Fjölrit RALA - 15.06.2004, Side 55

Elemental composition of Reference European Volcanic Soils
A. Martínez-Cortizas, J.C. Nóvoa, X. Pontevedra and E. García-Rodeja
Dept. Edafología y Química Agrícola, Facultad de Biología, Universidad de Santiago de Compostela
Within the framework of EU-COST action 622 twenty soils developed on volcanic materials
from Italy (IT: N1 to N4), Azores Islands (AI: N5, N6), Iceland (IC: N7 to N9), Canary
Islands (CI: NIO to N12), Greece (GR: N13, N14 N14A), France (FR: N15, N16) and
Hungary (HG: N17 to N19) were described, sampled and analyzed for a large number of soil
properties by different research groups. Here we describe the results of the analysis of 27
elements (Si, Al, Fe, K, Ca, Mg, Na, P, Cl, Ti, Cr, Mn, Ni, Cu, Zn, As, Se, Br, Rb, Y, Zr, Pb,
Th, U, and Hg). Subsamples from each soil horizon were air dried and homogenized, and all
elements except for Hg were determined by XRF analysis. Mercury was measured with a
LECO-ALTEC AMA-354 Hg analyzer, which is a single-purpose atomic absorption
spectrophotometer for solid and liquid samples. No sample pretreatment was done for any of
the determinations.
In general terms each volcanic area showed a specific elemental composition (Table 1). For
example, Italian soils have the highest K, As, Rb, Sr, Pb, Th and U and the lowest Mg, Ti, Cr,
and Fe concentrations of all soils; soils from Azores are very rich in Mn, Fe, Br and Hg and
the poorest in Si, Ca, and Sr; Icelandic soils have the highest Mg, Cu, Zn and Y and the
lowest, K, As, Rb, Pb and Th concentrations; soils from the Canary Islands are the richest in
Al, Ti, Cr, Ni, Ga, and Zr and the poorest in Na; Greek soils are rich in Si, Na and Ca and
poor in metallic elements; while soils from France and Hungary have intermediate
concentrations for almost all elements. The most similar soils are those from Azores Islands
and Canary Islands, due to their richness in many metallic elements (Al, Ti, Cr, Fe, Ni, Zn,
Ga). This similarity is confirmed by PCA analysis, since the horizons for soils N5, N6, NIO,
N11 and N12 plot very close in the axis projections.
Table 1 Relative elemental composition of soils from the different volcanic areas. Values
between parenthesis are the maximum (rich) and the minimum (poor) average concentrations.
(Si, Al, Ca, Mg, Na, K, P, Cl, Ti and Fe are in % and the rest of the elements in pg g"1 except
for Hg which is in ng g'1).
Volcanic area Rich Poor
ITALY K (5.3), As (24.5), Rb (282), Sr (613), Pb (81.4), Th (48.3), U (15) Mg (0.5), P, Ti (0.4), Cr (<d.l.), Mn, Fe (2.7), Ni, Zn
AZORES Is. Al, Mg, P, Ti, Cr, Mn (3039), Fe (10), Ni, Zn, Ga, Br (362), Hg (216) Si (13.1), Ca (1.0), Sr (157), Pb
ICELAND Ca, Mg (1.2), Mn, Cu (75.5), Zn (128), Y (44.8) K (1.0), As (<d.l.), Rb (17.6), Pb (0.9), Th (2.9)
CANARY Is. A1 (14.4), Ti (3.9), Cr (470), Fe, Ni (125), Zn, Ga (33.2), As, Br, Zr (699), Th, Hg Na (0.7)
GREECE Si (28.2), Na (2.3), Ca (3.5) Al (7.9), P (<d.l.), Ti, Mn (707), Fe, Ni (8.2), Cu, Zn (60), Ga, As, Br, Sr, Y, Zr (179), flg (11.9)
FRANCE P (0.7), Sr Si, K, Rb, Y (22.1), Zr, Th
HUNGARY Si, Mg, Rb, Pb Al, Na, Ca, Cu (27.4), Ga (14), Br (6.5), Y
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