Geoscience Reference
In-Depth Information
of the Baltic Sea. This utilization has already a long history. Jöns describes that the
maritime (coastal) zone of the Baltic basin was, during all the phases of its settle-
ment history, of special importance to the people living there because of resources,
transportation, and communication. This is especially true in areas with high rates of
shore displacement, where the data and models can be used to reconstruct environ-
mental conditions and to date prehistoric coastal sites. Conversely, well-excavated
and dated archaeological sites that were originally located on the shore can pro-
vide detailed information about the sea level at the time of their occupation and
can be used as sea level index points. In his paper, Jöns discusses the opportu-
nities and problems arising from the use of shore displacement models for the
interpretation of archaeological sites. Both models and sites are introduced in case
studies that represent not only the different areas and localities but also the differ-
ent stages in the development of the Baltic Sea. One of the current requirements
is an integrated management of the coastal zone. Spiridonv et al. claim mapping
and assessment of the geological hazard potential to be the main objectives for
the protection of coastal zones. Ecological hazards may threaten human life, result
in serious property damage, and may significantly influence normal development
of biota. They are caused by natural endogenic and exogenic driving forces or
generated by anthropogenic activities. An interaction of geological processes and
intense anthropogenic activities, e.g. construction of buildings, harbours, oil and gas
pipelines, hydro-engineering facilities, and land reclamation, has resulted in hazard
potential, especially for the densely populated areas of the Russian Baltic coastal
zone. These hazards may in addition be harmful for the sensitive ecosystem of the
Baltic Sea. Vallius et al. mention seafloor desertification as a possible future sce-
nario in parts of the Baltic Sea environment as the result of its utilization. During
its whole post-glacial history the seafloor of the gulf has been periodically anoxic,
and anoxia below halocline can thus be seen as a natural phenomenon. During the
last decades, however, this has been accompanied by an annually repeated seasonal
anoxia in the shallower basins triggered by substantial eutrophication of the sea,
and is a clear signal of anthropogenic pressure. Phosphorus, which is bound to oxic
seafloor sediments, is easily released from sediments during episodes of anoxia,
which further intensifies eutrophication. Schernewski et al. mention that phospho-
rus is today regarded as the key nutrient for Baltic Sea eutrophication management.
Major sources are large rivers like the Oder, Vistula, and Daugava in the south-
ern Baltic region. Taking the Oder/Odra estuary as an example, the authors analyse
the long-term pollution history and the major sources for phosphorus and calculate
a phosphorus budget, with special focus on anoxic phosphorus release from sed-
iments. A phosphorus emission reduction scenario is presented. Phosphorus load
reductions have only limited effect on the eutrophic state of the lagoon. The lagoon
is more sensitive to nitrogen load reductions. Therefore, the authors mention that
both elements have to be taken into account in measures to reduce eutrophication.
For the assessment of interrelation between the Baltic Sea basin and terrestrial
areas, subsurface water exchange has to be considered in
hydrogeological mod-
elling
(Part VII). Schafmeister and Barsow have analysed the possible change in
groundwater discharge from a medium-scale catchment to the Baltic by means of a
