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Wastewater, aeration gas, dewatered sludge, and incineration ash and flue gas (from dewatered sludge) were collected from 9 sewage treatment plants (STPs) located in Saitama Prefecture, Japan, and analyzed for seven cyclic and linear volatile methylsiloxanes (VMSs) namely, D3, D4, D5, D6, L3, L4, and L5. The mass loadings and distribution of VMSs in STPs were estimated based on measured concentrations in liquid, solid, and gaseous samples, including incinerated dewatered sludge. Mass loading of ΣVMS varied widely from 21 kg y−1 to 3740 kg y−1, depending on the volume of wastewater treated in each STP. Mass % of ΣVMS distributed in aeration gas was 15% and that in activated sludge was 78%. Approximately 6.6% of ΣVMS remained in the final effluent. Overall, partitioning onto the activated sludge was the dominant removal mechanism for D4, D5, and D6, whereas volatilization was also an important removal mechanism for D4. Incineration was effective to degrade VMSs in dewatered sludge, with a reduction rate of >99%. Activated carbon treatment removed >99% of VMSs from the aeration gas. In Saitama Prefecture, total emission of ΣVMS via STPs was estimated at 434 kg y−1, 86 kg y−1, and 0.065 kg y−1, to aquatic, atmospheric, and terrestrial environments, respectively, which accounted for 83%, 17%, and 0.01% of the total environmental emissions. Our results indicate that majority of VMSs in dewatered sludge can be removed by incineration and emission of VMSs through incineration ash landfill is negligible.

Bulk (wet and dry) deposition samples were collected in Saitama Prefecture, Japan throughout a year (February 8, 2012 to February 7, 2013) to estimate the influence of dioxins emitting from waste incinerators on river water quality. The annual deposition flux of dioxins was 3.3 ng-toxic equivalent (TEQ)/m 2 /year. Source identification using indicative congeners estimated that 82% of dioxin TEQ in the bulk deposition (2.7 ng-TEQ/m 2 /year) was combustion-originated, indicating that most of the dioxins in the deposition were derived from waste incinerators. In Saitama prefecture the annual flux of combustion-originated dioxins in depositions was apparently consistent with that of dioxin emission into the air from waste incinerators. The TEQ of combustion-originated dioxins in the deposition per rainfall was 2.4 pg-TEQ/L on annual average, exceeding the environmental quality standard (EQS) for water in Japan of 1 pg-TEQ/L. This suggests there is a possibility that dioxins in atmospheric deposition have a significant influence on the water quality of urban rivers which rainwater directly flows into because of many paved areas in the basins. The influence of combustion-originated dioxin in the deposition on the water quality of Ayase River, an urban river heavily polluted with dioxins, was estimated at 0.29 pg-TEQ/L on annual average in 2015. It seems that dioxins in atmospheric deposition from waste incinerators have a significant influence on water quality of some urban rivers via rainwater though the dioxins in the ambient air have achieved the EQS for atmosphere at all monitoring sites in Japan.

In Japan, Ayase River is one of the most polluted rivers by PCDDs, PCDFs and dioxin-like PCBs, which are referred to as dioxins in this paper. The water samples of the river were collected once per month for a year, and dioxins were analyzed to examine the dioxin sources and their contributions to toxic equivalent (TEQ). The WHO-2006 TEQs ranged from 0.26 to 7.0 pg-TEQ L−1 and the average was 2.7 pg-TEQ L−1; eight of 12 samples exceeded the environmental quality standard in Japan (1.0 pg-TEQ L−1). The TEQ value was high during the irrigation period from May to August. The most part of the dioxins in the river water existed in suspended solids (SS) and it seemed that the river received water with highly-dioxin-contaminated SS in the irrigation period. The homologue profiles of the water samples suggested that the dioxins were influenced by pentachlorophenol (PCP) and chlornitrofen (CNP) formulations which were widely used as herbicides for the paddy fields in Japan. According to TEQ apportionment estimated by using indicative congeners, the TEQ was mainly contributed by PCP. Moreover, it was also shown that the TEQ contributions of PCP and CNP formulations increased along with the increase of the total TEQ and the TEQ contribution was dominated by these herbicides during the irrigation period. Therefore, it was concluded that the herbicides-originated dioxins run off from the paddy fields into the river during the irrigation period and increased the dioxins level in the river water. The result from the principal component analysis was consistent with these conclusions.

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs) contained in the smoke generated from rice straw burning in post-harvest paddy fields in Japan were analyzed to determine their congener profiles. Both the apportionment of toxic equivalent (TEQ) by using indicative congeners and the comparison of the homolog profiles showed that the PCDDs/PCDFs/DL-PCBs present in the rice-straw smoke were greatly influenced by those present as impurities in pentachlorophenol (PCP) and chlornitrofen (CNP, 4-nitrophenyl-2,4,6-trichlorophenyl ether) formulations that had been widely used as herbicides in paddy fields in Japan. Further, in order to investigate the effects of paddy-field soil on the PCDDs/PCDFs/DL-PCBs present in rice-straw smoke, PCDD/PCDF/DL-PCB homolog profiles of rice straw, rice-straw smoke and paddy-field soil were compared. Rice-straw smoke was generated by burning rice straw on a stainless-steel tray in a laboratory. The results suggested that the herbicides-originated PCDDs/PCDFs/DL-PCBs and the atmospheric PCDDs/PCDFs/DL-PCBs contributed predominantly to the presence of PCDDs/PCDFs/DL-PCBs in the rice-straw smoke while the contribution of PCDDs/PCDFs/DL-PCBs formed during rice straw burning was relatively minimal. The major sources of the PCDDs/PCDFs/DL-PCBs found in the rice-straw smoke were attributed primarily to the paddy-field soil adhered to the rice straw surface and secondarily to the air taken by the rice straw. The principal component analysis supported these conclusions. It is concluded that rice straw burning at paddy fields acts as a driving force in the transfer of PCDDs/PCDFs/DL-PCBs from paddy-field soil to the atmosphere.

The major sources of dioxins (polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs)) in the environment in Japan have been considered to be combustion by-products, pentachlorophenol (PCP) formulations, chlornitrofen (CNP, 4-nitrophenyl-2,4,6-trichlorophenyl ether) formulations, and PCB products. Data on PCDDs, PCDFs and DL-PCBs from the four sources were analyzed, and indicative congeners whose concentrations were highly correlated with WHO-2006 toxic equivalencies (TEQs) were identified for each source sample. The indicative congeners for combustion by-products, PCP formulations, and CNP formulations were 2,3,4,7,8-pentachlorodibenzofuran, 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin, and 1,2,3,7,8-pentachlorodibenzo-p-dioxin, respectively; for PCB products, the indicative congeners were IUPAC Nos. #126- and #105-pentachlorobiphenyls. Moreover, using the data on PCDDs, PCDFs and DL-PCBs, we developed a set of equations for estimating the apportionment of TEQs from the four sources by using only the concentrations of the above-mentioned five indicative congeners. The equations were used along with the analysis results of different types of environmental samples collected from Japan, to determine the TEQ contributions of the four sources. The obtained values of TEQ contributions seemed to be reasonable. The estimation method was developed by using the data on major dioxin sources in Japan, and therefore, it is generally adaptable to environmental samples from any part of Japan. The method may be usable for regions outside Japan if source identification is carried out and the estimation equations are modified appropriately.

Pollution from 35 perfluorinated compounds (PFCs) in the water of the Tokyo Bay basin was examined. The water in the basin contained relatively high levels of perfluorononanoate (PFNA), perfluorooctanoate (PFOA), and perfluorooctane sulfonate (PFOS) compared to the other PFCs, which were present at concentrations of 20.1 ng/L, 6.7 ng/L, and 5.8 ng/L, respectively. In contrast, the concentrations of their precursors and degradation products were an order of magnitude lower. Sewage treatment plant (STP) effluent in the area also contained high levels of PFNA compared with the river water samples (Mann-Whitney U-test, p0.0002). From a spatial aspect, increases in PFC pollution levels correlated with increased urbanization in the study area suggested that there are nonpoint source contributors to the PFC pollution in this area. Branched isomers of the PFCs were also quantified. Samples that contained high concentrations of perfluoroalkyl carboxylates (PFCA) showed lower proportions of its branched isomer. This indicates that the branched isomers are more prominent in the area with lower PFC pollution. This analysis was beneficial for estimating the individual contributions of different PFCA production processes. This survey provided new information on the sources, spatial distribution, and behavioral characteristics of PFC pollutants in this area.

The concentrations of nonylphenol (NP), nonylphenol ethoxylates (NPnEOs: n = 1-15) and nonylphenoxy acetic acids (NPmECs: m = 1-10) in river water and sediment were determined seasonally at four sampling sites in the Kamo River, which is a typical urban river and was already known to be polluted by NP. In the water, the concentrations of NP, NPnEOs and NPmECs ranged from 0.13 to 3.65 microg/L, from 1.0 to 22.4 microg/L, and from 0.6 to 8.5 microg/L, respectively. NP, nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), nonylphenoxy acetic acid (NP1EC) and nonylphenol monoethoxy acetic acid (NP2EC) were predominant in the water. In the sediment, the concentrations of NP, NPnEOs and NPmECs ranged from 69 to 10,747 microg/kg dry weight (dw), from 74 to 6,101 microg/kg dw, and from 24 to 673 microg/kg dw, respectively. NP, NP1EO and NP2EO were predominant in the sediment. The total concentrations of NP, NPnEOs and NPmECs in both river water and sediment were higher in winter and spring than in summer and autumn. In the river water, the ratio in concentration of the sum of NP, NP1EO, NP2EO, NP1EC and NP2EC to the whole nonylphenolic compounds was correlated with water temperature. The surveyed results suggested that some point emission sources of nonylphenolic compounds were located in the river basin between the first sampling site and the second sampling site.