英文關鍵字
brook
canal
cascade
chemical
contamination
creek
danger
dangerous
dirty
disaster
discharge
dump
dumps
ecology
effluent
environment
environmental
fall
flow
flowing
forest
garbage
geyser
global
green
hazardous
industry
mountain
nature
outdoor
park
polluted
pollution
problem
recycling
refinery
river
rock
sewage
stone
stream
substance
swirls
toxic
tree
waste
water
waterfall
waterfalls