ESYS 10 Introduction to Environmental Systems February 28 Lecture: Chapter 8 Carbon cycle (organic portion today, inorganic on Thursday) Problems chapter 8, due Tuesday March 7 Review questions 1,5 Critical thinking problem 1a (part a only) Turn in problems from chapters 13 and 18 today (also Chapter 5 if not turned in already) Turn in Aquarium note page today or Thursday Mid-term discussion Case Study 3 part 1 - Biodiversity

Aquarium visit issues Anyone who hasn’t gone yet or had a problem getting in? I will leave your names at the Education office (past the bookstore).

Systems involved in carbon cycle: organic and inorganic Terrestrial ecosystem Marine ecosystem

Where is the carbon? “carbon reservoirs” Units are gigatons (Gt)

Vegetation: seasonal cycles Northern winter Northern summer

“Greenness” indices: global

Seasonal cycle of CO2 in the atmosphere (Mauna Loa observatory): imprint of biology - organic carbon cycle (plus increase from 1999 to 2000 to 2001) Respiration/ decomposition win Respiration/ decomposition win Photosynthesis wins

CO2 at Mauna Loa (“Keeling curve”): note seasonal cycle on top of long-term rise

Carbon cycle associated with biology (assuming steady state): Any imbalance results in change in atmospheric CO2 Natural cycle is likely steady state when averaged over several years.

Photosynthesis: dependence on CO2 content of atmosphere CO2 fertilization - addition of CO2 to the atmosphere. Causes increase in photosynthesis. But then plants use the CO2 and stabilize atmospheric CO2

Short-term organic carbon cycle Reservoir sizes and exchanges.

Marine organisms: phytoplankton and zooplankton

Ocean biological carbon cycle (“pump”) Upper ocean: sunlit zone Deeper ocean: no sunlight, decomposition by bacteria

Ocean’s biological “pump” and CO2

In phytoplankton, the relation between carbon, nutrients is nearly identical regardless of species: “Redfield ratios”

Effect of biological pump on carbon, oxygen, organic matter: ocean profiles with depth

Marine primary productivity (August): highest where there is upwelling to supply nutrients to surface layer (plus seasonal factors such as temperature and sunlight) Productivity map of the surface ocean waters from satellite surveys for August. The dark blue color that represents most of the ocean area indicates low productivity (i.e. low plankton). The lighter blue color in the equatorial upwelling and coastal upwelling areas indicate higher productivity (i.e higher plankton). Greens, yellows to red color zones indicate even higher productivity (the colors in the high artic are an artifact of the measurement technique, and do not indicate high productivity in the arctic region.)

Ocean circulation effect on all of this: water that’s been in the deep ocean a long time has high nutrients, high carbon, low oxygen. When it eventually upwells, it brings nutrients back to the surface.

Carbon-14 distribution in deep ocean: nothing to do with carbon cycle directly - just dating of waters Youngest waters Oldest waters

Nutrients and oxygen in the deep ocean nutrients high in old water oxygen low in old water

Reminder of marine ecosystem role in carbon cycle Terrestrial ecosystem Marine ecosystem

Organic carbon cycle including sedimentary rocks (mostly shales) Fossil fuels: peat, coal, petroleum, from sediments derived from land plants Residence time in sedimentary organic carbon reservoir is ~200 million years

Biodiversity case study Groups of 5 students Choose a fishery Identify at least 5 stakeholders Choose one position for each member of group Relevant issues?