Eutrophication is the enrichment of an ecosystem with chemical nutrients, typically compounds containing nitrogen, phosphorus, or both.

Eutrophication can be a natural process in lakes, occurring as they age through geological time.

All though it may sound like a good thing, 

it certainly isn't. 

Human activities can accelerate the rate at which nutrients enter ecosystems.

Runoff from agriculture and development, pollution from septic systems and sewers, and other human-related activities increase the flux of both inorganic nutrients and organic substances into terrestrial, aquatic, and coastal marine ecosystems (including coral reefs).
Eutrophication creats a dead zone because as the algae dies they use up the oxygen and all the other organisms die off aswell.

1. Rubbish is being generated faster than other environmental pollutants, including greenhouse gases. Plastic clogs the world's oceans and rivers, causing flooding in developing-world cities. Solid-waste management is one of the greatest costs to municipal budgets.

Soil degradation is the decline in soil quality caused by its improper use, usually for agricultural, pastural, industrial or urban purposes. 

Soil degradation is a serious global environmental problem and may be exacerbated by climate change. It encompasses physical, chemical and biological deterioration. Examples of soil degradation include loss of organic matter, decline in soil fertility, decline in structural condition, erosion, adverse changes in salinity, acidity or alkalinity, and the effects of toxic chemicals, pollutants or excessive flooding.