bad
brown
bubble
canal
chemical
chemistry
closeup
contaminated
contamination
corrosive
damage
danger
dangerous
dead
detail
dirt
dirty
drainage
earth
ecology
environment
environmental
foam
foaming
ground
industrial
industry
lake
mud
nature
outdoor
pattern
poison
pollute
polluted
pollution
pond
river
scum
sewage
soil
spume
toxic
unhygienic
waste
water