THE urge to explore strange new worlds leads some scientists deep into the
oceans or the weightlessness of space. Reinhard Hüttl’s final frontier was
easier to reach. He needed only to move east across Germany, from the Black
Forest town of Freiburg to the region known as Lausitz, near the Polish border.
Here HĂĽttl encountered a landscape as eerie and fascinating as another
planet’s: lakes as acid as vinegar but teeming with microorganisms, more than a
thousand square kilometres of sandy soil that threatens to collapse underfoot at
any moment, and rivers swollen with extraordinary quantities of water pumped
from deep underground.
This bizarre terrain is a legacy of decades of intensive coal mining. “We
have conditions here that are unique in the world,” says Hüttl, with a hint
of pride. He now occupies a newly established chair for Land Preservation and
Recultivation at the University of Cottbus, in the heart of the region.
For environmentalists, the coal mines are a disaster. But for HĂĽttl and
hundreds of researchers like him, they offer a remarkable research opportunity.
The German government is spending billions of marks to restore these areas to
productive uses, and has called on an army of geochemists, hydrologists and
microbiologists for advice on how to go about it. There are even those who see a
different sort of value in the region, and want to preserve it as a unique
natural habitat harbouring rare native species.
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What makes Germany’s mining regions extraordinary, says Hüttl, is their
colossal scale. During the 1970s and 1980s, tiny East Germany was second only to
China in coal production. Every year, the country dug up roughly 300 million
tonnes of lignite, a kind of soft, low-grade brown coal. Lignite contains a high
proportion of moisture and rock, but because East Germany couldn’t afford to
import oil or natural gas, it formed the basis of the country’s economy. It was
used not just in power plants and domestic furnaces, but also as raw material
for the synthesis of gas, rubber and plastics.
The seams of lignite were relatively easy to get at. They were wide, flat,
and lay 60 to 100 metres below the surface, under a layer of sand and gravel.
Before mining could begin, groundwater had to be pumped out to ensure the water
table was lower than the coal seam. Then mining machinery methodically stripped
out the coal, tossing aside the surface layers.
Over the years, lignite mines devoured 1300 square kilometres of East
Germany, even obliterating whole villages. “The only process that did anything
comparable was the last glaciation,” says Holger Weiss, director of research on
former mines at the government’s Environmental Research Centre in Leipzig. After
German unification, however, most of the mines were shut down. Demand for
lignite disappeared as factories and power plants in the former East Germany
became victims of tougher environmental standards and competition from the West.
Today, the mines are wastelands, huge pits that can cover more than 10 square
kilometres. A few are almost dry, but in the bottom of most of them, water is
collecting and forming lakes.
Fatal floors
It is hazardous terrain. The sides and floors of the pits are unstable, and
there are notices warning off trespassers. Anyone foolhardy enough to ignore the
warnings is at risk from landslides, which have already claimed several lives.
Even researchers are banned from going out on the flooded pits in boats, because
the landslides can set massive waves bouncing back and forth across the
lakes.
Where the floors of the mines are still dry, they must be stabilised by
giving them a good shaking. Explosive charges are set off deep underground. “The
ground shakes like a pudding, and you can see water squirting up,” says
±áĂĽłŮłŮ±ô.
Other dangers are less visible. The small dunes of sandy detritus that dot
the craters are full of pyrite and marcasite, compounds containing sulphur and
iron which are normally buried deep underground. Exposed to the air, they react
with oxygen and release sulphuric acid. In some areas, water collecting in the
bottom of the mines has a pH of between 2.5 and 3.5—as acid as
vinegar—and is filled with dissolved sulphur, iron and aluminium from the
underlying soil. Worse still, waste thrown into the water has left it laden with
heavy metals such as arsenic and manganese, which are soluble in acid water.
“There was a great temptation over the years to use these empty pits as dumps,”
says Weiss.
To make matters worse, part of eastern Germany has come to rely on the mining
regions for its water supply. Each year for the past 30 years, hundreds of
millions of cubic metres of water were pumped out of the ground to lower the
water table so that it did not interfere with mining operations. The water ended
up in the Spree and Schwarze Elster rivers, artificially swelling them by as
much as 50 per cent.
Although most of the mines have been shut down, the pumping continues,
draining groundwater from 3000 square kilometres of land. If this process
stopped overnight, the Spree would shrink to levels not seen since the 1950s,
Berlin would suffer water shortages in summer and trees in the Spree Forest
would die. Rising groundwater in the mining areas would flood the basements of
houses.
The German government now wants to solve all these problems in one bold
stroke that would neutralise the acid lakes, guarantee Berlin a steady water
supply, and turn the mines into a tourist centre. The plan is to flood more than
fifty of the pits with river water, turning the area into an attractive lake
district. Some local officials are even planning a Wild West theme park in the
heart of the area, featuring wild horses and bison, a “frontier” town with
saloons and rodeo shows, and an Indian village—all serviced by a modern
five-star hotel.
The flooding operation, already begun in a few areas, will kick off in
earnest this year. More than 200 million cubic metres of water a year will be
diverted into the pits from the Spree, the Schwarze Elster and the Neisse
rivers. “The slopes of the mines are not stable if the water comes up slowly,”
says Weiss. “They have to be flooded quickly, and that means with rivers.”
Unfortunately, the region receives little rainfall, and these are not large
rivers, so there isn’t enough water to fill all the mines at once. Engineers
will have to flood first one batch of mines, then another.
Water shortage
Most of the lakes will be filled in about twenty years, but a few will not be
completely flooded until late in the next century. Ludwig Luckner, from the
Dresden Groundwater Research Centre, who is planning the operation, says he
wishes the flooding could go faster. He would like to draw on water from the
river Oder, which marks the border with Poland, but this creates a diplomatic
complication: it would require approval from the Polish government, and German
authorities have so far been reluctant to ask Poland for help.
Several of the largest lakes, which will be connected to each other by
tunnels and canals, will serve as reservoirs for Berlin. They will store water
during times of heavy rainfall, and release up to 80 million cubic metres into
the Spree during dry months. This should replace the pumping of groundwater,
which will gradually decrease. The river water is also supposed to neutralise
the acidic water from the mines, creating lakes in which people can swim, boat
and fish.
At least that’s the plan. “The extent to which this happens probably isn’t
predictable,” says Stefan Peiffer, a geochemist at the University of Bayreuth.
Yet he supports the plan to flood the pits. “At this point, you just have to do
a large-scale experiment.” But if things go wrong, he says, “it could really be
a mess”.
Avoiding this “mess” depends on striking a delicate balance between two
different kinds of pollution: the highly acid waters of the mines, and river
water laden with phosphates and nitrates from inadequately treated sewage, an
all too common problem in the region. The optimistic view, says Weiss, is that
river and mine water will purify each other. “In river water alone, there is too
much biological activity,” he says. This can lead to eutrophication: a glut of
nutrients causes a bloom of algae, followed by an explosion of bacteria that
consume all the available oxygen and choke off any other life. There are
intriguing hints, however, that such polluted water may be the best medicine for
an acid lake.
Helmut Klapper, recently retired from the Environmental Research Centre,
points as an example to a narrow lake, 11 kilometres long, that has filled an
older mine near the town of Laubusch, some 50 kilometres southwest of Cottbus.
For years, the town pumped raw sewage into the lake, where it mixed with highly
acid water seeping from the sides and bottom of the mine. Today, says Klapper,
the lake water is clear and has a nearly neutral pH, and fish live in
it. Controversially, Klapper would like to pump sewage into some acid lakes that
lie far from any rivers. “That’s forbidden by German law today, but we are
preparing such proposals,” he says.
Some of the cleansing processes are straightforward chemical reactions. When
the two kinds of water mix, phosphates in the polluted water bind to iron oxide
in the acidic water. The compounds then fall to the bottom of the lake as
sediment, effectively locking them away. This process will not happen, however,
unless the two types of water thoroughly mix.
According to Klapper, mixing may not always take place because acid water has
a high salt content, making it denser than river water: it sinks to the bottom
while the river water forms a layer on top. Yet this process, too, can be
beneficial, he says. Biological activity in the upper layer will tend to starve
the bottom layer of oxygen. In these anaerobic conditions, sulphur will bind
directly to iron, and the resulting compounds will precipitate out as sediment.
For this set of reactions to happen, it is important to preserve anaerobic
conditions at the bottom of the lake, Klapper says. He believes it may be
necessary to stretch plastic booms across the lakes to damp down waves and so
prevent the layers of water from mixing.
Finally, bacteria, which prosper even in the most highly acid lakes, are
apparently able to feed on the sulphur, iron and other metals dissolved in their
waters. According to Brigitte Nixdorf of the University of Cottbus, many of
these organisms have yet to be identified. “We see some effects— sulphur
reduction, for example—but we do not know what is responsible for
łŮłó±đłľ.”
Biologists have been astonished by the variety of life found in the acid
lakes—not only unexpected species of phytoplankton and bacteria, but also
unique communities of microorganisms, which differ from lake to lake. Nixdorf
says that the extreme conditions in the lakes force the colonies of
phytoplankton to employ novel strategies for survival. Instead of colonising the
entire lake, they restrict themselves to particular regions where nutrients are
concentrated. Sheets of green algae, normally found on the surface, have been
discovered deep in these lakes at the boundary between layers of water, and
microbial activity is restricted to a narrow zone overlying the lake bed.
Nor is the biodiversity limited to microscopic forms of life. Michael
Altmoos, a biologist at the Environmental Research Centre, has catalogued some
of the wildlife in the coal mines. He has found large numbers of dragonflies,
beetles, toads, birds and flowers that are rare elsewhere in the country. “It’s
curious. These are the most orchid-rich areas in Germany,” he says. Such species
thrive in barren, nutrient-poor areas, in part because they face less
competition from other species.
Altmoos argues that the abandoned mines, in all their barrenness, have become
an ecological treasure. The government’s plans to turn them into lakes and
recreational parks, he says, are an expensive mistake, although he admits that
his views aren’t shared by many in Germany. “There is a very great chance for
European nature conservation here,” he says. “And I’m afraid it will
±ą˛ą˛Ôľ±˛őłó.”
Altmoos believes that it will be impossible to return the landscape to its
once idyllic beauty. That has gone and can never be resurrected. What’s left is
another kind of landscape, just as fascinating, and far more rare, with its own
kind of strange beauty. “We must seize this opportunity here, because the way it
was before has vanished forever.”
