Screening analysis of organic micro-pollutants in groundwater in Northern Vietnam: Occurrence, sources and risk assessment

Groundwater, a primary drinking water source in Vietnam, is threatened by increasing contamination from organic micropollutants (OMPs). We applied an automated identification and quantification system (AIQS) with gas chromatography- (GC-MS) and liquid chromatography-time of flight (LC-QTOFMS) mass spectrometry databases to screen ~ 1500 OMPs in groundwater in Vietnam. Due to sample transport restrictions, an international sample transfer method (“travel analysis”) using solid-phase extraction cartridges was applied to adsorb and transport analytes in samples from Vietnam to Japan. Designated quality control tests confirmed the stability of multiple analytes during travel analysis. This method was applied to investigate OMPs occurrence in 19 well water samples collected from urban, suburban, agricultural, and industrial areas in northern Vietnam. OMPs were observed in all samples, with 60 OMPs being detected. OMPs (~ 40) were identified for the first time in the Vietnamese groundwater samples. Pharmaceuticals, personal care products (PPCPs), plasticizers, and fire retardants were frequently detected. Higher levels of OMPs contamination were observed in urban and agricultural areas than those in the other areas. Specifically, PPCPs and plasticizers were more frequently found in agricultural wells, whereas fire retardants, pesticides, and household-use chemicals were more prevalent in urban sites. In addition to infiltration from surface sources, another possible route for OMP to reach groundwater is suggested via leaky boreholes. The coexistence of persistent and short-lived OMPs revealed that Vietnamese aquifers likely face both ongoing and legacy contamination. No significant health risks were observed based on our results.