Describe the human activities that could contribute significantly to the creation of dead zones.

There are many human activities that could contribute significantly to the creation of dead zones, and here are some of them:
1. the use of chemical fertilizers
2. urban land use
3. coastal littering, as well as runoff from sewage
4. use of harmful phosphates in detergents
Dead zones are places in waters on Earth where there is so little oxygen left due to pollution that marine life cannot survive there.