Screening analysis of organic micro-pollutants in groundwater in Northern Vietnam: occurrence, sources, and risk assessment
摘要
Groundwater, a primary drinking water source in Vietnam, is increasingly affected by 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 Vietnamese groundwater. Due to sample transport restrictions, an international sample transfer method (“travel analysis”) using solid-phase extraction cartridges was applied to transport analytes from Vietnam to Japan. Quality control experiments showed generally acceptable analyte stability during travel analysis. This method was applied to investigate OMP occurrence in 19 groundwater samples collected from urban, suburban, agricultural, and industrial areas in northern Vietnam. OMPs were observed in all samples, 60 OMPs being detected with total concentrations (∑OMPs) of 201–11,200 ng L−1 (median 1370 ng L−1). OMPs (~40) were first reported in Vietnamese groundwater under comprehensive screening using AIQS. Personal care products (PCPs), plasticizers, and fire retardants were frequently detected. Higher OMP contamination was observed in urban and agricultural areas than other land-use types. Specifically, PCPs, plasticizers, and sterols were more frequently found in agricultural wells, whereas pesticides and household-use chemicals were more prevalent in urban sites. In addition to infiltration from surface sources, leaky boreholes may be a potential pathway for OMP entry into aquifers. The coexistence of persistent and short-lived OMPs suggests that aquifers in the studied region may be influenced by both ongoing and legacy contamination. Based on current measured concentrations and available toxicological data, the calculated risk assessment did not indicate immediate human health risks.