Distribution and elimination of polycyclic musks in three sewage treatment plants of Beijing, China

The two representative polycyclic musks, 1-（5,6,7,8-tetrahydro-3,5,5,6,8,8-hexamethyl-2-naphthenyl）-ethanone （AHTN） and 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[g]-2-benzopyrane （HHCB）, were measured in aqueous samples and sludge samples of three sewage treatment plants （STPs） in Beijing, China using a gas chromatograph-mass spectrometry. The HHCB and AHTN concentration ranges in the influents were 1251.4-3003.8 ng/L and 111.9-286.3 ng/L, respectively. Meanwhile, the ranges of 492.8-1285.3 ng/L for HHCB and 47.3-89.3 ng/L for AHTN were present in the effluents. The musks in the sludges were three to four orders of magnitude higher than those in aqueous sewages. The removal efficiencies.of the two musks varied in the ranges of 41.7%- 70.1% for HHCB, and 25.5%-68.8% for AHTN. Adsorption onto suspended particulate matter played an important role in removing musks from the sewages. The HHCB/AHTN ratio along the treatment processes showed that the two musks had high similarity of removal from sewage by each reactor in STP. The musks in the effluent sewages may pose a low potential risk to aquatic environment in terms of the predicted-non-effect concentration. Nevertheless, considering the possible additive and synergistic effects with other compounds emitted via STPs, their bioconcentration and bioaccumulation in aquatic organisms and so on, it is essential to monitor these compounds in various compartments and to study their environmental fate.

Ecotoxicological effects of polycyclic musks and cadmium on seed germination and seedling growth of wheat(Triticum aestivum)

Single and joint toxic effects of polycyclic musks including 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[g]-2- benzopyran （HHCB） and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronapthalene （AHTN） and cadmium （Cd） on seed germination and seedling growth of wheat （Triticum aestivum） were investigated. The results showed that the toxicity sequence of HHCB toxic to wheat seed germination and seedling growth was similar to that of AHTN, that is, germination rate 〉 shoot elongation 〉 root elongation, while the toxicity of Cd was in the sequence of root elongation 〉 shoot elongation 〉 germination rate, according to the LC50 and EC50 values. It is suggested that polycyclic musks and Cd had different toxicological mechanisms. Root and shoot elongation of wheat might be good bioindicators for the contamination of polycyclic musks and Cd in soil. The mixture of polycyclic musks and Cd had synergistic effects on T. aestivum according to the equi-toxic mixture approach when root elongation was selected as the toxicological endpoint. Thus, the joint toxicity of HHCB and Cd was significantly higher than the single toxicity of HHCB or Cd, which was also confirmed by the EC50mix value of the mixture （EC50mix = 0.530 TUrnix）. The EC50mix value of the mixture of AHTN and Cd was 0.614 TUmix, which indicated that the mixture toxicity was strengthened when AHTN coexisted with Cd.

Occurrence and removal of selected polycyclic musks in two sewage treatment plants in Xi＇an, China

Polycyclic musks are widely used for cos- metics and other personal care and household cleaning products. The occurrence and removal of two representa- tive polycyclic musks, galaxolide （HHCB） and tonalide （AHTN） were investigated in three different processes of two sewage treatment plants （STPs） in Xi＇an, China. The samples were preconcentrated by solid phase extraction procedure and analyzed using a gas chromatography mass spectrometry （GC/MS） by a modified procedure. The HHCB was in the range of 82.8 to 182.5 ng.L1 in the influents and 22.6 to 103.9ng.L-1 in the effluents. The AHTN ranged from 11.0 to 19.3 ng. L-1 in the influents and 2.2 to 8.8 ng. I_~1 in the effluents. The removal efficiency of the two musks varied in the ranges of 43.1%-70.4% for HHCB and 54.2%-84.4% for AHTN. Concentrations of the two musks in aqueous phase of three processes slightly increased along the primary process, and significantly removed during the biologic treatment processes, revealing that the selected musks could be remarkably removed in varied activated sludge processes. Advanced processes of activated sludge did not show a significant superiority on selected musk removal compared to the conventional process. The selected musk removal mainly resulted from the adsorption function of activated sludge. There was no significant change of HHCB/AHTN ratios along the treatment flow, indicating that each sewage treatment structure had a similar removal efficiency for the two musks.