19 May 2009 - Baltic
countries need to continue to reduce their
input of the nutrients nitrogen and phosphorous
to the Baltic Sea . Technological fixes
are not the solution for hypoxia and algal
blooms conclude researchers from, among
other institutions, Denmark's National Environmental
Research Institute, Aarhus University.
During the summer of
2008 record areas of the Baltic Sea were
affected by hypoxia in bottom waters, killing
bottom-living organisms and limiting area
for fish and other fauna over 70,000 km2
– almost twice the area of Denmark. Moreover,
the dead seafloor leaks large amounts of
phosphorous causing blooms of blue-green
algae in late summer.
In recent years, the
question has been raised of whether engineering
technologies – bioengineering – can be applied
to alleviate some of the problems of hypoxia?
In order to answer this question approx.
60 researchers from around the world – but
with strong representation from the Baltic
countries – met in a series of workshops
in Sweden and Finland during the course
of 2007 and 2008. The results of these workshops
have been published in two articles in the
journal ‘Environmental Science & Technology’.
The conclusions can be summarized as follows:
- If the problem in the
Baltic Sea is hypoxia – can more oxygen
then be added to bottom waters?
Calculations demonstrate that 2-6 million
tonnes of oxygen a year would need to be
added to the marine area to keep the Baltic
Sea sufficiently oxygenated. This is equivalent
to 20,000-60,000 lorry loads full of oxygen
– an impossible task.
- Can inputs of oxygenated
saltwater to the Baltic Sea be increased
to flush the oxygen-depleted bottom water
away?
This is technically possible but does not
solve the problem of hypoxia in deep waters.
A drastically increased inflow of saltwater
would just aggravate the problem by enhancing
stratification of the waters, thereby increasing
hypoxia.
- How about conversion
of the Baltic Sea to a lake?
This too is technically feasible, but would
have dramatic consequences for the sea.
As a lake, the Baltic Sea would have an
entirely new composition of fauna and flora,
and all organisms dependent on saltwater,
such as cod, would disappear.
- Can we oxygenate the
water masses with wind turbines?
The Swedish government has financed several
projects in order to explore this possibility.
In theory it is possible, but whether the
method could work in practice is doubtful.
The feasibility and costs of such a project
should be carefully examined, and more important
still, the consequences of such a project
for the water circulation and fauna and
flora in the Baltic Sea need to be investigated.
- Can we bind phosphorous
by adding aluminium to the waters, thereby
reducing algal bloom?
This would require enormous amounts of aluminium
and it is uncertain how aluminium would
react in a brackish environment such as
the Baltic Sea . In the worst case, the
aluminium would be poisonous to organisms.
Moreover, this measure would be in conflict
with the international convention forbidding
dumping of chemicals in the sea.
Some the above methods
could work on a smaller scale, e.g. in enclosed
coastal areas, but not as solutions to the
problems in the Baltic Sea . In order to
combat hypoxia, it is therefore of crucial
importance that the amount of nitrogen and
phosphorous flowing into the Baltic Sea
from the surrounding land continues to be
reduced.
Contact: Professor Jacob
Carstensen, tel. +45 4630 1345, jac@dmu.dkjac@dmu.dk
Hypoxia-Related Processes
in the Baltic Sea . Daniel J. Conley, Svante
Björck, Erik Bonsdorff, Jacob Carstensen,
Georgia Destouni, Bo G. Gustafsson, Susanna
Hietanen, Marloes Kortekaas, Harri Kuosa,
H. E. Markus Meier, Baerbel Müller-Karulis,
Kjell Nordberg, Alf Norkko, Gertrud Nürnberg,
Heikki Pitkänen, Nancy N. Rabalais,
Rutger Rosenberg, Oleg P. Savchuk, Caroline
P. Slomp, Maren Voss, Fredrik Wulff, and
Lovisa Zillén.
Tackling Hypoxia in
the Baltic Sea : Is Engineering a Solution?
Daniel J. Conley, Erik Bonsdorff, Jacob
Carstensen, Georgia Destouni, Bo G. Gustafsson,
Lars-Anders Hansson, Nancy N. Rabalais,
Maren Voss, and Lovisa Zillén.
+ More
Monitoring at olivine
mine at Seqi
19 May 2009 - The olivine
mine at Seqi. - Olivine has been mined and
exported at Seqi in West Greenland since
2005. In 2004 and 2005 baseline studies
were performed in order to describe the
occurrence of fish, marine bottom invertebrates,
and birds in the area and to obtain information
on sediment characteristics.
An area in the inner
parts of Tasiussarsuaq, close to the olivine
deposit, was found to be anoxic at depths
greater than 100 m. To assess possible impacts
of the olivine deposit prior to mining,
a range of elements was analysed in lichens,
brown seaweed and blue mussels before the
olivine mining started. There were no measurable
natural elevations of elements originating
from the olivine deposit.
In 2007 a spreading
of dust was indicated after the mining started.
The dust contains elevated concentrations
of chromium and nickel and some other elements
as reflected in the increased levels of
these elements in lichens collected close
to Seqi. In seaweed and blue mussels this
dusting has resulted in elevated concentrations
of chromium and nickel, but only at one
station very close to the deposit. No chromium
or nickel pollution could be detected in
fish or in water samples from the lake.
Thus the effect of the mine is very local.
Baseline and monitoring studies at olivine
mine 2004 to 2007. Asmund, G., Boertmann,
D. & Johansen, P. 2009. National Environmental
Research Institute, Aarhus University ,
Denmark . 88 pp. - NERI Technical Report
No. 715.
