CHAPTER 3 -part 2- Biogeochemical Cycles

3-4 What Happens to Matter in an Ecosystem? Concept 3-4 Matter, in the form of nutrients, cycles within and among ecosystems and the biosphere, and human activities are altering these chemical cycles.

Nutrients Cycle in the Biosphere Biogeochemical cycles, nutrient cycles Hydrologic Carbon Nitrogen Phosphorus Sulfur Nutrients may remain in a reservoir for a period of time

Water Cycles through the Biosphere Natural renewal of water quality: three major processes Evaporation Precipitation Transpiration Alteration of the hydrologic cycle by humans Withdrawal of large amounts of freshwater at rates faster than nature can replace it Clearing vegetation Increased flooding when wetlands are drained

Figure 3.16: Natural capital. Condensation Condensation Ice and snow Transpiration from plants Precipitation to land Evaporation of surface water Evaporation from ocean Runoff Lakes and reservoirs Precipitation to ocean Runoff Increased runoff on land covered with crops, buildings and pavement Infiltration and percolation into aquifer Increased runoff from cutting forests and filling wetlands Runoff Figure 3.16: Natural capital. This diagram is a simplified model of the water cycle, or hydrologic cycle, in which water circulates in various physical forms within the biosphere. Major harmful impacts of human activities are shown by the red arrows and boxes. Question: What are three ways in which your lifestyle directly or indirectly affects the hydrologic cycle? Groundwater in aquifers Overpumping of aquifers Water pollution Runoff Ocean Natural process Natural reservoir Human impacts Natural pathway Pathway affected by human activities Fig. 3-16, p. 67

Glaciers Store Water Figure 3.17: Hubbard glacier in the U.S. state of Alaska stores water for a long time as part of the hydrologic cycle. However, mostly because of recent atmospheric warming, many of the world’s glaciers are slowly melting. Fig. 3-17, p. 68

Water Erodes Rock in Antelope Canyon Figure 3.18: Water flowing over the earth’s surfaces for millions of years played a major role in the formation of the Antelope Canyon in the U.S. state of Arizona. Fig. 3-18, p. 69

Science Focus: Water’s Unique Properties Properties of water due to hydrogen bonds between water molecules: Exists as a liquid over a large range of temperature Changes temperature slowly High boiling point: 100˚C Adhesion and cohesion Expands as it freezes Solvent Filters out harmful UV

Hydrogen Bonds in Water Figure 6 Hydrogen bond: The slightly unequal sharing of electrons in the water molecule creates a molecule with a slightly negatively charged end and a slightly positively charged end. Because of this electrical polarity, the hydrogen atoms of one water molecule are attracted to the oxygen atoms in other water molecules. These fairly weak forces of attraction between molecules (represented by the dashed lines) are called hydrogen bonds. Supplement 4, Fig 6

Carbon Cycle Depends on Photosynthesis and Respiration Link between photosynthesis in producers and respiration in producers, consumers, and decomposers Additional CO2 added to the atmosphere Tree clearing Burning of fossil fuels Warms the atmosphere

Carbon dioxide in atmosphere Respiration Photosynthesis Animals (consumers) Burning fossil fuels Diffusion Forest fires Plants (producers) Deforestation Transportation Respiration Carbon in plants (producers) Carbon dioxide dissolved in ocean Carbon in animals (consumers) Decomposition Carbon in fossil fuels Marine food webs Producers, consumers, decomposers Figure 3.19: Natural capital. This simplified model illustrates the circulation of various chemical forms of carbon in the global carbon cycle, with major harmful impacts of human activities shown by the red arrows. Question: What are three ways in which you directly or indirectly affect the carbon cycle? Carbon in limestone or dolomite sediments Compaction Process Reservoir Pathway affected by humans Natural pathway Fig. 3-19, p. 70

Increase in Atmospheric Carbon Dioxide, 1960-2009 Figure 14 This graph shows the atmospheric concentration of carbon dioxide (cO2) measured at a major atmospheric research center in Mauna Loa, Hawaii, 1960–2009. The annual fluctuation in CO2 values occurs because land plants take up varying amounts of CO2 in different seasons. (Data from Scripps Institute of Oceanography, 2010, and U.S. Energy Information Agency, 2010) Supplement 9, Fig 14

Nitrogen Cycles through the Biosphere: Bacteria in Action (1) Nitrogen fixed by lightning Nitrogen fixed by bacteria and cyanobacteria Combine gaseous nitrogen with hydrogen to make ammonia (NH3) and ammonium ions (NH4+) Nitrification Soil bacteria change ammonia and ammonium ions to nitrate ions (NO3-) Denitrification Nitrate ions back to nitrogen gas

Nitrogen Cycles through the Biosphere: Bacteria in Action (2) Human intervention in the nitrogen cycle Additional NO and N2O in atmosphere from burning fossil fuels; also causes acid rain N2O to atmosphere from bacteria acting on fertilizers and manure Destruction of forest, grasslands, and wetlands Add excess nitrates to bodies of water Remove nitrogen from topsoil

Nitrates from fertilizer runoff and decomposition Process Nitrogen in atmosphere Denitrification by bacteria Reservoir Nitrification by bacteria Pathway affected by humans Natural pathway Nitrogen in animals (consumers) Electrical storms Nitrogen oxides from burning fuel and using inorganic fertilizers Volcanic activity Nitrogen in plants (producers) Decomposition Nitrates from fertilizer runoff and decomposition Uptake by plants Figure 3.20: Natural capital. This diagram is a simplified model of the circulation of various chemical forms of nitrogen in the nitrogen cycle in a terrestrial ecosystem, with major harmful human impacts shown by the red arrows. Question: What are three ways in which you directly or indirectly affect the nitrogen cycle? Nitrate in soil Nitrogen loss to deep ocean sediments Nitrogen in ocean sediments Bacteria Ammonia in soil Fig. 3-20, p. 71

Human Input of Nitrogen into the Environment Figure 16 Global trends in the annual inputs of nitrogen into the environment from human activities, with projections to 2050, are shown in this graph. (Data from 2005 Millennium Ecosystem Assessmentt) Supplement 9, Fig 16

Phosphorus Cycles through the Biosphere Cycles through water, the earth’s crust, and living organisms Limiting factor for plant growth Impact of human activities Clearing forests Removing large amounts of phosphate from the earth to make fertilizers Erosion leaches phosphates into streams

Pathway affected by humans Process Reservoir Pathway affected by humans Natural pathway Phosphates in sewage Phosphates in fertilizer Plate tectonics Phosphates in mining waste Runoff Runoff Sea birds Runoff Phosphate in rock (fossil bones, guano) Erosion Ocean food webs Animals (consumers) Phosphate dissolved in water Phosphate in shallow ocean sediments Phosphate in deep ocean sediments Figure 3.21: Natural capital. This is a simplified model of the circulation of various chemical forms of phosphorus (mostly phosphates) in the phosphorus cycle, with major harmful human impacts shown by the red arrows. Question: What are three ways in which you directly or indirectly affect the phosphorus cycle? Plants (producers) Bacteria Fig. 3-21, p. 73

Sulfur Cycles through the Biosphere Sulfur found in organisms, ocean sediments, soil, rocks, and fossil fuels SO2 in the atmosphere H2SO4 and SO4- Human activities affect the sulfur cycle Burn sulfur-containing coal and oil Refine sulfur-containing petroleum Convert sulfur-containing metallic mineral ores

Sulfur dioxide in atmosphere Sulfuric acid and Sulfate deposited as acid rain Burning coal Refining fossil fuels Smelting Sulfur in animals (consumers) Dimethyl sulfide a bacteria byproduct Sulfur in plants (producers) Mining and extraction Uptake by plants Sulfur in ocean sediments Figure 3.22: Natural capital. This is a simplified model of the circulation of various chemical forms of sulfur in the sulfur cycle, with major harmful impacts of human activities shown by the red arrows. Question: What are three ways in which your lifestyle directly or indirectly affects the sulfur cycle? Decay Decay Process Sulfur in soil, rock and fossil fuels Reservoir Pathway affected by humans Natural pathway Fig. 3-22, p. 74