Groundwater Contamination
Groundwater quality is an issue throughout many areas the world. Contamination of groundwater resources is areas of karst topography is no different. Groundwater quality and its suitablility for various uses must be understood in order to make responsible decisions regarding pollution prevention, resource management, groundwater protection, and water-development policies (In Focus, 2001)
Some sources of groundwater contamination are pollutants such as runoff from paved areas like parking lots, pesticides, fertilizers, concentrations of animal waste, materials leaking from septic tanks and landfills, or chemical spills. Due to the characteristics of the karst topography, these contaminants can easily find their way through the subsurface and into the groundwater reserves with little amounts of filtration or chemical change (Ruthven, C. et el, 2002).
Contamination of groundwater resources ranges in severity from case to case. Severity and extent of contamination depends on two factors: distance to the source and kind of contaminants involved, as well as the recurrence interval of recharge. If the recharge areas contain contaminants, the severity of the problem will increase (http://www.dyetracing.com, 2004).
Diagram of possible groundwater contamination sources in karst areas http://www.dyetracing.com/karst/ka01013.html
To better understand the flow of groundwater reserves, hydrologists employ dye-tracing experiments to map the path of flow. Dye-tracing involves environmentally safe dyes boing added into sinking streams or springs. Sinking streams are streams that flow into the bedrock at some point along their channel, completely dissappearing under the surface. Packest of dye-absorbing materials are paired with anchors and placed in springs, awaiting the dyes to be brought in through the system of sub-surface streams. The discovery of direction and paths of flow allow for the mapping of flow paths of the groundwater resources. Upon contamination, these maps may be consulted in order to estimate the range and severity of contamination by locating karst groundwater basins.(Ruthven, C. et al, 2002).
Image of a dye tracing study performed with red dyes in a karst area
A partnership of conservation organizations published a pamphlet entitled Sinkholes, Groundwater, and other Mysteries Below Your Feet in Southern Indiana that gives four simple rules that have been established for protecting groundwater resources. They area as follows: 1. Never dump anything into sinkholes. It is illegal as well as environmentally hazardous. 2. Maintain and frequently check your septic system. 3. Keep vegetation around a sinkhole to aid in run-off filtration. 4. Follow directions when applying household, farm, or lawn chemicals.
Groundwater contamination is all too common in karst areas. Below are links to more information on groundwater contamination:
http://www.caves.org/conservancy/ikc/images/sinkhole.pdf - for the pamphlet listed above
http://www.kellysearch.com/us-product-120616.html - for 29 links to some contamination services
