Hydrogeochemistry and quality of water resources in the Tahroud Region of Bam, east of Kerman Province

The objective of this study is to investigate the quality of water resources in Tahroud region in the northwest of Bam city, Kerman province through hydrogeochemical studies. For this purpose, 13 water samples, including 5 samples from the agricultural wells, 4 samples of Ghanats, 3 samples from springs and 1 sample of Tahroud river were sampled and analyzed in the laboratory using Inductively coupled plasma mass spectrometry (ICP-MS) method. Based on the hydrogeochemical analysis, the water resources of the studied area have dominant Na-Cl facies and are classified as saline waters. The average concentration of EC (6230 µS/cm), TDS (4050 mg/L) as well as of Clˉ (1391 mg/L), Na+ (9031 mg/L) and SO42- (771 mg/L) in the investigated water samples were remarkably higher than the normal or recommended values. The highest amount of these soluble ions were observed in the water samples collected from the playa section of the catchment basin, which was mainly covered by the Quaternary fine-grained deposits. In addition to the hot and dry climate and the high evaporation rate, the existence of Neogene formations containing gypsum and sodium salt under these sediments is another important factor that increase the solutes in underground water sources in this area. Among the investigated potentially toxic elements, the concentration of arsenic with natural origin and higher than the permissible limit of drinking water was observed in some water samples. The evaluation of the water quality of the region using the Schuler diagram also showed that these water sources have an unfavorable to unusable quality for drinking and even for agriculture in some cases.