DOC Sources, Sinks, Concentration & Distribution

Question 1

How is DOC made?

Answer 1

Biological: Cell Death (Decomposition of Life), Sloppy Feeding, Cell Lysis, Dissolution by Enzyme

Physical/Chemical/Geological: Transport, Diffusion/Mixing, Deposition, Physical Dissolution

Tends to be made during Primary Production.

Question 2

Relationship between DOC & Atmospheric Carbon

Answer 2

DOC Pool = Atmospheric Carbon Pool

Question 3

DOC Concentration in Ocean Basins

Answer 3

Spatial Variability in DOC:

DOC concentrations are higher in the deep Atlantic and lower in deep Pacific. This is because deep ocean water is formed in North Atlantic —where surface waters have high DOC concentrations.

The deep ocean waters of the Atlantic tend to be younger, as well. Younger age indicates more DOC concentration.

Question 4

Autochthonous DOC

Answer 4

DOC that originates within the ocean (e.g marine life)

Question 5

Allochthonous DOC

Answer 5

DOC originating from outside sources (e.g rivers, vents, atmospheric deposition, diffusion from sediment)

Question 6

Primary Sinks of DOC

Answer 6

Microbial Respiration, Photooxidation, Particle Scavenging, Hydrothermal Alteration

Question 7

How do we sort DOC Pool?

Answer 7

Based on Reactivity ! (Reactive vs. Nonreactive)

Question 8

Steps for Measuring DOC

Answer 8

1. Collect sample with CTD Rosette
2. Remove POC by filtering sample through 0.2-0.7 micrometer filter
3. Remove DIC from sample through acidification
4. Oxidize DOC with DOC analyzer—amount of CO2 = amount of DOC

Question 9

Who Uses DOC as Food Source?

Answer 9

Heterotrophic Bacteria ! (by turning inaccessible DOC to accessible POC)

Question 10

What do we classify as DOC?

Answer 10

Viruses, Macromolecules, small peptides, metabolites, colloids, monomers, and “truly dissolved”