Study the different phases of sulphur in the soil around the gas refinery and their relationship with other soil characteristics, an example from the NE Iran

To study soil quality in Shahid Hashemi Nezhad gas refinery region in view of pollution level of produced sulfur in this industrial unit, 22 soil samples collected from inside and adjacent areas of the refinery. Sulfate content of soil was extracted in three phases water soluble, absorbed, and occluded with carbonates by deionized water, 0.032 M NaH2PO4 and 1 M HCl, respectively. The concentration of total sulfate was determined by soil complete digestion with a mixture of HF, HCl and HNO3. The content of organic matter and CO32- and HCO3- anions concentrations in the soil samples were measured using titration method. Organic, occluded with carbonates, water soluble and absorbed sulfate had the maximum concentration in the soil samples respectively, that inside refinery samples had more concentration than the other samples regarding all these phases. Water soluble sulfate had a reverse correlation with soil pH that showed sulfate occurrence could slightly oxidize sulfur and its compounds and acidic environment dominance in the soil.