Occurrence and Behavior of Methylsiloxanes in Urban Environment in Four Cities of China

Abstract

Methylsiloxanes (MSs), used in industrial production and personal care products, are released in various environmental media. In this study, we combined monitoring and modeling to investigate the occurrence and behavior of MSs in the urban environment in China. MSs were widely found in the air, water, soil and sediment of four cities in China. The concentrations of MSs in all four environmental media of Zhangjiagang were higher than those in the other three cities (Beijing, Kunming and Lijiang), indicating that the siloxane production plant had a significant impact on the pollution level of MSs in the surrounding environment. The samples with high MS concentrations were all from the sample sites near the outlet of the WWTPs, which showed that the effluent of the WWTPs was the main source of MS pollution in the surrounding environment. The modeling results of the EQC level III model showed that D4 discharged into the environment was mainly distributed in the air, while D5 and D6 were mainly distributed in the sediment. CMSs (D4–D6) discharged into various environmental media could exist in the urban environment for a long time with low temperatures in cities. When the temperature was 0 °C, the residence time of D5 and D6 could be 68.1 days and 243 days in the whole environmental system in Beijing. This study illustrates the importance of CMSs (D4–D6) in low-temperature environments and the potential environmental risks that they may pose.

Spatial distribution and temporal trends of cyclic and linear siloxanes in sediment from semi-enclosed and industrialized bays of Korea, in 2013 and 2021

“…The levels of ƩLinear (mean: 151 ng/g dw in 2013, 156 ng/g dw in 2021) in sedimentary materials observed in this study were similar to or higher than those presented in rivers and Korean coasts (9.38-85.5 ng/g dw; Lee et al, 2019b;Wang et al, 2021;Chen et al, 2022;Kim et al, 2022), rivers and lakes in China (12.2-146 ng/g dw; Zhi et al, 2019;He et al, 2021;Jiang et al, 2022), and rivers near Tokyo Bay, Japan (117 ng/g dw; Horii et al, 2022b). By comparison, our results showed that the ƩLinear concentrations in this study were obviously lower than those detected in rivers and oil fields in China (165-1558 ng/g dw; Zhi et al, 2018;Zhi et al, 2019;Jiang et al, 2022), Korean industrial bays (467 ng/g dw; Lee et al, 2018a), and Tokyo Bay, Japan (1310 ng/g dw; Horii et al, 2022b). Pollution levels of siloxanes in the aquatic environment from different research areas has varied significantly, which may be affected by regional sources and/or industrial demand (Lee et al, 2018a;Chen et al, 2022).…”

“…The overall ƩCyclic concentrations in this study were 10 to 1000 times higher than those reported in rivers and along the Korean coasts (3.39-106 ng/g dw; Wang et al, 2021;Chen et al, 2022;Kim et al, 2022), freshwater from China (28.5-58.1 ng/g dw; Zhi et al, 2018;He et al, 2021;Jiang et al, 2022), rivers near Tokyo Bay in Japan (71.9 ng/g dw; Horii et al, 2022b), river water in Spain (3.39 ng/g dw; Sanchıś et al, 2013), and river water in Canada (50.9 ng/g dw; Pelletier et al, 2022). In contrast, our results were lower than those observed in sediment from Tokyo Bay, Japan (905 ng/g dw; Horii et al, 2022b), waters in Zhangjiagang, Kunming, and Beijing, China (978-1035 ng/g dw; Jiang et al, 2022), Rubı́Brook, Spain (2070 ng/g dw; Sanchıś et al, 2013), and waters in northern Vietnam (2518 ng/g dw; Nguyen et al, 2022).…”

“…The previous investigation on POPs (including PBDEs, PCDD/Fs, PCBs, and perfluorinated compounds) in sediment near the outfall of a WWTP in Masan Bay also revealed that the discharge of WWTP effluents is a key source of these compounds in sediment (Moon et al, 2008b;Jin et al, 2016). Earlier studies have confirmed that WWTPs could not completely remove siloxanes in influents (Lee et al, 2014a;Horii et al, 2022a;Jiang et al, 2022).…”

Concentrations of Volatile Methyl Siloxanes in New York City Reflect Emissions from Personal Care and Industrial Use

“…Data from our study site when combined with previous data in the literature show that there is a strong and statistically significant relationship ( R 2 = 0.59, p < 0.001) between log D5 concentrations and the log of average population density within 10 km of the location in which the measurements were conducted (Figure , Figure S3). ,,− ,− ,,, We selected 10 km because it was the strongest predictor out of the distances we tested between 1 and 20 km. Furthermore, the agreement between our data and the historical trend shows that the per capita emission rate of D5 in the United States has not significantly declined despite industry suggestions that EU restrictions may be causing a voluntary phase out of VMS in U.S. manufacturing. , However, comparisons between our data and previous VMS measurements also show that the relationship between concentration and population density is not as strong for all VMS congeners.…”

“…A number of previous studies employing field measurements and atmospheric models have provided estimates of atmospheric VMS concentrations in areas ranging from remote parts of the arctic to major cities, with the majority of work to date occurring in the United States, Western Europe, or Eastern Asia. ,,,− One trend consistently observed in these studies is that concentrations of all VMS congeners tend to be higher in densely populated urban areas. ,,,, This is unsurprising given that the primary emissions source of VMS is personal care products and other volatile chemical products. Even though the emissions and concentrations of VMS tend to be very high in these areas, measurements of VMS concentrations in large cities remain scarce.…”