enviro CH7

define: positive feedback loops

A positive feedback loop tends to accelerate it.

define: fertilizer

A chemical or natural substance added to soil to increase its fertility.

define: aquifers

A body of permeable rock that can contain or transmit groundwater.

define: negative feedback loops

A negative feedback loop is one that tends to slow down a process

define: nutrients

A substance that provides nourishment essential for growth and the maintenance of life.

what causes a dead zone?

Aquatic and marine dead zones can be caused by an increase in chemical nutrients (particularly nitrogen and phosphorus) in the water, known as eutrophication. These chemicals are the fundamental building blocks of single-celled, plant-like organisms that live in the water column, and whose growth is limited in part by the availability of these materials. Eutrophication can lead to rapid increases in the density of certain types of these phytoplankton, a phenomenon known as an algal bloom.

what is a "dead zone"?

Dead zones are hypoxic (low-oxygen) areas in the world's oceans and large lakes, caused by "excessive nutrient pollution from human activities coupled with other factors that deplete the oxygen required to support most marine life in bottom and near-bottom water.

define: hypoxia

Deficiency in the amount of oxygen reaching the tissues.

define: eutrophication

Excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life and death of animal life from lack of oxygen

what are the consequences of a dead zone?

Low oxygen levels recorded along the Gulf Coast of North America have led to reproductive problems in fish involving decreased size of reproductive organs, low egg counts and lack of spawning; death of keystone species within the marine ecosystem

what are solutions to dead zones?

One obvious solution is to simply discontinue the use of synthetic fertilizers because they are the clear source of nitrogen and phosphorous, which are the leading cause of hypoxia.

what is the "water cycle"?

The cycle of processes by which water circulates between the earth's oceans, atmosphere,

define: feedback loops

feedback circuit: a circuit that feeds back some of the output to the input of a system.

define: ground water

underground water that is held in the soil and in pervious rocks.

define: evaporation

vaporization: the process of becoming a vapor.