Marine Pollution Introductory paragraph

This is the introduction of my 1500 words research essay. Can you guys criticize? Just comment as you think.

Water is the main source of survival for all creatures. In fact, there is a saying, "Rice's life lasts for 7 days, water's life lasts for one morning", which means we cannot survive without water even for a day. But, something is really wrong with some of the sources of water on which every living thing is depending. That is, the marine pollution and it is considered as one of the most serious pollutions because approximately 75% of the Earth is covered with water. The major causes of marine pollution are oil spills, industrial disposals and Carbon dioxide absorption.

Source of survival is a strange phrase. It might be better to write:
Water is the most crucial factor for the survival of...

But, something is really wrong with some of the sources of water on which every living things depend.

The major causes of marine pollution are oil spills, industrial disposals and Carbon dioxide absorption.--- This makes me think the essay will be about these three topics. Is that what you are doing? If so, this is great, though a little boring and obvious. You might find a way to make your essay unique by making an observation that others may not have made. If you find a way to do this, you can add a little to this thesis statement to make your original point.

:-)