Sympathetic vs parasympathetic nervous system define and contrast

Sympathetic nervous system:

Sympathetic nervous system helps the body to prepare at conditions such as threat and danger. This system increases the heart beat and cause muscle contraction. This system is referred as "fight or flight" system.

Parasympathetic nervous system:

Parasympathetic nervous system controls the body to prepare at rest. This system maintains the homeostasis, decreases the heart beat and causes the relaxation of muscles. This system is referred as "rest and digest" system.

affects the water bodies: excessive use of fertilizers causes eutrophication. the fertilizers which are used on plants affect the quality of land on which it is used, further causing erosion of soil. the fertilizers used on plants contain harmful chemical fumes which affect the environment.