『Abstract
The effect of rainfall on the behavior of Fe, Mn, Cu, Zn, Pb,
and Ti in mature soils developed on same-age volcanic bedrock
in Hawaii was studied. Concentrations of the mentioned metals
in total digested and weak acid-leached soil and bedrock samples
were analyzed. Mass transport calculations yields the quantity
of metal enrichment or depletion in the soils relative to the
bedrock. In addition, elemental mobility and the distribution
between the labile and the residual fraction were examined.
Based on mass transport calculations there is no significant
effect of rainfall amount on the enrichment or depletion of any
elements (except Cu) within soils receiving less than 570 mm/yr
(4 sites). In the intermediate sites (4 sites, 930-1380 mm/yr)
there is a variable effect of rainfall on all elements in the
soil, but the extent of variation differs from one metal to the
other. In the rainy site (2500 mm/yr) there is a large degree
of enrichment or depletion of certain metals. Manganese and Zn
are highly depleted and Pb is strongly enriched, whereas Fe and
Cu do not show a significant mass change. Among all elements,
Pb is the only one that has a continuous effect of rainfall throughout
the transect. Lead is enriched in all the sites and this enrichment
is well correlated with increasing rainfall. Iron is immobile
in the soil, reflecting the relative stability of the Fe-rich
phases and its high correlation with Ti. The mass change of Mn
throughout the transect is remarkably correlated with Al (R
2=0.87). The behavior of the trace metals Pb,Zn,
and Cu in the Kohala soils is different because of the phases
with which these metals are likely to be associated. Lead is probably
adsorbed and coprecipitated mostly with Fe oxides and hydrous
oxides. Zinc is presumably associated with Mn and Al oxides and
hydrous oxides and with organic matter, whereas Cu is mostly complexed
by organic matter.』
1. Introduction
2. Study area
3. Experimental methods
3.2. Sample collection and processing
3.3. Analytical procedures
4. Results
5. Discussion
5.1. Mass transport
5.2. The acid-leached fraction and metal behavior in the soil
5.2.1. Iron and Mn - the oxides and hydrous oxides forming metals
5.2.2. Lead, Zn, and Cu - the adsorbed metals
6. Conclusions
Acknowledgments
References