A closed municipal landfill as a source of emerging contaminants in adjacent groundwater: pharmaceuticals and personal care products occurrence and environmental risk assessment

The aim of this study was to determine the occurrence and perform the environmental risk assessment (ERA) for emerging contaminants, primarily pharmaceuticals and personal care products (PPCPs), in the groundwater near a closed municipal landfill, on the example of a site in Tychy (southern Poland). Groundwater from a shallow aquifer was sampled in two seasons from eight piezometers located upstream, downstream, and on top of the landfill. The analysis covered 128 PPCPs. Additionally, surfactants, phenols, field parameters, and basic groundwater chemical composition were determined. ERA was performed using indices like the horizontal ratio (HR), risk quotient (RQ), frequency of a predicted no-effect concentration (PNEC) exceedance (F), prioritisation index (PI), and persistence-bioaccumulation-toxicity ranking (PBTr). The number of detected PPCPs in the groundwater reached up to 54, with total PPCP concentrations ranging from 492 to 3,230,036 ng/L. The study also revealed the presence of phenols (up to 62 mg/L) and surface active agents, particularly anionic surfactants (up to 77.7 mg/L). The highest concentrations of analysed compounds were observed in groundwater from a piezometer screened directly below the landfill bottom. The lowest values were recorded for the observation well located upstream of the landfill, confirming its negative impact and the release of PPCPs into the aquifer. The influence of the landfill was also reflected by low HR values (below 1) and high values of the site-specific risk quotient (above 1). Based on PI results, ibuprofen, bisphenol A, propyphenazone, and sulfamerazine were considered the compounds of highest risk. The same substances were among compounds with the highest PBTr values. The results showed that closed, unlined municipal landfills are a threat to groundwater in terms of organic micropollutants due to conditions that favour their persistence in the aquifer, and that concentrations of some contaminants still pose an environmental risk.