Characterization and Distribution of Heavy Metals, Polybrominated Diphenyl Ethers and Perfluoroalkyl Substances in Surface Sediment from the Dayan River, South China

This review describes the sources, fate, and transport of perfluorocarboxylates (PFCAs) in the environment, with a specific focus on perfluorooctanoate (PFO). The global historical industry-wide emissions of total PFCAs from direct (manufacture, use, consumer products) and indirect (PFCA impurities and/or precursors) sources were estimated to be 3200-7300 tonnes. It was estimated that the majority (approximately 80%) of PFCAs have been released to the environment from fluoropolymer manufacture and use. Although indirect sources were estimated to be much less importantthan direct sources, there were larger uncertainties associated with the calculations for indirect sources. The physical-chemical properties of PFO (negligible vapor pressure, high solubility in water, and moderate sorption to solids) suggested that PFO would accumulate in surface waters. Estimated mass inventories of PFO in various environmental compartments confirmed that surface waters, especially oceans, contain the majority of PFO. The only environmental sinks for PFO were identified to be sediment burial and transport to the deep oceans, implying a long environmental residence time. Transport pathways for PFCAs in the environment were reviewed, and it was concluded that, in addition to atmospheric transport/degradation of precursors, atmospheric and ocean water transport of the PFCAs themselves could significantly contribute to their long-range transport. It was estimated that 2-12 tonnes/ year of PFO are transported to the Artic by oceanic transport, which is greater than the amount estimated to result from atmospheric transport/degradation of precursors.

This study makes a new estimate of the global historical production for perfluorooctane sulfonyl fluoride (POSF), and then focuses on producing a first estimate of the global historical environmental releases of perfluorooctane sulfonate (PFOS). The total historical worldwide production of POSF was estimated to be 96,000 t (or 122,500 t, including unusable wastes) between 1970-2002, with an estimated global release of 45,250 t to air and water between 1970-2012 from direct (manufacture, use, and consumer products) and indirect (PFOS precursors and/or impurities) sources. Estimates indicate that direct emissions from POSF-derived products are the major source to the environment resulting in releases of 450-2700 t PFOS into wastewater streams, primarily through losses from stain repellent treated carpets, waterproof apparel, and aqueous fire fighting foams. Large uncertainties surround indirect sources and have not yet been estimated due to limited information on environmental degradation, although it can be assumed that some POSF-derived chemicals will degrade to PFOS over time. The properties of PFOS (high water solubility, negligible vapor pressure, and limited sorption to particles) imply it will reside in surface waters, predominantly in oceans. Measured oceanic data suggests approximately 235-1770 t of PFOS currently reside in ocean surface waters, similar to the estimated PFOS releases. Environmental monitoring from the 1970s onward shows strong upward trends in biota, in broad agreement with the estimates of use and emissions made here. Since cessation of POSF production by 3M in 2002, a reduction in some compartments has been observed, although current and future exposure is dependent on emission routes, subsequent transport and degradation.

Environmental pollution due to uncontrolled e-waste recycling activities has been reported in a number of locations of China. In the present study, metal pollution to the surrounding environment from a primitive e-waste processing facility was investigated. Soils at sites where e-waste is burned in the open air, those of surrounding paddy fields and vegetable gardens, as well as common vegetable samples were collected and analyzed for heavy metals. The results showed that the soils of former incineration sites had the highest concentrations of Cd, Cu, Pb, and Zn with mean values of 17.1, 11,140, 4500, and 3690 mg kg(-1), respectively. The soils of nearby paddy fields and vegetable gardens also had relatively high concentrations of Cd and Cu. In the edible tissues of vegetables, the concentrations of Cd and Pb in most samples exceeded the maximum level permitted for food in China. Sequential leaching tests revealed that the Cu, Pb, and Zn were predominantly associated with the residual fraction, followed by the carbonate/specifically adsorbed phases with the exception of Cd, which was mainly in the extractable form in paddy fields and vegetable soils. The data showed that uncontrolled e-waste processing operations caused serious pollution to local soils and vegetables. The cleaning up of former incineration sites should be a priority in any future remediation program. Copyright © 2010 Elsevier B.V. All rights reserved.