Conservative Type
Owing to their low reactivity, conservative type
transition metals and heavy metals (V, Mo, W, Re,
and Tl) are present in sea water at relatively high
concentrations that are in constant proportion to
salinity. Conservative metals have long mean oceanic
residence times (4 410
5 y), their distributions are
considerably homogeneous throughout the ocean
due to the ocean’s 1000-year circulation, and their
concentrations are controlled by physical processes
(e.g., advection and turbulent mixing).
Scavenged Type
Scavenged type transition metals and heavy metals
(Mn, Co, Ga, In, Te, Pb, Bi, Ce) typically have strong
interactions with particles, short mean oceanic residence times (10
2 À 10
3 y), and low concentrations.
Their removal from sea water is dominated by adsorption onto the surfaces of particles and transport
to the sediment via interactions with large, rapidly
settling particles. Their depth profiles typically show
enrichment in surface waters owing to sources from
rivers and atmospheric dust, and rapid depletion to
low concentrations at depth.
Nutrient (Recycled) Type
Metals having nutrient type distributions (Fe, Ni,
Zn, Ge, Se, Y, Ag, Cd, Ba, La) are characterized by
surface water depletion and enrichment at depth.
Surface depletion is caused by biological uptake, and
Table 1 Oceanic concentrations of transition metals and heavy metals
Element
Concentration units
a
North Pacific
North Atlantic
Surface
Deep
Surface
Deep
Sc
pmol l
À1
8
1 8
1 4
2 0
Ti
pmol l
À1
4–8
200–300
30–60
200
V
nmol l
À1
32
36
23
Cr
nmol l
À1
3
5
3.5
4.5
Mn
nmol l
À1
0.5–3
0.08–0.5
1–3
0.25–0.5
Fe
nmol l
À1
0.02–0.5
0.5–1
1–3
0.25–0.5
Co
pmol l
À1
4–50
10–20
18–300
20–30
Ni
nmol l
À1
2
11–12
2
6
Cu
nmol l
À1
0.5–1.3
4.5
1.0–1.3
2
Zn
nmol l
À1
0.1–0.2
8.2
0.1–0.2
1.6
Ga
pmol l
À1
12
30
25–30
Ge
pmol l
À1
5
100
1
20
Y
pmol l
À1
66–187
306–383
Zr
pmol l
À1
12–95
275–325
100
Nb
pmol l
À1
2.8
3.9
Mo
nmol l
À1
93
105
Rh
fmol l
À1
370
900
Pd
pmol l
À1
0.18
0.66
Ag
pmol l
À1
1–5
23
0.69–4.6
2.7–6.9
Cd
pmol l
À1
1–10
1000
1–10
350
In
pmol l
À1
0.09–1.8
0.07–0.09
2.7
0.9
Sn
pmol l
À1
4
10–20
8
Te
pmol l
À1
1.2
1
1–1.5
0.4–1
La
pmol l
À1
20
50–70
12–15
80–84
Hf
pmol l
À1
0.2–0.4
1–2
0.4
Ta
pmol l
À1
0.09
0.3
W
pmol l
À1
41
51
Re
pmol l
À1
28–82
32–43
Os
fmol l
À1
20
15
17
Ir
fmol l
À1
0.5
0.8
Pt
pmol l
À1
0.4
0.3–1.2
0.2–0.4
0.2–0.4
Au
fmol l
À1
50–150
50–150
Hg
pmol l
À1
0.5–10
2–10
1–7
1
Tl
pmol l
À1
60–80
80
60–70
60
Pb
pmol l
À1
14–50
3–6
100–150
20
Bi
pmol l
À1
0.2
0.02
0.25
a 1 nmol l
À1 ¼ 10
À9 mol l
À1 ; 1 pmol l
À1 ¼ 10
À12 mol l
À1 ; 1 fmol l
À1 ¼ 10
À15 mol l
À1 .
TRANSITION METALS AND HEAVY METAL SPECIATION 73
Owing to their low reactivity, conservative type
transition metals and heavy metals (V, Mo, W, Re,
and Tl) are present in sea water at relatively high
concentrations that are in constant proportion to
salinity. Conservative metals have long mean oceanic
residence times (4 410
5 y), their distributions are
considerably homogeneous throughout the ocean
due to the ocean’s 1000-year circulation, and their
concentrations are controlled by physical processes
(e.g., advection and turbulent mixing).
Scavenged Type
Scavenged type transition metals and heavy metals
(Mn, Co, Ga, In, Te, Pb, Bi, Ce) typically have strong
interactions with particles, short mean oceanic residence times (10
2 À 10
3 y), and low concentrations.
Their removal from sea water is dominated by adsorption onto the surfaces of particles and transport
to the sediment via interactions with large, rapidly
settling particles. Their depth profiles typically show
enrichment in surface waters owing to sources from
rivers and atmospheric dust, and rapid depletion to
low concentrations at depth.
Nutrient (Recycled) Type
Metals having nutrient type distributions (Fe, Ni,
Zn, Ge, Se, Y, Ag, Cd, Ba, La) are characterized by
surface water depletion and enrichment at depth.
Surface depletion is caused by biological uptake, and
Table 1 Oceanic concentrations of transition metals and heavy metals
Element
Concentration units
a
North Pacific
North Atlantic
Surface
Deep
Surface
Deep
Sc
pmol l
À1
8
1 8
1 4
2 0
Ti
pmol l
À1
4–8
200–300
30–60
200
V
nmol l
À1
32
36
23
Cr
nmol l
À1
3
5
3.5
4.5
Mn
nmol l
À1
0.5–3
0.08–0.5
1–3
0.25–0.5
Fe
nmol l
À1
0.02–0.5
0.5–1
1–3
0.25–0.5
Co
pmol l
À1
4–50
10–20
18–300
20–30
Ni
nmol l
À1
2
11–12
2
6
Cu
nmol l
À1
0.5–1.3
4.5
1.0–1.3
2
Zn
nmol l
À1
0.1–0.2
8.2
0.1–0.2
1.6
Ga
pmol l
À1
12
30
25–30
Ge
pmol l
À1
5
100
1
20
Y
pmol l
À1
66–187
306–383
Zr
pmol l
À1
12–95
275–325
100
Nb
pmol l
À1
2.8
3.9
Mo
nmol l
À1
93
105
Rh
fmol l
À1
370
900
Pd
pmol l
À1
0.18
0.66
Ag
pmol l
À1
1–5
23
0.69–4.6
2.7–6.9
Cd
pmol l
À1
1–10
1000
1–10
350
In
pmol l
À1
0.09–1.8
0.07–0.09
2.7
0.9
Sn
pmol l
À1
4
10–20
8
Te
pmol l
À1
1.2
1
1–1.5
0.4–1
La
pmol l
À1
20
50–70
12–15
80–84
Hf
pmol l
À1
0.2–0.4
1–2
0.4
Ta
pmol l
À1
0.09
0.3
W
pmol l
À1
41
51
Re
pmol l
À1
28–82
32–43
Os
fmol l
À1
20
15
17
Ir
fmol l
À1
0.5
0.8
Pt
pmol l
À1
0.4
0.3–1.2
0.2–0.4
0.2–0.4
Au
fmol l
À1
50–150
50–150
Hg
pmol l
À1
0.5–10
2–10
1–7
1
Tl
pmol l
À1
60–80
80
60–70
60
Pb
pmol l
À1
14–50
3–6
100–150
20
Bi
pmol l
À1
0.2
0.02
0.25
a 1 nmol l
À1 ¼ 10
À9 mol l
À1 ; 1 pmol l
À1 ¼ 10
À12 mol l
À1 ; 1 fmol l
À1 ¼ 10
À15 mol l
À1 .
TRANSITION METALS AND HEAVY METAL SPECIATION 73