Geoscience Reference
In-Depth Information
c attention is given to the seas and inland reservoirs. A typical example is
the Baltic Sea (Knuuttila et al. 2011). This region is controlled by the Helsinki
Commission which is concerned about reliable data on inputs into the Baltic Sea
from land-based sources, as well as information about the signi
Speci
cance of different
pollution sources. Data on waterborne inputs to the Baltic Sea and the development
in these inputs have been even more important after the agreement on the
HELCOM Baltic Sea Action Plan (BSAP) in 2007. The BSAP recognizes the need
to reduce nutrient (nitrogen and phosphorus) inputs to a maximum allowable level.
BSAP is an ambitious programme to restore the good ecological status of the Baltic
marine environment by 2021.
The Baltic Sea is a relatively young and ecologically vulnerable water body. The
state of the pelagic and coastal waters has suffered from human activities. Rhein-
heimer (1998) has given a detailed analysis of the pollution problems related to the
Baltic Sea at the end of the 20th century. The health of the Baltic Sea has been
seriously damaged since the 1960s due to the excessive pollution from the countries
in its catchment area. The Baltic Sea is almost totally surrounded by land and,
therefore, more endangered by pollution than other marine areas. The sources of
marine pollution are municipal and industrial waste that outputs directly into the sea
or via rivers, and atmospheric inputs mainly from traf
c and agriculture. The
increase of inorganic plant nutrients (NH
3
,NO
x
,PO
4
) caused eutrophication and,
consequently, oxygen depletion in coastal bottom waters as well as in the depths of
the open sea. In the anoxic sediments, hydrogen sul
de can be produced by protein-
decomposing and sulfate-reducing bacteria. The bottom fauna will be destroyed and
only H
2
S tolerant microorganisms can survive. Originating from cellulose manu-
facturing and from paper mills, large amounts of poisonous chlorinated compounds
contaminated the coastal waters of Sweden and Finland until the 1980s. Most of
this material is still present in sediments of the central Baltic Sea and can be
resuspended by near bottom currents. To reduce pollution and improve the situation
in the Baltic Sea, the surrounding countries organized the Helsinki Convention,
which came into force on 3.5.1980. The Helsinki Commission (HELCOM),
founded in 1974, acts as coordinator and is responsible for the enforcement of the
Baltic monitoring program and international research projects. The activities of
HELCOM have led to the reduction of dangerous pollutants which in turn has
caused the regeneration of
flora and fauna in some areas. Rheinheimer (1998)
expressed that further improvements can be expected.
The beginning of 21st century is characterized by attempts to harmonize the
policies and actions in the coastal countries through various conventions and pro-
grams in order to improve the state of the Baltic Sea. Knuuttila et al. (2011) present
the main results from the PLC-5 Project. These include quanti
fl
ed annual water-
borne total loads of nitrogen and phosphorus from 1994 to 2008 to provide a basis
for evaluating any trends in the total
flow normalized waterborne inputs to the
Baltic Sea. The contributions from different point and diffuse sources, including the
natural background load, are also estimated and described. An estimate of the total
inputs of some heavy metals is also included. Furthermore, the report includes
fl
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