『Abstract
Six hundred and sixty-five soil samples were taken from Changxing
County in Zhejiang Province, China, to characterize the spatial
variability of Hg, Cd, Pb, Cu, As and Cr. The geostatistics and
geographic information system (GIS) techniques were applied, and
the ordinary kriging and lognormal kriging were used to map the
spatial patterns of the six heavy metals. Hg, Pb, Cu and As were
fitted to the spherical model with a range of 85.75, 82.32, 86.10,
and 23.17 km, respectively. Cr was fitted to the exponential model
with a range of 6.27 km, and Cd was fitted to the linear model
with a range of 37.66 km. Both Pb and Cu had strong spatial dependence
due to the effects of natural factors including parent materials,
topography and soil type. Hg, Cd, Cr and As had, however, moderate
spatial dependence, indicating an involvement of human factors.
Meanwhile, based on the comparison between the original data and
the guide values of the six metals, the disjunctive kriging technique
was used to quantify their pollution risks. The results showed
that only Cd and Hg exhibited pollution risks in the study area.
The pollution source evaluated was closely corresponded with the
real discharge of industrial production and the application of
organomercury pesticides. The results of this study provide insight
into risk assessment of environmental pollution and decision making
for agricultural production and industrial adjustment of building
materials.
Keywords: Geostatistics; Heavy metals; Spatial variability; Geographic
information system』
Introduction
Material and methods
Study area
Soil sampling and analysis
Geostatistical methods
Data treatment
Results
Descriptive parameters and probability distribution of the
raw data set
Geostatistical analysis
Spatial distributions and risk assessment
Discussions
Conclusions
Acknowledgments
References