EARTH 222 Final: ocean final exam study guide

11 Pages
Unlock Document

Earth and Environmental Sciences
Brian Arbic

LIGHT, NUTRIENTS, PHOTOSYNTHESIS, PRIMARY PRODUCTION (Lectures 20-22) ● 4 ingredients for photosynthesis ○ Water, CO2, nutrients, energy ● 2 ingredients for photosynthesis that are typically limiting ○ Nutrient availability ○ Energy- solar radiation is the primary energy source, light availability determines where and when photosynthesis occurs ● key factors that affect transmission of light through water (absorption and reflection) ○ Absorption: Water absorbs sunlight, very little penetrates to depths below ~100 m ■ Only short wavelength, high energy part of spectrum makes it to 10m and below (blue-green light) ○ Reflection and scattering: Light rays encounter rough, uneven surface and reflect in different directions ■ Upward scattering is termed backscattering ■ In clear water, scattering is limited and most red and yellow light absorbed, reflected light is blue-green ■ In turbid, ie high particle content water, most visible wavelengths are backscattered ● why is the ocean blue and the Huron River brown? ○ Ocean has clear water- absorbs red and yellow light; reflects blue and green back ● difference between photic zone and aphotic zone ○ Photic Zone: Zone in the upper ocean where light is of sufficient intensity to support photosynthesis (~21% of the surface value) ■ Most marine plants live in photic zone ○ Aphotic Zone: Portion of a lake or ocean where there is little or no sunlight ■ Depths beyond which less than 1% of sunlight penetrates ● basic chemical equations describing photosynthesis and respiration ○ Photosynthesis: 6CO2+6H2O→ C6H12O6+6O2 ○ Respiration: C6H12O6+6O2→ 6CO2+6H2O ● difference between autotrophs and heterotrophs ○ Autotrophs: Create their own food using external energy source through primary production ■ Plants, algae, some bacteria ○ Heterotrophs: Unable to make organic compounds from inorganic compounds, must eat autotrophs or other heterotrophs ■ All animals, most bacteria and fungi ■ Heterotrophs live only where autotrophs provide food source ● key limiting nutrient in the ocean and why it is required for photosynthesis ○ Iron ■ There are other things going on that require iron ● in the water column, where does primary production typically exceed respiration? where does the reverse occur? how does this affect the nutrient concentrations in these two zones? ○ Rate of primary production falls off rapidly with water depth, but respiration remains constant ○ Where P>R, autotrophs can grow and reproduce, producing more organic matter than they consume, creating food supply for heterotrophs ○ Where P=R, primary production and respiration are comparable. Typically at ~1% light intensity ○ Where P
More Less

Related notes for EARTH 222

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.