Sources of Nitrate and Bromide ContaminantsinGroundwater ofthe Alluvial Aquifer of Arak, Iran

The present study investigated NO3- and Br- contamination in groundwater of Arak aquifer, Markazi province, Iran. Correlation and factor analyzes were used to detecti nterrelations and sources of NO3- and Br- ion concentration and other physicochemical variables. No correlation was observed between NO3- and otherscontents, but a positive correlation was identified between Br-and other majorvariables such as EC, TDS, Cl- and SO42-in the groundwater.The results showed that groundwater samples of two areas of Arak aquifer were severely contaminated by NO3- (up to 50 mg/L) and Br-(up to 0.5mg/L),which exceededthe WHO and EU provision alguideline values. Nitrate showed an anthropogenic source  that originated from sewage water from domestic and industrial activities. Bromide originated from palaeo-salty water of Mighan Lake with a geogenic source.