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Extraction and processing of disseminated metalliferous ores, porphyry copper in particular, results in significant tonnages of waste and can cause severe disturbances and contamination in natural ecosystems. This is particularly important in semi-arid climates where natural soils are often deprived of organic matter and nutrients. This study was conducted on seven sites around Sungun Copper Mine, northwest Iran. Soil texture, EC, pH, and concentrations of nutrients, organic matter, along with 16 metal and metalloids were measured in 94 soil samples. Results showed a gradient of contamination from low contamination in natural hillsides to high contamination in mine waste depositories, Waste Dump and Oxide Dump, alongside Pakhir and Sungun Rivers. Nutrient deficiency occurred in disturbed sites. The main contaminant point sources were Waste Dump, mine pit drainage, and Oxide Dump. The results of Non-metric multidimensional scaling ordination showed elevated Cd, Zn, Fe, Cu, Pb, As, Mo, Mn, Co, S concentrations, high EC, and higher sand percentage in the sites affected by mine waste and acid mine drainage. Geo-Accumulation and Potential Ecological Risk Indices indicated that Pakhir riverside, Sungun riverside, and Oxide Dump have severe to moderate levels of environmental risks. Positive correlations between certain metal elements suggest common sources and similar reaction pathways, which may contribute to their similar geochemical behaviour in transport, deposition, and interdependence. Overall, the deficiency of organic matter and nutrients along with the soil sandy texture in contaminated sites of Sungun Copper Mine are the main limiting factors in managing metal mobility and soil remediation. [ABSTRACT FROM AUTHOR]

Wheat straw biochar (WSB) and lignite are counted as soil conditioners which used to improve soil properties and promote plant growth. Astragalus podolobus Boiss. & Hohen is a palatable species from Fabaceae family that is used for restoring of rangelands and fodder production as well as soil conservation against erosion. In this experiment, we studied the influence of WSB and lignite on soil properties and the plant traits of A. podolobus. For this purpose, the WSB and lignite were incorporated at levels of 0%, 1.25%, 2.5%, and 3.75% (w/w) in six repetitions. For this purpose, the experiment was done in pots at greenhouse condition. Data were analyzed statistically by one-way analysis of variance in SPSS21 software. The results demonstrated that WSB and lignite addition improve the soil microbial biomass (SMB) and chemical properties, e.g., electrical conductivity (EC), soil organic carbon (SOC), total N, phosphorus, and magnesium, but A. podolobus did not respond positively to these amendments. Also, lignite 3.75% (w/w) is the most effective treatment on improving soil properties. The SOC (g.kg−1) varied from 1.9 in the control to 4.6 and 6.5 by WSB and lignite at 3.75% (w/w), respectively. On the other hand, SMB (µg100gr−1 of soil) was significantly increased from 5.52 in the control to 11.5 and 11.67 by lignite and WSB 3.75% (w/w), respectively. The highest plant biomass (10.50 g) and the lowest roots dry weight (3.01 and 2.69 g) were observed in soil receiving lignite at 2.5% (w/w) and 1.25% (w/w), respectively. The amendment of WSB and lignite strongly enhance the properties of clay loam solonchak rangeland soil. It is suggested to add lignite soil conditioner at level 3.75%w/w in plantation the degraded rangelands but the response of other species must be tested to rate species that responds positively to the soil properties enhancement. [ABSTRACT FROM AUTHOR]