| Summary: | Due to the prohibition of polybrominated diphenyl ethers, organophosphate flame retardants (OPFRs) and tetrabromobisphenol A (TBBPA) have become emerging flame retardants. However, knowledge about their occurrence, especially their transformation products, is still limited. This study collected sediment samples from two rivers, i.e., Lianjiang River (located at an e-waste dismantling area) and Xiaoqing River (situated at a flame retardant production base), to investigate the occurrence, composition, and spatiality distribution of OPFRs, TBBPA, and their transformation products. Both targets were detected in the Lianjiang River in the range of 220–1.4 × 104 and 108–3.1 × 103 ng/g dw (dry weight) for OPFRs and TBBPA, and 0.11–2.35 and 4.8–414 ng/g dw for their respective transformation products, respectively. The concentrations of OPFRs and TBBPA in the Xiaoqing River ranged from 4.15 to 31.5 and 0.76–2.51 ng/g dw, respectively, and no transformation products were detected. Different compositional characteristics of OPFRs and distinct spatial distribution from mainstream and tributary observed between the two rivers are attributed to the difference in the local industries. Spatial distribution and principal component analysis indicated that e-waste dismantling activities could be a vital source of local pollution. Besides, the confluence of tributaries seemed to determine the contaminant levels in the Xiaoqing River. Also, concentration ratios and Spearman’s correlation between metabolites and parent chemicals were analyzed. Low concentration ratios (3.6 ×10–4 to 0.16) indicated a low transformation degree, and Spearman’s correlation analysis suggested transformation products were partly stemming from commercial products. Considering the limited study of these transformation products, more studies on their sources, transform mechanism, and toxicity are required.
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