Interim report of the HELCOM CORESET project

Present status assessments
Known temporal trends (also from sediment core profi les)
With some exceptions particularly from coastal sites, HCB, HCHs (alpha and gamma) and DDTs show distinct
decreasing trends in biota within the last two decades (chapter 2.2.5 BSEP 120 B). In the last time,
concentrations have reached a relatively low level, and a small resulting trend may be masked by the
within- and between-year variability of the data.
No suffi cient information on sediment time series found! Water is only analysed offi cially by two member
states.
Spatial gradients (incl. sources)
For DDE in 1995 a spatial gradient from the northern to the southern Baltic Sea is obvious with increasing
concentrations by a factor of about seven, in principle sill remaining also 2005, but the factor has
decreased to only half (3.6) of that ten years before. For gamma-HCH, in 1995 also an increasing gradient
from north to south with a ratio of 3 can be observed, but in 2005 concentrations in all areas are at an
comparable level and no gradient occurs any longer.
Table 5.5. Spatial and temporal trends of DDE and gamma-HCH (lindane).
DDE 1995 DDE 2005 Gamma-HCH 1995 Gamma-HCH 2005
Bothnian Bay: 80 μg/kg lw 40 μg/kg lw 10 μg/kg lw < 5 μg/kg lw
Bothnian Sea 150 μg/kg lw 70 μg/kg lw 12 μg/kg lw < 5 μg/kg lw
Gulf of Finland 4 μg/kg ww 1 μg/kg ww
North. Baltic Proper: 22μg/kg lw 5 μg/kg lw
Arkona Basin 570 μg/kg lw 143 μg/kg lw 29 μg/kg lw 6.3 μg/kg lw
4.1 μg/kg lw (in 2009)
The data in BSEP 120 B in fi g. 2.19 and 2.20 are displayed on a different basis. In 1995 (and following years)
the small herring samples from the Arkona Sea had extractable lipids in muscle between 3-4% . Calculating
on lipid basis and compared with the other areas would result in the estimate sshown in this table.
Recommendation
Recommended matrices (in order of priority):
1. Biota: HCH (alpha-, beta- and gamma-) and 4,4’-DDE, 4,4-DDD and 4,4’-DDT, (HCB only where of local
relevance)
2. Water: HCH (alpha-, beta- and gamma-), 4,4’-DDE, 4,4-DDD and 4,4’-DDT
3. Sediment: 4,4’-DDE, 4,4-DDD and 4,4’-DDT
For HCHs and DDTs the relative pattern within each group is indicating local differences as well as changes
due to recent inputs or remobilization. HCB is relatively uniform distributed, so that it may be less suitable
for geographical differentiation.
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