Oceanography Final :P

4 Major organic compounds

Carbohydrates, lipids, proteins, nucleic acids. Abundant in seawater.

Salinity

Sum of major organic compound ions

Minor Elements

Elements with abundances in the parts per million range.

Trace Elements

Elements in the parts per billion range

Limiting Element

the substance in a chemical reaction that limits the amount of product that can be formed. When primary producers can’t thrive because there is not enough of a particular element.

Nitrogen

Likely the limiting nutrient. Not always in a form useable to primary producers. A lot in atmospshere and ocean as ocean form. Not a lot of pp in ocean to be bioavailable. Used in agricultural fertilizers and eventually are taken to the ocean via rivers where they can lead to productivity blooms.

Phosphorous

Limiting nutrient in some. Bioavailable as phosphate which primarily enters the ocean via rivers, which bring ____ weathered from rocks. Used in agricultural fertilizers and eventually are taken to the ocean via rivers where they can lead to productivity blooms.

Nitrogen Fixation

Prokaryotes can break N2 bond to make ammonia (NH3) which is usable by primary producers.

Carbon Fixation

Similar to nitrogen fixation, but done by photosynthesizers.

Fixation

Changes elements into bioavailable forms

Apatite

Riverine phosphate in solid mineral form.

Remineralization

Primary producers can use the inorganic P in dissolved phosphate which they turn into solid organic P. Organic P can be buried in seafloor sediments or can be turned back into phosphate when organic matter decomposes. Even if phosphate stays dissolved, this process still works.

Redfield Ratio

A consistent atomic ratio of carbon, nitrogen, and phosphorus (CNP) (106:16:1) found in marine phytoplankton and throughout almost all of the deep ocean. for every 106 atoms of carbon, there are approximately 16 atoms of nitrogen and 1 atom of phosphorus in phytoplankton.

How does bioavailable N and P become part of CHONP?

Photosynthesizers use bioavailable N and P as part of their metabolism. The end result is solid, particulate organic matter that can be described as CHONP.

There is more nitrogen than phosphorous in the ocean. Why is nitrogen the limiting nutrient in many parts of the ocean?

The photosynthesis reaction needs 16 times more N than P. Most of the N in the ocean is in the form of N2; only about 14ppb of N is bioavailable.

Human cells are full of CHONP. Where does this CHONP come from?

The CHONP that makes up the proteins, lipids, carbohydrates, and nucleic acids comes from the food that we eat, which is solid particulate organic matter.

How does N and P in organic matter become bioavailable to primary producers again?

The decomposition or decay of organic matter releases CHONP as dissolved, bioavailable nutrients. Decay can be thought of as the opposite of photosynthesis.

If photosynthesis produces oxygen, but decay is the opposite of photosynthesis, what happens during decay with respect to oxygen?

Oxygen is consumed during decay because it reacts with particulate organic matter, which is turned back into inorganic carbon (CO2) and dissolved nutrients. This is called aerobic decay. Aerobic decay does not occur without oxygen.

CHONP

used to remember the four most common elements found in biological molecules: carbon, hydrogen, oxygen, and nitrogen, and also phosphorus. These elements play vital roles in the structure and function of all living organisms.

Oxygen in the Ocean

high at the surface, then starts to decrease below a few hundred meters depth until it reaches the Oxygen Minimum Zone (OMZ). Lower at 200m. Higher at 3000m in Atlantic, lower in Pacific. Same at 4000m in Atlantic, higher in Pacific

Oxygen Minimum Zone (OMZ)

varies in depth and thickness from place to place. below it, oxygen increases again because of recently down-welled water.

Why is the increase of oxygen with depth so much less in the Pacific?

When NADW forms, it is rich in oxygen, but that oxygen gets consumed during decay as NADW travels south. • By the time NADW enters the Pacific, much of the oxygen has been lost to decay...that water is old water.

Why do areas with upwelling have such high productivity?

When organic matter decays, CHONP becomes bioavailable again to primary producers. Much decay occurs in oxygen rich deep waters, so they are loaded with bioavailable N and P. Upwelling of deep water brings N and P to the photic zone.

True statements about anthropogenic impacts on the dissolved oxygen content of the ocean?

Rising seawater temperatures decreases the amount of dissolved oxygen in the oceans. The deoxygenation of the surface ocean will eventually impact the deep ocean by decreased oxygen levels in North Atlantic Deep Water.

True statements about anthropogenic effects on the phosphorous cycle?

Earth's supply of usable phosphorous is limited, Phosphorous used for agriculture eventually makes its way back to the oceans where they can promote productivity blooms.

true statements about the anthropogenic impacts on nitrogen?

Humans have learned how to harness N2 from the atmosphere and turn it into bioavailable fertilizer, Anthropogenic nitrogen ends up being carried by rivers to the oceans where they promote increased productivity.

Inorganic carbon in seawater

in its oxidized forms CO2, HCO3, CO3 and CaCO3

Dissolved Inorganic Carbon (DIC)

sum of the abundances of CO2, HCO3, CO3. Increased amounts of this is how the ocean helps absorb some of this increased carbon dioxide.

Marine Solubility Pump

CO2 from the atmosphere dissolves into cold surface ocean waters to become all of the DIC forms. This then sinks to the deep via downwelling. Very important way in which Earth removes CO2 from the atmosphere and stores it in the ocean.

Reservoirs

The atmosphere, the ocean, land, and, the mantle.

The global carbon cycle

the movement of carbon through the Earth's atmosphere, oceans, land, and living organisms. It's a dynamic process where carbon is exchanged between these different reservoirs or "sinks". This cycle is essential for maintaining a stable climate and carbon balance on Earth. Made up of reservoirs, sources, and sinks.

Ocean reservoirs

Most important reservoir because they store the most carbon that is readily available to the atmosphere.

Ocean carbon

Mostly in the form of DIC, but is also stored in sediments as minerals and organic carbon.

Anthropogenic Flux of carbon cycle

Adds an additional 4.9 GtC/year

Extra Human CO2

is mostly caused by the burning of fossil fuels (87%) and deforestation (13%), which decreases an important sink (photosynthesis) and leads to increased decomposition. • Most of that carbon dioxide (45%) ends up in the atmosphere, 29% gets consumed by photosynthesis on land, and 23% gets transferred into the oceans.

Atmospheric CO2

Dissolves into cold surface waters. Thermohaline circulation causes that colder water to sink to the deep ocean. Where deep waters upwell, the water warms and releases CO2 as gas to the atmosphere. controlled by the chemical weathering of silicate rocks, which consumes CO2 and turns it into DIC which is carried to the oceans via rivers.

Surface Ocean

Experiences most of the increase in atmospheric CO2. It takes about 7 years for the ____ to equilibrate with a change in atmospheric CO2.

Deep Ocean

It takes about 1000 years for the ____ to equilibrate with a change in surface ocean CO2.

CO2 is more soluble in?

Cold waters

Upwelling zones

bring both nutrient- and CO2-rich deep water up to the surface, which leads to increased primary productivity and a net release of CO2 to the atmosphere.

Equatorial Pacific

Where most of the release of CO2 from the ocean to the atmosphere occurs

The ocean’s CO2 uptake is influenced by

CO2 solubility (temperature and salinity) • Ocean current patterns • Ocean stratification (i.e., the strength of thermohaline circulation • Wind speeds over the ocean • Ocean acidification. All of these are likely to change as climate warms and atmospheric CO2 increases. Therefore, it is hard to predict how the ocean will behave as a reservoir for CO2 in the future.

Organic Carbon

Refers to the reduced form of carbon, which usually refers to solids produced via photosynthesis wherein CO2 is turned into sugars such that carbon gains electrons

Marine Biological Carbon Pump

CO2 from the atmosphere enters the surface ocean, is consumed by primary producers and turned into particulate organic carbon (POC, or Corg) which sinks toward the seafloor.

POC

It represents the carbon that is found in the organic particles, such as living organisms, detritus, and other organic materials, that are retained by a filter. 99% of sinking ___ is consumed by respiration by animals or decay by microbes. Only 1% of makes it to the seafloor and gets buried in sediments. The buried ___ can become oil or natural gas over time. Most petroleum originates from buried marine ___.

Export of Organic Carbon to Deep Ocean

Phytoplankton take CO2, turn it into POC, die or get eaten. Animal poop is also POC, now in a denser clumped form. All of this POC sinks.

Atmospheric CO2 interacts with three nested cycles of marine organic carbon.

Net primary production (50 PgC/year). Residence time 21 days (=0.06 year)

Export of POC from the surface ocean (4 PgC/year) and remineralization to DIC in the deep ocean, followed by upwelling or mixing back to the surface. Residence time 1000 years.

Sedimentary organic carbon burial (0.05 PgC/year). Eventually added to contents by plate tectonics and weathered to DIC (or combusted by humans) back to atmospheric CO2. Natural residence time 300 million years.

Rivers bring about 1 PgC/year back to oceans as DIC. Humans produce 9.5 PgC/year by taking sedimentary organic carbon and combusting it to CO2.

Solar Luminosity

(slowly getting brighter, 10% every billion years) This helps explain major climate events in deep time (major ice ages between 2.5 and 0.6 Ga)

Milankovitch Cycles

(changes to Earth’s orbital parameters) have a profound effect on insolation and thus climate. at 65°N is of particular importance because that is where continental ice sheets can form and melt.

Albedo

how much light and energy goes out (reflectivity of the planet) The presence or absence of ice sheets is a major factor in Earth’s ___. seasonality plays a major role in Earth’s ___. Whiter colors tend to reflect more light than darker colors. Thus, ice reflects much more of the solar energy that hits it (85-90%) than rocks and plants (20%), and ocean water (10%) The amount of ice cover on Earth plays an important role in keeping Earth cool. Ice affects this.

Greenhouse Gasses

(heat trapped in the atmosphere and bounced back to Earth) Those that have more than two atoms, the most important being: H2O, CH4, CO2. When infrared radiation hits ___ , it causes them to get excited, vibrate, and emit radiation back in all directions (including back toward Earth), which keeps the energy from leaving Earth.

Precession

Earth’s axis wobbles such that the northern hemisphere cycles from pointing toward the sun to away from the sun every 23-26ky. Affects the timing of the seasons, i.e, what part of the year each hemisphere is tilted toward the Sun, and how strong of an effect the other orbital forcings have.

Obliquity

Earth’s axis goes from being tilted 22.1° to 24.5 ° every 41ky. Earth’s current tilt is 23.4° and is decreasing. Increased tilt increases seasonality such that summers are warmer and winters are colder.

Eccentricity

Earth’s orbit around the sun changes from circular to ovular every 100ky. Increased eccentricity Increases seasonality such that summers are warmer and winters are colder.  Sometimes earth is more circular, distance is roughly the same all the time. Sometimes orbit is more ovular, bigger distance to sun from some parts or others. Seasons are more extreme with ovular. Circular seasons are more evenly timed. Seasons longer. 

Lower Seasonality

Favors the growth of ice sheets.

Higher Seasonality

Winters are very strong, which makes for very cold, dry winters, without much precipitation as snow. The following summers are also very strong, which favors the melting of ice.

Insolation

Glacial periods tend to start as ___ starts to decrease.

Diatomic Molecules

Like N2 and O2 (the most abundant gasses in the atmosphere), can only vibrate in one direction, which is not conducive to interaction with infrared radiation.

Polyatomic Molecules

There are more directions in which to vibrate, which allows infrared radiation to interact with them.

Decreasing temperature of oceans

Increases its ability to hold CO2 as DIC, and vice versa.

60 MYA

CO2 was much higher than it had been for the past 1 million years. During this time, it was so hot that there was no ice on Antarctica.

50 MYA

India and Asia collide, CO2 decreased dramatically, eventually reaching levels low enough for ice sheets to develop on Antarctica.

Silicate rocks

More available in times of mountain building. High rates of subduction tends to increase atmospheric CO2 via volcanism.

Antarctic Circumpolar Current

Caused by rifting away of India and Australia from Antarctica. Allowed for water to flow around Antarctica and get colder— further cooling the planet and increasing the ability of the ocean to store DIC.

Climate Change deniers

We experience natural cooling and warming periods, but current warming period can’t be explained by natural cycles. Caused by increase in human emissions.

Sun is getting brighter, but by 105 every billion years, doesn’t explain current climate crisis but climate events many many years ago. 

Climate activity from fossil fuels is primary cause. Atmospheric carbon levels have increased since industrial revolution 

What drives Earth Climate

Amount of solar energy that comes in versus the energy that is reflected/emitted.

Isotopes

Atoms of an element that have the same number of protons but different numbers of neutrons.

Protons

Number of this determines which element the atom is.

Protons and Neutrons

Have the same mass. Number of these combined determines the mass of an atom.

Radioactive Isotopes

Don’t like to be together. Expel particles to reach a stable state. 

Stable Isotopes

A non-radioactive form of an element, meaning its nucleus doesn't decay into another element or form over time.

Del Notation

Isotopic ratio of two isotopes