The aim of this study was to assess the pollution profiles of various typical brominated flame retardants in water and surface sediment near a typical electronic waste dismantling region in southern China. We found that polybrominated diphenyl ethers (PBDEs), 2,4,6-tribromophenol (TBP), pentabromophenol (PeBP), tetrabromobisphenol A (TBBPA), and bisphenol A (BPA) were ubiquitous in the water and sediment samples collected in the study region. In water, Σ19PBDEs (sum of all 20 PBDE congeners studied except BDE-209, which was below the detection limit) levels ranged from 0.31 to 8.9 × 102 ng L−1. TBP, PeBP, TBBPA, and BPA concentrations in the water samples ranged from not being detectable (nd—under the detection limit) to 3.2 × 102 (TBP), from nd to 37 (PeBP), from nd to 9.2 × 102 (TBBPA) and from nd–8.6 × 102 ng L−1 (BPA). In sediment, Σ19PBDEs ranged from nd to 5.6 × 103 ng g−1, while BDE-209 was the predominant congener, with a range of nd to 3.5 × 103 ng g−1. Tri- to hepta-BDE concentrations were significantly (p < 0.01) correlated with each other, except for BDE-71 and BDE-183, and octa- to nona-BDEs concentrations were significantly (p < 0.05) correlated with each other, except for BDE-208. BDE-209 was not significantly correlated with tri- to nona-BDEs. Risk assessments indicated that the water and sediment across the sampling sites posed no estrogenic risk. However, different eco-toxicity risk degrees at three trophic levels did exist at most sampling sites.

The pollution levels of typical semivolatile organic compounds (SVOCs) consisting of 15 polycyclic aromatic hydrocarbons (PAHs), 20 organic chlorinated pesticides (OCPs), and 15 phthalate esters (PAEs) were investigated in small rivers running through the flourishing cities in Pearl River Delta region, China. The concentrations of ∑15PAHs were 2.0–48 ng/L and 29–1.2 × 103 ng/g in the water and sediment samples, respectively. The ∑20OCPs were 6.6–57 ng/L and 9.3–6.0 × 102 ng/g in the water and sediment samples, respectively. The concentrations of ∑15PAEs were much higher both in the water and sediments. The partition process of the detected SVOCs between the water and sediment did not reach the equilibrium state at most of the sites when sampling. The combustion of petroleum products and coal was the major source of the detected PAHs. The OCPs were mainly historical residue, whereas the new inputs of dichlorodiphenyltrichloroethane (DDT), chlordane, and endosulfan were possible at several sites. The industrial and domestic sewage were the major source for the PAEs; storm water runoff accelerated the input of PAEs. No chronic risk of the SVOCs was identified by a health risk assessment through daily water consumption, except for the ∑20OCPs that might cause cancer at several sites. Nevertheless, the integrated health risk of the SVOCs should not be neglected and need intensive investigations.

In the present study, a new bacterial strain isolated from activated sludge has been identified as Lysinibacillus sphaericus based on its morphology, physiochemical properties, and the results of 16S ribosomal RNA (rRNA) gene sequence analysis. This new bacterial strain uses ethanethiol as both carbon source and energy source. The key factors for controlling the degradation efficiency of ethanethiol by this strain were found to be initial ethanethiol concentration, temperature, and pH value of solutions. Under the optimized conditions, as well as 4 mg l−1 ethanethiol, 30°C, and pH = 7.0, almost 100% ethanethiol can be degraded within 96 h and sulfate as a final product was detected in aqueous medium. The degradation reaction of ethanethiol over this newly isolated strain can be described by pseudo first-order equation in which the maximum degradation rate constant K and the minimum half-life were respectively calculated to be 0.0308 h−1 and 22.5 h under the optimal conditions.

The photocatalytic degradation of toluidine over titanium oxide (TiO2) thin films under UV irradiation was investigated. The degradation efficiency of 98.7% was obtained for a toluidine concentration of about 4500 μg L−1 and illumination of 240 min. The degradation intermediates produced during photocatalytic oxidation were identified using Fourier transform-infrared spectrometry (FTIR) and gas chromatography–mass spectrometry (GC–MS). Only a small amount of intermediates, including phenol and toluene, were found in the gas phase. Many other trace amount intermediates, such as 2-hydroxybenzaldehyde, 2-nitrobenzaldehyde, 2-hydroxybenzenemethanol, 2-hydroxybenzoic acid, phenol etc., were detected on the TiO2 surface. An Ames assay of the Salmonella typhimurium strains TA98 and TA100 was employed to evaluate the mutagenicity of toluidine and its gaseous photocatalytic degradation intermediates. With or without rat liver microsomal fraction (S9 mix) activation, neither toluidine nor its gaseous intermediates presented mutagenic activity against strains TA98 (±S9) and TA100 (−S9) at all tested doses. Toluidine, however, can induce a weak positive response to the TA100 strain with an S9 mix at doses as high as 4000 μg plate−1. An increase of revertants per plate was obtained after 30 min photocatalysis in the TA100 strain with S9 mix. As reaction time further increased, photocatalytic technology exhibited the ability to completely and efficiently detoxify toluidine. Both our chemical analysis and toxic evaluation indicate that all mutagenic intermediates in the gas can be completely eliminated within 240 min, which further suggests that photocatalytic technology is an effective approach for degrading aromatic amines.Graphical abstractAs for a mutagenic pollutant, toluidine, the mutagenicity to strains TA100 (+S9) increase firstly after 30 min photocatalytic oxidation and then decrease and totally detoxify with further increasing degradation time..Research highlights▶ Two intermediates of toluene and phenol were found in the gas phase. ▶ Six trace amounts degradation intermediates were found on the surface of TiO2. ▶ o-Toluidine presented weak mutagenic activity against the TA100 strain with S9. ▶ Mutagenic toxicity of gaseous intermediates increased first and then decrease soon. ▶ Gaseous o-toluidine was successfully detoxified using photocatalytic technology.