Occurrence and risk assessment of organophosphate esters in urban rivers from Piracicaba watershed (Brazil)

Photoelectrocatalytic degradation of organophosphate esters using tio2 electrodes produced from 3d-printed ti substrates

3D printed electrode substrates with novel geometries may significantly improve the efficacy of photoelectrocatalysis for degradation of recalcitrant pollutants such as organophosphate flame retardants (OPFRs). However, the 3D printed substrates often have an irregular topology that can lead to a less uniform arrangement of nanotubes following anodisation. This study investigated the effect of polishing 3D-printed Ti substrates prior to anodisation to form TiO2 nanotube array electrodes, and their subsequent applicability for photoelectrocatalytic treatment of OPFRs in water matrices. Polished and non-polished electrodes exhibited differences in morphology in terms of average roughness, (0.38 and 3.10 µm, respectively), leading to more uniform TiO2 nanotubes of the former. Water contact angle measurements revealed the non-polished electrode was super-hydrophilic and the polished electrode hydrophilic (water contact angles of 6.4˚ and 16.1˚, respectively). Despite these differences, the polished and non-polished electrodes exhibited very similar electrochemical responses. In fact, the purity and electrical conductivity of water matrices affected the photoelectrocatalytic performance more than the electrode morphology. The purified water (PW) matrix facilitated the highest degradation/removal of OPFRs, compared to tap water matrices. In particular, individual OPFR degradation levels in PW were 74% ± 9, 37% ± 10, 33% ± 9, 31% ± 11 and 3% ± 5 for triphenyl phosphate, tris(butyl) phosphate, tris(isobutyl) phosphate, tris(2-butoxyethyl) phosphate and tris(2-chloroisopropyl) phosphate, respectively. The removal of OPFRs was relative to their reactivity to hydroxyl radicals, which was higher for the aryl then alkyl straight-chain and then chlorinated compounds. This study reveals that polishing of electrode substrates is not required for the preparation of effective photoelectrocatalytic reactors to treat recalcitrant pollutants (e.g. OPFRs), Importantly, future development of novel high-profile 3D printed electrode will not be hindered by the requirement to polish the substrates prior to anodisation.

Prioritization, Identification, and Quantification of Emerging Contaminants in Recycled Textiles Using Non-Targeted and Suspect Screening Workflows by LC-ESI-HRMS

Recycled textiles are becoming widely available to consumers as manufacturers adopt circular economy principles to reduce the negative impact of garment production. Still, the quality of the source material directly impacts the final product, where the presence of harmful chemicals is of utmost concern. Here, we develop a risk-based suspect and non-targeted screening workflow for the detection, identification, and prioritization of the chemicals present in consumer-based recycled textile products after manufacture and transport. We apply the workflow to characterize 13 recycled textile products from major retail outlets in Sweden. Samples were extracted and analyzed by liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS). In positive and negative ionization mode, 20,119 LC-HRMS features were detected and screened against persistent, mobile, and toxic (PMT) as well as other textile-related chemicals. Six substances were matched with PMT substances that are regulated in the European Union (EU) with a Level 2/3 confidence. Forty-three substances were confidently matched with textile-related chemicals reported for use in Sweden. For estimating the relative priority score, aquatic toxicity and concentrations were predicted for 7416 features with tandem mass spectra (MS2) and used to rank the non-targeted features. The top 10 substances were evaluated due to elevated environmental risk linked to the recycling process and potential release at end-of-life.

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.

Occurrence of organophosphorus flame retardants in Xiangjiang River: Spatiotemporal variations, potential affecting factors, and source apportionment

The environmental occurrence of organophosphorus flame retardants (OPFRs) is receiving increasing attention. However, their distribution in the Xiangjiang River, an important tributary in the middle reaches of the Yangtze River, is still uncharacterized, and the potential factors influencing their distribution have not been adequately surveyed. In this study, the occurrence of OPFRs in the Xiangjiang River was comprehensively investigated from upstream to downstream seasonally. Fourteen OPFRs were detected in the sampling area, with a total concentration (∑OPFRs) ranging from 3.16 to 462 ng/L, among which tris(1-chloro-2-propyl) phosphate was identified as the primary pollutant (ND - 379 ng/L). Specifically, ∑OPFRs were significantly lower in the wet season than in the dry season, which may be due to the dilution effect of river flow and enhanced volatilization caused by higher water temperatures. Additionally, Changsha (during the dry season) and Zhuzhou (during the wet season) exhibited higher pollution levels than other cities. According to the Redundancy analysis, water quality parameters accounted for 35.7% of the variation in the occurrence of OPFRs, in which temperature, ammonia nitrogen content, dissolved oxygen, and chemical oxygen demand were identified as the potential influencing factors, accounting for 28.1%, 27.2%, 24.1%, and 11.5% of the total variation, respectively. The results of the Positive Matrix Factorization analysis revealed that transport and industrial emissions were the major sources of OPFRs in Xiangjiang River. In addition, there were no high-ecological risk cases for any individual OPFRs, although tris(2-ethylhexyl) phosphate and tributoxyethyl phosphate presented a low-to-medium risk level. And the results of mixture risk quotients indicated that medium-risk sites were concentrated in the Chang-Zhu-Tan region. This study enriches the global data of OPFRs pollution and contributes to the scientific management and control of pollution.

Proposal for priority emerging pollutants in the Nakdong river, Korea: Application of EU watch list mechanisms

The Nakdong River, the longest in Korea, has received numerous pollutants from heavily industrialized and densely populated areas while being used as a drinking water source. A number of research have reported occurrences of emerging pollutants (EPs) in the river. The results requested efficient monitoring and systematic management strategies such as EU watch list under Water Framework Directive. The aim of this study is to propose a watch list through preliminary monitoring of the river and risk-based prioritization approach. As candidates for monitoring target, 632 substances were selected based on literature and database searches. Among them, 175 substances were subjected to target screening method whereas 457 were evaluated via suspect screening. A risk-based prioritization was applied to substances quantified through target screening based on concentrations, and a scoring-based prioritization was applied to substances tentatively identified through suspect screening. Sampling campaigns (n = 12) were conducted from October 2020 to September 2021, at 8 sampling sites along the river. As a result, 130 target substances were quantified above the LOQ. Among the 21 substances whose priority score was assigned through risk-based prioritization, telmisartan and iprobenfos were identified with very high environmental risk while candesartan, TBEP, imidacloprid, azithromycin and clotrimazole were classified with high or intermediate risk. As result of the scoring system for 39 tentatively identified substances, 6 substances (benzophenone, caprolactam, metolachlor oxanilic acid, heptaethylene glycol, octaethylene glycol and pentaethylene glycol), which were then confirmed with reference standards, showed a potential environmental risk. Those substances prioritized through target and suspect screening followed by scoring systems can be a subset for the watch list and potential targets for nationwide water quality monitoring program in the future.

Investigating the presence of organophosphate esters in sediments from a typical fishing port agglomeration in Dalian, North China

The presence of 14 organophosphate esters (OPEs) in surface sediments from a typical fishing port agglomeration in Dalian, North China was investigated for the first time. Tris(2-ethylhexyl) phosphate (TEHP), triphenylphosphine oxide (TPPO), and tris(2-chloroethyl) phosphate (TCEP) dominated 12 detectable OPEs (∑OPEs), with concentrations ranging widely from 0.56 to 352 ng/g (dry weight basis). The ∑OPE levels in sediments varied significantly across fishing harbors of various grades, and within the same grade, highlighting uneven distribution of OPE sources and inputs to harbors. The first- and second-class fishing harbors had higher geometric mean of ∑OPE contents compared to center and natural harbors, reflecting higher OPE pollution in these areas. Although there were significant correlations among the OPE congeners with high detection frequencies, the composition patterns of sediment OPEs varied considerably among fishing ports. The sediments in the center and first-class harbors had higher abundance of non-chlorinated OPEs (non-Cl-OPEs), suggesting heterogeneity in source strength and pollution characteristics of Cl- and non-Cl-OPEs in fishing ports. The distribution of OPEs in sediments was weakly associated with sediment organic carbon, but not socioeconomic variables, indicating complex controlling factors of their distributions in port sediments. The ecological risks of sediment OPEs were evaluated, and while OPE accumulations ranged broadly (7-684 ng/cm2), exposure hazards were negligible. The sediments in first- and second-class fishing harbors, which had greater OPE accumulation, were identified as reservoirs of OPEs in port aquatic environments.

A modified QuEChERS method for determination of organophosphate esters in milk by GC-MS

Organophosphate esters (OPEs) are substances that have been detected in several matrices due to their use as flame retardants and plasticizers. Human exposure to OPEs can cause endocrine disruption, hormonal problems, and reproductive disturbance. Ingestion of contaminated food can be a significant route of exposure to OPEs. Food can be contaminated by OPEs in the food chain, during cultivation, and by contact with plasticizers during the production chain of processed foods. In this study, a method for the determination of 10 OPEs in commercial bovine milk was developed. The procedure was based on QuEChERS extraction and gas chromatography coupled to mass spectrometry (GC-MS) analysis. QuEChERS modification included a freezing-out step after the extraction followed by the concentration of the entire acetonitrile phase before the clean-up step. Calibration linearity, matrix effects, recovery, and precision were evaluated. Significant matrix effects were observed, which could be compensated by the isotopically labeled internal standard quantification and matrix-matched calibration curves. Recoveries ranged from 77 to 105%, with a relative standard deviation ranging from 3 to 38%. The method detection limits (MDLs) were in the range of 0.031-6.7 ng mL^-1, while the method quantification limits (MQLs) were within the range from 0.27 to 20 ng mL^-1. The proposed method was successfully validated and applied to determine the concentrations of OPEs in bovine milk. The 2-ethylhexyl diphenyl phosphate (EHDPHP) was detected in the analyzed milk samples but at levels below the MQL.

Dynamic variation and inhalation exposure of organophosphates esters and phthalic acid esters in face masks

The coronavirus pandemic (COVID-19) has posed a huge global health threat since December 2019. Wearing face masks is known as an effective measure for controlling the wide spread of COVID-19 and its variants. But on the other hand, face masks could be a potential source of organophosphate esters (OPEs) and phthalic acid esters (PAEs) as they are extensively added in masks. However, knowledge associated with the occurrence as well as inhalation risks of OPEs and PAEs in masks is limited. In this study, OPEs and PAEs were determined in different types of mask samples collected from the local market. OPEs and PAEs were detected in mask samples ranging from 36.7 to 855 ng/g, and from 251 to 3830 ng/g, respectively. Relatively lower OPEs and PAEs concentrations were observed in disposable mask for toddlers. Simulated inhalation experiment indicated that the mass loss of OPEs and PAEs was 136 and 3910 ng/mask in disposable masks, 71.9 and 763 ng/mask in disposable mask for toddlers, 924 and 1020 ng/mask in N95 mask after 12 h, respectively. Significantly negative correlations were exhibited between the decrement of OPEs in masks and the increment of OPEs in corresponding polyurethane foams (PUFs) during the course, elucidating OPEs released from masks could be well captured by PUFs. With regard to the variation over time, predominant OPE and PAE analogues showed semblable release and absorption tendency in mask and corresponding PUF. Inhalation exposure risk of OPEs and PAEs was estimated based on the increment of pollutants in PUF. The estimated daily intakes (EDIs), hazard index (HI) and carcinogenic risk (CR) were also calculated and they were within the threshold levels. This study provides the evidence of OPEs and PAEs releasing from the face masks during wearing and unveiled a potential source of OPEs and PAEs exposure to humans.

A New Method for Environmental Risk Assessment of Pollutants Based on Multi-Dimensional Risk Factors

Pollutant discharge causing the deterioration of the watershed environment has seriously threatened human health and ecosystem function. The importance of improving the risk warning system is becoming more and more prominent. Traditional chemical risk assessment methods focused on toxicity and the exposure of pollutants without considering the impact of persistent pollutants in different environmental media. In this study, a new approach was proposed to reflect multi-dimensional evaluation with a synthetic risk factor (SRF) of pollutants. The integrating parameters of SRF include toxicity endpoint values, environmental exposure level, persistent properties, and compartment features. Selected pesticides, perfluorinated compounds, organophosphate esters and endocrine disruptors were analyzed by the proposed and traditional methods. The results showed a higher risk outcome using SRF analysis for PFOS, imazalil, testosterone, androstenedione and bisphenol A, which were different from those obtained by the traditional method, which were consistent with existing risk management. The study demonstrated that the SRF method improved the risk assessment of various pollutants in different environmental media in a more robust fashion, and also provided a more accurate decision basis for ecological environment protection.

Occurrence, distribution, source identification, and risk assessment of organophosphate esters in the coastal waters of Beibu Gulf, South China Sea: Impacts of riverine discharge and fishery

As emerging pollutants, the environmental geochemistry of organophosphate esters (OPEs) in the coastal zone with multiple functional areas are still less recognized. This study investigated spatiotemporal distribution, sources and risks of 11 widely used OPEs in surface waters from seagoing rivers and multiple coastal functional areas of the Beibu Gulf. The results indicated that significantly higher ∑₁₁OPEs (total concentrations of 11 OPEs, ng/L) occurred in summer (34.2-1227) than in winter (20.6-840), as a result of the high emission caused by climate reasons. In general, higher ∑₁₁OPEs occurred in rivers (41.2-1227) than in the coast (34.2-809) in summer, especially in the urban rivers, while in winter, higher ∑₁₁OPEs occurred in the coast (23.4-840 vs 20.6-319 in rivers) because of obviously higher ∑₁₁OPEs in marine fishery areas (99-840). Source identification revealed that fishery activity, especially fishing vessels, and urban rivers were the main sources of OPEs in the Beibu Gulf. For the individual OPE, only tri-n-butyl phosphate (TNBP) may have ecological risks to aquatic organisms in a few sites, but if considering the additive effects, the OPEs mixtures would pose a high risk to algae and low to medium threats to crustaceans and fish.

Ecological risk assessment for organophosphate esters in the surface water from the Bohai Sea of China using multimodal species sensitivity distributions

Organophosphate esters (OPEs) as the foremost substitutes of brominated flame retardants have been ubiquitously found in the aquatic environment around the world. However, the information on the community-level risks induced by OPEs to the marine ecosystem remains scarce. This study adopted ten commonly used species sensitivity distribution (SSD) parametric statistical approaches coupled with the acute-to-chronic transformation for the toxicity data to fit the sensitivity distributions of different species to four major OPE congeners including triethyl phosphate (TEP), tri-n-butyl phosphate (TnBP), tri(2-chloroethyl) phosphate (TCEP), and tris(1-chloro-2-propyl) phosphate (TCPP) in the surface water of the Bohai Sea. All SSD models except Exponential for TnBP, TCEP, and TCPP fitted well the chronic toxicity data for the four OPE congeners. Discrepancies appeared among the best fitting models for different congeners, which also happened to the fitting results from the multiple SSD models for each congener. Based on the best fitting models, the hazard concentrations corresponding to the cumulative probability of 5% were 3.58 mg/L, 0.116 mg/L, 1.30 mg/L, and 1.44 mg/L for TEP, TnBP, TCEP, and TCPP, respectively. The risks induced by the four OPE congeners to the Bohai Sea ecosystem were negligible during the monitoring period because of both the risk quotients and the hazard indexes far <0.1. This study drew a clear picture of the joint ecological risks of TEP, TnBP, TCEP, and TCPP to the Bohai Sea environment. The application of multimodal SSD statistical methods will benefit the accurate derivation of water quality criteria and the community-level ecological risk assessment for pollutants.