Variability of Available Cadmium in Relation to Soil Properties and Landuse in an Arid Region in Central Iran

Abstract

Due to potential problems associated with their toxicities, concentration of heavy metals in soils is of great environmental concern. To evaluate Cd content, its spatial pattern, and availability in the surface soils of agricultural, industrial and urban regions of Isfahan, central Iran, we collected 255 topsoil samples (0-20 cm) from the nodes of an irregular grid in a study area of 6800 km 2 . In the soil samples we measured total and DTPA-extractable Cd concentrations, soil pH, organic mater (OM), clay content, soil salinity, and chloride concentration. The total Cd concentration in 90% of the samples exceeded the suggested Swiss thresholds of 0.8 mg kg −1 . Landuse had a significant effect on total concentration of Cd in the soil but had no effect on DTPA-extractable Cd. High values of total Cd were found in industrial and urban areas whereas low values occurred in uncultivated lands. The correlation analysis revealed that soil salinity alone explained 36% of the Cd variation in the entire study area. The correlation was particularly strong in uncultivated areas (R 2 = 0.70). Spatial analysis of available Cd using indicator kriging and soil salinity showed a spatial co-occurrence of these two variables.

Single and Sequential Extraction of Cadmium in Some Highly Calcareous Soils of Southwestern Iran

“…As the proportion of metals fractions is controlled by the soil properties (Naidu et al, 1994), correlation analysis was made to assess the soil properties controlling Cd fractionation in these soils. DTPA-extractable Cd Concentrations were positively correlated with soil electrical conductivity (r = 0.65, p< 0.01), it was reported before by Amini et al (2005).…”

Cadmium uptake and subcellular distribution in rice plants as affected by phosphorus: Soil and hydroponic experiments

“…It is generally accepted that the pH of a soil is one of the most important factors controlling the uptake of heavy metals by plants (Amini et al, 2005). The increase in pH after P-application was due to ligand exchange reactions, where surface hydroxyl groups coordinated with a metal cation (e.g., Fe and Al) are replaced by phosphate ions (Bolan et al 2003).…”

Spatial distribution of soil heavy metals in different land uses of an industrial area of Tehran (Iran)

“…RL with the highest percentage of clay maintains more available Cu on their adsorption exchange sites. Negative correlation between CaCO 3 and Cu may be originated from precipitation process and mostly Cu carbonate as Renella et al (2004) and Amini et al (2005) reported. Therefore, although there was no significant difference between total Cu in three land uses, it seems that different land uses resulted in significant differences in Cu DTPA forms through higher amounts of clay content and lower percentages of CaCO 3 .…”

“…In addition, several researchers have also described the potential risks of heavy metals entering into human bodies through edible plants grown in contaminated soils (Bai et al 2010a;Dumat et al 2006;Notten et al 2005). Whereas total heavy metal concentrations and the concentrations of extractable heavy metals can be used to assess the level of contamination (Zhao et al 2012), the available soil metal concentrations predict metal transfer from soil to crops better than total metal concentrations (Amini et al 2005). Zhao et al (2012) showed that the areas with the highest human health risks do not directly coincide with the areas of highest heavy metal concentrations, but do coincide with the areas of lower soil pH.…”