Table 1 A compilation of pK n , pK n *, pQ n data and equilibrium speciation schemes appropriate to seawater (S 35) at 25°C. Equilibrium constants are expressed on the free hydrogen ion concentration scale.
From: Inorganic speciation of dissolved elements in seawater: the influence of pH on concentration ratios
Atomic number | Element | Principal species | Equilibrium data |
|---|---|---|---|
1 | H | H+ (68%), HSO4 - (29%), HF0 (3%) | |
2 | He | He | |
3 | Li | Li+ (98%), LiSO4 - (2%) | |
4 | Be | Be2+/BeOH+/Be(OH)2 0 | pK1* = 5.69; pK2* = 8.25 |
5 | B | B(OH)3 0/B(OH)4 - | pK* = 8.74 |
6 | C | CO2/HCO3 -/CO3 2- | pK1 = 6.00; pK2 = 9.09 |
7 | N | NO3 -, NO2 -, N2; NH4 +/NH3 | pK = 9.35 |
8 | O | O2 | |
9 | F | F- (50%), MgF+ (50%) | |
10 | Ne | Ne | |
11 | Na | Na+ 98%, NaSO4 - (2%) | |
12 | Mg | Mg2+ (90%), MgSO4 0 (10%) | |
13 | Al | A1(OH)2 +/A1(OH)3 0/A1(OH)4 - | pK3* = 5.7; pK4* = 7.7 |
14 | Si | Si(OH)4/SiO(OH)3 - | pK = 9.32 |
15 | P | H2PO4 -/HPO4 2-/PO4 3- | pK2 = 6.10; pK3 = 8.93 |
16 | S | SO4 2- (33%), NaSO4 - (35%), MgSO4 0 (20%) | |
HSO4 -/SO4 2- | pK ≅ 1 | ||
17 | Cl | Cl- (100%) | |
18 | Ar | Ar | |
19 | K | K+ (99%) | |
20 | Ca | Ca2+(89%), CaSO4 0(11%) | |
21 | Sc | Sc(OH)2 +/Sc(OH)3 0/Sc(OH)4 - | pK3* = 6.4; pK4* = 9.6 |
22 | Ti | Ti(OH)3 +/Ti(OH)4 0 | pK* = 2.5 |
23 | V | VO2(OH)2 - /VO3(OH)2-/VO4 3- | pK2 = 7.4; pK3 ≤ 13 |
24 | Cr | Cr(OH)2 +, Cr(OH)3 0, Cr(OH)4 - | pK3* = 8.3; pK4* = 9.1 |
25 | Mn | Mn2+ (72%), MnCl+ (21%) | |
26 | Fe | Fe(OH)2 +/Fe(OH)3 0, Fe(OH)4 - | pK3* = 6.60; pK4* = 8.5 |
27 | Co | Co2+ (65%), CoCl+ (14%) | |
28 | Ni | Ni2+ (53%), NiCl+ (9%) | |
29 | Cu | Cu2+/CuOH+, Cu2+/CuCO3 0 | pK1* = 8.11; pQ1 = 6.93 |
30 | Zn | Zn2+ (64%), ZnCl+ (16%) | |
31 | Ga | Ga(OH)2 +/Ga(OH)30/Ga(OH)4- | pK3* = 4.4; pK4* = 6.0 |
32 | Ge | Ge(OH)4 0/GeO(OH)3 -/GeO2(OH)2 2- | pK1 = 8.98; pK2 = 11.8 |
33 | As | H2AsO4 -/HAsO4 2-/AsO4 3- | pK2 = 6.15; pK3 = 9.84 |
As(OH)3/As(OH)4 - | pk* = 9.03 | ||
34 | Se | SeO4 2- (100%) | |
H2SeO3/HSeO3 -/SeO3 2- | pK1 = 2.3; pK2 ≤ 7.8 | ||
35 | Br | Br- (100%) | |
36 | Kr | Kr | |
37 | Rb | Rb+ (99%), RbSO4 - (1%) | |
38 | Sr | Sr2+ (86%), SrSO4 0 (14%) | |
39 | Y | Y3+/YCO3 +/Y(CO3)2 - | pQ1 = 6.63; pQ2 = 7.89 |
40 | Zr | Zr(OH)3 +/Zr(OH)4 0/Zr(OH)5 - | pK4* = 4.6; pK5* = 5.99 |
41 | Nb | Nb(OH)4 +/Nb(OH)5 0/Nb(OH)6 - | pK5* ≅ -0.6; pK6* = 7.4 |
42 | Mo | HMoO4 -/MoO4 2- | pK ≅ 3.5 |
43 | Tc | TcO4 - (100%) | |
44 | Ru | Ru(OH) n 4-n | pK n (?) |
45 | Rh | RhCl a (OH) b 3-(a+b) | pK n (?) |
46 | Pd | PdCl4 2-/PdCl3OH2- | pK* = 8.7 |
47 | Ag | AgCl3 2- (66%), AgCl2 - (26%) | |
48 | Cd | CdCl+ (36%), CdCl2 0 (45%), CdCl3 - (16%) | |
49 | In | In(OH)2 +/In(OH)3 0/In(OH)4 - | pK3* = 4.58; pK4* = 9.37 |
50 | Sn | Sn(OH)3 +/Sn(OH)4 0 | pK*≅ 1.2 |
51 | Sb | Sb(OH)5 0/Sb(OH)6 - | pK* = 2.5 |
52 | Te | Te(OH)6 0/TeO(OH)5 -/TeO2(OH)4 2- | pK1 = 7.35; pK2 ≅ 10.2 |
Te(OH)4 0/TeO(OH)3 -/TeO2(OH)2 2- | pK1≅ 3.5; pK2 = 8.85 | ||
53 | I | IO3 - (89%); I- (100%) | |
54 | Xe | Xe | |
55 | Cs | Cs+ (99%) | |
56 | Ba | Ba2+ (86%), BaSO4 (14%) | |
57 | La | La3+/LaCO3 +/La(CO3)2 - | pQ1 = 7.38; pQ2 = 8.47 |
58 | Ce | Ce3+/CeCO3 +/Cd(CO3)2 - | pQ1 = 7.05; pQ2 = 8.34 |
59 | Pr | Pr3+/PrCO3 +/Pr(CO3)2 - | pQ1 = 6.88; pQ2 = 8.20 |
60 | Nd | Nd3+/NdCO3 +/Nd(CO3)2 - | pQ1 = 6.83; pQ2 = 8.15 |
61 | Pm | Pm3+/PmCO3 +/Pm(CO3)2 - | -- |
62 | Sm | Sm3+/SmCO3 +/Sm(CO3)2 - | pQ1 = 6.65; pQ2 = 7.97 |
63 | Eu | Eu3+/EuCO3 +/Eu(CO3)2 - | pQ1 = 6.63; pQ2 = 7.89 |
64 | Gd | Gd3+/GdCO3 +/Gd(CO3)2 - | pQ1 = 6.72; pQ2 = 7.95 |
65 | Tb | Tb3+/TbCO3 +/Tb(CO3)2 - | pQ1 = 6.65; pQ2 = 7.72 |
66 | Dy | Dy3+/DyCO3 +/Dy(CO3)2 - | pQ1 = 6.55; pQ2 = 7.69 |
67 | Ho | Ho3+/HoCO3 +/Ho(CO3)2 - | pQ1 = 6.56; pQ2 = 7.59 |
68 | Er | Er3+/ErCO3 +/Er(CO3)2 - | pQ1 = 6.50; pQ2 = 7.53 |
69 | Tm | Tm3+/TmCO3 +/Tm(CO3)2 - | pQ1 = 6.43; pQ2 = 7.45 |
70 | Yb | Yb3+/YbCO3 +Yb(CO3)2 - | pQ1 = 6.30; pQ2 = 7.55 |
71 | Lu | Lu3+/LuCO3 +/Lu(CO3)2 - | pQ1 = 6.36; pQ2 = 7.42 |
72 | Hf | Hf(OH)3 +/Hf(OH)4 0/Hf(OH)5 - | pK4* = 4.7; pK5* = 6.19 |
73 | Ta | Ta(OH)4 +/Ta(OH)5 0/Ta(OH)6 - | pK5* ≅ -1; pK6* = 9.6 |
74 | W | HWO4 -/WO4 2- | pK ≤ 3.5 |
75 | Re | ReO4 - (100%) | |
76 | Os | OsO4 0 (?) | |
77 | Ir | IrCl a (OH) b 3-(a+b) | pK(?) |
78 | Pt | PtCl4 2-/PtCl3OH2- | pK* ≅ 8.7 |
79 | Au | AuCl2 - | |
AuCl3(OH)-/AuCl2(OH)2 -/AuCl(OH)3 - | pK22* = 6.4; pK13* = 7.4(?) | ||
80 | Hg | HgCl4 2- (88%), HgCl3 - (12%) | |
81 | Tl | Tl+ (61%), T1C10 37% | |
T1C14 -/T1(OH)3 0 | pK≅ 7.1 (?) | ||
82 | Pb | PbCl n 2-n/PbCO3 0 | pQ = 7.85 |
83 | Bi | Bi(OH)2 +/Bi(OH)3 0/Bi(OH)4 - | pK3* = 4.86; pK4* ≅ 12.7 |