Cycles & Human Impacts The Hydrologic Cycle The Carbon Cycle The Nitrogen Cycle The Phosphorus Cycle Understanding cycles provides a basis for determining how disturbances change ecosystems. In what ways are human interactions disturbing the hydrologic, carbon, nitrogen, phosphorus, and sulfur cycles? Hydrologic Removal of large quanities for use in irrigation Removal of vegetation causes increased run off and less infiltration Excess nutrients (fertilizer/sewage) cause algal blooms, hypoxic conditions, & dead zones. Eutrophication! Carbon Fossil fuel combustion- releases C from rocks; adds CO 2 to atm & increased acidity of oceans Animal waste- adds CH 4 to atm Deforestation less CO 2 removed from atm Nitrogen Combustion NO x + H 2 0 HNO 3 in atmosphere Fertilizers- increases N into aquatic ecosystems and causes plant/nutrient pollution (eutrophication) Phosphorus Fertilizers, detergents- plant/nutrient pollution (eutrophication) Sulfur Coal combustion Smelting sulfide minerals Both of which result in So x exhaust + H20 H 2 SO 4 AMD The N & P Cycles and Impacts on Aquatic Ecosystems Define nutrient. How do excess nutrients like nitrogen (and/or phosphorus) affect population sizes? How might a decrease in nutrients affect population sizes? Eutrophication An aquatic ecosystems response to an influx of nutrients (N & P mostly). Leads to slow death of pond or lake Eutrophication 1.Nutrients enter water 2.Algae blooms; limits Ps and decreases O 2 production 3.Algae die; Dead algae fall to bottom, begin decomposing 4.Decomposers consume O 2 breaking down dead algae 5.Other organisms suffocate from lack of oxygen hypoxia Eutrophication cwh.triplepointwater.com Where do the excess N & P come from? Humans! Nutrients run off from lawns, farms, golf courses, etc Nitrogen Fertilizers Livestock waste Phosphorus Laundry detergents Livestock waste Eutrophication Video 1mentalScience/course%20files/multimedia/less on78/animations/5a_Lake_Eutrophication.html Eutrophication Videos 2 & 3 Montreal LakesBarnegat Bay