied systematically from winter to summer (from 0 to 0.6 pmol L−1 d−1). Pnet was correlated at zero lag with SST, SSR, and Chla (R2 = 0.55, 0.67, and 0.73, respectively, p << 0.01). The lagged cross-correlation analysis indicated that SSR led Pnet by 1 month, whereas the strongest cross correlations with Chla were at lags of 0 to +1 month, and SST lagged Pnet by 1 month. The broad seasonal peak of Pnet makes it difficult to determine the key factor controlling CH3I net production using in situ concentration data alone