Organophosphate Esters Concentrations Research Articles

Potential impact of organophosphate esters on thyroid eye disease based on machine learning and molecular docking

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers in daily commodities and building materials. Some OPEs, acting as agonists of the thyroid-stimulating hormone receptor (TSHR), may contribute to the development of thyroid eye disease (TED). This study analyzes the serum and urine of patients and control groups, using machine learning and molecular docking to investigate the potential impact of OPEs on TED. Results indicate significantly higher concentrations of OPEs and di-OPEs of TED patients compared to controls (Mann-Whitney U test, p < 0.05). Aryl OPEs exhibit the strongest binding affinity with TSHR. We developed a predictive model for OPE-TSHR affinity to explore the impact of OPE structural features on TSHR activity and effectively capture the complex relationships between changes in OPE side chains and their effects on TSHR. Predictions from the USEPA's database indicate that 28 % of 1011 OPEs have a tendency to bind with TSHR. Furthermore, a high-accuracy classification model successfully identified key substructures associated with high affinity for TSHR. This study not only enhances our understanding of the complex relationship between the structural diversity of OPEs and their thyroid impact but also offers molecular design insights to prevent releasing OPEs with high thyroid harm potential into the environment.

An assessment of the levels of emerging and traditional organophosphate ester flame retardants in dairy products in China and their combined dietary risks

A comprehensive survey was conducted by investigating 25 emerging and traditional organophosphate esters (OPEs) in 182 dairy products collected in China. The concentrations of total OPEs (ΣOPEs) ranged from 0.0261 to 1178 ng/g wet weight (ww) in all the dairy samples. The major contaminants were triethyl phosphate (proportion: 94 %) and tris(1-chloro-2-isopropyl) phosphate (proportion: 2 %). Among types of dairy products, the concentrations of ΣOPEs decreased in the following order: milk powder (mean: 80.8 ng/g ww, proportion: 86 %) > cheese (9.43 ng/g ww, 10 %) > milk tablets (2.72 ng/g ww, 3 %) > liquid dairy (1.05 ng/g ww, 1 %). The significant correlation between emerging and traditional OPEs suggests that they likely share similar sources or are used together in commercial applications. OPEs contamination was related to the OPEs properties, local OPEs production and application, and dairy types. For the general Chinese population, the average and high estimated daily intakes of ΣOPEs via dairy products were 31.5 and 83.6 ng/kg bw/day, respectively. Dairy exposure in toddlers and children were higher than other age groups. Although the high-exposure risk of ΣOPEs was 3.50 × 10−3, potentially toxic tris(1-chloro-2-isopropyl) phosphate accounted for 38 % of the total hazard quotients.

Distribution, transport and ecological risk prediction of organophosphate esters in China seas based on machine learning

Organophosphate esters (OPEs), widely used globally, have been detected in significant amounts in various environmental media, raising concerns about their persistence, bioaccumulation, and associated risks. Traditional sampling and detection methods are time-consuming and labor-intensive, limiting a comprehensive understanding. This study employs Extreme Gradient Boosting (XGBoost) and Light Gradient Boosting Machine (LGBM) models, using 12 feature variables and 463 OPEs concentration data points, to investigate the distribution and ecological risk of total OPEs (T-OPEs), chlorinated alkyl OPEs (Cl-OPEs), and aryl-OPEs in seawater of China Seas. The LGBM model proved optimal for predicting T-OPEs and Cl-OPEs concentrations, with RMSE of 0.48 and 0.46 and R2 values of 0.79 and 0.76. XGBoost was superior for aryl-OPEs, yielding an RMSE value of 0.82, and an R2 value of 0.87. Analysis revealed complex nonlinear relationships between features and OPEs concentrations. Maps showed higher OPEs pollution in urban agglomerations and estuaries, particularly in summer. The XGBoost model was the best predictor for ecological risks, with most sites categorized as low-risk, and a few as moderate-risk. This study offers valuable data and insights for managing OPEs pollution and ecological risks in the China Seas.

Occupational exposure to traditional and emerging organophosphate esters: A comparison of levels across different sources and blood distribution

Currently, there is limited knowledge regarding occupational exposure of traditional and emerging organophosphate esters (OPEs) from e-waste and automobile dismantling activities, and their distribution within the human blood. In the present study, we collected dust and urine samples from e-waste (ED) (n = 91 and 130, respectively) and automobile dismantling (AD) plants (n = 93 and 94, respectively), as well as serum-plasma-whole blood samples (sets from 128 participants) within ED areas for analyzing traditional and emerging organophosphate tri-esters (tri-OPEs) and organophosphate di-esters (di-OPEs). Median concentration of ∑tri-OPEs and ∑di-OPEs in dust (37,400 and 9,000 ng/g in ED, and 27,000 and 14,700 ng/g in AD areas, respectively) and urine samples (11.8 and 21.9 ng/mL in ED areas, and 17.2 and 15.0 ng/mL in AD areas, respectively) indicated that both e-waste and automobile dismantling activities served as important pollution source for OPEs. Dust ingestion has been evidenced to be the main exposure pathway compared to dermal absorption and inhalation. The median concentration (ng/mL) of OPEs in blood matrices descended order as follow: whole blood (13.1) > serum (11.6) > plasma (10.4) for ∑tri-OPEs, and plasma (3.51) > serum (0.36) > whole blood (0.23) for ∑di-OPEs. Concentration ratios of OPEs varied across blood matrices, depending on the compounds, suggesting that the essentiality of appropriate biomonitoring matrix for conducting comprehensive exposure assessments.

Organophosphate esters in Tianshan glacier runoff: Occurrence, degradation, risk, and flux

Organophosphate esters (OPEs) are a class of chemicals of emerging concern. However, little is known about the environmental behavior, transformation and ecological risk of OPEs in mid-latitude glacial environments. This study investigated the concentration and composition characteristics of organophosphate triesters (tri-OPEs) and organophosphate diesters (di-OPEs) in the runoff of Urumqi No. 1 Glacier and Koxkar Glacier in the Tianshan Mountains, and estimated the output of them from glacial rivers. The total concentration of tri-OPEs (Σ13tri-OPEs) was 8565 pg/L in glacier surface meltwater and 6568 pg/L in proglacial rivers. Di-OPEs exhibited lower concentrations, with 99 pg/L and 117 pg/L (Σ10di-OPEs) in glacier surface meltwater and proglacial rivers, respectively. Tri-OPEs exhibited clear diurnal variations, which are presumed to be related to environmental temperature, while di-OPEs did not show an obvious trend. Although risk quotients (RQs) indicated that the concentrations of OPEs pose minimal risk to the glacier aquatic environment, the Toxicological Priority Index (ToxPi) score results showed that tris(2-chloroethyl) phosphate (TCEP) has the highest priority and therefore requires more attention. The total output flux of OPEs (Σ13tri-OPEs and Σ10di-OPEs) in glacial rivers throughout the entire Tianshan region was estimated to be ∼ 847 kg/year. Given the continuity of glacial melting and the accumulation of emerging pollutants in glaciers, the process of melting poses an increasing risk to freshwater resources, warranting heightened attention.

Occurrence Characteristics and Health Risk Assessment of Organophosphate Esters in Tap Water of Shanghai

To explore the occurrence characteristics and health risk levels of the new pollutants organophosphate esters （OPEs） in tap water in Shanghai, based on the water supply areas of the Qingcaosha Reservoir, Chenhang Reservoir, Dongfeng Xisha Reservoir, and Upstream Huangpu River water sources, a total of 52 large shopping malls in Shanghai were selected as tap water sampling sites. Solid phase extraction and gas chromatography-triple quadrupole mass spectrometry were used to determine eight types of OPEs in tap water from shopping malls, including three types of chlorinated OPEs, two types of alkyl OPEs, and three types of aryl OPEs. On this basis, the health risk assessment of the substances with high detection frequency and concentration was carried out. The results showed that six types of OPEs were generally detected, and the average levels of eight types of OPEs in tap water collected in summer and winter were 64.3 ng·L-1 and 60.5 ng·L-1, respectively. The concentration levels and detection rates of different types of OPEs in tap water followed the order of： chlorinated OPEs &gt; alkyl OPEs &gt; aryl OPEs. From the perspective of water sources, the average concentration of OPEs in tap water with Upstream Huangpu River water sources as the water source was the highest （132 ng·L-1 in summer and 170 ng·L-1 in winter）, and OPEs in tap water with Dongfeng Xisha Reservoir as the water source was the lowest （25.1 ng·L-1 in summer and 6.62 ng·L-1 in winter）. The average concentration of chlorinated OPEs in summer （62.1 ng·L-1） was higher than that in winter （53.9 ng·L-1）. Based on the reference dose of OPEs, there were no health risks to people of all ages through drinking water exposure. However, the OPE exposure in tap water of Shanghai was higher compared with that of other countries and regions, which requires further attention and research.

Regulation of Ocean Surface Currents and Seasonal Sea Ice Variations on the Occurrence and Transport of Organophosphate Esters in the Central Arctic Ocean.

Organophosphate esters (OPEs) have been observed in the remote Arctic Ocean, yet the influence of hydrodynamics and seasonal sea ice variations on the occurrence and transport of waterborne OPEs remains unclear. This study comprehensively examines OPEs in surface seawater of the central Arctic Ocean during the summer of 2020, integrating surface ocean current and sea ice concentration data. The results confirm significant spatiotemporal variations of the OPEs, with the total concentration of seven major OPEs averaging 780 ± 970 pg/L. Chlorinated OPEs, particularly tris(1-chloro-2-propyl) phosphate (TCPP), were dominant. The significant impact of hydrodynamics on the OPE transport is demonstrated by higher OPE concentrations in regions with strong surface currents, especially at the edge of the Beaufort Gyre and the confluence of the Beaufort Gyre and the Transpolar Drift. Furthermore, OPE levels were generally higher in drifting-ice-covered regions compared to ice-free regions, attributed to the volatilization of dissolved OPEs formerly trapped below the sea ice or newly released from melting snow and sea ice. Notably, TCPP decreased by only 19% in the ice-free area, while the more volatile triphenyl phosphate decreased by 63% compared with the partial ice region.

Organophosphate esters in reservoir water from a metropolitan city in the Guangdong-Hong Kong-Macao Greater Bay Area, China, and their ecological risk

Organophosphate esters (OPEs) are emerging flame retardants widely used in products such as furniture, electronic equipment, construction, and plastics. It has been demonstrated that OPEs are harmful to humans and aquatic organisms, thus posing a threat to ecosystems. Considering that reservoirs are critical sources of drinking water for residents in Southern China, this study quantified nine OPEs in water samples collected from 29 reservoirs and their tributaries. The temporal and spatial distributions of OPEs were analyzed and their ecological risks were assessed. The results showed an extensive presence of OPEs in reservoirs, and the median concentration of Σ9OPEs was much higher in the dry season (65.3 ng/L) than in the wet season (21.3 ng/L). Triisobutyl phosphate (TiBP) (median: 5.24 ng/L) and tris(2-ethylhexyl) phosphate (TEHP) (median: 10.8 ng/L) dominated in the wet and dry seasons, respectively. Other OPEs varied considerably in concentrations over time, related to their physical and chemical properties, environmental factors (e.g., precipitation and temperature), and varied applications. Furthermore, the significant correlations of individual OPEs suggest their shared utilization, emission sources, and environmental behaviors. Spatially, there was no significant difference (P > 0.05) among the Σ9OPEs concentrations in water samples from different sites (inlet, reservoir, outlet, and tributary) of the reservoirs. Additionally, the concentrations of OPEs in reservoir water samples could be linked to industrial development, economic conditions, and population density. OPEs in the reservoir pose low ecological risks (RQ < 0.1), except for EDHPP and TEHP, which present median ecological risks (RQ = 0.54 and 0.38, respectively). Future studies could investigate more OPEs and their joint effects with other organic pollutants, as well as survey the chemical reactions and degradation pathways of OPEs in different environmental matrices to assess their potential ecotoxicity more comprehensively.

Occurrence, Bioaccumulation, and Risk Assessment of Organophosphate Esters in Rivers Receiving Different Effluents.

Organophosphate esters (OPEs), as alternatives to brominated flame retardants, are extensively used in both production and daily life, with their environmental contamination and toxic effects being a concern. This study investigated the concentration levels, bioaccumulation, and ecological effects of OPEs in five different effluent-receiving rivers. The results demonstrate that the concentration range of Σ13OPEs across the five rivers was between 142.23 and 304.56 ng/L (mean: 193.50 ng/L). The highest pollution levels of OPEs were found in rivers receiving airport and industrial wastewater, followed by agricultural wastewater, mixed wastewater, and domestic wastewater. Tris(2-chloroisopropyl) phosphate (TCPP), triethyl phosphate (TEP), and tricresyl phosphate (TCrP) were identified as the main pollutants. The accumulation concentrations of OPEs in fish ranged from 54.0 to 1080.88 ng/g dw, with the highest bioaccumulation found in Pelteobagrus fulvidraco, followed by Carassius auratus and Misgurnus anguillicaudatus. The brain was the primary organ of accumulation, followed by the liver, gills, intestine, and muscle. Tri-n-propyl phosphate (TPeP) and TEP exhibited the highest bioconcentration, with log BAF values exceeding three. The bioaccumulation of OPEs was influenced by pollutant concentration levels, hydrophobic properties, and biological metabolism. Ecological risk assessment revealed that the cumulative risk values of Σ13OPEs ranged from 0.025 to 16.76, with TCrP being the major contributor. It posed a medium-low risk to algae but a high risk to crustaceans and fish.

Organophosphate esters in terrestrial environments of Fildes Peninsula, Antarctica: Occurrence, potential sources, and bioaccumulation

Despite growing concerns regarding the long-range transport (LRT) and ecological risks of organophosphate esters (OPEs), information on the environmental behaviors of OPEs in polar terrestrial ecosystems remains inadequate. In the present study, 10 OPEs were analyzed in soil and vegetation samples collected from Fildes Peninsula, Antarctica. The OPE concentrations in Antarctic soils, mosses, and lichens ranged from 0.87 to 15.7 ng/g dry weight (dw), 9.8 to 113 ng/g dw, and 3.6 to 75.2 ng/g dw, respectively. Non-chlorinated OPEs predominated in terrestrial matrices, accounting for approximately 76 % of the OPE composition. Source identification indicated that OPE contamination in Antarctica likely resulted from local anthropogenic sources and LRT. Moreover, the bioaccumulation behavior of OPEs from soil to vegetation was assessed using bioconcentration factors (BCFs), revealing a significant non-linear trend of initial increase and subsequent decrease in BCFs relative to the lipophilicities of the octanol-air partition coefficient (log KOA) and octanol-water partition coefficient (log KOW). While low levels of OPEs in Antarctic terrestrial environments were reported in this study, their sustained inputs and potential ecological risks in polar regions warrant further attention.

Integration of Nontarget Screening and QSPR Models to Identify Novel Organophosphate Esters of High Priority in Aquatic Environment.

With the development of large numbers of novel organophosphate esters (OPEs) alternatives, it is imperative to screen and identify those with high priority. In this study, surface water, biofilms, and freshwater snails were collected from the flow-in rivers of Taihu Lake Basin, China. Screened by target, suspect, and nontarget analysis, 11 traditional and 14 novel OPEs were identified, of which 5 OPEs were first discovered in Taihu Lake Basin. The OPE concentrations in surface water ranged from 196 to 2568 ng/L, with the primary homologue tris(2,4-ditert-butylphenyl) phosphate (TDtBPP) being newly identified, which was likely derived from the transformation of tris(2,4-ditert-butylphenyl) phosphite. The majority of the newly identified OPEs displayed substantially higher bioaccumulation and biomagnification potentials in the biofilm-snail food chain than the traditional ones. Quantitative structure-property relationship models revealed both hydrophobicity and polarity influenced the bioaccumulation and biomagnification of the OPEs, while electrostatic attraction also had a contribution to the bioaccumulation in the biofilm. TDtBPP was determined as the utmost priority by toxicological priority index scheme, which integrated concentration, bioaccumulation, biomagnification, acute toxicity, and endocrine disrupting potential of the identified OPEs. These findings provide novel insights into the behaviors of OPEs and scientific bases for better management of high-risk pollutants in aquatic ecosystem.

Spatial variation, emissions, transport, and risk assessment of organophosphate esters in two large petrochemical complexes in southern China

Organophosphate esters (OPEs) serve as significant flame retardants and plasticizers in various petrochemical downstream products. The petrochemical industry could be a potential source of atmospheric OPEs, but their emissions from this industry are poorly understood. The present study revealed the spatial variation, emission, and atmospheric transport of traditional and novel OPEs (TOPEs and NOPEs, respectively) in atmospheric particulate matter (PM) across Hainan and Guangdong petrochemical complexes (HNPC and GDPC, respectively) in southern China. The total concentrations of TOPEs ranged from 232 to 46,002 pg/m3 and from 200 to 20,347 pg/m3 in the HNPC and GDPC, respectively, which were substantially higher than those of NOPEs (HNPC: 23.5−147 pg/m3, GDPC: 13.9−465 pg/m3). Enterprises involved in the production of downstream petrochemical products presented relatively high concentrations of OPEs, indicating evident emissions of these pollutants in the petrochemical industry. The correlations of PM-bound OPEs in the atmosphere are determined mainly by their coaddition to industrial products or their coexistence in technical mixtures. The annual emissions of TOPEs and NOPEs in the HNPC were 42.6 kg and 0.34 kg, respectively, and those in the GDPC were 116 kg and 1.85 kg, respectively. OPEs from the HNPC can reach Vietnam, Cambodia, and Guangxi Province, China, and those from the GDPC can reach Guangxi Province and Hunan Province via atmospheric transmission after 24 h of emission. The OPE concentrations reaching the receptor regions were generally less than 3.20 pg/m3. Risk assessment revealed that OPE inhalation exposure on two petrochemical complexes likely poses minor risks for people living in the study areas, but the risk resulting from two chlorinated OPEs should be noted since they are close to the threshold values. This study has implications for enhancing control measures for OPE emissions to reduce health risks related to the petrochemical industry.

Spatiotemporal distribution and transport flux of organophosphate esters in the sediment of the Yangtze River

The Yangtze River Basin is an important area for organophosphate esters (OPEs) consumption and emission. Studies proved high OPE detection in Yangtze River water, but there is limited information about the spatiotemporal distribution and transport flux of OPEs in sediment. The present study investigated 16 OPEs in sediment from upstream to mid-downstream of the Yangtze River. The mean concentration of OPEs was 84.30 ng/g, and alkyl-OPEs was the primary component. Great specific surface area and high content of organic carbon significantly increased OPE concentration in Three Gorges Reservoir (TGR) by physical adsorption and chemical bonds (p < 0.05), making TGR the most contaminated area in mainstream. No significant differences in OPE constituents were found in seasonal distribution. Four potential sources of OPEs were identified by principal component analysis and self-organizing maps, and traffic emissions were the dominant source for OPEs. The hazard quotient model results indicated that aryl-OPEs showed moderate risks in the mainstream of Yangtze River, alkyl-OPEs and Cl-OPEs showed low risks. TGR was a significant sink of OPEs in Yangtze River and buried 7.41 tons of OPEs in 2020, a total of 14.87 tons of OPE were transported into the sea by sediment.

Traditional and Novel Organophosphate Esters in Plastic Greenhouse: Occurrence, Multimedia Migration, and Exposure Risk via Vegetable Consumption.

The migration and risk of organophosphate esters (OPEs) in agricultural air-soil-plant multimedia systems due to plastic film application remain unclear. This study investigates the multimedia distribution of traditional OPEs (TOPEs), novel OPEs (NOPEs), and their transformation products (POPEs) in plastic and solar greenhouses. The total concentration of OPE-associated contaminants in air and airborne particles ranged from 594 to 1560 pg/m3 and 443 to 15600 ng/g, respectively. Significant correlations between air OPE concentrations and those in polyolefin film (P < 0.01) indicate plastic film as the primary source. Contaminants were also found in soils (96.8-9630 ng/g) and vegetables (197-7540 ng/g). The primary migration pathway for NOPEs was particle dry deposition onto the soil and leaf, followed by plant accumulation. Leaf absorption was the main uptake pathway for TOPEs and POPEs, influenced by vegetable specific leaf surface area. Moreover, total exposure to OPE-associated contaminants via vegetable intake was assessed at 2250 ng/kg bw/day for adults and 2900 ng/kg bw/day for children, with an acceptable hazard index. However, a high ecological risk was identified for NOPE compounds (median risk quotient, 975). This study provides the first evidence of the multimedia distribution and potential threat posed by OPE-associated contaminants in agricultural greenhouses.

Organophosphate ester in surface water of the Pearl River and South China Sea, China: Spatial variations and ecological risks

This study focused on investigating the concentrations, compositional profiles, partitioning behaviors and spatial variations of organophosphate esters (OPEs) in the Pearl River (PR), South China Sea (SCS) region, to evaluate their environmental risks. ∑OPEs concentrations in the surface water of the PR ranged from 117.5 to 854.8 ng/L in the dissolved phase and from 0.5 to 13.3 ng/L in the suspended particulate matter. In the surface seawaters of the northern and western parts of the SCS, ∑OPEs concentrations were 1.3–17.6 ng/L (mean: 6.7 ± 5.2) and 2.3–24.4 ng/L (mean: 7.6 ± 5.5), respectively. The percentage of chlorinated OPEs in surface water samples from the PR to the SCS was 79 ± 15%. Tripentyl phosphate (TPeP) (average: 28.3%) and triphenylphosphate (TPhP) (average: 9.6%) exhibited significant particulate fraction. A significant negative correlation (p < 0.05) between salt concentration and OPE congeners in seawater suggested that river runoff predominantly introduced OPEs into the coastal waters of the SCS. The findings also showed higher levels of OPEs in the PR and estuary than in offshore waters. The OPE loading from the PR into the SCS was estimated to be ∼119 t y−1. The presence of TCEP (RQmax = 2.1), TnBP (RQmax = 0.48) and TPhP (RQmax = 0.3) in PR water samples pose a high risk to aquatic organisms, whereas OPEs (RQ < 0.1) in SCS water samples do not pose a threat to aquatic organisms. This research emphasizes the environmental fate and impact of OPEs on surface waters of the PR and SCS.

Organophosphate esters in milk across thirteen countries from 2020 to 2023: Concentrations, sources, temporal trends and ToxPi priority to humans

Recent increases in organophosphate ester (OPE) application have led to their widespread presence, yet little is known about their temporal trends in food. This study collected milk samples from 13 countries across three continents during 2020–2023, finding detectable OPEs in all samples (range: 2.25–19.7; median: 7.06 ng/g ww). Although no statistical temporal differences were found for the total OPEs during the 4-year sampling campaign, it was interesting to observe significant variations in the decreasing trend for Cl-OPEs and concentration variations for aryl-OPEs and alkyl-OPEs (p < 0.05), indicating changing OPE use patterns. Packaged milk exhibited significant higher OPE levels than those found in directly collected raw unpackaged milk, and milk with longer shelf-life showed higher OPE levels, revealing packaging material as a contamination source. No significant geographical differences were observed in milk across countries (p > 0.05), but Shandong Province, a major OPE production site in China, showed relatively higher OPE concentrations. The Monte Carlo simulation of estimated daily intakes indicated no exposure risk from OPEs through milk consumption. The molecular docking method was used to assess human hormone binding affinity with OPEs, amongst which aryl-OPEs had the highest binding energies. The Toxicological-Priority-Index method which integrated chemical property, detection frequency, risk quotients, hazardous quotients and endocrine-disrupting effects was employed to prioritize OPEs. Aryl-OPEs showed the highest scores, deserving attention in the future.

Pollution characteristics and risk assessment of organophosphate esters (OPEs) in typical industrial parks in Southwest China.

As alternative substances of PBDEs, organophosphate esters (OPEs), an emerging organic pollutant, were increasingly produced and used in many kinds of industries and consumer products. However, OPEs also have various adverse toxic effects. Information on the pollution levels and exposure to OPEs in related industries is still limited. This study presented data on OPE contamination in the soil, leaf, and river water samples from seven typical industrial parks in Southwest China. Total concentration of seven OPEs (Σ7OPE) including tri-n-butyl phosphate (TnBP), tris-(2-ethylhexyl) phosphate (TEHP), tris-(2-butoxyethyl) phosphate (TBEP), tris-(2-carboxyethyl) phosphine (TCEP), triphenyl phosphate (TPhP), tris-(1,3-dichloro-2-propyl) ester (TDCPP), and tris-(chlorisopropyl) phosphate (TCPP) in the soil samples (36.2 ~ 219.7 ng/g) and the surrounding river water samples (118.9 ~ 287.7 ng/L) were mostly lower than those in other studies, while the Σ7OPE level in the leaves (2053.3 ~ 8152.7 ng/g) was relatively high. There were significant differences in the concentration and distribution of OPEs in the surrounding environment of different industrial parks. TDCPP, TnBP, and TCPP could be used as the characteristic compound in soil samples from auto industrial park, river samples from shoe making industrial park, and leaf samples from logistics park, respectively. The parameter m (the content ratio of chlorinated OPEs to alkyl OPEs) was suggested to distinguish the types of industrial park preliminary. When m ≥ 1, it mainly refers to heavy industries sources such as automobiles, electronics, and machinery, etc. When m<1, it mainly for the light industrial sources such as textile industry, transportation services, and resources processing, etc. For logistics park, furniture park and Wuhou comprehensive industrial park, the volatilization of materials was the main sources of OPEs in the surrounding environment, while more effort was required to strengthen the pollution control and management of the waste water and soil in the pharmacy industrial park, shoe making industrial park and auto industrial park. Risk assessment showed that there was a negligible non-cancer and carcinogenic risk in the soil, while high attention should be paid to the non-cancer risk for children.

Spatiotemporal patterns and deposition of organophosphate esters (OPEs) in air, foliage and litter in a subtropical forest of South China

Recent studies revealed the un-negligible impact of airborne organophosphate esters (OPEs) on phosphorus (P)-limited ecosystems. Subtropical forests, the global prevalence P-limited ecosystems, contain canopy structures that can effectively sequester OPEs from the atmosphere. However, little is known about the behavior and fate of OPEs in subtropical forest ecosystem, and the impact on the P cycling in this ecosystem. OPE concentrations in the understory air (at two heights), foliage, and litterfall were investigated in a subtropical forest in southern China. The median ∑OPE concentrations were 3149 and 2489 pg/m3 in the upper and bottom air, respectively. Foliage exhibited higher ∑OPE concentrations (median = 386 ng/g dry weight (dw)) compared to litter (median = 267 ng/g dw). The air OPE concentrations were ordered by broadleaved forest > mixed forest > coniferous forest, which corresponds to the results of canopy coverage or leaf area index. The spatial variation of OPEs in foliage and litter was likely caused by the leaf surface functional traits. Higher OPE concentrations were found in the wet season for understory air while in the dry season for foliage and litter, which were attributed to the changes in emission sources and meteorological conditions, respectively. The inverse temporal variation suggests the un-equilibrium partitioning of OPEs between leaf and air. The OPE concentrations during the litter-incubation presented similar temporal trends with those in foliage and litter, indicating the strong interaction of OPEs between the litter layer and the near-soil air, and the efficient buffer of litter layer played in the OPEs partitioning between soil and air. The median OPEs-associated P deposition fluxes through litterfall were 270, 186, and 249 μg P/m2·yr in the broadleaved, mixed, and coniferous forests, respectively. Although the fluxes accounted for approximately 0.2% of the total atmospheric P deposition, their significance to this P-limited ecosystem may not be negligible.

Distribution patterns and origins of organophosphate esters in soils from different climate systems on the Tibetan Plateau

Organophosphate esters (OPEs) are extensively applied in various materials as flame retardants and plasticizers, and have high biological toxicity. OPEs are detected worldwide, even in distant polar regions and the Tibetan Plateau (TP). However, few studies have been performed to evaluate the distribution patterns and origins of OPEs in different climate systems on the TP. This study investigated the distribution characteristics, possible sources, and ecological risks of OPEs in soils from the different climate systems on the TP and its surroundings. The total concentrations of OPEs in soil varied from 468 to 17,451 pg g−1 dry weight, with greater concentrations in southeast Tibet (monsoon zone), followed by Qinghai (transition zone) and, finally, southern Xingjiang (westerly zone). OPE composition profiles also differed among the three areas with tri-n-butyl phosphate dominant in the westerly zone and tris(2-butoxyethyl) phosphate dominant in the Indian monsoon zone. Correlations between different compounds and altitude, soil organic carbon, or longitude varied in different climate zones, indicating that OPE distribution originates from both long-range atmospheric transport and local emissions. Ecological risk assessment showed that tris(2-chloroethyl) phosphate and tri-phenyl phosphate exhibited medium risks in soil at several sites in southeast Tibet. Considering the sensitivity and vulnerability of TP ecosystems to anthropogenic pollutants, the ecological risks potentially caused by OPEs in this region should be further assessed.

Temporal trends of plastic additive contents in sediment cores of three French rivers (Loire, Meuse and Moselle) over the last decades

Sediment cores from three major French watersheds (Loire, Meuse and Moselle) have been dated by 137Cs and 210Pbxs from 1910 (Loire), 1947 (Meuse) and 1930 (Moselle) until the present in order to reconstruct trajectories of plastic additive contaminants including nine phthalate esters (PAEs) and seven organophosphate esters (OPEs), measured by gas chromatography–mass spectrometer (GC–MS–MS). Historical levels of ∑PAEs were higher than those of ∑OPEs in the Loire and the Moselle sediments, while ∑PAEs and ∑OPEs contents were of the same order of magnitude in the Meuse sediments. Although increases in concentrations do not evolve linearly, our results clearly indicate an increase in OPEs and PAEs concentrations from the 1950–1970 period onwards, compared with the first half of the 20th century. Our results show that, ∑OPE contents increase gradually over time in the Loire and Meuse rivers but evolve more randomly in the Moselle River. Trajectories of ∑PAEs depend on the river and no generality can be established, suggesting sedimentary reworking and/or local contamination. Data from this study allowed comparisons of contents of ∑OPEs and ∑PAEs between rivers, with ∑OPE concentrations in the Moselle River > Meuse River > Loire River, and concentrations of ∑PAEs in the Loire River > Moselle River > Meuse River. Among all PAEs, di(2-ethylhexyl) phthalate (DEHP) was the most abundant in all sediment samples, followed by diisobutyl phthalate (DiBP). Tris (2-chloroisopropyl) phosphate (TCPP) was the most abundant OPE in sediments of the three rivers. In addition, strong positive Pearson correlations were observed between organic matter (OM) parameters and OPE concentrations, and to a lesser extent, between OM parameters and PAE concentrations. This is particularly true for the Moselle River and for the Loire River, but less so for the Meuse River.