What are the effects of human interference in the nutrient cycles?

Nitrogen

Eutrophication Accumulation of excess nutrients which causes and algal bloom Dumping of raw sewage, urban runoff Algae rapidly deplete all of the oxygen in the water Inhospitable for fish and other aquatic organisms. 

Red Tides Microscopic algae that produce toxins that kill fish and make shellfish dangerous to eat. Bacteria that break down dead dinoflagellates use up O2 Bloom of algae often turns the water red.

Acid Rain Burning fossil fuels and wood contributes to a large amount of nitric oxide in the atmosphere  Nitric oxide (NO) can combine with oxygen gas (O2) to form nitrogen dioxide (NO2), which reacts with water vapour to form a nitric acid (HNO3)  Acid can damage trees and kill fish. 

Result  Altering the ecosystem Use of inorganic fertilizers Depleting nitrogen resources by overharvesting legumes (which have nodules in their roots formed by a symbiotic bacteria that fix nitrogen) Result  Altering the ecosystem

Carbon Use of coal, oil, and natural gas to supply energy demands Release of stored carbon in the process of combustion. C3H8 + 5O2 → 3CO2 + 4H2O Combustion of propane

Deforestation Cutting down of trees called deforestation When we cut down trees, we lose their ability to absorb carbon dioxide Carbon that was stored in the tree also added into the environment. Healthy living forests act as a carbon sink, but when we cut them down, they are a carbon source. http://youtu.be/rm8TyJ2fOaw

Water We take water out of the system to irrigate crops, to provide us with drinking water and to carry out many of our industrial processes Precipitation picks up pollutants May include farm pesticides, herbicides and fertilizers as well as wastes from faulty septic systems and improperly handled manure. In urban areas, the pollutants may include gas, oil, pet waste, fertilizers, pesticides, salt and treated human waste from sewage treatment plants.