Groundwater Contamination Assessment Involving Field Sampling and GIS Software

Water resources pollution has been one of the most important issues of concern to many researchers during recent decades. In this paper the main aim has been to assess the quality of Assaluyeh groundwater aquifer, south of IRAN, closed to Persian Gulf. South Pars gas field is one of the most important and most valuable economic resources in the world. The Iranian part of the field, Assaluyeh area, is about 3700 square kilometers with estimated of 14200 billion cubic meters of gas. In this research, the water quality assessment of the relevant area groundwater aquifer has been done by field sampling and laboratory analyses. Then the recorded data were analyzed using GIS software version 9.3. Also, based on the results, suggestions and possible actions were supposed in order to control the pollution sources. The major concern of the study area groundwater resources has been regarding insoluble oil and its derivatives contamination. The main parameters which were investigated in this study included: TPH (Total Petroleum Hydrocarbon) using GC-FID (Gas chromatography-Flame Ionization detector), Nitrate, EC measurements and pH. In this research the main emphasis has been put on the oil contaminants. All laboratory analyses were conducted using the facilities of the Water Quality and the Hydraulics Laboratories at the University of Tehran. Also, contaminant fields were plotted using GIS and the relevant Geo-statistical methods. According to the results, the average concentration of TPH compound in Assaluyeh groundwater samples is equal to 33.16 ppb and the maximum recorded of TPH contaminant is equal to 139.6 ppb, which is higher than the acceptable limit of drinking water. Also, the average and maximum amount concentrations of nitrate, in the study area, are about 5.7 ppm and 24 ppm, respectively, which in all cases are less than the maximum amount authorized, announced for drinking water by the World Health Organization.