environmental
bacteria
clean
clear
collect
collector
contaminated
danger
dangerous
dead
death
die
dirty
disaster
disease
ecological
ecology
ecosystem
environment
fish
float
hanoi
harmful
hazard
infection
kill
lake
many
natural
oxygen
pick
pile
poison
pollute
polluted
pollution
problem
remover
river
rotten
sea
tool
toxic
up
waste
water
westlake
worker