Rapid industrialization has led to an extraordinary increase in environmental pollution in Arak, Iran. This study classified the distribution of iron (Fe), manganese (Mn), lead (Pb) and cadmium (Cd) in sediments and soils of Mighan Playa (Iran) and analysed the pollution sources using geostatistical methods. Samples were taken from 250 points and the data analysed by means of SPSS, GS+ and ArcGIS. The soils were moderate to considerable polluted with Pb and high to very high polluted with Cd.

Due to widespread and fast-growing urban developments, large amounts of industrial, agricultural, and municipal wastewaters are produced which can change ecosystem functions after being released into rivers and lakes. The distributions of organic carbon (OC) and total phosphorus (TP) of soil were studied in the salt affected soils in the Meyghan Playa, Iran, to show the impacts of human activities on these soils and sediment properties in this arid region of the world. Samples were taken from 250 points and were analyzed geostatistically for electrical conductivity (EC), pH, TP, and OC. Although EC had the highest coefficient of variation (CV = 2.4) compared to CVs of the other soil properties, the sill/nugget ratio for EC in the geostatistical analysis was the highest one. Therefore, EC had the strongest spatial dependence compared to OC, TP, and pH with lower sill/nugget ratios and moderate spatial dependence. The maximum amount of OC was more than 2% which was observed near the entrance of municipal wastewater to the Meyghan Lake, and the highest soil TP was more than 400 kg mg^-1 near the entrance of municipal wastewater and also at river mouths, which can be attributed to leaching and runoff fertilizers from farmlands. Enrichment of OC in the entrance of municipal wastewater toward the lake is related to eutrophication and higher plant production.

The chemical fractionation and bioavailability of iron, manganese, lead, and cadmium in soils around Meyghan Lake, Arak, Iran, were studied. The samples were obtained from four sites of water entrance to the lake using a sequential extraction method. The soil sampled from the release site of wastewater of sodium sulfate plant had the lowest total heavy metal contents compared to other sites. Although the HNO 3 extractable fraction was the most important phase for the four heavy metals, this fraction in salty soils was not the main fraction for Cd. The KNO 3 extractable and bioavailability and contamination factor (CF) of the heavy metals were considerably high in the salt-affected soils. The NaOH extractable Fe of the non-salty soils was higher than that of the salty soils. The order of metal reactivity assessed by CF in the studied soils was observed to be Cd > Pb > Mn ≫ Fe. However, the increasing effect of salinity on promoting the metal-soluble and exchangeable form (mobility) followed the order of Cd > Mn > Pb ≫ Fe.