Temporal and spatial surveys of polybromodiphenyl ethers (PBDEs) contamination of soil near a factory using PBDEs in northern Taiwan

Abstract

Polybrominated diphenyl ethers (PBDEs), previously commonly used as flame retardants, should be monitored in the environment since some are listed as persistent organic pollutants. A contaminated site near a northern Taiwan factory using decabrominated diphenyl ether (deca-BDE) was identified based on a vegetable PBDEs monitoring project in 2013. The subsequent spatial and temporal survey of that contaminated site shows the contamination ingredients in soils were close to ones used by the factory, indicating that contamination was from the factory, possibly through an exhaust vent. The average concentration of deca-BDE in the main contaminated soil was 615 μg/kg d. w. (dry weight) soil in 2015, slightly decreasing to 604 μg/kg d. w. soil in 2016, increasing to 844 μg/kg d. w. soil in 2017, and then slightly decreasing to 670 μg/kg d. w. soil in 2018. The slight change of deca-BDE and the minor change in low brominated congener level indicate a low degradation rate. The contamination of peripheral sites was around 5000 μg/kg d. w. soil for one PBDEs sampling site that was higher than those around or within the main contaminated farm, indicating serious pollution. Concentrations of PBDEs in different soil depths show that depth 2–15 cm accounted for the greatest PBDEs accumulation, indicating that deca-BDE pollution had been present over time and transported into deeper soil. There can be PBDEs uptake by crops consumed by humans, as shown in our previous studies, so continuous monitoring of PBDEs in this site is important and treatments should be established urgently.