alga
algae
animal
bacteria
bubbles
carp
coast
contaminate
contaminated
danger
dangerous
dead
death
ecological
ecology
ecosystem
environment
fish
food
fresh
global
grass
green
greenpeace
industry
issue
lake
life
mekong river
mouth
nature
one
oxygen
poison
polluted
pollution
pond
problem
river
rock
rotten
sea
smell
summer
toxic
ugly
warming
waste
water
wet