times higher than those in the North Pacific at similar
depths – the largest interocean fractionation yet observed for any element (Figure 3). As the deep waters
travel from the western North Atlantic to the eastern
North Atlantic or on to the North Pacific, dissolved
aluminum is continually removed from the water.
Thus the lowest concentrations are found in the
oldest waters of the North Pacific.
0
2
4
6
8
120°W
130°W
140°W
150°W
Longitude
0
5
10
15
20
120°W
130°W
140°W
150°W
0
50
100
150
200
120°W
150°W
180°W
150°E
Longitude
0
0.5
1.0
1.5
2.0
Zr
Hf
0
20
40
60
80
0
300
600
900
1200
Nautical miles
0
20
40
60
80
73°W
74°W
75°W
Al (nmol kg
_
1
)
Ga (pmol kg
_
1
)
Hf (pmol kg
_
1
)
Zr (pmol kg
_
1
)
Ga (pmol kg
_
1
)
Al (nmol kg
_
1
)
(A)
(B)
(C)
Figure 2 The surface distribution of (A) aluminum, (B) gallium, and (C) zirconium and hafnium from coastal to open ocean regions in
the North Pacific and western North Atlantic. Note the scale changes between oceans. In all panels, the coastal locations are plotted at
the outside edges, with more oceanic locations in towards the middle. The data for Al and Ga in the eastern North Pacific are from
281N 1551W to 361N 1231W (Orians and Bruland, 1986, 1988b). For the Atlantic, the Ga data are from 371N 751W to 361N 731W
(Orians and Bruland, 1988b), and the Al data are from Rhode Island, across the Gulf Stream, into the Sargasso Sea, then down
toward the Caribbean (Measures et al, 1984, stations #0-1206). For Zr and Hf the western North Pacific data are from 381N 1461E to
161N 1691W, and in the eastern North Pacific from 501N 1451W to 491N 1261W (McKelvey and Orians, 1993; McKelvey, 1994).
REFRACTORY METALS 55