英文關鍵字
autumn
background
bacteria
biology
bottom
bright
bubbles
calm
clean
clear
colorful
creek
flow
flowing
forest
hydrogen
latvia
leaves
life
microorganisms
middle
mineral
moving
nature
organics
pond
pure
reserve
resource
river
shallow
silt
sludge
source
sourse
spring
stone
stream
sulfide
surface
transparent
underwater
vegetation
water