Occurrence of 1153 organic micropollutants in the aquatic environment of Vietnam

Abstract

The rapid increase in the number and volume of chemical substances being used in modern society has been accompanied by a large number of potentially hazardous chemicals being found in environmental samples. In Vietnam, the monitoring of chemical substances is mainly limited to a small number of known pollutants in spite of rapid economic growth and urbanization, and there is an urgent need to examine a large number of chemicals to prevent impacts from expanding environmental pollution. However, it is difficult to analyze a large number of chemicals using existing methods, because they are time consuming and expensive. In the present study, we determined 1153 substances to grasp a pollution picture of microcontaminants in the aquatic environment. To achieve this objective, we have used two comprehensive analytical methods: (1) solid-phase extraction (SPE) and LC-TOF-MS analysis, and (2) SPE and GC-MS analysis. We collected 42 samples from northern (the Red River and Hanoi), central (Hue and Danang), and southern (Ho Chi Minh City and Saigon-Dongnai River) Vietnam. One hundred and sixty-five compounds were detected at least once. The compounds detected most frequently (>40 % samples) at μg/L concentrations were sterols (cholesterol, beta-sitosterol, stigmasterol, coprostanol), phthalates (bis(2-ethylhexyl) phthalate and di-n-butyl phthalate), and pharmaceutical and personal care products (caffeine, metformin). These contaminants were detected at almost the same detection frequency as in developed countries. The results reveal that surface waters in Vietnam, particularly in the center of large cities, are polluted by a large number of organic micropollutants, with households and business activities as the major sources. In addition, risk quotients (MEC/PNEC values) for nonylphenol, sulfamethoxazole, ampicillin, acetaminophen, erythromycin and clarithromycin were higher than 1, which indicates a possibility of adverse effects on aquatic ecosystems.

Ethoxyquin: a feed additive that poses a risk for aquatic life

“…Using a safety factor of 300, a threshold EQ value for potential damage to aquatic fauna of 1 µg l −1 could be established. Since the maximum level that has been found in a water sample is 0.29 µg l −1 (Chau et al 2015), the environmental concentration of EQ can be assumed to be close to the PNEC in this study.…”

“…Since EQ is a lipophilic compound, this exposure route is the most important one. However, recent reports on EQ detection in surface water samples have raised concerns about how common a micropollutant EQ might be (Chau et al 2015). No sufficient data on the occurrence in water of the more hydrophilic metabolites of EQ are currently available, and they have rarely been investigated, even in aquatic organisms (Bohne et al 2007a(Bohne et al ,b, 2008.…”

“…Irrespective of its extensive global use, knowledge of the occurrence of EQ in surface water is scarce. In 18 water samples from surface waters in Vietnam, EQ was detected at levels above the level of detection (LOD) of 8 ng l −1 , and 6 of those samples showed EQ concentrations above 0.1 µg l −1 (Chau et al 2015). The maxi mum level found in a water sample was 0.29 µg l −1 .…”

Risk Assessment Approach for Prioritizing Danube Basin-Specific Pollutants: a Case Study in the Novi Sad Region

“…For defining a list of major pollutants a prioritization approach was applied based on a comparison of the compounds' measured exposure levels, referred as predicted environmental concentration (PEC) and ecological safety threshold, or predicted no-effect concentration (PNEC) [19]. All compounds with the PEC/PNEC risk ratio above 1 [20] were regarded as relevant and were ranked based on the ratio.…”

Detection, Occurrence and Fate of Emerging Contaminants in Agricultural Environments

“…Sulfamethazine exhibited the highest concentration and detection frequency, with a concentration of 0–53.41 ng/L and 4.84–138.66 ng/L, with a detection rate of 16.67% and 100% in August 2011 and May 2012, respectively. In a survey of 1153 organic micropollutants evaluated in the aquatic environment of Vietnam, Chau et al (2015) detected 13 antibiotics, including the veterinary antibiotic lincomycin. The maximum concentration of lincomycin in surface water was 2.66 ng/L.…”