Leibniz-Institut für Ostseeforschung, Warnemünde (IOW)
Bundesamt für Seeschifffahrt und Hydrographie (BSH), Hamburg, Rostock
(Summary of the Baltic Sea Monitoring 2008, Organic contaminants)
Since 1992 the Leibniz Institute for Baltic Sea Research (IOW) is performing the Baltic monitoring programme on behalf of the Federal Maritime and Hydrographic Agency (BSH) Hamburg und Rostock. In 2008 the monitoring area was redefined: Starting from the Kiel Bight up to the Bornholmsgatt samples were collected in the German exclusive economic zone (EEZ). To evaluate long term trends of organic compounds water samples were collected for PCBs (polychlorinated biphenyls), PAHs (polycyclic aromatic hydrocarbons) and DDTs (dichlorodiphenyltrichloroethane) using a pump/filtration system drawing water from the clean water line of the FS "Alkor”
(For sampled transects see Figure 1). Hereby an in-situ pump system (IPS) separated dissolved and SPM-associated contaminants. For HCHs (hexachlorocyclohexane) samples were collected at selected stations (Figure 1) with a 10 l. glass bowl sampler in 5 meter depth. In June 2008 14 sediment samples were taken in the area
of the German EEZ (Figure 2) and analysed for PCBs DDTs and PAHs.
The spatial distribution of HCH concentrations in the research area was affected by the water exchange between North- and Baltic Sea. Low concentrations of alpha-HCH (127 - 138 pg/L) and gamma-HCH (137 - 142 pg/L) with higher salinities (15.6 - 18.6)
in the Kiel Bight/Fehmarnbelt region compared with higher concentrations of alpha-HCH (231 - 261 pg/L) and gamma-HCH (219 - 364 pg/L) with lower salinities (7.7 - 8.2) in the Arkona Sea suggest a dilution with higher salinity water from the North Sea (Figure 3). After a strong decrease of the HCH
concentrations between 1975 and 1990 from a maximum of 10 ng/L to a level of 1 ng/L in the Nineties the declining trend continues. The results of 2008 at station 109 confirm this trend; HCH concentrations below 0.5 ng/L were observed (Figure 4).
The contamination of seawater with DDT and metabolites (5.2 - 8.1 pg/L) from the Kiel Bight up to the Arkona Sea ranged on levels of previous years, whereas higher values (14.8 - 29.0 pg/L) in the Oder Bight suggest an input of these compounds from the river Oder. A data set of seven years with dissolved concentrations
of p,p'-DDE and p,p'-DDT is used to estimate long term trends in the study area (Figure 5). Since 2003 the exposure of p,p'-DDE in the Mecklenburg Bight and Arkona Sea has ranged on a level of 4 - 5 pg/L. The indicated decreasing trend from 2004 to 2006 didn't continue in 2008, stagnation on a concentration
level of 3 - 4 pg/L was observed. High concentrations of p,p'-DDE (13.5 pg/L) and p,p'-DDT (8 pg/L) in the Oder Bight in 2008 can be a sign for a riverine input.
In 2008 the exposure of the surface water of the Baltic Sea with dissolved PCBs was indicated by no significant trend (Figure 6). The dissolved concentrations are better suited for judging the spatial distribution of contamination and for the determination of temporal trends. Since 2007 the indicated decreasing trend in the Mecklenburg Bight has not continued, stagnation on a concentration level between 0.5 pg/L (PCB 180) and up to 2 pg/L (PCB 52) was observed, whereas concentrations of PCB 28/31 ranged on a level of 3 pg/L. In the research area of the Arkona Sea similar concentrations were found. For PCB 28/31 a decreasing
trend was observed up to the year 2008. The comparison with data from 1988 (Schulz-Bull, 1995) indicated a reduction of 50 percent for all PCB congeners.
The pollution of the surface water with dissolved PAHs in the Mecklenburg Bight and the Arkona Sea was observed between 2002 and 2008, but no significant trend could be identified for PAHs with high and medium vapour pressure. The concentrations ranged on a level of 1 ng/L. The content of PAH's
with high vapour pressure is on a level of 0.5 ng/L. The pollution of the Oder Bight with PAH's with high and medium vapour pressure was more than tree times higher as for the rest of the research area.
In June 2008 14 surface sediment samples were collected for PCB and PAH analysis from the area Kiel Bight up to Oder Bight. The concentrations of PCB, p,p-DDE and p,p-DDD ranged between 7 and 2397 pg/g.
Highest concentrations were observed in the Mecklenburg Bight (IOW2, M2) and in the Arkona Basin (IOW5, K7, IOW6 and K4), whereas the lowest concentrations were found at the Kiel Bight (N3), Fehmarnbelt (N1), Darss Sill and northwest of Hiddensee (K8). Lowest concentrations were also found from the Oder Bight up to the South of the Arkona Basin (Figure 7). The pollution of the surface sediments samples with PAHs ranged between 0.1 - 411 ng/g. The spatial distribution of PAHs was similar to that of PCB's. There was a strong correlation between the PCB/PAH concentrations and the Corg content. For the Corg content no significant regional variations
were observed (Figure 8).
Figure 1: Map of the sampling stations (IOW-Code) in February 2008:
Sampled stations and pump-sampling transects I - IV.
Figure 2: Map of sediment sampling stations in June 2008
Figure 3: alpha-HCH und gamma-HCH concentrations (pg/L) in February 2008
in the surface water of the Baltic Sea.
Figure 4: HCH concentrations at Station 109 (Arkona Sea) between 1975 and 2008
Figure 5: DDE and DDT concentrations (dissolved, pg/L), 2002 - 2008
Mecklenburg Bight (MB), Arkona Sea (AS) and Oder Bight (OB)
Figure 6: PCB concentrations (dissolved), 2001 - 2008
Mecklenburg Bight and Arkona Sea
Figure 7: PCB, p,p'-DDE and p,p'-DDD concentrations in surface sediment
at 14 BLMP-stations in June 2008
Figure 8: PCB concentrations related to the Corg content (TOC - total organic carbon)
The complete monitoring report
Schulz-Bull, D., Hand, I., Lerz, A., Trost, E., Wodarg, D. (2009): Regionale Verteilung chlorierter Kohlenwasserstoffe (CKW) und polycyclischer aromatischer Kohlenwasserstoffe (PAK) im Pelagial und Oberflächensediment der Ostsee 2008. Jahresbericht des Institutes für Ostseeforschung. Im Auftrag des Bundesamtes für Seeschifffahrt und Hydrographie Hamburg, Rostock, 57 Seiten.
is available in German as a PDF-file (0,71 Mb)