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Text By Shannon Lugo
Karst landscapes are some of the most unique, beautiful and important habitats. But like most habitats they are threatened by society's progress
and development. They hold in them some of nature's most beautiful treasures. They also hold in them one of society's most important resources,
drinking water.
Water Pollution
Pollution is a problem in any landscape, however in karst regions the threat from pollutants is greater due to the
nature of the environment. The common denominator in a karst system is water. The water that creates features like caves and sinkholes flows
easily through the system from surface water to ground water, carrying pollutants with it. The porous rock common in these areas is a poor
barrier to pollutants and provides little natural filtration and purification. Water moves very quickly through karst aquifers, sometimes as
quickly as surface streams. This gives contaminants the opportunity to easily travel into aquifers, springs, and wells.
A sinkhole filled with rusting drums. This particular sink lies within the Ichetucknee Springs recharge zone.
(link) |
Pollutants can come from a wide range of sources. Runoff from agricultural sources can contribute pollutants such as pesticides, herbicides
and animal wastes. Buried storage tanks in urban landscapes often leak chemicals and petroleum products into the ground that leech into karst
aquifers below. Faulty sewage systems and septic tanks can do the same. This can become a public health hazard by allowing disease causing
microbes, like cholera, to contaminate aquifers.
In karst landscapes surface water runoff may flow directly into sinkholes and caves. Contaminants from the urban
landscape are carried with the runoff into the aquifer system with no filtration. Solid wastes like plastic bottles and bags also flow into
these features. Solid wastes may also be introduced by the practice of using sinkholes and caves as trash dumps. With karst landscapes any
contaminants left on the ground or in the ground, (oil, lead, fertilizers or plastic bags) have the potential to enter the system and then
into the water supply.
Development Pressures
Development of karst lands also puts stress on important groundwater resources. Excessive water extraction from aquifers in highly populated
areas can lead to disastrous outcomes. When water is extracted from the ground the Swiss cheese like holes in the rock are left empty. Without
the support of the groundwater the holes may collapse producing sinkholes. Structures on the surface like homes, stores and office buildings,
may collapse as well. Another problem with excessive water extraction is salt water intrusion. In coastal regions, fresh water and saltwater
meet underground. When freshwater is extracted from aquifers saltwater can be drawn in, contaminating wells. In some cases wells may have to
be abandoned completely. This is a problem that many coastal communities have had to face.
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| The photo on the left is the entrance to Belleview Formation Cave in Florida. The photo
on the right is the same entrance after the property was clearcut for development. |
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Other Threats
Water resources are not the only thing threatened by the development of karst. Sensitive and beautiful cave habitats often times are the hardest
hit. The most obvious threat to cave habitats is mining and quarrying. An entire cave and all of the animals and rare rock formations inside
can be wiped out with no chance of restoration. Because of their rarity and isolation, cave species are particularly sensitive to habitat destruction
or habitat change. A single pollution event in one cave or spring system can wipe out an entire species. Even the presence of humans can compact
soils which may not seem harmful but can be damaging to animal communities. If we want to preserve these natural wonders underground we must
be more conscious of what we do above ground.
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