Hello Eileen! This is an interesting question.
Sewage is where your toilet water goes, so you know that toilet water contains a lot of harmful germs!
Fertilizers are chemicals that will help algae, a harmful plant that grows in water, to grow very very fast!
Oil that are spilled in the sea will stick to seagulls' feathers, and it makes them very very heavy so they cannot fly!
Sulfur dioxide is an acidic gas that will go up into the sky and react with clouds... Acidic chemical and rain will give you acid rain!
Lastly, litters like plastic bags look like jelly fish, don't they? Turtles like to chomp on jelly fish and they will often mistake plastic bags to be their favourite snack, poor thing!
If you have anymore questions, you can ask me! :)