Assessment of groundwater pollution sources in the urban environment (Case Study: Tehran Municipality of District 14)

The important issue about groundwater resources includes; understanding the characteristics of the local watershed or aquifer، distinguishing cases leading to their contamination and managing them. In this study، during the October 1390 a total of 16 wells were sampled in order to evaluate and distinguish the quality and menacing agents of district14th، Tehran’s groundwater sources. The concentration of the anions (NO2، NO3، Cl، SO4، CO3 and HCO3)، cations (Mg، K، Na)، and certain heavy elements like Pb، Cd and Ag، as well as other physical parameters (temperature، color and odor)، chemical parameters (pH، EC، TSS، TDS) and MTBE were determined. Factors which were measured on the field were; pH، Electric Conductivity and temperature. The trace elements concentrations were measured by Graphite furnace atomic absorption، anion concentrations by potentiometric and titration method، cation concentrations (Mg by titration method، K and Na by flaming measurement method) and MTBE concentrations were measured by CP-3800 Gas Chromatograph. Anion test results manifested an increase of nitrate، sulfate and chloride concentration in the southern and western stations which can be associated with the region’s south-west to north-east slope، in addition to the sandy texture of the area. The cation pollution of the East and Northeast wells have been manifested and the high increase in the amount of potassium might be related to the clay texture، sewage of the absorption wells and the fertilizers that are used in the parks. Among the heavy metals only cadmium had concentrations more than the standard levels. Agricultural activities، municipal wastewater، surface run-offs، eroded soil texture of the area as well as the geological structure، lack of adequate boundaries in between the drinking and the waste water wells have caused an increase in the contaminating effects of these sources. MTBE contamination was not indicated in any of the wells.