The great pacific garbage patch will be difficult to physically clean up because

The Great Pacific Garbage Patch is an environmental problem of the Pacific ocean water. It is accumulated with a trash of 10 meters deep non-degradable plastics. These plastic wastes can trap marine animals and contaminate the quality of water.

The Great Pacific Garbage Patch will be difficult to physical clean up because it actually lies in the international water, and no single nation is responsible for it's creation, also the filtering out of the plastic will effect the marine animals and diversity of marine phtoplanktons and zooplanktons.

1. efficient use of space

2. elimination of groundwater contamination

3. energy generation

4. lower carbon footprint

im not intirely sure but i think the anwser is d relative humidity