Hydrology: Geochemistry - Chemistry of Ocean H20

H2O and minerals in solution = 1000 units of seawater = 965 water & 35 salt

Average salinity = 3.5% or 35ppt of mineral

All measures an relative to Cl-ion concentration

NAC1 - 45 Cl = 55 = chlorinity measure

Of all ions in sea H2O

All land sediment moves to ocean

Also airborne material

Trace element not found in sea H2O

Have been found in marine organisms

(iodine in seaweed, copper in blood-crabs, cobalt in lobsters & muscles, lead in ash of

marine organisms, nickel in mollusks)

(Soerdrop Johnson & Fleming) (The Ocean pg 175)

49 elements in Sea H2O

NA in combination with Cl, COs, BR, S04 (Sulphate)

Salt H20:

Sodium Chloride 77.76

Mg Chloride 10.88

Mg S04 4.74

Ca S04 3.60

K2 S04 2.46

CaC03 .34

MgBr .27

Salinity of H2O

Salinity of Open Ocean

34-37 part per thousand

avg. = 35

Gulf of Bothnea: 5 ppt+(Bothe)

Red Sea: 46 ppt

Saragasso Sea: 38

No Hemisphere surface is less salty than Southern Hemisphere

No = 34 avg.: more land

So = 35 avg.: much more water

Arctic 30 or less: density, land runoff, constrained circulation

Salinity of deep or bottom H2O

34.5 - 35 ppt.

Affected by rain fall & evaporation

(Arctic Bottom Water)

Salinity & Circulation

Movement of Life
Circulation is vertical: Upwelling/ Downwelling/ Outwelling

Heavy H20 sinks (cold & salty) vs. (warm & salty) Rises


1. Mammals: swim bladdens & salty tissue

2 . Cold: Rich in oxygen vs. warm oxygen depleted water

Mouth of Great Rivers Low

Salinity: Fresh H2O on top - cold salty on bottom

Amazon: Fresh H2O 300 miles - out into Atlantic Ocean

Organic Substance in H2O


(Plant bodies)

Bone to food web (Hard bone and Cartilaginous)

Little on sea bottom must dissolve ect. And uptake

Gasses in Solution:

02 – 34% (vs. 21% land) (less soluble than land)

C02-1.6% (vs. 03%) land

N2 – 64% in sea (78% on air) - Mammalian Bends - Caissons Disease

02 Solubility varies with

T, P, and salinity

Plants give little free 02 to H2O

T - Increase 02-Decrease

C02 twice solution as

H2C03 (HC03ect.)

Plants give above as a byproduct of Respiration

50 times greater solubility of C02 in H2O than land