Currents, Waves and Properties of Water Unit 4 Currents, Waves and Properties of Water

Water We live on a water planet Over 70% of the Earth’s surface is covered with water 97% of that is saltwater If it were not for water and its properties, life on Earth would not be possible

Water – Chemical Properties Formed by covalent bond 1 oxygen and 2 hydrogen atoms Polar molecule Positively and negatively charged ends attract each other

Properties of Water Chart Define each of the properties of water Describe how each property relates to the marine environment

Example: Adhesion The Lumpsucker Fish

Properties of Water Continued!

pH “Potential of Hydrogen” A system of classifying how acidic or basic something is

pH

Acids (0-6) Substances that release hydrogen ions (H+) when dissolved in water The more H+ ions released, the more acidic the solution becomes Reminder: *Ion – an atom that has gained or lost electrons

Bases (8-14) Substances that release hydroxide ions (OH-) when dissolved in water The more hydroxide ions a substance releases, the more basic (alkaline) the solution becomes

Neutral pH 7 (pure water) Equal amount of hydrogen ions (H+) and hydroxide ions (OH-)

pH and the Ocean pH ranges from 7.5 to 8.2 In saltwater, pH is closely related to dissolved CO2 CO2 is a reactant of photosynthesis and a product of respiration. It dissolves easily in saltwater. Decreases in pH could result in lowered enzyme activity and could dissolve the shells of marine animals

Global Climate Change Causes Increased CO2 & Methane from burning of fossil fuels Deforestation Pollution

Global Climate Change Consequences Ocean acidification Rising sea level Changing weather patterns Habitat loss

Global Climate Change Solutions Educate Alternative energy Sustainable practice Legislation

Biogeochemical Cycles The movement (or cycling) of matter through a system Matter refers to elements (C, N, O) or molecules (water) All matter cycles; it is neither created nor destroyed

Biogeochemical Cycles Include: Hydrologic Cycle Nitrogen Cycle Oxygen Cycle Carbon Cycle

Dissolved Gases Dissolved Nitrogen Most prevalent Cannot be used by organisms until it is attached to oxygen in a process called nitrogen fixation Nitrogen fixation is important because blue-green algae convert nitrogen to a usable form that animals need for building amino acids

Dissolved Oxygen Important to the survival of organisms Too much can be toxic Comes from marine plants and algae (through photosynthesis); also wave action Below the thermocline, there is very little oxygen Thermocline – a thin but distinct layer in which temp changes more rapidly with depth than it does in the layer above or below it

Carbon Dioxide Comes from air, respiration Very soluble More carbon dioxide in the ocean than in the atmosphere (carbon sink)

pH is Logarithmic Each whole number on the pH scale differs by a factor of 10 Example: A pH of 2 is 10X more acidic than a pH of 3 A pH of 2 is 100X more acidic than a pH of 4, 1000X more acidic than a pH of 5 and 10,000X more acidic than a pH of 6…

Effects of Carbon Dioxide on pH Demonstration Effects of Carbon Dioxide on pH

Acid Neutral Base *Bromethymol Blue pH indicator in an acidic, neutral & basic solution

Ocean Acidification A decrease in ocean pH due to the absorption of CO2 from the atmosphere.

4 Key Concepts The amount of CO2 in the atmosphere is increasing The chemistry of the ocean depends on the chemistry of the atmosphere Water becomes more acidic (lower pH) the more CO2 it contains Increased ocean acidity impacts marine organisms’ abilities to make and keep their shells

Cartoon: Ocean Acidification By the Alliance for Climate Change

The Battle for Carbonate Carbonate ions (CO3) (found naturally in seawater) are used by animals to make shells When CO2 reacts with seawater, it releases H+ ions The more H+ ions there are, the more acidic the ocean becomes. As a result, shelled creatures need to spend their energy making shells instead of finding food

Acid Test: The Global Challenge of Ocean Acidification What are the effects of ocean acidification on the marine environment?

Calcium carbonate part Coral skeleton Skeleton (test) Shell Component of fronds Calcium carbonate part Stony coral Sea urchins Pteropods Coralline algae Fish

Effects of Ocean Acidification: Thinner, smaller and weaker shells in shellfish (especially at the larval stage) Fitness Effect - Lower survival due to: Increased crushing & drilling by predators Increased risk of desiccation at low tide

Reduced hearing ability in some fish Ear bones (otoliths) made of CaCO3 Fitness Effect - Lower survival due to easier predation Increased photosynthesis & growth for marine algae Lower pH means more CO2 fuel for growth Fitness Effect – higher survival and pop growth