Power of Simplicity
The EPA’s Citizen’s Guide to Cleanup Technologies
Series 13: Evapotranspiration Covers
See our Newsletter, Environmental Enlightenment #200, for introduction to one highly valuable, plainly written series of Citizen’s Guides published by the EPA at http://www.clu-in.org/products/citguide
With this issue we introduce the EPA’s Citizen’s Guide to Evapotranspiration Covers. You can reach it through the hyperlink under the blue header below.
Evapotranspiration is a made-up combination word: short for Evaporation + Transpiration.
Evaporation from the land
Transpiration from plants
|Transpiration is the release of water from plant leaves.
(Perspiration is the release of water through the pores of the skin.)
|These pictures show water vapor transpired from plant leaves after a plastic bag has been tied around the stem for about an hour.
Credit: Ming Kei College, Hong Kong
An acre of corn gives off about 3,000 to 4,000 gallons of water each day.
(Credit: USGS, Water Science for Schools)
During a growing season, a leaf will transpire many times more water than its own weight.
In cases of buried contamination, if water percolates through the contamination it will leach out injurious elements and carry them down to groundwater.
|Caps provide protection from injurious elements in the environment.
Evapotranspiration covers are caps placed over contaminated material to prevent water from reaching it.
Evapotranspiration covers hold the water.
They prevent water from reaching the buried waste.
In time the cover releases the water back to the atmosphere through evaporation from the land and transpiration from the plants.
Credit: NASA Earth Observatory
Evapotranspiration covers do not destroy or remove contaminants.
They isolate contaminants and keep them in place to prevent the spread of contamination.
Go to the EPA’s Citizen’s Guide to Evapotranspiration Covers http://www.clu-in.org/download/Citizens/a_citizens_guide_to_evapotranspiration_covers.pdf for the rest. It is simple and fun to read.