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By: Amanda and Andrew

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Co ntents:

C arb o nateC arb o nate System

C arb o nate EquilibriumOcean Acidificati o nDep o sitio n in So luti o n

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C arb o nate:

Measured by am o unt o f CO2 and pH presentand varies with differing pressures.

Mo st c o mm o n is calcite/calcium carb o nate(present in limest o ne and shells)

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Carb o nate SystemSimilar t o the bicarb o nate system in the

human bl oo d streamC arb o nate system is the maj o r so urce o f pHbuffering in the o cean

Diurnal and seaso

nal variatio

ns caused byrem o val o f CO2 by ph o to synthesis and radialheating.

Ex: Iro n in s o il is diss o lved by acidicrain, it seeps thr o ugh s o il int o gro undwater (remains acidic). Acidicgro undwater with minerals reachessea and is neutralized, Ir o n isdr o pped there.

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Carb o nate System c o nt.

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C arb o nate EquilibriumC

O2 disso

lves very easily in waterWhen CO2 mixes with water it bec o me carb o nic acid and o therino rganic carb o n io nsSeawater can c o nsume m o re CO2 then Freshwater due t o bicarb o nates

Pro cess:First the carb o n di o xide reacts with water t o f o rm carb o nic acidand reacts with carb o nate i o ns and f o rms bicarb o nate. Over alo ng time scale, o cean acidificati o n leads t o a decrease in theco ncentrati o n o f carb o nate i o ns in seawater.Ex: If there is a dr o p in pH levels o f 0.4 units. This c o uld causecarb o nate i o ns t o gether with calcium i o ns (basic building bl o ckso f carb o nate skelet o ns and shells) t o stay present. Theref o re,this decline w o uld have a direct effect o n the ability o f many

marine o rganisms t o pr o duce bi o genic carb o nates.

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Ocean Acidificati o n

A co ntinu o us decrease o f the pH o f water bydiss o lving CO2.CO2 gets c o nverted t o C arb o nic acid H CO3 inthe o ceans surface and releases an H + io n int o so luti o n.So me regi o ns o f the Atlantic are expected t o

have pH decrease o f .50Since pH o perates o n a l o g ten scale changeso f .10, while seemingly small, are actuallyquite large.

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Ocean Acidificati o n

Increases in atm o spheric CO2 such as the o nesh o wn bel o w have led t o a dramatic increasein pH o f o cean water.

Anthr o po genic input o f CO2 has thr o wn o ff thenatural balance o f theC arb o n C ycle and led t o an excess dep o sitio n o f CO2 int o the o cean.

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The imp o rtance o f Ocean Acidificati o n

No t an effect o f glo bal warming, but aseparate issue o f it so wn

Natural pro

cesses wo

uld take hundredso

f th o usands o f years t o repair the damage d o neAll pro po sed ge o engineering s o luti o ns t o glo bal warming d o no t address this issueMay have a very large impact o n shelledmarine invertebrates

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Dep o sitio n in s o luti o n

Under n o rmal c o nditi o ns, carb o nace o usexo skelet o ns are built by animals usingcalcium carb o nate fr o m their surr o undings.When the c o ncentrati o n o f C aCO3 dr o ps m o reeff o rt has t o be exerted by these animals t o actively maintain their shells againstdiss o lving.In the case o f extreme dr o ps in pH and[C aC O3] shells can actively diss o lve.

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Carb o nate Co mpensati o n Depth ( CC D)

The maximum depth at which the am o unt o f C alcium C arb o nate pr o duced as o rganisms asskeletal material in the o verlying waterco lumn is equal t o the rate at which it isdiss o lved in the water.C alcare o us oo ze is o nly p o ssible ab o ve thisdepthNo rmally ar o und 4500 m. Varies by l o cati o nAcidificati o n decreases the depth o f the CC D

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R eferences

An Intr o ducti o n t o the W o rld s Oceans. ByKeith A. SverdrupC

arbo

nate Equilibrium.wo rld o ceanreview.c o mC arb o nate equilibria in natural waters.Stephen K. L o werThe Glo bal C arb o n C ycle. http://www.icsu-sco pe. o rg

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Extra Material:

NR DC do cumentaryhttp://www.y o utube.c o m/watch?v=5cq C vcX7bu o

Nati o nal Ge o graphic articlehttp://ngm.nati o nalge o graphic.c o m/2011/04/o cean-acidificati o n/k o lbert-text/3

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