Tilførsler av næringsstoffer, metaller og andre miljøgifter til ...

in the River Skienselva, significant contributions to the Grenland fiords derives from land
based industry, sewage treatment plants and discharge from impermeable surfaces in the city
areas, both regarding metals and organic pollutants as PCB and PAH. We also assume
discharges of these compounds from polluted land and waste disposal sites as being
important, but so far data from these sources are insufficient.
The total supply of metals and organic pollutants to the Grenland fiords shows a significant
decline in 2008 compared with earlier reported data (Helland et al. 2004). Largest declines
are documented for Hg (91 %) and dioxins (88 %), but also the declines in discharge of many
other metals are significant, i.e. Pb (87 %), Cd (69 %), Cu (46 %) and Zn (53 %). Only the
supplies of Ni and Cr have shown an increase in 2008 compared with the supply estimates in
Helland et al. (2004).
Regarding other micro-pollutants, we will recommend an implementation of a screening
survey in sediments in the Lake Norsjø (upstream the Skotfoss site in River Skienselva) and
in the Grenland fiords, and in water or in the suspended particle fraction from sewage
treatment plants discharge. If so, one should focus on “new” micro-pollutants compared with
what monitored today, of which several compounds have been banned for several decades
already. Also new agricultural pesticides should be incorporated, particularly those which are
used in very low concentration due to their high toxicity. Regarding documentation,
quantification and monitoring of organic micro-pollutants with low water solubility, one
should focus on analyses in the following matrixes:
� Sediments
� Suspended particles in water
� Fish (primary piscivorious fish)
This is important as these micro-pollutants are lipophilic and thus very strongly associated to
particle and also strongly biomagnify in the food web. Today several new sampling methods
are developed to better collect suspended particles in water, by use of centrifuges, passive
samplers, “torpedo” sampling devices etc. Accordingly it is also highly important that these
methods are standardized.
Keyword: Environmental pollutants, discharges, the Grenland fiords
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