JWSS - Journal of Water and Soil Science

Terraces are old geomorphic surfaces that are not related to present streams and are best places to study the effect of time on soil formation (chronosequence). This research was carried out to study some physico-chemical parameters especially different forms of iron as soil development indices on terraces of Karaj River in Hassan-Abad, southern Tehran. To determine soil development indices in 4 profiles occurring on 4 terraces, some physical and chemical properties were measured and free iron(Fed), aluminum(Ald), silica(Sid) and manganese(Mnd), amorphous Fe(Feo), Al(Alo), Si(Sio), Mn(Mno) and Fe, Al, Si-humus complexes were extracted. Results showed that clay, fine clay/total clay, CEC, the color redness and leaching of calcium carbonate increase toward higher terraces. Contents of Fed, Ald and Sid increases from lower terrace (T1) to the higher terrace (T4). Fed-Feo and Feo/Fed as the most important indices of soil development were enhanced and reduced from lower terrace (T1) to higher terrace (T4) soils, respectively, which indicate an increase in iron oxides crystalinity and soil profile development. Contents of Fed-Feo in the B horizons from T1 to T4 were 600, 800, 1000, and 1400 mg/kg soil, respectively. Calculation of Ferrihydrate and Fe-hydr(oxide) such as goethite and hematite showed that the amounts of these components were increased from T1 to T4 terraces confirming the variation of (Fed-Feo), (Feo/Fed) and (Feo-Fep) indices.

Mobarakeh Steel Complex has been using treated industrial wastewater for irrigation of green space to combat water shortage and prevent environmental pollution. This study was performed to assess the impact of short-, middle-, and long-term wastewater irrigation on soil quality attributes in green space of this complex. Soils were sampled from the wet bulb produced by under-tree trickles in three depths of forested lands irrigated with treated wastewater (for 2, 6 and 18 years) or groundwater. Several chemical, physical and biological characteristics of the soil samples were determined in the laboratory and compared to those of the native unirrigated soils as the controls. The results showed that pH was significantly reduced in the wastewater-irrigated soils as compared to the control. Organic matter content and cation exchange capacity significantly increased in the irrigated soils due to the incorporation of tree leaves into soil. Soil salinity also increased as the irrigation period increased because of the relatively high salinity of water and wastewater used for irrigation. Microbial basal respiration and arginine ammonification were greater in the irrigated soils in comparison to the control. In general, forestation and irrigation management have improved most of the soil quality indexes in the Mobarakeh Steel Complex green space, but some soil characteristics, such as salinity, need to be monitored and improved in future.