separation-identification-conventional-microplastics-from-farmland

Separation and Identification of Conventional Microplastics from Farmland Soils

Microplastics (MPs) pollution in the terrestrial environment has received increasing attention over the last decade, with increasing studies describing ...

China National Environmental Monitoring Centre

Isotopic dilution gas chromatography combined with high resolution mass spectrometry (GC/HRMS) has overwhelming advantages with respect to the accuracy of congener-specific ultratrace analysis of complex persistent organic pollutants (POPs) in environmental matrices. However, an isotopic dilution GC/HRMS method for analysis of chlorinated and brominated polycyclic aromatic hydrocarbons (Cl-PAHs and Br-PAHs) using C-labelled congeners as internal standards has not been established. In this study, a method for identification and quantification of 38 congeners of Cl-PAHs and Br-PAHs in atmosphere and stack gas samples from waste incinerators was developed using the isotopic dilution GC/HRMS technique. The instrumental detection limits of the GC/HRMS method ranged from 0.2pg to 1.8pg for Cl-PAH congeners, and 0.7pg to 2.7pg for Br-PAH congeners, which were about three orders of magnitude lower than those of the GC/quadrupole MS method. This new method developed was also the first to enable determination of Cl-PAH and Br-PAH homologs comprising congeners with the same molecular skeleton and chlorine or bromine substitution numbers. Among the detected congeners, seven Cl-PAH congeners and thirteen Br-PAH congeners that were abundant in the atmosphere and stack gases released from waste incinerators were firstly detected in real samples and reported using the established isotopic dilution GC/HRMS method. The developed isotopic dilution GC/HRMS is significant and needed for better studying the environmental behavior and health risk of Cl-PAHs and Br-PAHs.

Congener-specific determination of ultratrace levels of chlorinated and brominated polycyclic aromatic hydrocarbons in atmosphere and industrial stack gas by isotopic dilution gas chromatography/high resolution mass spectrometry method.

The generation of and extent to which chlorinated and brominated polycyclic aromatic hydrocarbons (Cl/Br-PAHs) are formed and released from secondary copper smelters remain unknown. This field study, to our knowledge, is the first to identify secondary copper smelters as new sources of Cl/Br-PAHs. Mass concentrations of ∑Cl-PAHs and ∑Br-PAHs ranged from 5.8 to 271 ng Nm and 0.59 to 52.4 ng Nm, respectively. A comparison of Cl/Br-PAH concentrations in stack gas and fly ash from secondary copper smelters indicated that the use of scrap copper as raw material or the addition of coal or heavy oil as reductant may contribute to the elevated formation and emission of Cl/Br-PAHs. Congener profiles of Cl/Br-PAHs in stack gas and fly ash from secondary copper smelters were different with those of Cl/Br-PAHs from waste incinerations and other previously reported sources, thus could be used as possible fingerprints and source apportionments of environmental Cl/Br-PAHs. Atmospheric levels of Cl/Br-PAHs in the workplace or smelter surroundings were determined and potential exposures were assessed. Although chlorination of PAHs was previously recognized as an important formation pathway of Cl/Br-PAHs, it was not verified to be the major formation pathway for Cl/Br-PAHs from secondary copper smelters in this study.

Secondary Copper Smelters as Sources of Chlorinated and Brominated Polycyclic Aromatic Hydrocarbons.

The amounts and characteristics of polychlorinated naphthalenes (PCNs) emitted by a secondary copper smelter were investigated. Differences in the amounts and characteristics of PCNs emitted during different smelting stages were investigated, and the main stage during which PCNs were emitted was identified. PCN concentrations in stack gases emitted during secondary copper smelting were 477.0-762.5 ng/m (4.4-8.3 pg toxic equivalents/m). The contributions of the different stages to total PCN emissions decreased in the order feeding-fusion stage (65% of total PCN emissions) > oxidation stage (27%) > deoxidation stage (8%). The main contributor to PCN emissions during secondary copper smelting was the feeding-fusion stage. PCN concentrations and profiles in stack gas, fly ash, and deposit ash collected during different smelting stages were determined. PCNs in stack gases were mainly less-chlorinated homologs, and fly ash and deposit ash were dominated by highly-chlorinated homologs. These results will help improve strategies for decreasing and eliminating PCN emissions during secondary copper production.

Polychlorinated naphthalene (PCN) emissions and characteristics during different secondary copper smelting stages.

Chlorinated paraffins (CPs) can accumulate in sediment and pose risks to ecological systems and human health. The Haihe River Basin is one of the seven main river basins in China and is mainly in the Beijing-Tianjin-Hebei region, which is densely populated and very urbanized. There is therefore a high probability of CP pollution in the Haihe River Basin. However, CP pollution and the environmental risks posed by CPs in the Haihe River are not well understood. In this study, the concentrations of short-chain CPs (SCCPs) and medium-chain CPs (MCCPs) in sediment from six rivers in the Haihe River Basin system were determined using two-dimensional gas chromatography electron-capture negative ionization mass spectrometry. The total SCCP and MCCP concentrations in the sediment samples ranged from 131.83 to 1767.71 and from 89.72 to 1442.82 ng/g dry weight, respectively. The total organic carbon content did not significantly correlate with the CP concentrations. The dominant SCCP congener groups were CCl and the dominant MCCP congener groups were CCl. Significant relationships (R = 0.700, p < 0.05) were found between the SCCP and MCCP concentrations, indicating that SCCPs and MCCPs may have similar sources. Hierarchical cluster analysis and principal component analysis indicated that sediment in the study area was contaminated with CPs through the use of the CP-42 and CP-52 commercial products in industrial processes and human activities. The ecological risks posed by CPs were assessed and SCCPs were found to pose high risks in the Yongding New River but moderate risks in the other rivers. MCCPs were found to pose minimal risks to the aquatic environment at most of the sampling points.

Xiaoxu Jiang

China National Environmental Monitoring Centre

Separation and Identification of Conventional Microplastics from Farmland Soils