LIVING IN THE ENVIRONMENT 17THMILLER/SPOOLMAN

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

Fig. 3-16, p. 67

Condensation Condensation

Ice and snow

Transpiration from plants

Precipitation to land Evaporation of

surface water Evaporation from ocean

Runoff

Lakes and reservoirs Precipitatio

n to oceanRunoff

Increased runoff on land covered with crops, buildings and pavementInfiltration and

percolation into aquifer

Increased runoff from cutting forests and filling wetlands

Runoff

Groundwater in aquifers

Overpumping of aquifers

RunoffWater pollution

Ocean

Natural process

Natural reservoir

Human impacts

Natural pathwayPathway affected by human activities

Glaciers Store Water

Fig. 3-17, p. 68

Water Erodes Rock in Antelope Canyon

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

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

Fig. 3-19, p. 70

Carbon dioxide in atmosphere Respiration

Photosynthesis

Animals (consumers) Burning

fossil fuelsDiffusion Forest fires

Plants (producers)Deforestation

Transportation RespirationCarbon in

plants (producers)

Carbon dioxide dissolved in ocean

Carbon in animals

(consumers)Decomposition

Marine food webs Producers, consumers, decomposers

Carbon in fossil fuels

Carbon in limestone or dolomite sediments

Compaction

Process

Reservoir

Pathway affected by humans

Natural pathway

Increase in Atmospheric Carbon Dioxide, 1960-2009

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 cycle1. Additional NO and N2O in atmosphere from burning

fossil fuels; also causes acid rain2. N2O to atmosphere from bacteria acting on

fertilizers and manure3. Destruction of forest, grasslands, and wetlands4. Add excess nitrates to bodies of water5. Remove nitrogen from topsoil

Fig. 3-20, p. 71

ProcessNitrogen in atmosphere

Denitrification by bacteriaReservoirNitrification by bacteriaPathway affected by humans

Natural pathwayNitrogen in

animals (consumers)Nitrogen oxides

from burning fuel and using inorganic fertilizers

Volcanic activity

Electrical storms

Nitrogen in plants

(producers)

DecompositionNitrates from

fertilizer runoff and

decompositionUptake by plants

Nitrate in soil

Nitrogen loss to deep ocean sediments

Nitrogen in ocean sediments

Bacteria

Ammonia in soil

Human Input of Nitrogen into the Environment

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 activities1. Clearing forests2. Removing large amounts of phosphate from the

earth to make fertilizers3. Erosion leaches phosphates into streams

Fig. 3-21, p. 73

ProcessReservoir

Pathway affected by humansNatural pathway

Phosphates in sewage

Phosphates in fertilizer Plate

tectonicsPhosphates in mining waste RunoffRunoff

Sea birds

RunoffPhosphate in rock (fossil bones, guano)

ErosionOcean food webs

Animals (consumers) Phosphate

dissolved in water

Phosphate in shallow ocean sediments

Phosphate in deep ocean sediments

Plants (producers)

Bacteria

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

Fig. 3-22, p. 74

Sulfur dioxide in atmosphere

Sulfuric acid and Sulfate deposited as acid rain

Smelting Burning coal

Refining fossil fuels

Dimethyl sulfide a bacteria byproduct

Sulfur in animals

(consumers)

Sulfur in plants

(producers)Mining and extraction Uptake

by plantsSulfur in ocean sediments

Decay

Decay

Process Sulfur in soil, rock

and fossil fuelsReservoirPathway affected by humansNatural pathway