a. Particulate organic material (plant detritus)

    b. Particulate inorganic material (minerals)

2. Gases

    a. Conservative (N₂, Ar, Xe)

    b. Nonconservative (O₂ and CO₂)

3. Colloids (passes through 0.45 mm filter, but is not dissolved)

    a. Organic

    b. Inorganic

4. Dissolved Solutes

    a. Inorganic solutes

      1. Major ( > 1 ppm )

      2. Minor ( < 1 ppm )

    b. Organic solutes
 

Bergman (1779) made the earliest chemical analysis of seawater

Marcet (1819)    was the first to suggest that the relative composition of sea salt is nearly constant (the first law of chemical oceanography)

Forchhammer (1865)  made first reliable measurements of major components on several hundred surface waters from all parts of the world.
Dittmar (1884) analyzed 70 seawater samples collected at various depths for the major oceans during the cruise of the H.M.S. Challenger (1873-1876).

Lyman and Fleming (1940) recalculated Dittmar's results using modern atomic weights

Cox and Culkin (1966)  made measurements of major components of waters collected through out the world as part of salinity study.

Riley et al. (1967) made measurements of major components of waters collected through out the world as part of salinity study.
 
 
 

Ag⁺ + Seawater ®  AgCl(s) + AgBr(s)

2Ag⁺ + CrO₄^2-  ®  Ag₂CrO4₄ (red solid)

Cl(‰) = -0.050 + 15.66367R₁₅ + 7.08943 R₁₅² - 5.91110 R₁₅³ +  3.31363 R₁₅⁴ - 0.73240 R₁₅⁵

Sulfate

BaCl₂ + Seawater  ®  BaSO₄ ¯

Ca²⁺, et al. can co-precipitate.  Measurements relative to standard seawater of known concentration can yield very precise measurements.

Bromine
 
Ag⁺ + Seawater ®  AgCl(s) + AgBr(s)
AgBr (s)  + chromic acid or K₂MnO₄  ®  Br₂ ­
Br₂ +  Na₂S₂O₃  ®  Color Change

Fluorine

Colorimetric methods or using a specific ion electrode

Bicarbonate and Carbonate

At least two parameters  pH, TA (total alkalinity) TCO2 (the total carbon dioxide) and the partial pressure of CO₂ (pCO₂).  More details of these measurements will be discussed later.
 
Boric acid and borate

Boron  +  mannitol ®  Complex
Converted to B(OH)₃ and titrate with NaOH
Colorimetric techniques using a colored indicator  curcumin complex

Magnesium

Mg²⁺ +  ammonium phosphate (after the Ca²⁺ is removed) ®  PPT.
Mg²⁺   +  EDTA ®  color indicator

Calcium

Ca²⁺ + Oxalate ®  PPT.  weigh as CaCO₃ or CaO
Ca²⁺  +  EGTA  ®  color change (The endpoint by Potentiometrically or colorimetrically using metallochromic indicators).

Potassium

K⁺  +  chloroplatinate  ® K₂PtCl₆  (insoluble in 80% ethanol)
K⁺  +  Na tetraphenylboron ® K tetraphenylboron (insoluble).

Sodium

Balance Equivalents and determine Na⁺ is by difference
 
 

    Na⁺              0.5556             0.5555                  0.5567                 0.55661
    Mg²⁺           0.06695           0.06692                 0.06667               0.06626
    Ca²⁺            0.02106           0.02126                 0.02128               0.02127
    K⁺               0.0200             0.0206                   0.0206                 0.02060
    Sr²⁺             0.00070           0.00040                 0.00042               0.00041
    Cl^-               0.99894                --                           --                   0.99891
    SO₄^2-          0.1394                  --                      0.1400                0.14000
    HCO₃^-         0.00735                --                           --                  0.00552
    Br-               0.00340                --                      0.003473            0.00347
    CO₃^2-              --                     --                            --                  0.00083
    B(OH)₄^-           --                     --                            --                  0.000415
    F^-                     --                     --                            --                  0.000067
    B(OH)₃        0.00137                        0.001002
 
      å  =           1.81484                                                                  1.81540
 

A. Dittmar as recalculated by Lyman and Fleming.
B. Cox and Culkin (1966)
C. Riley and Tongadai (1967); Morris and Riley (1966).
D. Millero (1996).

              Cl^-                       0.99891                       0.545879
              SO₄^2-                  0.1400                         0.056470
              HCO₃^-                 0.005524                     0.001754
              Br^-                       0.00347                       0.000841
              CO₃^2-                  0.000830                     0.000536
              B(OH)₄^-               0.000407                     0.000100
              F^-                         0.000067                     0.000068
              OH^-                                                        0.000008

                                                                   åe_i  = 0.605659
 

           Cations                      g_i/Cl                       e_i (eq kg^-1)
              Mg²⁺                   0.06626                      0.105634
              Ca²⁺                    0.02127                      0.020564
              K⁺                       0.02060                      0.010208
              Sr²⁺                     0.00041                      0.136587

                                                                     åe_i =    0.136588

                 e(Na)/Cl = 0.605659 - 0.136588
                              = 0.469071

                 g(Na)/Cl = e(Na)/Cl x FW
                              = 0.469071 x 22.9898/19.374
                              = 0.556614

Cl^-                            0.99891                       0.545879
SO₄^2-                       0.1400                         0.056470
HCO₃^-                      0.005524                     0.001754
Br^-                            0.00347                      0.000841
CO₃^2-                       0.000830                    0.000536
B(OH)₄^-                    0.000407                    0.000100
F^-                              0.000067                    0.000068
OH^-                                                            0.000008

                                                            åe_i  = 0.605659
 

Cations                         g_i/Cl                       e_i (eq kg^-1)
 Mg²⁺                          0.06626                   0.105634
Ca²⁺                            0.02127                   0.020564
K⁺                               0.02060                   0.010208
Sr²⁺                             0.00041                  0.136587

                                                      åe_i =    0.136588

           e(Na)/Cl = 0.605659 - 0.136588
                        = 0.469071

           g(Na)/Cl = e(Na)/Cl x FW
                        = 0.469071 x 22.9898/19.374
                        = 0.556614

1/2 å =                                                   0.028895        0.031261    0.035994

B(OH)₃         0.000996         61.8322       0.000016        0.000016

    å =           1.815402                            0.028903       0.031261
 

For average seawater S = 35, Cl = 19.374, pH_SWS = 8.1, TA = 2.400 mmol kg^-1,
and t = 25^oC.
 
 
 
 
 

Species               X_i                    N_i                         E_i                       I_i

Na⁺                  0.306606          0.837672            0.774485            0.672685
Mg²⁺                0.036499          0.094321            0.174313           0.303023
Ca²⁺                 0.011716          0.018362            0.033954           0.058988
K⁺                    0.011347          0.018229            0.016854           0.014639
Sr²⁺                  0.000226          0.000l62             0.000299           0.000520
Cl^-                    0.550242           0.974836            0.901303           0.782945
SO₄^2-               0.077118           0.050422            0.093238           0.161999
HCO₃^-              0.003043           0.003132            0.002896           0.002668
Br^-                    0.001911           0.001503            0.001389           0.001206
CO₃^2-               0.000457           0.000479            0.000885           0.001112
B(OH)₄^-            0.000229           0.000182            0.000168           0.000119
F^-                      0.000039           0.000122            0.000113           0.000097
OH-                   0.000004           0.000014            0.000013           0.000012
B(OH)₃              0.000552           0.000561            0.000544               -----

Species            g_i                   n_i              e_i              I_i

Na⁺              10.7838        0.46907         0.46907     0.46907
Mg²⁺             1.2837        0.05282         0.10563     0.21127
Ca²⁺              0.4121        0.01028         0.02056     0.04113
K⁺                 0.3991        0.01021         0.01021      0.01021
Sr²⁺              0.0079         0.00009         0.00018     0.00036
Cl^-              19.3529         0.54588         0.54587      0.54587
SO₄^2-           2.7124         0.02824         0.05648      0.11294
HCO₃^-          0.1070         0.00175         0.00175      0.00175
Br^-                0.0672         0.00084         0.00084      0.00084
CO₃^2-           0.0161        0.00027          0.00054      0.00107
F-                 0.0068         0.00068          0.00068      0.00068
B(OH)₄^-       0.0010         0.00010          0.00010      0.00010
OH^-              0.0008        0.00008           0.00008     0.00008

        1/2å =                    0.55981           0.60566     0.69717

B(OH)₃         0.0194       0.00031           0.00031

g_T  =  35.172    n_T  = 0.56012  m_T  = 0.60597  I_T  = 0.69717

a) To convert to molar units multiply by the density.  To convert to molal units divide by X_H2O = 0.96483

Total Moles                             n_T = 1/2 å n_i + n_B = 0.028903 Cl(‰)

Total Equivalents                     e_T =  1/2 å e_i + n_B=0.031260 Cl(‰)

Total Ionals                              I_T = 1/2 å n_iZ_i² = 0.035989 Cl(‰)

Mean Molecular Weight         M_T =  å N_iM_i = 62.793

Mean Equivalent Weight        M_T' =  å E_iM_i' = 58.046

Total Grams per Kg                g = 1000 - 1.8154 Cl(‰)

Total Molarity                       c_T = 0.028903 Cl(‰) x r

Total Molality                       m_T = 28.890 Cl(‰)/[1000 - 1.8154 Cl(‰)
]
Total Normality                     N_T = 0.031260 Cl(‰) x r

Total Equivalent Molality       e_T = 31.260 Cl(‰)/[1000 - 1.8154 Cl(‰)]

Volume Ionic Strength            I_V = 0.03599 Cl(‰) x r

Molal Ionic Strength               I_m = 35.990 Cl(‰)/[1000-1.8154 Cl(‰)]
r is the density in g cm^-3

Convert to Functions of Salinity  Using S(‰) = 1.80655 Cl(‰)
 

Forch, Knudsen and Sorensen defined the salinity as

"the weight in grams of dissolved inorganic salts in one kilogram of seawater, when all bromides and iodides are replaced by an equivalent quantity of chlorides, and all the carbonates are replaced by an equivalent quantity of oxides"

    2HCO₃^- ® [MO₂] + H₂O + 2CO₂
    CO₃^2-  ® [MO₂] + CO₂
 
Knudsen                            S(‰) = 1.805 Cl(‰) + 0.030
Forchhammer                    S_T = 1.812 Cl(‰)
Dittmar                             S_T = 1.8056 Cl(‰)
Lyman and Fleming          S_T = 1.8148 Cl(‰)
Millero                              S_T = 1.8154 Cl(‰)
JPOTS                              S(‰) = 1.80655 Cl(‰)

            Cl(‰) = 19.374, S(‰)  = 35.000 and S_T = 35.172
 
S(‰) = - 0.08996 + 28.2970 R₁₅ + 12.80832 R₁₅² - 10.67869 R₁₅³ +
           5.98624  R₁₅⁴ - 1.32311 R₁₅⁵

where  R₁₅ = Conductance of Sample/Conductance of Standard at 15^oC
 
 
 

S = a₀ + a₁ R_T^1/2 + a₂ R_T + a₃ R_T^3/2 + a₄ R_T² + a₅ R_T^5/2 + DS

where

DS =  [(t - 15)/ (1 + k(t-15))] b₀ + b₁ R_T^1/2 + b₂ R_T + b₃ R_T^3/2  + b₄R_T² + b₅ R_T^5/2
 
        a₀ =  0.0080      b₀ =  0.0005
        a₁ = -0.1692      b₁ = -0.0056        k = 0.0162
        a₂ = 25.3851      b₂ = -0.0066
        a₃ = 14.0941      b₃ = -0.0375
        a₄ = -7.0261       b₄ =  0.0636
        a₅ =  2.7081       b₅ = -0.0144

       åa_i = 35.000     å b_i = 0.0000

R_T = C(S, t, 0)/C(35, t, 0) at atmospheric pressure (p = 0)

Conductivity
 
 

The specific conductivity is defined as

L_SP= k/R = l /A R 

where R is the resistance and the cell constant k equals the distance (l) between the electrodes (usually platinum) divided by the cross-sectional area (A) of the electrodes. The equivalent conductance L is defined as the conductance of 1 gm equivalent of the electrolyte

L =  1000 L_SP/N

where N is the normality [eq/liter].  Since conductance is a function of temperature, it is necessary to make the measurements at a constant or known temperature for precision's of ± 0.001 in salinity.
 

Density

S = 1.3343 (r - r₀)10³ + 2.155306 x 10^-4 x [(r - r₀)10³]² -1.171160 x 10^-5
  [(r - r₀)10³]³
 
 
Sound Speed

S = 0.91712 (U - U₀) + 7.670097 x 10^-4 x (U - U₀)² - 1.107557
      x 10^-5 (U - U₀)³

Refractive index

S = 35.00 + 5.3302 x 10^-3 Dn + 2.274 x 10^-5  Dn² + 3.9 x 10⁶ Dn³
  + 10.59 Dn (t - 20) + 2.5 x 10² Dn² (t - 20)²
 

A. Gravimetric Salts

Salt                    grams/kg        moles/kg          M.W.

NaCl                      23.9849                0.41040                58.4428
Na₂SO₄                  4.0111                0.02824               142.0372
KCl                         0.6986                 0.00937                74.5550
NaHCO₃                0.1722                 0.00205                84.0070
KBr                        0.1000                 0.00084               119.0060
B(OH)₃                  0.0254                 0.00041                 61.8322
NaF                        0.0029                 0.00007                 41.9882
                             28.9951

B. Volumetric Salts

Salts             grams/kg          moles/kg                M.W.

MgCl₂           5.0290              0.05282          95.211
CaCl₂            1.1409              0.01028        110.986
SrCl₂             0.0143              0.00009        158.526

Use  1 molar MgCl₂ ,  CaCl₂  and  SrCl₂ (standardize by  AgNO₃ titration). 52.8 ml of 1 molar MgCl₂ , 10.3 ml of 1 molar CaCl₂ and 0.1 ml of 1 molar SrCl₂  are needed. The densities of these solutions are 1.017 g/ml and 1.013 g/ml, respectively, for MgCl₂ , CaCl₂ and SrCl₂  solutions at 1 molar. The grams of water of in each solution are given by

H₂ O = g_SOLN - g_SALT =  ml x density  - g_SALT

C.  Addition of Water

g_H2 O to add = 1000 - g_H2 O from MgCl₂ , CaCl₂ and SrCl₂
 
 
 

                          Before Evaporation          After Evaporation

                          gms HCO₃^-     0.1070          gms          0.0137
                          gms CO₃^2-      0.0161          gms          0.0043
                          gms CO₂         0.0005          gms          0.0000
                          gms Br^-           0.0672          gms Cl      0.0298
                                                 0.1908                           0.0478

gms of salts loss from
          HCO₃^-, CO₃^2- and Br^-  0.1908 - 0.0478 = 0.1430
gms of B(OH)₃ lost                                          = 0.0275
total salts  lost                                                 = 0.1705

g_T                       35.1716
Loss of salts        -0.1705
                                  35.0011

    2)  Evaporation to dryness                                         ±  0.01

    3)  Chlorinity                                                             ±  0.002

    4) Sound Speeds                                                        ±  0.03

    5)  Density                                                                 ±  0.004

    6)  Conductivity                                                        ±  0.001
 
    7) Refractive index                                                    ±  0.05

A. Estuaries

The total grams of salts (g_T ) are given by

    g_T = g_R + [(35.171 - g_R)/19.374]  Cl(‰)  

where g_R is the grams of river salts.

                [g_E - g_SW] 19.374
      g_R  = ¾¾¾¾¾¾¾¾
                19.374 - Cl(‰)

      g_SW = k_i x Cl(‰)

where k_i is the average ratio of g_i/Cl for seawater.

g(E) = 0.092 + 1.80271 Cl(‰)

B. Evaporation in isolated basins

C. Admixture with brines

D. Precipitation and dissolution

E. Submarine Volcanism

F. Exchange between atmosphere and sea

G. Anoxic Basins

H. Freezing

I. Interstitial Waters
 

Solute     Lyman & Fleming         Best Estimate

Na⁺                  ---                          5.4 ± 3.8
Mg²⁺                  2.3                      2.9 ± 0.5
Ca²⁺                 15.4                    21.1 ± 0.6
K+                    --                            0  ± 0.5
Sr²⁺                  --                               ----
Cl-                     --                               ----
SO₄^2-                6.1                       6.0 ± 1.0
HCO₃^-             49.3                     84.6 ± 4.2
Br^-                    --                          0.0 ± 0.8
B(OH)₄^-           --                              ----
F^-                     --                         0.06 ± 0.1
B(OH)₃             --                         0.8 ± 0.03

Totals              72.8                  120.7 ± 11.5

g_T = 0.073 + 1.8110 Cl (‰),  Lyman and Fleming (1900 data)

g_T = 0.120 + 1.8092 Cl (‰), Millero (1967 data)

Ion                  Surface                    Deep                Weighted
                        Waters                    Waters               Average

Na⁺                  5.4 ± 8.3              5.3 ± 10.1              5.3 ± 9.3
K⁺                   -0.8 ± 1.5             -0.9 ± 1.8              -0.9 ± 1.7
Ca²⁺                21.1 ± 1.1            20.9 ± 1.3             21.0 ± 1.2
Mg²⁺                2.9 ± 1.3               3.0 ± 2.1               3.0 ± 1.8
HCO₃^-             84.6 ± 4.7             88.1 ± 4.7             86.5 ± 4.7
SO₄^2-                6.0 ± 3.8               3.3 ± 5.0              4.4 ± 4.5
Br^-                   -0.7 ± 0.2              -1.1 ± 0.6             -0.9 ± 0.4
F^-                      0.06 ± 0.02           0.06 ± 0.03          0.06 ± 0.03
B(OH)₃             0.8 ± 0.4               0.8 ± 0.4               0.8 ± 0.4

Total =           119.4 ± 21.3            118.5 ± 26.0            119.4 ± 24.0
 

Composition of 1 Liter of Average World River Water
 
Species              10⁶g_i             10³n_i         10³e_i          10³I_i

Na⁺                     6.5              0.283           0.283         0.283
Mg²⁺                   4.1             0.169            0.337         0.674
Ca²⁺                  15.0             0.374            0.749         1.496
K⁺                       2.3             0.059            0.059         0.059
Cl^-                       7.8             0.220            0.220         0.220
SO₄^2-                11.2             0.117            0.233         0.466
HCO₃^-               58.4             0.950            0.950         0.950
CO₃^2-                  ---             0.002            0.004          0.008
NO₃^-                    1.0            0.016            0.016         0.016
Si(OH)₃O^-             ---            0.005            0.005          0.005

1/2å =                                  1.086            1.428          2.089

Si(OH)₄                     21.5              0.213                 0.213              --------

                            g_T = 126.8    n_T  = 1.299      e_T  = 1.641          I_T  = 2.089

To convert to molar units multiply by the density.  To convert to molal units divide by X_H2O = 0.96483
 

                            E_i  L⁰_i^a
 
Ion               L⁰ _i         Seawater              River              St. Lawrence
                                                                Water             River

Ca²⁺            59.51            46.97                  31.41                35.40
Mg²⁺           53.50              9.32                  12.71                13.15
Na⁺             50.10            38.71                    9.67                  7.24
K⁺               73.50             1.24                    3.06                   0.91
HCO₃^-         44.50             0.14                   29.79                25.19
SO₄^2-          89.02             7.46                   13.14                 13.89
Cl^-               76.35            68.77                  11.83                 18.61
NO₃^-           71.46              0.20                    0.81                    -

                   L⁰ =              127.85^b             112.2                114.41
 

a)  E_i is the equivalent function of species
b)  L⁰ =  å E_i L⁰_i

Stage          Density          Wgt % liq.          Solid                        % of Total
                                                                                                        Solid
                   1.026               100
 

I                 1.140                 50                CaCO₃ + MgCO₃                1
II               1.214                 10                 CaSO₄ (gypsum)                 3
III              1.236                3.9                NaCl (halite)                       70
IV                ---                    ---                Na-Mg-K-SO₄ and             26
                                                                    KCl, MgCl₂
 

                                                                                  %
Seg.      First Appearance        C.F.           H₂O        I       a(H₂O)       Faces
                                                                                  Left

a    G + Sol.                               3.62          27.63        2.6      0.929   pene-saline
b    A + Sol.                               9.82          10.18        6.6      0.772
c    A + H + Sol.                          0.82           9.24        7.2       0.744        saline
d    A + H + Gl + Sol.                  13.15           7.60        7.5       0.738
e                                            29.17            3.43         9.1     0.714
f    A  + H + Gl + Po + Sol.          38.50           2.60        10.1     0.697    super-saline
g   A + H + Po + Sol.                  44.76           2.23        10.7     0.685
h   A + H + Po + Ep + Sol.           73.56           1.36        13.0     0.590
      A + H + Po + Hx + Sol.           85.05           1.18        13.8     0.567
      A + H + Po + Ki + Sol.          102.40            0.98       14.9     0.498
i    A + H + Po + Ki + Car + Sol.  117.11           0.85        15.15   0.463
      A + H + Ki + Car + Sol.         159.74           0.62        15.33   0.457
      A + H + Ki + Car + Bi + Sol.   246               0.41         17.40  0.338

C.F.  is the concentration factor (C.F. = 1.0 for seawater)
I  is the ionic strength
a(H₂O)  is the activity of water
Sol.  is the solution

Mineral Abbreviations:  A, anhydrite, CaSO₄; Bi, bischofite, MgCl₂·H₂O; Car, carnallite, KMgCl₃·6H₂O; Ep, epsomite, MgSO₄·7H₂O; G, gypsum, CaSO₄·2H₂O; Gl, glauberite, Na₂Ca(SO₄)₂; H, halite, NaCl; Hx, hexahydrite, MgSO₄·6H₂O; Ki, kieserite, MgSO₄·H₂O; Po, polyhalite, K₂MgCa₂(SO₄)₄·2H₂O.
 

Water                  Portion in                  Portion in              Comparable
Molecule             Total water               Heavy water           Concentration

  ¹H₂¹⁶O                          99.73                               -                                      -

  ¹H₂¹⁸O                            0.20                             73.5                                 Mg

  ¹H₂¹⁷O                            0.04                             14.7                                 Ca

  ¹H₂H¹⁶O                         0.032                           11.8                                 K

  ¹H₂H¹⁸O                       6 x 10^-5                          0.022                              N

  ¹H₂H¹⁷O                       1 x 10^-5                          0.003                              Al

  ²D₂¹⁶O                          3 x 10^-6                          0.001                              P

  ²D₂¹⁸O                          6 x 10^-9                        2 x 10^-6                            Hg

  ²D₂¹⁷O                          1 x 10^-9                        3 x 10^-7                            Au
 
 
 
 

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Borchert, H., Principles of Oceanic Salt Deposition and Metamorphism, Chapter 19, Chemical Oceanography, Vol. 2, 1st Ed., J. P. Riley and G. Skirrow, Academic Press, New York, 205-276 (1965).

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Wallace,  C. Development of the Chlorinity-Salinity Concept, Elsivier, New York, (1974).

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