(3) http://commons.wikimedia.org/wiki/File:Macquarie_perch.jpg. GNU-FDL.(4) http://commons.wikimedia.org/wiki/File:
Bioretention_cell_rain_garden_US_winter.jpg. Public Domain.(5) Bengt Olof ARADSSON.http://commons.wikimedia.org/wiki/Image:
Somalia_termitstack_B%C3%85n.jpg. GFDL/CC-BY-2.5.(6) Stephen Codringto.
http://commons.wikimedia.org/wiki/Image:Strip_coal_mining.jpg. CC-BY
2.5.(7) Keith Weller of the Agricultural Research Service.
http://commons.wikimedia.org/wiki/Image:GEM_corn.jpg. Public Domain USDA
ARS.(8) http://commons.wikimedia.org/wiki/File:Soilcontam.JPG. CC-BY-SA.(9) http://commons.wikimedia.org/wiki/File:Acid_rain_woods1.JPG. CC-BY-SA.(10) NASA.
http://commons.wikimedia.org/wiki/File:Lake_Valencia,_Venezuela.jpg.
Public Domain.
(11) http://commons.wikimedia.org/wiki/Image:Andropogon_gerardii.jpg. Public
Domain US Government.
(12) http://commons.wikimedia.org/wiki/Image:
Asbestos-Covered_Pipes_CNE-v1-p58-E.jpg. Public Domain.
(13) http://commons.wikimedia.org/wiki/Image:Air_.pollution_1.jpg. Public
Domain, US Federal Government.
(14) Reservoirhill.http://commons.wikimedia.org/wiki/File:
Tallgrass_Prairie_Nature_Preserve_in_Osage_County.jpg. Public Domain.
(15) Chuck Szmurlo.
http://commons.wikimedia.org/wiki/Image:Bruce-Nuclear-Szmurlo.jpg.
GNU-FDL.
(16) Mihael Simonic.http://commons.wikimedia.org/wiki/Image:Solar_cells.jpg.
CC-BY-SA-3.0.
(17) http://commons.wikimedia.org/wiki/File:Sand_mining(1).jpg. GNU-FDL.
.jpg.){kind=link}
(18) Anthony Bley.http://commons.wikimedia.org/wiki/Image:
Wetlands_Cape_May_New_Jersey.jpg. Public Domain US Army USACE.