Oceans serve as significant reservoirs for carbon dioxide (CO2), absorbing a substantial portion (approximately one-third) of anthropogenically generated emissions, thus acting as a buffering mechanism against climate change. However, this absorption process contributes to a phenomenon known as ocean acidification, which denotes alterations in oceanic chemistry.
Ocean acidification is characterized by a reduction in ocean pH, attributable to an augmented concentration of hydrogen ions resulting from the absorption of carbon compounds from the atmosphere.
Chemical Reaction involved in ocean acidification
With the increasing uptake of atmospheric carbon dioxide by the ocean, the concentration of hydrogen ions rises. Concurrently, the concentration of carbonate ions decreases, leading to a decline in the pH of the oceans. Consequently, the oceans undergo a shift toward reduced alkalinity. This process, recognized as ocean acidification, raises concerns due to its potential adverse impacts on marine ecosystems and organisms.
Seawater and CO2: Seawater naturally absorbs CO2 from the air, creating compounds like carbonic acid and carbonate ions.
Importance of Carbonate Ions: Carbonate ions are essential for the building process of marine organisms such as corals, sea urchins, and lobsters, forming their shells and skeletons.
Problem with More CO2: Elevated levels of atmospheric CO2 lead to increased acidity in the ocean, affecting the balance of carbonic acid and carbonate ions.
Consequences of Less Carbonate Ions: The reduced availability of carbonate ions makes it challenging for marine creatures to perform calcification, impacting their ability to build structures like shells.
Resulting Challenge: This difficulty in building structures due to decreased carbonate ions may have significant consequences for ocean life, particularly for economically important marine species.
Long-Term Fate of Carbon:
Upwelling:
Coastal Upwelling
Definition: Sometimes, ocean areas get a visit from deep water that's full of nutrients and CO2.
Effect of Ocean Acidification: Because the upper ocean is becoming less saturated with CO2 each year due to ocean acidification, these visits might bring up water that could affect sea life, especially creatures that make shells.
Rock Weathering
Rock Weathering: However, the process of rocks soaking up CO2 is slow and can't quickly get rid of the CO2 we're putting into the air.
Short-Term Carbon Cycling:
Carbon Cycling
Internal Feedback: Over shorter times (more than 1,000 years), the ocean has a way of managing carbon. It's like a self-regulating system that involves carbonate-rich sediment.
Ocean Layers: The upper ocean is good at keeping carbonate (like a shell material) without it dissolving. Deeper ocean layers dissolve carbonate.
Lysocline: Think of the lysocline as the point where deep ocean dissolving really starts to kick in.
Sinking Shells: Shells from sea creatures sink to the ocean floor. In shallow water, they get buried and stick around for a long time. But in deep water, most of them dissolve, not trapping carbon for millions of years.
Carbonate Compensation Depth (CCD)
Impact of Ocean Acidification: More CO2 going into the ocean messes up this balance. As the ocean becomes more acidic, it makes the lysocline and another depth (called carbonate compensation depth or CCD) shallower. This exposes more trapped shells to conditions that might dissolve them, which helps a bit with ocean acidification, but it takes a long time—like a thousand years.
Some Benefit: Certain marine plants and phytoplankton might grow more and do better with higher CO2 levels.
Not a General Rule: But this doesn't happen for all plants. It's not a rule that applies to everyone.
Varied Responses: For some, more CO2 and increased acidity might be bad or not really affect them much.
Important Action: To stop ocean acidification from getting worse, it's crucial to lower the levels of CO2 in the air. This needs to happen before it's too late.
So, some marine plants will do well, some might struggle, and others may not show any clear changes, but change is bound to happen.
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1. What is ocean acidification and how is it caused by CO2? |
2. What are some local influences on ocean acidification? |
3. How does ocean acidification affect marine life? |
4. What are some mitigation strategies for ocean acidification? |
5. How does ocean acidification impact the fate of carbon in the system? |
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