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Questions and Answers
What does the pH scale measure?
What does the pH scale measure?
What is the chemical reaction that occurs when CO2 dissolves in seawater?
What is the chemical reaction that occurs when CO2 dissolves in seawater?
How does ocean pH change with depth?
How does ocean pH change with depth?
What is the approximate pH value of today’s ocean?
What is the approximate pH value of today’s ocean?
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What is the projected change in ocean pH by the year 2100?
What is the projected change in ocean pH by the year 2100?
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What is the impact of acidification on carbonate saturation depth?
What is the impact of acidification on carbonate saturation depth?
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How does ocean acidification impact marine larvae?
How does ocean acidification impact marine larvae?
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What are pteropods?
What are pteropods?
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How can ocean acidification impact fisheries?
How can ocean acidification impact fisheries?
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What is the significance of the carbonate ion (CO3^2-) in the context of ocean acidification?
What is the significance of the carbonate ion (CO3^2-) in the context of ocean acidification?
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Flashcards
pH definition
pH definition
pH is the negative logarithm of hydrogen ion concentration.
pH scale
pH scale
A logarithmic scale ranging from 0 to 14 measuring acidity or alkalinity.
Ocean acidification
Ocean acidification
Ocean acidification is the decrease in pH due to dissolved CO2.
Carbonate ion decrease
Carbonate ion decrease
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Future pH projections
Future pH projections
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Buffering in seawater
Buffering in seawater
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Impact on marine larvae
Impact on marine larvae
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Effects on shellfish
Effects on shellfish
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Carbonate saturation depth
Carbonate saturation depth
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Impact on food webs
Impact on food webs
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Study Notes
Ocean pH & Acidification
- The pH scale is logarithmic, meaning a 0.1 decrease in pH represents a 30% increase in acidity.
- Pre-industrial levels of acidity increased by 16% by the year 2100.
- By 2100 there will be a decrease of 0.3 to 0.4 units in pH, a 100-150% increase in acidity, and a 50% decrease in carbonate ion levels.
- Ocean water is slightly alkaline, but this alkalinity decreases with depth.
- Upwelling brings lower pH surface waters to the surface.
- pH is defined as the negative logarithm of hydrogen ion concentration.
- Increasing CO2 in seawater lowers ocean pH.
Chemical Reactions
- Carbon dioxide (CO2) dissolved in seawater reacts with water (H2O) to form carbonic acid (H2CO3).
- Carbonic acid dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3−).
- Hydrogen ions increase, driving down pH and making the water more acidic.
- Carbonate ions (CO32-) are formed, making the water more alkaline.
Carbonate Saturation Depth
- Ocean acidification impacts the carbonate saturation depth.
- The saturation depth is the depth at which the concentration of carbonate ions is low enough for calcium carbonate to dissolve.
- Ocean acidification decreases the carbonate ion concentration, causing this depth to occur shallower in the water column.
Impacts on Biological Organisms
- Organisms that produce calcium carbonate shells or skeletons are most affected by ocean acidification.
- Calcification responses vary among organisms.
- Some crustaceans, urchins, certain algae, and corals are affected by decreasing Ω (saturation state), while shellfish also show some impacts.
- Ecological implications of these impacts are not yet fully understood.
Impacts on Food Webs and Fisheries
- Ocean acidification impacts the lower levels of the food web (e.g., coccolithophores, pteropods, and copepods).
- If organisms at the lower trophic levels cannot survive, it will have negative impacts up the food web to species, such as Pacific Salmon.
- Valuable commercial fisheries depend on species that are sensitive to ocean acidification.
- Predators that feed on calcifiers are also impacted when the food source is impacted.
Future Estimates
- Increased atmospheric CO2 levels are projected to cause ocean acidification.
- Ocean pH will decrease by 0.3−0.4 units in the coming decades.
- Ocean acidity is expected to increase by 100-150% by 2100.
- Carbonate ion concentration will decrease by 50%.
Potential Impacts on Fisheries
- Valuable fisheries depend on commercial, shellfish, and predator species that feed on calcifiers.
- Commercial landings and values for U.S. commercial fisheries were down 5.3% in 2018.
- Estimated values of the major fish species in this industry are also decreasing.
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Description
Test your knowledge on ocean pH levels and acidification processes. This quiz covers the impact of carbon dioxide on ocean chemistry, the logarithmic nature of the pH scale, and the significance of carbonate saturation depth. Dive into the effects of increasing acidity on marine ecosystems.
