Osling 5 (Siklus Penting di Laut).pdf

8/18/2019 Osling 5 (Siklus Penting di Laut).pdf

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PROGRAM STUDI OSEANOGRAFI ITB

OS 3106 Oseanografi Lingkungan/ Dr. Susanna Nurdjaman/Dr. Ivonne

SIKLUS PENTING DI LAUT

Materi Kuliah

OS 3106OSEANOGRAFI LINGKUNGAN


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Biogeochemical Cycles• natural processes that recycle nutrients in variouschemical forms from the non-living environment, to living

organisms, and then back to the non-living environment.• The flow of a nutrient from the environment to living

organisms and back to the environment• Main reservoir for the nutrient is in the environmentThree Categories :• Hydrologic cycle

– Water

• Atmospheric cycles – Nitrogen and carbon

• Sedimentary cycles – Phosphorus and sulfur


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Nutrient:• Any element that an organism musttake in to live, grow and reproduce.

• Macronutrients: C, N, O, P, S, H, water• Micronutrients: Si, K, Cu, Zn, Se, Mn, Fe, Ca


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Hydrologic Cycle• oceans are major source of water(1) ocean 97.3%

(2) polar ice caps 2.06%(3) groundwater 0.67%(4) rivers and lakes 0.01%(5) in motion via atmosphere and rivers 0.08%

• b. atmosphere picks up oceanic moisture and:c. stored on land in:

• d. lost on land back to:• e. or lost back to ocean via:

• f. vegetation modified cycle by(1)interception =(2)transpiration =(3)loss of vegetation therefore:

• g. water cycle key to transport of all of the nutrients


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Hydrologic Cycle

Atmosphere

Ocean Land

evaporationfrom ocean

425,000

precipitationinto ocean

385,000

evaporation from landplants (evapotranspiration)

71,000

precipitationonto land111,000

wind-driven water vapor40,000

surface andgroundwaterflow 40,000


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Consequences of the Hydrologic Cycle(Natural Capital)

• Climate• Erosion

• Sediment transport• Nutrient mobilization• Water purification

• Air purification• Water needs of plants and animals


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Hum an in f luenc e

• Water quantity – Over-use water-table – Deforestation and global warming

• Flooding/banjir, drought/kekeringan, & erosion • Water quality

– Human and industrial waste pollution• effluents (surface water)

• solid waste (ground water)• air (acid rain)

– Excess irrigation salinization


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Carbon Cycle

• Carbon moves through the atmosphere andfood webs on its way to and from the ocean,

sediments, and rocks• Sediments and rocks are the main reservoir• Enters water through diffusion

• Remain as CO 2 or convert to CO 32-

or HCO 3-

• Biological processes fix as CaCO 3


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The Carbon Cycle

CO 2 exchange controlled by:• Temperature of ocean surface waters

• Amount of CO 2 in water and inatmosphere• Ocean currents


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• Human influence:Ø deforestationØ combustion of fossil fuelsØ agricultureØ release of methane

• Consequence:Ø global WarmingØ depletion of soil organic matter


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OS 3106 Oseanografi Lingkungan/ Dr. Susanna Nurdjaman/Dr. IvonneCarbon Cycle - Land

photosynthesis aerobicrespirationterrestrial

rocks

soil water

land foodwebs

atmosphere

peat,fossilfuels

combustion ofwood

sedimentation

volcanic action

death, burial,compaction overgeologic time

leaching, runoff

weathering

combustion of

fossil fuels


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diffusion betweenatmosphere and ocean

bicarbonate andcarbonate in ocean

water

marine foodwebs

marine sediments

combustion of fossil fuels

incorporation into

sediments

death,sedimentation uplifting

sedimentation

photosynthesis aerobic

respiration

Carbon Cycle - Marine


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Carbon in Atmosphere• Atmospheric carbon is mainly carbon

dioxide• Carbon dioxide is added to atmosphere

– Aerobic respiration, volcanic action,burning fossil fuels

• Removed by photosynthesis


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Greenhouse Effect

• Gas-gas Greenhouse menghalangi

keluarnya panas dari permukaan bumi


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Rising Atmospheric CO 2 • Due to the increased burning of fossil

fuels

Figure 54.24

C O

2 c o n c e n

t r a

t i o n

( p p m

)

390

380

370

360

350

340

330

320

310

3001960 1965 1970 1975 1980 1985 1990 1995 2000 2005

1.05

0.90

0.75

0.60

0.45

0.30

0.15

0

0.15

0.30

0.45

T e m p e r a

t u r e v a r i a

t i o n

( C )

Temperature

CO 2

Year



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Ozone layer

Figure 54.26

O z o n e

l a y e r t h

i c k n e s s

( D o

b s o n u n

i t s

)

Year (Average for the month of October)

350

300

250

200

150

100

50

01955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005



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Carbon Dioxide :• Tingkat karbondioksida berfluktuasi secara

musiman• Rata-ratanya meningkat terus• Pembakaran bahan bakar dan penggundulan

hutan/deforestation berperan dalampeningkatannya

Other Greenhouse Gases :• CFCs - synthetic gases used in plastics and in

refrigeration• Methane (CH 4)- produced by termites and bacteria• Nitrous oxide(N 2O) - released by bacteria,

fertilizers, and animal wastes



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CFC’s (not all bad news!)

• The destruction of atmospheric ozone

Figure 54.27

1

2

3

Chlorine from CFCs interacts with ozone (O 3),forming chlorine monoxide (ClO) andoxygen (O 2).

Two ClO moleculesreact, formingchlorine peroxide (Cl 2O2).

Sunlight causesCl2O2 to breakdown into O 2 and freechlorine atoms.The chlorineatoms can beginthe cycle again. Sunlight

Chlorine O 3

O2

ClO

ClO

Cl2O2

O2

Chlorine atoms



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Oceans as a sink for CO 2•

Oceans gain 2 Gt of carbonannually. As the saturationpoint is reached the oceans willno longer be a reservoir forexcess carbon from theatmosphere.

• As the CO 2 levels get closer tothis saturation point, theoceans will begin absorbingatmospheric carbon at a slowerrate.

• This could exacerbate the CO 2 problems in our atmosphere andaccelerate global climate

change.



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• A second problem associated with increased dissolvedCO2 in the ocean is its acidity. When CO2 dissolves inwater some of it combines with water to produce H+

and HCO3-. This lowers the pH, which could have aharmful effect on marine life.

• Lastly, if the ocean surface waters warm up as aresult of global warming, the ocean's capacity fordissolved CO 2 decreases and it would then give offCO2 to the atmosphere. This would accelerate globalclimate change.



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Carbon Cycle• Oceans cover 70% of the surface area of the

Earth• Oceans only absorb 25% of the emitted CO 2,

as opposed to the 25% absorbed by plants• There is 60x more carbon in the ocean than

the atmosphere, thus the ocean drives thecarbon cycle

• Absorption of CO 2 by the ocean is also very

slow• Once CO 2 is absorbed, the carbon isestimated to stay for ~500 years*



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Phytoplankton• Large populations of this organism,sustained over long periods of time, could

significantly lower atmospheric carbondioxide levels and, in turn, lower averagetemperatures.

• The larger the world's phytoplanktonpopulation , the more carbon dioxide getspulled from the atmosphere , and the lower

the average temperatures on Earth .• The larger the world's phytoplanktonpopulation, the more CO 2 that is transferredto the depths of the ocean.



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CARBON SINKS WON'T SOLVE GLOBALWARMING - Britain's Royal Society REPORT

• Forests and farmlands cannot be relied onto soak up environmentally damaginggreenhouse gases, and cuts in emissions are

the only long-term way to reduce globalwarming, scientists said on July, 2001• This report said too little is known about

how much farmlands and forests, so-calledcarbon sinks, can absorb carbon dioxide(CO2), the main greenhouse gas, from theatmosphere.



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• According to the report, carbon sinks and soilabsorb about 40 percent of CO 2 emissions andcould soak up as much as 45 percent.

•

But it added that the maximum that could beabsorbed would only be equivalent to a quarter ofthat needed by 2050 to prevent major rises inglobal temperature. "The primary benefit of

land carbon sinks is that they can beeffective immediately and provide afinancial incentive for the preservation andsustainable use of forests and agricultureland," the report said.

• But the long-term solution must be cuts inCO2 emissions through energy saving andreplacing fossil fuels with renewable and

nuclear energy.



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Nitrogen Cycle• Nitrogen is used in amino acids and nucleic

acids• Main reservoir is nitrogen gas in the

atmosphere• Hum an in f luenc e:

Ø combustion: Nitric acidØ N-rich fertilizerØ deforestation

• Consequences :Ø acid rainØ nutrient lossØ groundwater contaminationØ cultural eutrophication



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Cultural Eutrophication

• process by which lakes progressfrom a nutrient poor state(oligotrophic) to a nutrient rich state(eutrophic) from human activities.The intermediate stage is termedmesotrophic.



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• Nitrogen Fixation – Plants cannot use nitrogen gas – Nitrogen-fixing bacteria convert nitrogen gas into

ammonia (NH 3) – Ammonia and ammonium can be taken up by

plants

• Ammonification & Nitrification

– Bacteria and fungi carry out ammonification -conversion of nitrogenous wastes to ammonia

– Nitrifying bacteria convert ammonium to nitritesand nitrates



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• Nitrogen Loss – Nitrogen is often a limiting factor in ecosystems – Nitrogen is lost from soils via leaching and runoff – Denitrifying bacteria convert nitrates and nitrites to

nitrogen gas

• Human Effects – Humans increase rate of nitrogen loss by clearing

forests and grasslands

– Humans increase nitrogen in water and air by using

fertilizers and by burning fossil fuels – Too much or too little nitrogen can compromise plant

health



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Phosphorus Cycle

• Phosphorus is part of phospholipids and allnucleotides• It is the most prevalent limiting factor in

ecosystems• Main reservoir is Earth’s crust; no gaseous

phase• Human Effects

– In tropical countries, clearing lands for agriculturemay deplete phosphorus-poor soils

– In developed countries, phosphorus runoff is causingeutrophication of waterways



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Phosphorus Cycle

• Has no gas phase —so can notdiffuse from seawater into air

• The only phosphorus that gets takenout is from fishing —once in stays

• Phosphorus comes from deadanimals, fertilizer, rocks, humanwaste and molting

PROGRAM STUDI OSEANOGRAFI ITBPhosphorus Cycle


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Phosphorus Cycle

GUANO

FERTILIZER

TERRESTRIAL ROCKS

LAND FOODWEBS

DISSOLVEDIN OCEAN

WATER

MARINEFOODWEBS

MARINE SEDIMENTS

excretion

weathering

mining

agriculture

uptakeby autotrophs

death,decomposition

sedimentation

settling outleaching, runoff

weathering

uplifting

over geologic time

DISSOLVED INSOILWATER,

LAKES, RIVERS

uptakeby autotrophs

death,decomposition



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Phosphorus Cycle

• Hum an inf luenc e:Ø fertilizer manufacture and use

- release of elemental P

- over-application of P-rich fertilizer- soil erosionØ human and animal wastes

• Consequences :Ø toxicityØ cultural eutrophication



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SulfurCycle



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Sulfur Cycle

• Hum an inf luence: atm osp her ic ox idesof su l fu rØ com bus t ion o f foss i l fuel sØ pro cess ing of m etal -su l f ide ores(Sulfuric acid is a useful by-product)

• Cons equ enc es :Ø acid RainØ smog


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