AS Test 1 - big concepts

List everything you know about: Oxygen

• If oxygen is present, it will dominate

• Drives Redox and TEA ladder

• Things that thrive w/o oxygen cannot do so unless they’re in an anoxic environment

• In aquatic sediment if there’s OM available, about 1mm before anoxic environment

• CO2 needs oxygen so it’s also just in that top mm of sediment

• Dissolves in water 10,000x slower than CO2

• 1. Most O gets into the water from photosynthesis

• 2. Also mixing from wind - O dynamics are very different depending on wind direction

  • Enough wind can mix the water to cause resuspension, will oxygenate the sediments and restart the TEA ladder

• 3. Plant transport

  • Wetland plants have special aerenchyma tissue, acts like straws to bring oxygen down to the roots

List everything you know about: Nitorgen

• Nodes do nitrogen fixing in a peanut plant - made anoxic just to run those reactions

• Strong ass triple bond

• Bacteria takes reduced N and makes amino acids (protein) - used in building biomass

• WE NEED REDUCED FORMS TO MAKE BIOMASS

• Organic Nitrogen (DNA, amino acids) → NH4 (Ammonification)

• NH4 (reduced molecules needed to build molecules) → Organic N (Immobilization)

• NH4 → NO3 (Nitrification)(needs oxygen to happen)

• NO3 → N2O → N2 (Denitrification)(main process of using N as a terminal electron acceptor)(N2 is very hard to use since triple bonded, removal of Nitrogen from the environment since very hard to use)

  • Need:

    • NO3

    • OM

    • Bacteria

    • Anoxic environment

• N2 → NH3 → Organic Nitrogen (Nitrogen Fixation, backwards denitrification)

  • Need:

    • Specialized bacteria to break that double bond

    • Enzymes

    • Anoxic environment

      • It is an investment to break the N2 triple bonds, uses a lot of ATP

• All of this is driven by BACTERIA, oxygen, and OM (When you see nitrogen, think bacteria)

• Bacteria is in turn driven by what type of carbon (recalcitrant vs labile, C/N ratio)

List everything you know about: Phosphorus

• Phosphorus doesn’t make gases

• Phosphorus is geologic in nature and biogeochemistry

  • Once in the sediments, CANNOT LEAVE

    • Nitrogten can leave through denitrification

    • Carbon can leave as CO2 and CH4

• Phosphorus likes to bind to things BUT it first must be bioavailable

• When people measure P, they measure soluble reactive phosphorus

• As an algae or bacteria, very hard to get P inside of you so they must make an enzyme to seuester it (phosphotase)

• DNA, ATP, and phospholipids need phosphorus → organic P is bound up in these things

• When phosphorus binds, it becomes unavailable

  • In acidic conditions, Al and Fe bind phosphorus

  • In basic conditions, Ca bind phosphorus

  • MUST HAVE OXYGEN THERE TO BIND

  • If you introduce S into the complex, iron will immediaely bind with it and release phosphorus

• In anoxic conditions, it unbinds

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• NaHCO3 - P (sodium bicarbonate phosphorus)

  • Bioavilable, first P to be consumed

• Microbial P

  • P inside microbes

• HCl P (mineral P)

  • inorganic P, using HCl to pull apart means it’s primarily attatched to calcium

• Fulvic and humic acid P

  • Organic P and iron-bound P

• Residual P

  • what’s left

List everything you know about: Mercury

• Heavy metal most likely to be deposited through the atmosphere. Only heavy metal that has stabe gaseous phase - TRAVELS

• When methane attatches to mercury it can make methyl mercury

  • It becomes non-polar and like dissolves like (fats are also non polar)

  • Can now invade biology → all parts of cells are made of phospholipids, all of biology is fat based

• Bioaccumulation: as you get higher up the food chain, the concentration goes up

• Recipe for Methyl mercury:

  • OM

  • bacteria

  • anoxic conditions

• Exact recipe as denitrification

• IF MERCURY GETS INTO THE SEDIMENTS IT WILL METHYLLATE

List everything you know about: Organic Carbon

• Known from LOI

• Want to know labile vs recalcitrant (Is origin allocthanus (terrestrial) or autocthanus (aquatic)?

• Rate (C/N ratio)

  • Low C/N, labile material → gets digested fast, oxygen is used up fast, start the TEA ladder

List everything you know about: Inorganic Carbon

• Mostly found in CaCO3 (makes up shells)

• Eventually goes to carbonic acid

• Has a basic pH

• CO2 and H2O make CaCO3 (CO2 dissolves in water easily)

• Photosynthesis makes bodies of water more basic. Ex: high pH → harmful algal blooms

List everything you know about: heavy metals in the sediments

• Metals are more soluble in a reduced form (absence of oxygen, metals will move more)

• Pb

• Se (pH controlled)

• As( historically used in ag chemicals)

• Cr (industry specific)

• Co

• Cu (most common heavy metals in these systems)

• Zn (most common heavy metals in these systems)

• Hg (only heavy metal that makes a gas) → doesn’t have to be local like the other HMs

List everything you know about: Lake Annie

• Very deep

• Lowest water column P

• Acidic (therefore high in organic C

• Smallest lake

• Has very high P, unexpected since it’s oligitrophic and by definition, should not have a lot of nutrients

• Is deep, sediment is just sitting there

• No algae (oligotrophic)

• High C/N

  • recalcitrant materials sink and nothing happens so it just stores

• Fulvic and humic (organic bound P majority)

List everything you know about: Lake Ok

• Highest P in water column

• Basic

• Largest lake, therefore larger fetch

• Shallow, resuspension, introduces oxygen to a system, resets TEA ladder

• Not high in OM, so a lot of minerals

• P likes to bind, would bind to a lot of minerals

• Higher bulk density, larger chunks, makes a lot of sense for a lot of minerals

• Majority mineral phosphorus

List everything you know about: Lake Apopka

• Shallow, resuspends often

• Basic

• High electric conductivity (P likes to bind to ions)

• Medium sized lake

• Very high OM

• Would expect a lot of autocthanus mateiral (C/N values of twelve because of algae, labile)

• High microbial activity

• Super fast rate

• High microbial P because stuff is moving round from resuspension, anoxic and oxic microbes can find a niche to live in because of how fast it’s moving (everybody’s happy)

• Microbial phosphorus majority

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• Meroplankton - type of algae that sit on the bottom and take up nutrients and stores them inside itself

  • Stores P, called polyphosphate

List everything you know about: the differences between aquatic environments

Aquatic environments need: water, OM, oxygen

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1. Lakes

   1. Oxygen from photosynthesis (algae)

   2. Anoxic

   3. A lot of algae → dead algae → labile → bacteria will go crazy → will suck all the oxygen out of the sediments

2. Rivers

   1. More oxygen (physical mixing)

   2. A lot of allocthanus OM, filled with recalcitrant material

3. Wetland

   1. Very little mixing, very stable environment

   2. Wind blocked by plants

   3. Reduced environment

   4. Sitting water

   5. Sediment is recalcitrant in a wetland (no algae in wetlands)

4. Estuaries

   1. Lots of mixing (wind, tides, dynamic environment)

List everything you know about: dating

Is it a good idea to date something like shell? Why or why not?

• There are carbons with different numbers of neutrons (isotopes)

• Only carbon fourteen decays radioactively

• Can go back about 8 half lives or roughly 40,000 years

• C fourteen gets into the environment through photosynthesis (CO2 gets into plants)

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No, the hardwater effect can be at play. If your resivoir has a lot of CaCO3, the rocks are constantly releasing carbon into the water and the shells are taking it up. There is no carbon 14 in CaCO3. The shelled organism has been taking in all that old carbon and will give you back an incorrect date. A little chunk of wood, leaf, or seed would be ideal, as it is allocthanous and recalcirant

List everything you know about: Hydric Soils

• Definition: Under 3 m of water or less where water is up to the top of the soil

  • Ex of hydric soils: wetland environment

• Are organic matter rich

• Gray in color (glayed - evidence of a reduced, anoxic environment)

• Saturated (water is what is driving the reduced environment)

• Add water to anything → reduced environment

• If it’s going to stay under water for a long time, then it goes through the redox ladder

List everything you know about: the Eh of sediments

• Measurement of electrons

• Eh goes from 700 (oxic environment) to -400 (reduced environment)

oxidized/reduced

• O (aerobic)(700), O2 → H2O

• N (anaerobic)(300-400), NO3 → N2(aerobic)

• Mn/Fe(anaerobic)(0) (only ones that are not gases), Mn/Fe → Mn/Fe2+

• S (anaerobic)(), SO42- → H2S

• C (anaerobic)(), CO2 → CH4

• (anaerobic) H2O → H2

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If he blew CO2 and O2 deep into sediment where methanogenesis was present, O2 would win (most electronegative, will give the microbes the most energy)

STABILITY MUST BE MAINTAINED TO HAVE THESE ANAEROBIC MICROBES - OXYGEN RESETS THE WHOLE SYSTEM

Eh is primarly changed by presence of oxygen !

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3 important factors drive the Nernst equation:

• Oxygen

• Temp

• pH (need Hydrogens)

What three factors drive recycling?

(Look an Nernst equation)

• Oxygen

• Temperature

• pH

Organic material is mostly acidic or basic? Why?

Acidic

• Tanic and fulvic acid

How do gases move through water

In order:

1. Diffusion

2. Ebullition (caused by heat and pressure)

3. Microbes

4. Plants (acting like tubes)

5. Source material

List everything you know about: Organic mateirlal

Allocthanous material:

• material that originates outside the system, think leaves, twigs, sticks (terrestial stuff)

• Recalcitrant, hard to break down

Autocthanous material:

• material that originates inside the system: yummy algae (aqueous in source)

• Labile (easy to digest, bacteria love it)

• Because it’s labile, bacteria will go on a frenzy (speed up rate) and use up all the O in the system - Will speed run the TEA ladder (TEA ladder is reset the moment oxygen is introduced)

• Measure OM by LOI (%) - burned at 550 degrees C, weight before and after

• Measure if labile or recalcitrant using C/N ratio

  • lower the C/N ratio, easier to break down

    • algae is 10-12

    • aquatic plants is 12-16

    • 20+ is terrestrial

  • All of this OM is made of CHONPS

• All macromolecules are labile (carbs, fats, proteins, nucleic acids)

• Some molecules are reclacitrant: lignin, fiber

• Within recalcitrant stuff, the carbs and fats can be eaten off

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degredation = mineralization = diagenesis = easy to break down

Why is hydrogenase important?

• You need reduced hydrogens to make molecules

• Will get a lot of reduced hydrogens in an anoxic environment

List everything you know about: types of sediment components and their reactivity

Sand:

• Large grain size, porous

• Made of quartz

• Not reactive

• Can use OSL (sand preserves the light that hits it and it fades over time)

Silt:

• Medium grain size, semi-porous

• Made of quartz

• A little reactive

Clay:

• Small grain size, not porous

• Highly reactive, as the tiny particles are held together by electrostatic

• Think of clay as an unbelievebly smll charged particle

• In ionic solutions, clay can just grab stuff

• Will also stay in solution for a very long time

• Water is charged

Organic Matter:

• Normally in the top layer of soil

• A lot of organic carbon - lots of degrading living material

• OM holds water

• Acidic (tanic and fulvic acids)

What does oxygen being highly electronegative mean?

It has a high affinity for electrons. OXYGEN LOVES ELECTRONS

List everything you know about: laminated sediments

• stripes of darker and lighter layers in a core

• Can find in Sweden

• Indicate an environment was switching from basic to acidic over time

• Brown layer: OM, acidic terrestrial

• White layer: CaCO3, environment must have been basic for it to be deposited or else it would have reacted and not been deposited. Evidence of a basic environment → photosynthesis in the water makes it basic → ALGAE

• Super laminated sediments can occur in stable environments

Oxidation vs Reduction, go.

Oxidation = loss of electrons

Reduction = gainging of electrons, happens when oxygen is removed. REDOX IS DRIVEN BY OXYGEN

According to Deevy, why is mud good?

• Hosts microbes that perform nutrient recycling

• Provides the anoxic environemnt where anhydrase can exist

• AN ANOXIC ENVIRONMENT ALLOWS THE MICROBES TO RECYCLE NUTRIENTS

What are the ecosystem services of a reduced environment?

• Nutrient recycling

• Microbial activity

• Reduced forms are what is used in biomaass genesis

• N-fixation: changing of unusable N2 (strong ass triple bond) to usable nitrogen - done by cyanobcteria

Lake paper → briefly explain main differences between hypereutrophic, mesotrophic, and oligotrophic lakes

hypereutrophic: a lot of algae (green), a lot of nutrients, would expect a lot of P

mesotrophic: in the middle

oligotrophic: clear, very little nutrients, would not expect a lot of P

List everything you know about: sediment N/P ratios

• Perfect ratio to grow algae is C:N:P → 106:16:1

  • CO2 dissolves easily in water so it is rarely the limiting factor

  • Real world ratio of N:P is roughly 7:1 because of weight

• The same mechanisms DO NOT govern both elements

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Sediment Nitrogen:

• Gaseous form (N2, NH3 (Ammonia))

• Denitrification makes N2 in the sediments

• Denitrification = OM + anoxic environment + bacteria

• Because this is extremely common in sediments, denitrification is happening often

• N2 is highly recalcitrant, triple bond

Sediment Phosphorus:

• No gaseous form

• Not a terminal electron acceptor (not on the ladder)

• Will bind in an oxygenated environment (Fe or Al in acidic, or Ca in basic)

• Will unbind in anoxic environment