11 October 2007 - Food
shortages probably due to large-scale, climate-related
ecological changes have caused a wide-ranging
collapse in reproduction for at number of
seabird species in the southern part of
the North Atlantic (Iceland, Faroe Islands,
Scotland, W Norway) over the last four years.
In the long term this may cause a marked
population decline, warns a Nordic group
of experts gathered at a workshop in Tórshavn,
Faroe Islands, in September. The workshop
was attended by three scientists from The
Danish National Environmental Research Institute
(NERI) at the University of Aarhus.
For northern fulmar (Fulmarus glacialis),
black-legged kittiwake (Rissa tridactyla),
Arctic tern (Sterna paradisaea), common
guillemot (Uria aalge) and Atlantic puffin
(Fratercula arctica ), the severe pressure
has led to a decreasing number of birds
showing up in the colonies, and local populations
are in trouble with few chicks being raised.
For instance, populations of black-legged
kittiwake and Arctic tern in Shetland have
declined by more than 75 per cent.
Danish emissions of greenhouse gases 11000-2005
12 October 2007 - This report is Denmark
’s National Inventory Report for submission
to the United Nations Framework Convention
on Climate Change (UNFCCC), for 15 April
2007. The report contains information on
Denmark ’s inventories for all years from
11000 to 2005. The structure of the report
is in accordance with the UNFCCC guidelines
on reporting and review. The report includes
detailed information on the inventories
for all years, from the base year to the
year of the current annual inventory submission,
in order to ensure transparency.
The greenhouse gases reported under the
Climate Convention are:
Carbon dioxide CO2
Methane CH4
Nitrous Oxide N2O
Hydrofluorocarbons HFCs
Perfluorocarbons PFCs
Sulphur hexafluoride SF6
For the National Total CO2 Equivalent Emissions
without Land-Use, Land-Use Change and Forestry
(LULUCF), the general impact of the improvements
and recalculations performed is small and
the changes for the whole time-series are
between -0.02 % and +0.18 %. Therefore,
the implications of the recalculations on
the level and on the trend, 11000-2004,
of this national total are small.
For the National Total CO2 Equivalent Emissions
with Land-Use, Land-Use Change and Forestry
(LULUCF), the general impact of the recalculations
is rather small, although the impact is
larger than without LULUCF due to recalculations
in the LULUCF sector for 2003 and 2004.
The differences vary between –1.01 % and
+0.14 %. These differences refer to recalculated
estimates, with major changes in the LULUCF
for those years.
+ More
New finding: Enhanced availability of hydrophobic
organic chemicals by binding to dissolved
organic matter
10 October 2007 - By Jens C. Pedersen -
It is usually believed that the biological
availability of hydrophobic organic chemicals
decreases when they bind to various types
of dissolved organic matter. This is challenged,
however, by new findings of a Danish team
of scientists showing that the opposite
may also be true. The uptake of hydrophobic
organic chemicals into organisms is often
limited by the diffusive mass transfer through
a very thin layer of unstirred water. The
new research demonstrated an enhanced diffusive
mass transfer of 12 different polycyclic
aromatic hydrocarbons (PAHs) through such
unstirred layers of various artificial and
natural solutions. The artificial solutions
contained, for instance, humic acids, detergents
and cyclodextrin, and the natural solutions
were gut fluid from a sediment worm, soil
solution and horse manure solution. The
transport of benzo(a)pyrene through a thin
aqueous layer increased 74 times in the
gut fluid from a marine sediment worm compared
to water. This contributes to our understanding
of why even very poorly soluble pollutants
can be taken up in the digestive system.
These findings also imply that the addition
of detergents to polluted soil not only
enhances the release of the pollutants,
but also enhances their uptake into micro-organisms.
This can be crucial knowledge for improved
bioremediation strategies.
It is normally assumed that the binding
of contaminants reduces their availability
for biological uptake. However, a team of
scientists from the Danish National Environmental
Research Institute at University of Aarhus
has recently shown that the opposite can
also be the case, namely when the pollutants
are bound to certain dissolved organic compounds,
like humic acids or detergents. The Danish
scientists found a substantially enhanced
mobility of the tar compound benzo(a)pyrene
by adding digestive fluid of a deposit-feeding
marine worm, a polychaete. This made the
transport of benzo(a)pyrene increase by
a factor of 74 compared to pure water. The
transport took place by diffusion through
a thin layer of liquid, cf. the figure below.
Cross-section of the experimental apparatus
used by the Danish scientists. They investigated
the diffusion of benzo(a)pyrene and other
tar compounds (PAHs) by loading them onto
silicone disks and then measure their transport
through a 0.1 mm layer of artificial and
natural solutions. Diffusion is the dispersal
of molecules from high to low concentration,
as shown in the figure. It is the result
of the random motion of many molecules.
Here the molecules are tar compounds, but
all chemical substances are transported
by diffusion. The arrow indicates the net-direction
of diffusion from the loaded silicone disk
through the thin aqueous layer and into
the clean silicone disk.
The enhancement is probably due to surfactants
in the digestive fluid. Horse manure, different
engineered detergents and the carbohydrate
cyclodextrin also enhanced the diffusion
of the tar compounds.
Important for biodegradation
What does this new finding mean to us? Senior
scientist Philipp Mayer from the National
Environmental Research Institute at University
of Aarhus explains:
- The enhanced diffusion increases the
dynamics of the pollutants. This increase
is most important when dealing with compounds
of low water solubility, e.g. the heavier
tar compounds. A thin aqueous film often
acts as an efficient barrier for the environmental
transport of these compounds.
-The enhanced diffusion does not change
the environmental equilibrium partitioning
of the pollutants, but it means that equilibrium
is attained faster.
Adding detergents or cyclodextrin to polluted
soil, however, can also be beneficial to
the bacteria that can degrade the pollution
– and hereby for us. This is already common
practice for biodegradation companies, and
the new study contributes to an improved
process understanding, enabling us to optimize
the biodegradation of soil pollutants.
An extra element in risk assessment
The new finding is also important for the
risk assessment of soil pollution. According
to Philipp Mayer, there are now three parameters
scientists and environmental authorities
should take into consideration when assessing
the risk of a pollution:
The pool of pollutants, which can be released
and thereby become available for organisms.
The chemical activity, which drives the
diffusion and partitioning of the pollutants.
The ability of the soil solution to transport
pollutants within and out of the soil matrix,
for instance by diffusive mass transfer.
Philipp Mayer assesses that the first two
parameters will remain most important, but
what does the new point 3 add?
- It is hardly significant for the most
water soluble compounds, but the mobility
can be substantially enhanced for the highly
hydrophobic substances. Therefore, I will
expect a more pronounced enhancement for
compounds that are even less water soluble
than the tested PAHs, like e.g. dioxins
and brominated flame retardants. Even low
concentrations of humic acid or detergents
will here be of significance for the diffusive
mass transfer and thus for the biological
uptake, judges Philipp Mayer.
The results have been published in the
international journal Environmental Science
and Technology: Mayer, P., Fernqvist, M.M.,
Christensen, P.S., Karlson, U. & Trapp,
S. 2007: Enhanced Diffusion of Polycyclic
Aromatic Hydrocarbons in Artificial and
Natural Aqueous Solutions . (on-line access
for subscribers only) - Environmental Science
and Technology 41: 6148-6155.
