Continuous Monitoring of Persistent Organic Pollutants in China for the Effectiveness Evaluation of the Stockholm Convention: 2007–2014

Article 16 of the Stockholm Convention requires the Conference of the Parties to periodically evaluate whether the Convention is an effective tool for achieving the objective of protecting human health and the environment from persistent organic pollutants (POPs). A global monitoring plan for POPs, which has been put in place under the Convention, is a key component of the effectiveness evaluation that provides a harmonized framework for identifying changes in POP concentrations over time and information on the regional and global transport of POPs in the environment. To meet the requirements of the effectiveness evaluation of the Stockholm Convention, we monitored concentrations of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) and polychlorinated biphenyls (PCBs), including dioxin-like (DL-PCBs) and indicator PCBs, in air in China from 2007 and 2011. We also monitored perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in water in 2013. We collected air from 11 remote sites in China, 3 urban sites, and 3 rural sites using high volume samplers with a size-selective inlet that only accepted particles with diameters less than 10 µm. The remote air sampling sites were referred to as background sites because the PCDD/F and DL-PCB concentrations were typical of background levels and ranged from 2.64 to 101.7 World Health Organization toxic equivalents (WHO-TEQ) fg/m3 (average 21.7 WHO-TEQ fg/m3). The concentrations of PCDD/F were highest in eastern China, where there is intensive economic activity. The PCDD/F and DL-PCB concentrations in the air samples from the 3 urban and 3 rural sites ranged from 98.1 to 212.2 WHO-TEQ fg/m3 and from 11.2 to 46.4 WHO-TEQ fg/m3, respectively. The average PCDD/Fs concentrations were much higher at urban sites than at the background and rural sites. The indicator PCB concentrations in the air samples from the 11 background sites, 3 urban sites, and 3 rural sites ranged from 5.2 to 44.9 pg/m3 (average 18.5 pg/m3), from 55.1 to 90.6 pg/m3 (average 71.6 pg/m3), and from 4.62 to 10.3 pg/m3 (average 7.32 pg/m3), respectively. The levels of PCDD/Fs and PCBs in the air samples from the background sites were lower than, or comparable to, those detected in the air at other sites worldwide. The concentrations of PFOA and PFOS were monitored in two lakes and two coastal marine areas. The average concentration of PFOS and PFOA in Taihu Lake was 32 ng/L. The concentrations of PFOA and PFOA at the other sites were below the detection limit. There were no consistent temporal trends in the POP concentrations in the air samples from the background sites.