Lecture biology Nutrient Cycle

Nutrient Cycles PRODUCER CONSUMER DECOMPOSER Physical Environment Types of Nutrient Cycles Biogeochemical: – Bio: Processes through living organisms – Geo: Geological processes – Chemical: Chemical processes (interactions of chemicals in the environment) Types of Nutrient Cycles Biogeochemical: • Gaseous Cycle: – Main source of nutrients are the atmosphere and ocean (freshwater to a much lesser extent) – Have global circulation patterns (follow ocean currents and prevailing weather currents) • Sedimentary Cycles: – Main source of nutrients are the soil and rocks of the Earth’s crust – Rely upon weathering to release nutrients – Salt Phase: After weathering, nutrients enter water as soluble salts – Rock Phase: Accumulation of salts, silts, etc become rock General Model of Nutrient Cycling: •Inputs •Internal Cycling •Outputs Inputs to the Cycle • Through either gaseous or sedimentary cycles • Wetfall- Precipitation takes nutrients from the atmosphere or as water runs off surfaces • Dryfall- from airborne particles and aerosols Internal Cycling Recycling of nutrients WITHIN an ecosystem Requires microbial decomposers to transform organic nutrients into mineral forms (Mineralization) This makes these nutrients available for plant uptake (Primary production which drives the ecosystem) Internal Cycling Loss of nutrients from the ecosystem, inputs must be equal for the system to not experience a net loss of nutrients CO2 cycling in the atmosphere Downstream transport in lotic aquatic systems (River Continuum Concept based on nutrient flow) Ecosystems are interrelated and depend upon processing occurring at larger scales Generalized compartmental model of nutrient cycles Atmospheric cycles (e.g., N) Sedimentary cycles (e.g., P) Nutrients are recycled within an ecosystem Water Carbon Oxygen Nitrogen Phosphorus Sulfur Water Cycle • Condensation of water vapor in the air leads to precipitation • Evaporation returns water vapor to the atmosphere • Infiltration of rainwater replenishes groundwater supplies • Surface runoff of rainwater replenishes surface water supplies Denitrification Phosphorus Cycle How does the phosphorus cycle work? Phosphorus carries energy to cells It is found in phosphate (PO43-) rock and sediments on the ocean floor Weathering- through chemical or physical means -breaks down rock, releasing phosphate into the soil from longer-term stores Organisms take up phosphorus When they die, decomposers return phosphorus to the soil Excess phosphorus settles on floors of lakes and oceans, eventually forming sedimentary rock It remains trapped for millions of years until it is exposed through geologic uplift or mountain building Phosphorus Cycle How human activities affect the phosphorus cycle? Commercial fertilizers and phosphate-containing detergents enter waterways and contribute additional phosphate to the phosphorus cycle Slash-and-burn forest clearance reduces phosphate levels, as phosphate in trees enters soil as ash It leaches out of the soil and settles on lake and ocean bottoms, unavailable to organisms Phosphorus Cycle in Soil Phosphorus Cycle in Water Phosphorus in the biosphere (103 million tons P) Schlesinger, 1997 4.000.000 200 90 10 Land plants Soils Minable rock Oceans Sediments Phosphorus flux (million tons P/ yr) Schlesinger, 1997 19 20 18 16 14 12 12 10 2 Reactive River transport Mining Bound Sulfur Cycle The sulfur cycle are the collection of processes by which sulfur moves to and from minerals (including the waterways) and living systems Biogeochemical cycles are important in geology because they affect many minerals Biogeochemical cycles are also important for life because sulfur is an essential element , being a constituent of many protein and cofactors Human activity plays a dominant role in the sulfur cycle We must include the inputs due to industrial activity Sulfur Cycle The ocean represents a major reservoir of sulfur on Earth, with large quantities in the form of dissolved sulfate and sedimentary minerals The sulfur cycle has both sedimentary and gaseous phases In the long term sedimentary phase, sulfur is tied up in organic and inorganic deposits, released by weathering and decomposition, and carried to terrestrial ecosystems in salt solution The gaseous phase of the cycle permits sulfur circulation on a global scale Sulfur Cycle Steps of the sulfur cycle are: Mineralization of organic sulfur into inorganic forms, such as hydrogen sulfide (H2S), elemental sulfur, as well as sulfide mineralss Oxidation of hydrogen sulfide, sulfide, and elemental sulfur (S) to sulfate (SO42–) Reduction of sulfate to sulfide Incorporation sulfide into organic compounds (including metal-containing derivatives) Sulfur cycle for the Everglades Sulfur Cycle in Soil Questions Why is the Water/Carbon/Oxygen/Nitrogen/Phosphorus/ Sulfur /cycle important? How is Water/Carbon/Oxygen/Nitrogen/Phosphorus/ Sulfur / stored? How is Water/Carbon/Oxygen/Nitrogen/Phosphorus/ Sulfur / cycled? Name several human activities that affect the Water/ Carbon/Oxygen/Nitrogen/Phosphorus/ Sulfur / cycle? ... on nutrient flow) Ecosystems are interrelated and depend upon processing occurring at larger scales Generalized compartmental model of nutrient cycles Atmospheric cycles (e.g., N) Sedimentary cycles... dioxide Cycle Oxygen Cycle The oxygen cycle is the cycle that helps move oxygen through the three main regions of the Earth: • The Atmosphere • The Biosphere • The Lithosphere 3 Oxygen Cycle The... currents) • Sedimentary Cycles: – Main source of nutrients are the soil and rocks of the Earth’s crust – Rely upon weathering to release nutrients – Salt Phase: After weathering, nutrients enter water