ATOC 1060 1nd EditionBased on Chapter 8 Lecture 13 Outline of Last Lecture I. CarbonA. Organic vs. InorganicB. Major reservoirs for Organic CarbonC. Major components for Organic Carbon CycleII. Short term Organic Carbon CycleA. PhotosynthesisB. RespirationIII. Terrestrial vs. MarineA. Short term Organic Carbon CycleB. Implications of human activitiesOutline of Current Lecture I. Review From Last LectureII. Short Term/ Long Term Reservoirs III. CarbonIV. CO2 Ocean ChemistryV. Carbon Released from Limestone VI. Summary Longer Term Carbon CycleCurrent LectureI. Review Questions and Answers from Last lecture1. Why is soil part of the organic carbon cycle? Isn’t dirt actually dead? All the carbon that ends up in soil is “organic” carbon (originated somewhere alive). The processes that put carbon into soil (carbon fixing by roots) are organic. 2. Are there any feedbacks associated with the terrestrial carbon cycle? Yes! Decomposition is accelerated in warm environments, so if the Earth warms up, rates of decomposition will increase. This will add more CO2to the atmosphere, which will increase surface temperatures... These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.3. Does Ekman pumping have anything to do with productivity? Yes! Ekman transport is responsible for the narrow bands of water divergence, upwelling, and productivity along the Equator. 4. Why are the poles regions of high productivity? Marine productivity requires sunlight, CO2 and other nutrients. The poles receive continuous sunlight for half the year; CO2 dissolves more readily in cold water; density stratification in polar oceans means that surface water gets dense enough to sink and produce upwelling. 5. How does carbon get from marine reservoirs back to terrestrial reservoirs? Some dissolved CO2just cycles back into the atmosphere. Some is released through respiration by zooplankton and other marine animals. Some is released by burning fossil fuels. Most is released through volcanoes. Anything that ends up in the atmosphere can be used for photosynthesis. II. Short Term/Long Term CyclesBiology can turn into rocks by adding heat pressure and time- Roots, leaves, and dead plants decompose in soil -consumed by microbes LONG TERM-Geologic scales (thousands-millions of years)- Rocks- Carbon stays locked in reservoirs, out of atmosphere, for a long time SHORT TERM- Human scales (days, months, years, decades)- Biology- CO2 cycles fairly rapidly between reservoirs- Anything not consumed by microbes collects as sediment - Layers of sediment build up over time -heat and pressure from overlying layers turn sediment into coal Lithification: process of turning something into a rock Is Coal a long term reservoir?Yes and No - Buried coal can remove CO2 from atmosphere for millions of years - Burned coal releases CO2 back into atmosphere in decades-centuries - Coal is produced from the terrestrial organic cycle - Other fossil fuels are produced from the Marine Organic Cycle Biological pump: Organic matter that reaches the seafloor is deposited as sediment - Same process as coal formation. Add heat and pressure! Oil Shale- Contains kerogen- First step to petroleum = requires more time, heat, and pressure - Deposition settings: lakes, shallow marine, lagoons = anaerobic settings- Generally formed from algae but sometimes from terrestrial plants - Would also be a long-term reservoir... except when used as a fossil fuelIII. CarbonHow is it naturally released?- Burning fossil fuels speeds up the process - Earth has natural ways to remove carbon from rocks Physical/mechanical weathering: rocks break down by physical processes, such as ice growth, wind or sand erosion, plant growth, heat stress Chemical weathering: rocks break down by exposure to chemicals, such as acid rain - Weathered Carbon goes into the ocean and contributes to marine inorganic carbon cycle - Marine inorganic carbon cycle has the largest reservoir: limestone- The ocean is very important for removing CO2 from the atmosphereHow does carbon get into the ocean (making limestone)? 1. Organic material transported by rivers 2. Rivers transport inorganic minerals in weathered rock 3. Diffusion of inorganic carbon into Surface Ocean from atmosphere DIFFUSION REVIEW- Material moves from reservoirs with high concentration to reservoirs with lowerConcentration: down the gradient - Atmospheric CO2> oceanic CO2 so inorganic carbon diffuses into surface ocean - Surface ocean concentration depends on temperature - CO2 dissolves in liquid - Cold liquids can dissolve more CO2 which is why we keep drinks in a cooler at a BBQ = keep them carbonatedIV. CO2 Ocean ChemistryChemical reactions with CO2 are an important part of the marine inorganic carbon cycleRemember – trying to get atmospheric CO2 into limestoneWhat happens with the weathered minerals from rocks?Oceans get calcium, silica, and carbonateOceans already have dissolved CO2, which reacts with calcium and silicaHow?Plankton do the work!Phytoplankton take up CO2 through photosynthesis and through shell formation Phytoplankton use CO2- Calcium silicate combines with carbon dioxide to form calcium carbonate - Phytoplankton use CO2 to create their CaCO3 shells - Shell formation removes CO2 from surface of the ocean, so the ocean can absorb more CO2 from atmosphere- CaCO3 (Phytoplankton shells) plates are made of inorganic carbon - When phytoplankton die, their plates sink to the deep ocean - The shells can dissolve or be eaten... But some plates survive - Plates deposited on seafloor = carbonate deposition - Lithification of CaCO3plates = limestone- Formation of limestone removes CO2 semi-permanently from ocean and therefore from atmosphere Semi Permanently: Seafloor sediments ≠ weathered Exposed if: -Oceans dry up -Rocks brought to surface -VolcanismV. Carbon Released from LimestonePlate tectonics: Earth’s crust is made of a number of thin rigid plates that are constantly moving - Sometimes a plate moves underneath another one and the intense heat/pressure melts it- If the rocks in the tectonic plate are limestone, the limestone melts and releases its stored CO2- Tectonic movement and limestone melting happen on long timescales. Volcanoes