The Odra Estuary is one of the most polluted coastal waters of the southern
Baltic. To investigate how and whether the estuary acts asa filter and tra
nsformation area For the fluviogenic material, different models were develo
ped and an intensive monitoring programme was carried out. Summarizing diff
erent methodological approaches, it could be shown that the total system fi
lter capacity reaches 2...5% for nutrients and 10...15% for some heavy meta
ls related to the current mean annual input. In the western part of the est
uary, the retention is more important and amounts to 10...40% of the annual
nutrient yield. Carbon flux studies revealed that both a reduction of the
inputs and more internal and external nutrient sinks are needed to reverse
the anthropogenic eutrophication process.