『Abstract
This paper contributes to increase the knowledge of the contents
and sources of heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and
Zn) to agricultural soils in Castellon（oの頭に´）
province (Spain), a representative area of the European Mediterranean
region. The surface horizons of 77 agricultural soils under vegetable
crops were sampled and heavy metals were analysed by atomic absorption
spectroscopy (AAS) after microwave extraction using the USEPA
3051A method. Mean heavy metal contents were similar to those
obtained in other areas of this region. However, Heavy metal contents
(e.g. Cr, Pb) in some soils were above the maximum limit set in
the 86/278/CEE Directive. Multivariate analysis (correlation analysis
and principal component analysis - PCA) was performed so as to
identify the sources of heavy metals to soils. Co, Fe and Ni were
highly correlated amongst them (r＞0.800; p＜0.01), whereas Cr and
Mn were less correlated with Co, Fe and Ni (r＞0.500; p＜0.01).
Other relationships among heavy metals (i.e. Cu, Pb and Zn) were
also identified, although correlation coefficients were not so
high as those among Co, Fe and Ni (r＜0.500; p＜0.01). Contents
of Co, Fe, Mn and Ni were interpreted to be mainly associated
with parent rocks corresponding to the first principal component
(PC1). On the other hand, Cd, Cu, Pb and Zn were interpreted to
be mainly related to anthropogenic activities and comprised the
second (Pb and Zn) and the third (Cd and Cu) principal components
(PC2 and PC3,respectively), designated as anthropogenic components.
Remarkably, Cr appears to be related in the study area to both
the lithogenic and the anthropogenic components. Lithogenic elements
were highly correlated with soil properties. Positive relationships
with CEC (r＞0.200; p＜0.05) and clay (r＞0.400; p＜0.01), and negative
relationships with carbonates (r＞-0.400; p＜0.01) and sand (r＞-0.300;
p＜0.01) were observed. Anthropogenic elements were less correlated
with soils properties, since these elements are generally more
mobile because they form more soluble chemical species associated
to anthropogenic sources. Particularly, no correlation was found
between Cd and Zn and soil properties. These findings extend results
achieved in other parts of the region, highlighting the need to
set soil quality standards in order to declare soils affected
by anthropogenic pollution, particularly in the case of anthropogenic
metals such as Cd, Cu and Pb, and also Cr and Zn in some areas.
Further knowledge from other areas in this region would improve
the basis for proposing such standards at regional level, which
is a priority objective in Europe according to the European Thematic
Strategy for Soil Protection.
Keywords: Agricultural soils; European Mediterranean region; Heavy
metal origin; Multivariate analysis; Soil pollution』
1 Introduction
2 Materials and methods
2.1 Site characteristics, soil sampling and pretreatment
2.2 Soil analysis
2.3 Statistics
3 Results
3.1 Soil properties
3.2 Heavy metal contents
3.3 Multivariate analysis
3.3.1 Correlation analysis
3.3.2 Principal component analysis (PCA)
3.4 Relationships between heavy metal contents and soil properties
4 Conclusions
Acknowledgements
References