Environmental risk assessment of volatile organic contaminants in the Sava river aquifer, Belgrade, Serbia

The aim of this study was to investigate the environmental risk from the gasoline range volatile organic contaminants in the Sava river aquifer. The investigated area is located in New Belgrade, in the vicinity of the largest heating plant in Belgrade, the capital of Serbia. Our previous research on the oil pollutants in the groundwater at this locality was focused on the origin and spatial distribution of these contaminants, and estimation of potential human health risks from exposure to these compounds. [1] The purpose of our present study is a Tier I Environmental risk assessment in this part of the aquifer. Groundwater samples were collected from 28 hydrogeological boreholes. Preliminary analyses of the organic compounds extracted from the groundwater samples were conducted by gas chromatography with flame ionization detection (GC-FID), and by gas chromatography – mass spectrometry (GC-MS). Volatile organic compounds (VOCs) were analyzed and identified by headspace gas chromatography – mass spectrometry. Chemicals of concern were quantified by headspace gas chromatography with flame ionization detection (HS-GC-FID). In the groundwater samples analyzed, the most frequently detected VOCs were from the group of the gasoline range organics. Concentrations of the individual VOCs ranged from below detection limits to 5.2 mg/L. For each of the compounds quantified, the Risk Quotient (RQ) was calculated as the ratio of the measured concentration of that compound in the groundwater sample and the lowest Predicted Non-Effect Concentration for freshwater aquatic organisms (PNEC). The PNEC values were adopted from the European chemicals agency’s (ECHA) Registration Dossier database. [2] At some of the sampling points, the detected concentrations of VOCs were higher than that of the PNEC values with resulting RQ > 1. Considering the fact that the VOC compounds analyzed were present as mixtures, the mixture RQ was calculated (as a sum of the individual RQs) for each sampling point. Out of 28 sampling points, at 7 of them the mixture RQs were higher than 1 which indicates a potentially medium to high ecological risk from these compounds in this part of the aquifer. In addition to the conclusion from our previous study on the human risk assessment from exposure to the volatile organic compounds in the groundwater at this location, [1] this research emphasizes a necessity for a continuous monitoring of the water quality in the investigated area