Spatial distribution and benthic risk assessment of cyclic, linear, and modified methylsiloxanes in sediments from Tokyo Bay catchment basin, Japan: Si-based mass profiles in extractable organosilicon.

We investigated the spatial distribution, mass profiles, and benthic risk assessment of a wide range of methylsiloxanes (MSs), including 7 cyclic MSs (CMSs; D3-D9; the number refers to the number of SiO bonds), 13 linear MSs (LMSs; L3-L15), and 15 modified and other MSs (MMSs) in sediments from the Tokyo Bay catchment basin, Japan. We observed widespread distribution of MSs (ΣCMS, ΣLMS, and ΣMMS) in the sediment samples, with concentrations of 1.0-6180 ng/g dry weight (dw), 1.8-10,100 ng/g dw, and < 0.31-210 ng/g dw, respectively. Our study is the first to measure various MMSs modified with hydrogen, vinyl, or phenyl groups; however, only methyltris(trimethylsiloxy)silane and phenyltris(trimethylsiloxy)silane were detected with high occurrence frequency. Notably, no elevated concentrations of MSs were observed downstream of silicone manufacturers, whereas the sediment was characterized by a specific D4/D5 ratio. With the Si-based mass profiles in extractable organosilicon (EOSi), the measured CMSs, LMSs, and MMSs accounted for 5.4%, 7.8%, and 0.2%, respectively. Unidentified EOSi (unknown fraction) constituted a major proportion of the EOSi in the sediment, with a mean of 87%, suggesting that the organosilicon environmental emissions were more than the measured MSs. In risk assessment of the adverse effects of D4, D5, and D6 in sediment on benthic organisms, the respective distributions indicated no overlap between the 95th percentile field sediment concentration and the 5th percentile chronic sediment no-effect concentration in organic carbon-normalized concentration. Although the hazard quotient compared with the predicted no-effect concentration for D5 and D6 exceeded the threshold level (hazard quotient ≥1), the results of probabilistic risk assessment for the three CMSs were not high enough to indicate a threat to benthic organisms in the study area.

Distribution characteristics of methylsiloxanes in atmospheric environment of Saitama, Japan: Diurnal and seasonal variations and emission source apportionment.

The large production volume of methylsiloxanes (MSs), combined with their high mobility/volatility and persistence, is a matter of concern from the atmospheric pollution perspective. Therefore, we evaluated of the concentrations and emission sources of MSs, including 7 cyclic methylsiloxanes (D3-D9; CMSs, the number refers to the number of Si-O bonds) and 13 linear methylsiloxanes (L3-L15; LMSs) in ambient air collected from Saitama, Japan. This is a first study regarding the evaluation of 20 methylsiloxanes in the Japanese atmosphere. We improved the air sampling methodology by determination the stability of D5 during a 7-d air sampling and arbitrary sample storage period using polystyrene-divinyl benzene copolymer sorbent (Sep-Pak plus PS-2). We analyzed air samples for MSs seasonally collected from nine locations in Saitama, including urban, suburban, rural, and mountainous areas. The mean CMS and LMS concentrations were 358 ng m-3 and 13.4 ng m-3, respectively. The D5 concentrations were distributed widely, with high concentrations in urban/suburban populous areas and dispersed at low concentrations in surrounding areas (north and mountainous areas). We analyzed 7-d air samples collected every week over a year and found apparent seasonal and periodic trends in the CMS concentrations. In the diurnal sampling campaign, we observed periodic fluctuations in ambient CMSs, with an inverse relationship with the atmospheric boundary layer development during the day. Backward trajectories and the prevailing wind direction during the sampling period indicated that the specific profiles of D4 observed in fall/winter weeks and north of Saitama could be ascribed to northwestward air-mass advection. We employed a novel approach in estimating CMSs emission sources and source apportionment by using non-negative matrix factorization (NMF). The concentration matrix was divided successfully into two factors (emission sources) namely, personal care and household products and industrial activities.

Influence of combustion-originated dioxins in atmospheric deposition on water quality of an urban river in Japan.

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 3.3ng-toxic equivalent (TEQ)/m2/year. Source identification using indicative congeners estimated that 82% of dioxin TEQ in the bulk deposition (2.7ng-TEQ/m2/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 2.4pg-TEQ/L on annual average, exceeding the environmental quality standard (EQS) for water in Japan of 1pg-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 0.29pg-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.

Effects of characteristics of waste incinerator on emission rate of halogenated polycyclic aromatic hydrocarbon into environments.

We determined the concentrations of halogenated polycyclic aromatic hydrocarbons (XPAHs), some of which are carcinogenic and/or mutagenic compounds, in fly and bottom ashes and stack gas collected from waste incinerators in Japan. The dominant XPAHs in stack gas were consistent with those in the urban atmosphere. The dioxin-like toxic equivalent (TEQ) concentration ranges of the XPAHs in stack gas, fly ash, and bottom ash were 0.00497-20.5ng-TEQm-3, 0.0541-101ng-TEQg-1, and 0.000914-2.00ng-TEQg-1, respectively. The TEQ concentrations of the XPAHs targeted in this study were higher than those of polychlorinated dibenzo-p-dioxins/dibenzofurans and polychlorinated biphenyls reported in the literature. The annual amounts of XPAHs produced in the waste incinerators ranged from 25.1 to 881g. The mass balance of XPAHs in each waste incinerator was calculated to evaluate the emission rate of XPAHs from waste incinerators. Less than 6.7% of the XPAHs produced in the waste incinerators were emitted into the atmosphere from the facilities in which the flue gas was treated by using a combination of bag filter and activated carbon. In contrast, from the facility using a bag filter only, approximately 50% of the XPAHs produced were emitted into the atmosphere. Thus, the flue gas treatment process appears to be a key determinant of the emission rate of XPAHs produced during waste incineration.

Distribution characteristics of volatile methylsiloxanes in Tokyo Bay watershed in Japan: Analysis of surface waters by purge and trap method.

Surface waters including river water and effluent from sewage treatment plants (STPs) were collected from Tokyo Bay watershed, Japan, and analyzed for seven cyclic and linear volatile methylsiloxanes (VMSs), i.e., D3, D4, D5, D6, L3, L4, and L5 by an optimized purge and trap extraction method. The total concentrations of seven VMSs (ΣVMS) in river water ranged from <4.9 to 1700ng/L (mean: 220ng/L). The individual mean concentrations of cyclic VMSs in surface waters were; 10ng/L for D3, 13ng/L for D4, 180ng/L for D5, and 18ng/L for D6. The concentrations of ΣVMS determined in STP effluents varied widely from 99 to 2500ng/L and the individual mean concentrations were 21ng/L for D3, 27ng/L for D4, 540ng/L for D5, and 45ng/L for D6. D5, which is widely used in personal-care products, was found to be the most abundant compound in both river water and STP effluent. Linear VMSs were detected at much lower frequency and concentrations than those of cyclic VMSs. The measured concentrations of D4 were below the no-observed effect concentration (NOEC). The annual emission of ΣVMS through STPs into Tokyo Bay watershed was estimated at 2300kg. Our results indicate widespread distribution of VMSs in Tokyo Bay watershed and the influence of domestic wastewater discharges as a source of VMSs in the aquatic environment.

Temperature dependence on the pesticide sampling rate of polar organic chemical integrative samplers (POCIS).

Laboratory experiments were performed to determine the sampling rates of pesticides for the polar organic chemical integrative samplers (POCIS) used in Japan. The concentrations of pesticides in aquatic environments were estimated from the accumulated amounts of pesticide on POCIS, and the effect of water temperature on the pesticide sampling rates was evaluated. The sampling rates of 48 pesticides at 18, 24, and 30 °C were obtained, and this study confirmed that increasing trend of sampling rates was resulted with increasing water temperature for many pesticides.

Dioxin distribution characteristics and health risk assessment in different size particles of fly ash from MSWIs in China.

During the process of treating and recycling Municipal Solid Waste Incinerators (MSWIs) fly ash, polychlorinated dibenzo-p-dioxins (PCDD/Fs) and polychlorinated dibenzofurans (dl-PCBs) in fly ash may potentially mobilize in the atmosphere and be widely distributed in the environment because of the inevitable re-suspension. Thus, this work presents the distributions of PCDD/Fs and dl-PCBs in inhalable coarse particles (Dp10-2.5 (particle diameter in µm)), fine particles (Dp<2.5) of fly ash and original fly ash from four MSWI plants in China. The results show that PCDD/Fs and dl-PCBs preferentially concentrated in Dp10-2.5 and Dp<2.5. Their mass concentrations and TEQ were significantly higher than those in the original fly ash, but the distribution of PCDD/Fs congeners in Dp10-2.5 and Dp<2.5 was close to that in the original fly ash. The main TEQ contribution included 1,2,3,7,8-PeCDD, 2,3,7,8-TeCDD in PCDDs and 2,3,4,7,8-PeCDF in PCDFs for Dp10-2.5, Dp<2.5 fractions and the original fly ash. Furthermore, the mass and TEQ contribution of dl-PCBs was relatively low. In addition, compared with the fluidized bed, the samples from the grate-type furnaces had significantly lower dioxin concentrations. In terms of potential health risk, the non-carcinogenic risk of PCDD/Fs in Dp10-2.5 and Dp<2.5 were estimated at 9.87 × 10(-1) to 4.81 and 1.19-7.95. For the carcinogenic risk of PCDD/Fs, both accumulation of Hazard Quotients (HQ) in Dp10-2.5 and Dp<2.5 exceeded the threshold limit and should be considered as unacceptable risk for onsite workers. The above findings could provide data to support the risk management of MSWI fly ash during the process of recycle and disposal.

Characteristics of dioxins content in fly ash from municipal solid waste incinerators in China.

MSWI fly ashes sampled from 15 large-scale commercial municipal solid waste incineration plants in China were analyzed for seventeen polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDFs) as well as twelve dioxin-like polychlorinated biphenyls (dl-PCBs). The concentration of PCDD/PCDFs and dl-PCBs in fly ash samples ranged from 2.8 to 190ngg(-1), and 59.6ngg(-1) on average. The toxic equivalent (TEQ) ranged from 34 to 2500ng WHO(2005)-PCDD/PCDF-PCB-TEQkg(-1), and 790ng WHO(2005)-PCDD/PCDF-PCB-TEQkg(-1) on average. For PCDDs, hexa-chlorinated homolog was the dominant compound except two fly ash samples. Tetra-chlorinated homolog was dominant for PCDFs except one sample. The ratio of PCDDs/PCDFs ranged from 0.32 to 2.44 (average 0.97). The contribution of dl-PCBs to total concentration and TEQ was relatively minimal. Correlation between the concentration of three congeners and total TEQ values of fly ashes was also established. The findings obtained in this work provided overview information on the PCDD/PCDF-PCB content characterization of MSWI fly ash in China, which can be available for MSWI fly ash management in the environment.

[Spatial distribution of three endocrine disrupting chemicals in sediments of the Suzhou Creek and their environmental risks].

Three environmental endocrine disrupting chemicals (EDCs), named nonylphenol (NP), octylphenol (4-t-OP) and bisphenol A (BPA), in sediments of the Suzhou Creek and its branches were detected using gas chromatography-mass spectrometry (GC-MS) method. The results showed that the concentration of three chemicals varied greatly from site to site, which ranged from < 1.0-5 800, < 0.10-39 and 0.90-180 microg x kg(-1), respectively. In general, the accumulation of pollutants in sediments closely related to the intensity of anthropogenic activities: the concentration of three chemicals in sediments of municipal section of the creek are significantly higher than those in the sections of suburb of Shanghai city and Jiangsu province; the chemical concentrations in sediments of branches are significantly higher than those of the main stream of the creek. Significant correlations between each two of the three chemicals in sediments were observed, implying their similar source provenance. Taking nonylphenol as an example, the environmental risks of the EDCs in sediments were assessed. The result indicated that this chemical in the entire creek except the Wujiagang Bridge point had posed potential toxic risks to ecological system. Therefore, more countermeasures should be taken to prevent EDCs from entering the creek.

Distribution, characteristics, and worldwide inventory of dioxins in kaolin ball clays.

Distribution, characteristics, and global inventory of dioxins (polychlorinated dibenzo-p-dioxins [PCDDs] and dibenzofurans [PCDFs] and dioxin like polychlorinated biphenyls) in kaolin clays collected from 10 countries were investigated. Dioxins were found in all kaolin clay samples analyzed, at total concentrations ranging from 1.2 pg/g (Brazil) to 520,000 pg/g (USA). Dioxin concentrations in kaolin clays from a few countries (e.g., Brazil and UK) were lower than those reported for background soils in Japan. Dioxin profiles in kaolin clays were characterized by the domination of the congener octachlorodibenzo-p-dioxin (OCDD), and the concentrations of other congeners decreased in the order of reduction in the levels of chlorination. Furthermore, specific distribution of congeners, with predominant proportions of 1,4,6,9-substituted PCDDs within each homologue group, was found in most clay samples. The ratios of concentrations of PCDD to PCDF and 1,2,3,7,8,9-HxCDD to 1,2,3,6,7,8-HxCDD indicated differences in the profiles found for anthropogenic sources (including pentachlorophenol) and kaolin clays. Concentrations of PCDD/Fs in kaolin clays, except for American ball clays, did not exceed the environmental criteria set by the Law Concerning Special Measures against Dioxins in Japan. Based on the average concentrations measured in our study, inventories of PCDD/Fs from the production/usage of ball clays on a global scale were estimated to be 650 kg/yr; the corresponding value on a TEQ basis is 2400 g-TEQ/yr. More than 480 kg of OCDD is estimated to be released annually from the production of kaolin clays worldwide, suggesting that kaolin clays can be a major contributor for additional source of dioxins, especially OCDD, in the environment.

Seasonal change of PCDDs/PCDFs/DL-PCBs in the water of Ayase River, Japan: pollution sources and their contributions to TEQ.

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-TEQL(-1) and the average was 2.7 pg-TEQL(-1); eight of 12 samples exceeded the environmental quality standard in Japan (1.0 pg-TEQL(-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, dibenzofurans, and dioxin-like polychlorinated biphenyls in rice straw smoke and their origins in Japan.

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.

A simplified determination method of dioxin toxic equivalent (TEQ) by single GC/MS measurement of five indicative congeners.

Here, we proposed a simplified determination method for dioxin (polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls (PCBs)) toxic equivalency (TEQ; based on the World Health Organization-2006 toxicity equivalent factor) in environmental samples collected in Japan. This method has estimated the total TEQ from the concentrations of only five indicative congeners, namely, 2,3,4,7,8-pentachlorodibenzofuran; 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin; 1,2,3,7,8-pentachlorodibenzo-p-dioxin; and PCBs of IUPAC Nos. #126 and #105, which were obtained from a single GC/MS measurement using a combination of columns of 10-meter-long DB-5ms (injector side) and 20-meter-long DB-17ms (detector side). Applying this simplified determination method to various environmental samples (ambient air, river water, river sediment, and soil) showed that the estimated TEQ was in good agreement with TEQ obtained by the corresponding official methods. Moreover, this method could estimate the TEQ contributions of the four major dioxin sources in Japan: combustion by-products, pentachlorophenol formulations, chlornitrofen formulations and PCB products.

Apportionment of TEQs from four major dioxin sources in Japan on the basis of five indicative congeners.

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.