Spatial Dependence of Geochemical Elements in a Semiarid Agricultural Field: II. Geostatistical Properties
- Ronny Berndtsson ,
- Akissa Bahri and
- Kenji Jinno
Experimental variograms may be used to infer the spatial structure of geochemical elements. This information is needed to control the transport of toxic elements through the unsaturated zone. Geostatistical properties of total soil contents for 20 major and trace elements were investigated for a soil in northern Tunisia. The analysis showed that all elements have a clear spatial structure. Several elements displayed a significant trend that was removed by fitting the raw data to a second-order polynomial. Variograms for the residuals showed that most elements reach sills at ranges of ≈10 to 20 m. Exceptions are Co with a range of ≈1 m and Zn with a range of ≈5 m. The elements Be and Sr have larger ranges of ≈30 m. Calculation of direction-dependent variograms showed that most elements depended on direction. Autocorrelation analysis of the residuals indicated no spatial correlation. The ranges found in this study can be used in sampling strategies to obtain independent values of geochemical elements.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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