Preliminary Evaluation of the Possible Occurrence of Pesticides in Groundwater Contaminated with Nitrates—A Case Study from Southern Poland

Abstract

This paper addresses groundwater pollution and the potential presence of pesticides within the catchment areas of two reservoirs that are sources of drinking water. The two reservoirs are Goczałkowice and Kozłowa Góra, both in Southern Poland. Agricultural and rural areas dominate both catchments. Archival data showed local groundwater contamination with nitrates. This indicated the possible presence of pesticides in shallow groundwater. In total, 13 groundwater samples from shallow sandy aquifers were collected. All the samples were tested for the presence of 35 organophosphate pesticides and 28 organochlorine pesticides. Additionally, in order to determine the current groundwater conditions, physicochemical parameters were measured in the field, and water samples were subjected to analysis of their chemical composition (incl. the determination of nitrates). The research outcomes showed that pesticides were not detected above the detection limits in any of the samples. Due to variations in the persistence and degradation rates of pesticides, the occurrence of these substances in the groundwater environment and the possibility of their migration to aquifers should not be completely excluded. Natural processes and factors (e.g., sorption, biodegradation, hydrolysis and redox conditions) may gradually reduce the pesticide concentrations in groundwater. The chemical analyses revealed high concentrations of nitrates in the groundwater. This suggests the possible influence of agriculture and fertilizer application on groundwater quality; however, a proportion of NO3- ions may be connected with improper sewage management within the two catchments. The absence of pesticides in groundwater impacted by agriculture may result from processes occurring in the aquifer and the rapid degradation of these compounds due to photolysis and prevailing weather conditions. In the vicinity of dwellings, nitrates also originate from domestic wastewater. Thus, the occurrence of pesticides in groundwater contaminated with NO3 cannot always be expected.

Identification of Water Contamination Sources Using Hydrochemical and Isotopic Studies—The Kozłowa Góra Reservoir Catchment Area (Southern Poland)

“…Among the groundwater samples, the highest concentrations of NO 3 − were reported for W2, which exceeded the drinking water limit (i.e., 50 mg/L [38]) in two sampling campaigns. In the past, elevated concentrations of NO 3 − in groundwater from this well were also observed [39]. Given the land use in the vicinity of these wells, the probable source of nitrate is agricultural activities, i.e., the application of manure or fertilisers.…”

Xeno-Estrogenic Pesticides and the Risk of Related Human Cancers

“…In a recent study, groundwater polluted with pesticides was found to increase susceptibility to estrogen-mediated cancers, in spite of the ban on these chemicals for decades [ 46 ]. Likewise, alarmingly high levels of these chemicals have also been reported from other regions of the world in recent studies [ 47 , 48 , 49 ]. Additionally, a Brazilian study from the year 2022 linked pesticide residue with an increased risk of cancer in one province [ 50 ].…”

Groundwater Vulnerability to Pollution Assessment

“…Ślósarczyk et al [9] presented the potential presence of pesticides within the catchment areas of Goczałkowice and Kozłowa Góra reservoirs (Southern Poland) that are destined for drinking water supply. Agricultural and rural areas dominate both catchments.…”