Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

ocean acidification

3,066 views

Published on

ocean acidification

Published in: Education
  • Be the first to comment

ocean acidification

  1. 1. OCEAN ACIDIFICATION Kajal Kamble MBT- I
  2. 2. The oceans have been absorbing large amounts of carbon dioxide since the Industrial Revolution (approximately 1750). It is this increasing amount of carbon dioxide in the oceans that is causing ocean acidification •Definition :- When carbon dioxide (CO2) is absorbed by seawater, chemical reactions occur that reduce seawater pH, carbonate ion concentration, and saturation states of biologically important calcium carbonate minerals. These chemical reactions are termed "ocean acidification" or "OA" for short.
  3. 3. CARBON CYCLE •Fluxes of carbon dioxide (CO2) - oceans, terrestrial biosphere, lithosphere, and the atmosphere. •CO2 dissolves - reacts with water - form dissolved free carbon dioxide (CO2(aq)), carbonic acid (H2CO3), bicarbonate (HCO− 3) and carbonate (CO2− 3). •Ratio of these species depends - seawater temperature and alkalinity . •These different forms of dissolved inorganic carbon are transferred from an ocean's surface to its interior by the ocean's solubility pump.
  4. 4. ACIDIFICATION  Increase in CO2 level - achieve chemical equilibrium - extra carbonic acid molecules react with a water – give bicarbonate ion, hydronium ion - increasing ocean "acidity" (H+ ion concentration).  CO2 (aq) + H2O <-> H2CO3 <- > HCO3 − + H+ <-> CO3 2− + 2 H+
  5. 5. THE BIOLOGICAL IMPACTS  Photosynthetic algae and sea grasses may benefit from higher CO2 conditions in the ocean.  More acidic environment effects calcifying species, including oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton. When shelled organisms are at risk, the entire food web may also be at risk.  Today, more than a billion people worldwide rely on food from the ocean as their primary source of protein. Many jobs and economies around the world depend on the fish and shellfish in our oceans.
  6. 6. CALCIFICATION :-  Calcium carbonate - building blocks - skeletons and shells of marine organisms.  Areas where most life now congregates in the ocean, the seawater is supersaturated with calcium carbonate minerals causes abundant building blocks for calcifying organisms to build their skeletons and shells.  Calcification involves the precipitation of dissolved ions into solid CaCO3 structures, such as coccoliths.
  7. 7. IMPACTS OF OCEAN ACIDIFICATION ON OCEANIC CALCIFYING ORGANISMS :- Increased ocean acidity affects marine organisms’ abilities to make and keep their hard parts. The more acidic the ocean, the more CO3 reacts with hydrogen, and the LESS CO3 left for marine organisms to convert into their hard parts.    “Battle” for carbonate! • Organisms must use more energy or make less hard part material • Existing hard parts dissolve (chemical reaction goes “the wrong way”)
  8. 8. OCEAN ACIDIFICATION: IMPACTS ON INDIVIDUAL MARINE ORGANISMS  Shellfish:- o Thinner, smaller and weaker shells in shellfish o Especially larval stages, which already have thin shells. o Fitness effect: Lower survival due to increased crushing and drilling by predators.  Coral:- Ocean acidification could compromise the successful fertilization in coral. • Deformed flagellum in sperm that impacts their swimming • Fitness effect: lower population growth Norma l Acidi c Reall y acidic
  9. 9. Ocean acidification: Impacts on individual marine organisms Anemone fish :- Reduced hearing ability in anemone fish (clown fish) larvae • Deformed morphology of CaCO3 fish ear bones (otoliths). • Disruption of acid-base balance in neuro-sensory system. • Fitness effect: lower survival due to higher predation. Tropical Oceans Predictions: • Corals will become increasingly rare • Algae will become more abundant • Because coral reefs support so many animals, biodiversity will decline
  10. 10. Ocean acidification: Impacts on individual marine organisms Amount of dissolved carbon Lots Little Lots Little Photosynthesis Growth Non-calcifying marine algae: Increased photosynthesis and growth • Lower pH means more dissolved CO2 for photosynthesis to fuel growth • Fitness effect: higher survival and population growth
  11. 11. What can be done? Ecological options to OA • Marine species have 4 possible options: 1. Tolerate 2. Adapt 3. Move 4. Total extinction
  12. 12. Tolerate the change through acclimatization • Acclimatize = change phenotype (traits) in response to OA • Case study: Urchin fertilization • Eggs have acid-protecting jelly coating. Sea urchin Normal Acidic Cool water Warm water Hot water
  13. 13. Move (i.e., shift distribution to non-OA waters) • In Theory, this is possible because • Larger animals can swim away • Larvae can drift away Adapt (i.e., change genetically over many generations) • Species would need a fast generation time relative to rate of pH change. e.g. California species genetically adapted for OA
  14. 14. Total extinction • A distinct possibility if ocean acidification continues. Present First modern corals Million years ago High coral growth Earth’s two most recent mass extinction events Both associated with high CO2 levels
  15. 15. OPTIONS TO PREVENT OA • Reduce fossil fuel emissions • Support policies to reduce carbon emissions • Reduce personal carbon footprint.  Iron fertilization :- Iron fertilization of the ocean could stimulate photosynthesis in phytoplankton. The phytoplankton would convert the ocean's dissolved carbon dioxide into carbohydrate and oxygen gas, some of which would sink into the deeper ocean before oxidizing. More than a dozen open-sea experiments confirmed that adding iron to the ocean increases photosynthesis in phytoplankton by up to 30 times.  Carbon negative fuels :- Carbonic acid can be extracted from seawater as carbon dioxide for use in making synthetic fuel. If the resulting fuel exhaust gas was subject to carbon capture, then the process would be carbon negative over time, resulting in permanent extraction of inorganic carbon from seawater and the atmosphere with which seawater is in equilibrium. Based on the energy requirements, this process was estimated to cost about $50 per tonne of CO2.
  16. 16. REFERENCES :-  Jacobson, M. Z. (2005). "Studying ocean acidification with conservative, stable numerical schemes for no equilibrium air-ocean exchange and ocean equilibrium chemistry". Journal of Geophysical Research.  James C.; et al. (2005). "Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms“. Web sites www.google.com www.wikipedia.com
  17. 17. THANK YOU

×