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

2. Nitrogen

3. 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. 

4. 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.

5. 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. 

6. 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

7. 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

8. 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.

10. 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.