Specific groundwater vulnerability maps for selected micropollutants

Soil and groundwater can be contaminated by various micropollutants if treated wastewater or surface water that has been contaminated by this source are used for irrigation. Another source of contamination can be sewage sludge from wastewater treatment plants that is frequently used for soil enrichment. These contaminants can migrate through the soil environment and subsequently contaminate groundwater. Their leaching from soils and migration towards groundwater depends on the climatic conditions, properties of the vadose zone environment and behavior of a particular compound, i.e., its sorption onto soils and sediments, and stability in the environment. The Freundlich sorption isotherms were evaluated for twenty-one micropollutants (PPCPs, benzotriazoles, bishenols) and representative soils of the Czech Republic. Multiple linear regressions were used to derive equations for predicting the Freundlich sorption coefficient (KF) using the properties of tested soils. These equations, the soil map, and the database of soil properties were used to predict the KF value distributions within the Czech agricultural soils and subsequently to delineate classes of compounds’ mobility in the soil environment, i.e., mobility index. The dissipation and half-lives of all micropollutants were also evaluated for the representative Czech soils. This information was used to define compound’s stability index. General groundwater vulnerability map (i.e., distribution of the DRASTIC vulnerability index) was derived using the DRASTIC method. Next, specific groundwater vulnerability maps for each compound were obtained by combining the DRASTIC vulnerability index, mobility index and stability index. The resulting maps of specific groundwater vulnerability for selected compounds were confronted with the respective results of groundwater monitoring that is caried out by the Czech Hydrometeorological Institute. The work was supported by the Ministry of Agriculture of the Czech Republic, project No QK 23020018 and QL 24010384.