External energy source

PRIMARYPRODUCERS

CONSUMERS DECOMPOSERS

ABIOTIC ENVIRONMENT

Figure 51.1

Figure 54-14

THE GLOBAL CARBON CYCLE

Organisms, chemicalprocesses in ocean:

40,000

All values in gigatons of carbon per year Atmosphere: 778 (during 1990s)

Net uptake viaphotosynthesisby plants: 3.0

Net uptake viaphotosynthesis,

chemical processes: 1.5

Rivers (erosion):0.8

Organisms, soil,litter, peat: 2190

Aquatic ecosystems Terrestrial ecosystems Human-induced changes

Land-use change(primarily deforestation):

1.6Fossil-fuel use:

6.3

Land use

Fossil fuel use

Year

An

nu

al f

lux

of

carb

on

(10

15g

)

6

5

4

3

2

1

01860 1880 1900 1920 1940 1960 1980

Figure 51.12a

Human-induced increases in CO2 flux over time

Year

CO

2 co

nce

ntr

atio

n (

pp

m)

360

350

340

330

320

3101960 1970 1980 1990

Figure 51.12b

Atmospheric CO2

<3535–5555–90>90

Productivity ranges (g/m2/yr)

Figure 51.3b

Marine productivity

0–100100–200200–400400–600600–800>800

Productivity ranges (g/m2/yr)

Figure 51.3a

Terrestrial productivity

Figure 54-2

0

Net primary productivity(kgC/m2/year)

3

2

1

Figure 54-3

NPP per unit area Area covered, byecosystem type

Total NPP

TerrestrialAquatic

Figure 54-16

THE GLOBAL NITROGEN CYCLE

Nitrogen-fixingcyanobacteria: 15

All values in gigatons of nitrogen per year

Atmospheric nitrogen (N2)

Protein andnucleic acidsynthesis

Bacteria in muduse N-containingmolecules as energysources, excrete N2: 310

Decomposition ofdetritus into ammonia

Internal cycling:

1200

Industrialfixation: 100

Lightningand rain: 3

Internalcycling:

8000

Permanent burial: 10

Runoff: 36

Mud

Nitrogen-fixing bacteriain roots and soil: 202