Prediction of Spatial Distribution of Soil Organic Content and Nitrogen in Irrigated Lands (Case Study: Absard Plain- Damavand, Tehran Province)

The aim of this study was to investigate the origin and potential ecological risk of heavy metals (arsenic (As), cadmium (Cd), lead (Pb), nickel (Ni), zinc (Zn) and Cu (copper) in different land uses in West of Arak, Markazi Province. A total of 235 Surface soil samples were taken from the depth of 0-5 cm including 160, 46 and 29 samples from agricultural, rangeland and industrial land uses, respectively. The ranges of As, Pb, Zn, Ni, Cd and Cu in studied soils were 55.7–357.2, 6.8–256, 13.2–858, 26.7–172, 0.1–3.65 and 5.1–34.1 mg/kg, respectively. Comparison of the mean concentration of heavy metals in different land uses indicative of the same influence of land use to metal accumulations of As, Pb, Zn and Cu, but in the case of Ni and Cd showed that a differential influence of land use the distribution of these metals in the soil. When the average amount of crust was used as a reference background, the Cf values of As in all land uses were higher than other metals, indicating high level of pollution of soils in this region. The index of PLI in land uses comprised, industrial (3) > rangeland (2.4) > agriculture (2.39), indicating the pollution and gradual destruction of soil. The mean PER based on reference and local GB showed very high and low pollution level in all land uses, respectively. Principal component analysis (PCA) showed that Pb and Zn originated from common anthropogenic sources related to industrialization and mining, whereas Cu and Ni are probably in associated with geological sources. Cd was mainly derived from the input of agricultural and industrial activities, and As should be attributed to natural resources, emissions from local industries, mining, herbicides and the use of poultry manure and atmospheric dust.