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Polluters Determine Spatial Distribution of Old and Emerging Flame Retardants in Chinese Forest Soils TEXT SIZE: A A A

Flame retardants (FRs) are a class of chemicals used to reduce flammability in different kind of products. They are commonly added in construction materials, furniture, electronics, etc. However, due to their persistence, toxicity, bioaccumulative properties and can be long-range transport, some tetra-, penta-BDE, hexa-BDE and octa-BDE were added to the list of banned Persistent Organic Pollutants (POPs) under the Stockholm Convention. Restrictions on the use of PBDE congeners have paved the way for the use of “novel” BFRs (NBFRs). Forest soils, in particular have been pointed out as effective accumulators of several hydrophobic and persistent substances. Analyzing the current regional and global distribution of the environmental burden of POPs in the major reservoir compartments (such as soils) represent an effective approach to gather information useful for predicting possible future exposure conditions and fate.

The research group led by Dr. Zhang Gan of the State key laboratory of organic geochemistry, Guangzhou Institutes of Geochemistry has chosen thirty mountain sites across major accessible mountainous areas of China to explore the environmental behavior of old and emerging flame retardants in O- and A-horizons. Totally, 8 kinds of polybrominated diphenylethers (PBDEs) congeners, 6 kinds of emerging brominated flame retardants (DBDPE, TBPH, TBB, HBB, TBE and PBEB) and Dechlorane plus (DP) isomers were analyzed in 159 soil samples. Research shows that DBDPE was the most abundant flame retardant (25-18000 pg g-1 and 5-13000 pg g-1 in O-horizon and A-horizon, respectively), followed by BDE 209 (nd-5900 pg g-1 and nd-2400 pg g-1 in O-horizon and A-horizon, respectively). FRs distributions were primarily controlled by source distribution (figure 1). The distributions of most phasing-out PBDEs, DP isomers and TBPH were in fact correlated to a population density-based index used as proxy of areas with elevated usage and waste of FR containing products (figure 2). High concentrations of some NBFRs were however observed in industrialized regions and FR manufacturing plants. Strongly positive correlations were observed between PBDEs and their replacement products suggesting similar emission pattern and environmental behavior. Moreover, exposure of mineral sub-soils depended on precipitations driving leaching of FRs into the soil core. This was especially evident for some emerging BFRs (TBE, TBPH and TBB etc.) possibly indicating potential for diffuse ground water contamination.

This study was published in ENVIRONMENTAL SCIENCE & TECHNOLOGY , 2015, 49(5), 2904-2911. The work was supported by the National Natural Science Foundation of China, etc.




Figure 1. Spatial distribution of selected FRs in organic (O-horizon) soil samples. (a:BDE47, BDE99, anti-DP, syn-DP, TBPH, TBB, HBB and TBE; b:BDE 209;c:DBDPE) (Provided by LI Jun)



Figure 2. Correlation between selected FR concentrations and IPSI values. (Provided by LI Jun)

Key words: Persistent Organic Pollutants; Flame retardants; Spatial Distribution.


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