Atmospheric chemical reactions of alternatives of polybrominated diphenyl ethers initiated by OH: A case study on triphenyl phosphate

Mechanism of interaction between ascorbic acid and soil iron-containing minerals for peroxydisulfate activation and organophosphorus flame retardant degradation

Soil constituents may play an important role in peroxydisulfate (PDS)-based oxidation of organic contaminants in soil. Iron-containing minerals (Fe-minerals) have been found to promote PDS activation for organics degradation. Our study found that ascorbic acid (H2A) could enhance PDS activation by soil Fe-minerals for triphenyl phosphate (TPHP) degradation. Determination and characterization analyses of Fe fractions showed that H2A could induce the reductive dissolution of solid Fe-minerals and the increasing of oxygen vacancies/hydroxyl groups content on Fe-minerals surface. The increasing of divalent Fe (Fe(II)) accelerated PDS activation to generate reactive oxygen species (ROS). Electron paramagnetic resonance (EPR) and quenching studies showed that sulfate radicals (SO4•-) and hydroxyl radicals (HO•) contributed significantly to TPHP degradation. The composition and content of Fe-minerals and soil organic matter (SOM) markedly influenced ROS transformations. Surface-bond and structural Fe played the main role in the production of Fe(II) in reaction system. The high-concentration SOM could result in ROS consumption and degradation inhibition. Density functional theory (DFT) studies revealed that H2A is preferentially adsorbed at α-Fe2O3(012) surface through Fe-O-C bridges rather than hydrogen bonds. After absorption, H atoms on H2A may further be migrated to adjacent O atoms on the α-Fe2O3(012) surface. With the transformation of H atoms to the α-Fe2O3(012) surface, the Fe-O-C bridge is broken and one electron is transferred from the O to Fe atom, inducing the reduction of trivalent Fe (Fe(III)) atom. MS/MS2 analysis, HPLC analysis, and toxicity assessment demonstrated that TPHP was transformed to less toxic 4-hydroxyphenyl diphenyl phosphate (OH-TPHP), diphenyl hydrogen phosphate (DPHP), and phenyl phosphate (PHP) through phenol-cleavage and hydroxylation processes, and even be mineralized in reaction system.

Upregulation of oxidative stress by triphenyl phosphate (TPhP) exposure causes antioxidant insult and apoptotic process in Epithelioma papulosum cyprini (EPC) cells

Triphenyl phosphate (TPhP) is the predominant compound of organophosphate flame retardants (OPFRs), which can elicit a toxicological effect on physiological response and tissue development of fish. In this study, we investigated the effect of TPhP exposure on cell viability, antioxidant capacities, and apoptosis in EPC cells. Current study revealed that TPhP exposure could decrease cell viability and promote intracellular oxidative stress in EPC cells. In addition, high-dose TPhP exposure could facilitate antioxidant insults and cause mitochondrial collapse in a dose-dependent manner, along with increased gene expressions involved in apoptosis and unfolded protein response (UPR). These results indicated that reactive oxygen species (ROS)-induced cytotoxic stress and cell death were involved in antioxidant insults and apoptotic activation in TPhP-exposed fish cells.

An overlooked oxidation mechanism of toluene: computational predictions and experimental validations

Secondary organic aerosols (SOAs) influence the Earth's climate and threaten human health. Aromatic hydrocarbons (AHs) are major precursors for SOA formation in the urban atmosphere. However, the revealed oxidation mechanism dramatically underestimates the contribution of AHs to SOA formation, strongly suggesting the importance of seeking additional oxidation pathways for SOA formation. Using toluene, the most abundant AHs, as a model system and the combination of quantum chemical method and field observations based on advanced mass spectrometry, we herein demonstrate that the second-generation oxidation of AHs can form novel epoxides (TEPOX) with high yield. Such TEPOX can further react with H2SO4 or HNO3 in the aerosol phase to form less-volatile compounds including novel non-aromatic and ring-retaining organosulfates or organonitrates through reactive uptakes, providing new candidates of AH-derived organosulfates or organonitrates for future ambient observation. With the newly revealed mechanism, the chemistry-aerosol box modeling revealed that the SOA yield of toluene oxidation can reach up to 0.35, much higher than 0.088 based on the original mechanism under the conditions of pH = 2 and 0.1 ppbv NO. This study opens a route for the formation of reactive uptake SOA precursors from AHs and significantly fills the current knowledge gap for SOA formation in the urban atmosphere.

The aomogeneous and heterogeneous oxidation of organophosphate esters (OPEs) in the atmosphere: Take diphenyl phosphate (DPhP) as an example

Organophosphate esters (OPEs) are widely detected in the atmosphere. However, the atmospheric oxidative degradation mechanism of OPEs has not been closely examined. This work took density functional theory (DFT) to investigate the tropospheric ozonolysis of organophosphates, represented by diphenyl phosphate (DPhP), including adsorption mechanisms on the surface of titanium dioxide (TiO₂) mineral aerosols and oxidation reaction of hydroxyl groups (·OH) after photolysis. Besides, the reaction mechanism, reaction kinetics, adsorption mechanism, and ecotoxicity evaluation of the transformation products were also studied. At 298 K, the total reaction rate constants k_O3, k_OH, k_TiO2-O3, and k_TiO2-OH are 5.72 × 10^-15 cm³ molecule^-1 s^-1, 1.68 × 10^-13 cm³ molecule^-1 s^-1, 1.91 × 10^-23 cm³ molecule^-1 s^-1, and 2.30 × 10^-10 cm³ molecule^-1 s^-1. The atmospheric lifetime of DPhP ozonolysis in the near-surface troposphere is 4 min, much lower than that of hydroxyl radicals (·OH). Besides, the lower the altitude is, the stronger the oxidation is. The TiO₂ clusters carry DPhP promoting ·OH oxidation but inhibiting ozonolysis of DPhP. Finally, the main transformation products of this process are glyoxal, malealdehyde, aromatic aldehydes, etc., which are still ecotoxic. The findings shed new light on the atmospheric governance of OPEs.

Regional Distribution of Atmospheric Organophosphate Tri-/Diesters in the Pearl River Delta: Possible Emission, Photo-degradation, and Atmospheric Transportation

The regional characteristics of atmospheric organophosphate triesters (OPEs) and organophosphate diesters (Di-OPs) in the Pearl River Delta (PRD) were investigated by passive air samplers mounting quartz fiber filters. The analytes were found on a regional scale. Atmospheric OPEs, semi-quantified using sampling rates of particulate-bonded PAHs, were in the range of 537-2852 pg/m³ in spring and in the range of 106-2055 pg/m³ in summer, with tris(2-chloroethyl)phosphate (TCEP) and tris(2-chloroisopropyl)phosphate as the main components. While atmospheric Di-OPs were semi-quantified using sampling rates of SO₄^2-, in the range of 22.5-5576 pg/m³ in spring and in the range of 66.9-1019 pg/m³ in summer, with di-n-butyl phosphate and diphenyl phosphate (DPHP) being the main Di-OPs. Our results indicated that OPEs were mainly distributed in the central part of the region, which might be ascribed to the distribution of industry related to OPE-containing products. In contrast, Di-OPs were scattered in the PRD, suggesting local emission from their direct industrial application. Significantly lower levels of TCEP, triphenyl phosphate (TPHP), and DPHP were detected in summer than in spring, implying that these compounds might be partitioned off particles as the temperature increased and due to possible photo-transformation of TPHP and DPHP. The results also suggested the long-distance atmospheric transportation potential of Di-OPs.

Organophosphite Antioxidants and Novel Organophosphate Esters in Dust from China: Large-Scale Distribution and Heterogeneous Phototransformation

A large-scale survey was conducted by measuring five organophosphite antioxidants (OPAs) and three novel organophosphate esters (NOPEs) in 139 dust samples across China. The median summed concentrations of OPAs and NOPEs in outdoor dust were 33.8 ng/g (range: 0.12-53,400 ng/g) and 7990 ng/g (2390-27,600 ng/g), respectively. The dust concentrations of OPAs associated with the increasing economic development and population density from western to eastern China, whereas the NOPE concentration in Northeast China (median, 11,900 ng/g; range, 4360-16,400 ng/g) was the highest. Geographically, the distribution of NOPEs was significantly associated with annual sunshine duration and precipitation at each sampling site. Results of laboratory experiments further revealed that the simulated sunlight irradiation promoted the heterogeneous phototransformation of OPAs in dust, and this process was accelerated with the existence of reactive oxygen species and enhanced relative humidity. Importantly, during this phototransformation, the hydroxylated, hydrolyzed, dealkylated, and methylated products, e.g., bis(2,4-di-tert-butylphenyl) methyl phosphate, were identified by nontargeted analysis, part of which were estimated to be more toxic than their parent compounds. The heterogeneous phototransformation pathway of OPAs was suggested accordingly. For the first time, the large-scale distribution of OPAs and NOPEs and the phototransformation of these "new chemicals" in dust were revealed.

Biochar-goethite composites inhibited/enhanced degradation of triphenyl phosphate by activating persulfate: Insights on the mechanism

In this study, the biochar-goethite composites (MBC@FH) were synthesized through co-ball milling and the degradation of triphenyl phosphate (TPhP) was compared in persulfate (PDS) alone system and MBC@FH&PDS systems. The results showed that TPhP can be effectively degraded in PDS alone system and degradation efficiency reached up to 90 % within reaction of 8 h, at a PDS concentration of 10 mM, a reaction temperature of 30 °C and a system pH of 6.12. The obvious degradation can be ascribed to the reactive oxygen species (ROS) generated by self-decompose of PDS, among which ¹O₂, ∙OH and O₂∙^- play a major role in the degradation process. Although 350 °C biochar-goethite composites (MBC35@FH) and 800 °C biochar-goethite composites (MBC80@FH) facilitated PDS activation to produce more ROS, the catalytic degradation of TPhP was different in their systems. The degradation of TPhP was inhibited by MBC35@FH due to its stronger adsorption for TPhP, while MBC80@FH promoted TPhP degradation and degradation efficiency was up to 100 % within 6 h. ¹O₂ and SO₄∙^- played a stronger degradation role than ∙OH and O₂∙^- in above systems. The transformation of Fe species, functional groups (oxygen-containing functional groups, pyrrolic nitrogen) and persistent free radicals (PFRs) on the MBC@FH were involved in the PDS activation to produce ROS. Furthermore, MBC80@FH was more capable of activating PDS than MBC35@FH due to its abundant defect sites, larger specific surface area, more PFRs, higher Fe content and stronger electron transfer capability. In addition, seven possible TPhP intermediates were identified and possible degradation pathways of TPhP were proposed accordingly. This study illustrated that not all metallic carbon catalysts are necessarily beneficial for organic contaminants degradation.

Atmospheric Chemistry of Allylic Radicals from Isoprene: A Successive Cyclization-Driven Autoxidation Mechanism

The atmospheric chemistry of isoprene has broad implications for regional air quality and the global climate. Allylic radicals, taking 13-17% yield in the isoprene oxidation by ^•Cl, can contribute as much as 3.6-4.9% to all possible formed intermediates in local regions at daytime. Considering the large quantity of isoprene emission, the chemistry of the allylic radicals is therefore highly desirable. Here, we investigated the atmospheric oxidation mechanism of the allylic radicals using quantum chemical calculations and kinetics modeling. The results indicate that the allylic radicals can barrierlessly combine with O₂ to form peroxy radicals (RO₂^•). Under ≤100 ppt NO and ≤50 ppt HO₂^• conditions, the formed RO₂^• mainly undergo two times "successive cyclization and O₂ addition" to finally form the product fragments 2-alkoxy-acetaldehyde (C₂H₃O₂^•) and 3-hydroperoxy-2-oxopropanal (C₃H₄O₄). The presented reaction illustrates a novel successive cyclization-driven autoxidation mechanism. The formed 3-hydroperoxy-2-oxopropanal product is a new isomer of the atmospheric C₃H₄O₄ family and a potential aqueous-phase secondary organic aerosol precursor. Under >100 ppt NO condition, NO can mediate the cyclization-driven autoxidation process to form C₅H₇NO₃, C₅H₇NO₇, and alkoxy radical-related products. The proposed novel autoxidation mechanism advances our current understanding of the atmospheric chemistry of both isoprene and RO₂^•.

Tris(2,4-di-tert-butylphenyl)phosphate: An Unexpected Abundant Toxic Pollutant Found in PM2.5

A novel pollutant, tris(2,4-di-tert-butylphenyl)phosphate (I168O), was identified in urban fine particulate matter (PM_2.5) samples in a nontargeted screening based on mass spectrometry for the first time. I168O was detected in all samples collected from two typical cities far away from each other in China. The concentrations of I168O reached up to 851 (median: 153) ng/m³, indicating that it was a widespread and abundant pollutant in the air. The antioxidant Irgafos 168 [I168, tris(2,4-di-tert-butylphenyl)phosphite] popularly added in plastics was the most suspected source for the detected I168O. Simulation studies indicated that heating, UV radiation, and water contact might significantly (p < 0.05) transform I168 to I168O. In particular, I168O might be magnificently evaporated into the air at high temperatures. The outdoor inhalation exposure of I168O may exert substantial health risks.

Formation of Low-Volatile Products and Unexpected High Formaldehyde Yield from the Atmospheric Oxidation of Methylsiloxanes

With stricter regulation of atmospheric volatile organic compounds (VOCs) originating from fossil fuel-based vehicles and industries, the use of volatile chemical products (VCPs) and the transformation mechanism of VCPs have become increasingly important to quantify air quality. Volatile methylsiloxanes (VMS) are an important class of VCPs and high-production chemicals. Using quantum chemical calculations and kinetics modeling, we investigated the reaction mechanism of peroxy radicals of VMS, which are key intermediates in determining the atmospheric chemistry of VMS. L2-RSiCH₂O₂^• and D3-RSiCH₂O₂^• derived from hexamethyldisiloxane and hexamethylcyclotrisiloxane, respectively, were selected as representative model systems. The results indicated that L2-RSiCH₂O₂^• and D3-RSiCH₂O₂^• follow a novel Si-C-O rearrangement-driven autoxidation mechanism, leading to the formation of low volatile silanols and high yield of formaldehyde at low NO/HO₂^• conditions. At high NO/HO₂^• conditions, L2-RSiCH₂O₂^• and D3-RSiCH₂O₂^• react with NO/HO₂^• to form organic nitrate, hydroperoxide, and active alkoxy radicals. The alkoxy radicals further follow a Si-C-O rearrangement step to finally form formate esters. The novel Si-C-O rearrangement mechanism of both peroxy and alkoxy radicals are supported by available experimental studies on the oxidation of VMS. Notably, the high yield of formaldehyde is estimated to significantly contribute to formaldehyde pollution in the indoor environment, especially during indoor cleaning.

Experimental Study of OH-Initiated Heterogeneous Oxidation of Organophosphate Flame Retardants: Kinetics, Mechanism, and Toxicity

The environmental risks and health impacts associated with particulate organophosphate flame retardants (OPFRs), which are ubiquitous in the global atmosphere, have not been adequately assessed due to the lack of data on the reaction kinetics, products, and toxicity associated with their atmospheric transformations. Here, the importance of such transformations for OPFRs are explored by investigating the reaction kinetics, degradation chemical mechanisms, and toxicological evolution of two OPFRs (2-ethylhexyl diphenyl phosphate (EHDP) and diphenyl phosphate (DPhP)) coated on (NH₄)₂SO₄ particles upon heterogeneous OH oxidation. The derived reaction rate constants for the heterogeneous loss of EHDP and DPhP are (1.12 ± 0.22) × 10^-12 and (2.33 ± 0.14) × 10^-12 cm³ molecules^-1 s^-1, respectively. Using recently developed real-time particle chemical composition measurements, particulate products from heterogeneous photooxidation and the associated degradation mechanisms for particulate OPFRs are reported for the first time. Subsequent cytotoxicity analysis of the unreacted and oxidized OPFR particles indicated that the overall particle cytotoxicity was reduced by up to 94% with heterogeneous photooxidation, likely due to a significantly lower cytotoxicity associated with the oxidized OPFR products relative to the parent OPFRs. The present work not only provides guidance for future field sampling for the detection of transformation products of OPFRs, but also strongly supports the ongoing risk assessment of these emerging chemicals and most critically, their products.

Mechanism and predictive model development of reaction rate constants for N-center radicals with O2

Atmospheric oxidation of NH_x-containing (x = 1, 2) compounds can produce N-center radicals, a precursor of toxic nitrosamines. The reaction rate constant (k_O2) with O₂ has been considered as an important parameter to determine the nitrosamines yield in the subsequent reactions of N-center radicals. However, available k_O2 values of N-center radicals are limited. Here, a three-step scheme including mechanistic analysis and kinetics calculation of the reactions of 28 various N-center radicals with O₂, and model development was taken to solve the k_O2 data shortage. Mainly employed tools include highly cost-expensive coupled-cluster theory (CCSD(T)), kinetic model and statistics. The results indicate that the direct H-abstraction pathway is the most favorable for the reactions of all considered N-center radicals with O₂. The specific molecular conformation and the C-H bond energy of the N-center radicals are two important factors to determine k_O2 values. Based on the mechanistic understanding of k_O2 values, a quantitative structure-activity relationship (QSAR) model of k_O2 values was developed. The model has satisfactory goodness-of-fit, robustness and predictive ability. The determined k_O2 values and the in silico methods provide a scientific base for assessing formation risk of toxic nitrosamines in the atmosphere.

Understanding the Impact of Relative Humidity and Coexisting Soluble Iron on the OH-Initiated Heterogeneous Oxidation of Organophosphate Flame Retardants

The current uncertainties in the reactivity and atmospheric persistence of particle-associated chemicals present a challenge for the prediction of long-range transport and deposition of emerging chemicals such as organophosphate flame retardants, which are ubiquitous in the global environment. Here, the OH-initiated heterogeneous oxidation kinetics of organophosphate flame retardants (OPFRs) coated on inert (NH₄)₂SO₄ and redox-active FeSO₄ particles were systematically determined as a function of relative humidity (RH). The derived reaction rate constants for the heterogeneous loss of tricresyl phosphate (TCP; k_TCP) and tris(2-butoxyethyl) phosphate (TBEP; k_TBEP) were in the range of (2.69-3.57) × 10^-12 and (3.06-5.55) × 10^-12 cm³ molecules^-1 s^-1, respectively, depending on the RH and coexisting Fe(II) content. The k_TCP (coated on (NH₄)₂SO₄) was relatively constant over the investigated RH range while k_TBEP was enhanced by up to 19% with increasing RH. For both OPFRs, the presence of Fe(II) enhanced their k by up to 53% over inert (NH₄)₂SO₄. These enhancement effects (RH and Fe(II)) were attributed to fundamental changes in the organic phase state (higher RH lowered particle viscosity) and Fenton-type chemistry which resulted in the formation of reactive oxygen species, respectively. Such findings serve to emphasize the importance of ambient RH, the phase state of particle-bound organics in general, and the presence of coexisting metallic species for an accurate description of the degradation kinetics and aging of particulate OPFRs in models used to evaluate their atmospheric persistence.

The mechanism and rate constants for oxidation of indenyl radical C9H7 with molecular oxygen O2: a theoretical study

A theoretical study reveals the reaction mechanism of oxidation of the indenyl radical with molecular oxygen forming predominantly 1-H-inden-1-one + H under combustion conditions.

Atmospheric Oxidation of Piperazine Initiated by ·Cl: Unexpected High Nitrosamine Yield

Chlorine radicals (·Cl) initiated amine oxidation plays an important role for the formation of carcinogenic nitrosamine in the atmosphere. Piperazine (PZ) is considered as a potential atmospheric pollutant since it is an alternative solvent to monoethanolamine (MEA), a benchmark solvent in a leading CO₂ capture technology. Here, we employed quantum chemical methods and kinetics modeling to investigate ·Cl-initiated atmospheric oxidation of PZ, particularly concerning the potential of PZ to form nitrosamine compared to MEA. Results showed that the ·Cl-initiated PZ reaction exclusively leads to N-center radicals (PZ-N) that mainly react with NO to produce nitrosamine in their further reaction with O₂/NO. Together with the PZ + ·OH reaction, the PZ-N yield from PZ oxidation is still lower than that of the corresponding MEA reactions. However, the nitrosamine yield of PZ is higher than the reported value for MEA when [NO] is <5 ppb, a concentration commonly encountered in a polluted urban atmosphere. The unexpected high nitrosamine yield from PZ compared to MEA results from a more favorable reaction of N-center radicals with NO compared to O₂. These findings show that the yield of N-center radicals cannot directly be used as a metric for the yield of the corresponding carcinogenic nitrosamine.

Aqueous OH Radical Reaction Rate Constants for Organophosphorus Flame Retardants and Plasticizers: Experimental and Modeling Studies

Aqueous ·OH reaction rate constants ( k_OH) for organophosphate esters (OPEs) are essential for assessing their environmental fate and removal potential in advanced oxidation processes (AOPs). Herein experimental and in silico approaches were adopted to obtain k_OH values for a variety of OPEs. The determined k_OH for 18 OPEs varies from 4.0 × 10⁸ M^-1 s^-1 to 1.6 × 10¹⁰ M^-1 s^-1. Based on the experimental k_OH values, a quantitative structure-activity relationship model that involves molecular structural information on the number of heavy atoms, content index, and the most negative charge of C atoms was developed for predicting k_OH of other OPEs. Furthermore, appropriate density functional theory (DFT) and solvation models were selected, which together with transition state theory were employed to predict k_OH of three representative OPEs. The deviation between the DFT calculated and the experimental k_OH values ( k_cal/ k_exp) is within 2. Half-lives of the OPEs were estimated to be 0.5-22791.3 days in natural waters and 0.044-19.7 s in AOPs, indicating the OPEs are potentially persistent in natural waters and can be quickly eliminated by AOPs. The determined k_OH values and the in silico methods offer a scientific base for assessing OPEs fate in aquatic environments.

The growth mechanism of polycyclic aromatic hydrocarbons from the reactions of anthracene and phenanthrene with cyclopentadienyl and indenyl

Polycyclic aromatic hydrocarbons (PAHs) are highly toxic, mutagenic and/or carcinogenic to humans. To reduce the emission of PAHs, it's significant and indispensable to explore the PAH formation mechanism. In the present work, the growth mechanism of PAHs from the reactions of anthracene and phenanthrene with cyclopentadienyl and indenyl radicals was investigated with the aid of high-accuracy quantum chemistry calculation. The rate constants of key elementary steps were calculated by meaning of the canonical variation transition-state (CVT) theory with the small curvature tunneling (SCT) correction over the temperature range of 400-1400 K. The mechanism of the PAH formation involves in six elementary steps, addition reaction, ring closure, intramolecular H-shift, cleavage of CC bond, intramolecular H-shift and unimolecular elimination of CH₃ or H. The cleavage of CC bond is the rate-determining step due to the high barrier. The formation of PAHs from the reactions of anthracene with cyclopentadienyl and indenyl radicals is easier than that from the reactions of phenanthrene.

Effects of Atmospheric Water on ·OH-initiated Oxidation of Organophosphate Flame Retardants: A DFT Investigation on TCPP

Tris(2-chloroisopropyl) phosphate (TCPP), a widely used organophosphate flame retardant, has been recognized as an important atmospheric pollutant. It is notable that TCPP has potential for long-range atmospheric transport. However, its atmospheric fate is unknown, restricting its environmental risk assessment. Herein we performed quantum chemical calculations to investigate the atmospheric transformation mechanisms and kinetics of TCPP initiated by ·OH in the presence of O₂/NO/NO₂, and the effects of ubiquitous water on these reactions. Results show the H-abstraction pathways are the most favorable for the titled reaction. The calculated gaseous rate constant and lifetime at 298 K are 1.7 × 10^-10 cm³molecule^-1 s^-1 and 1.7 h, respectively. However, when considering atmospheric water, the corresponding lifetime is about 0.5-20.2 days. This study reveals for the first time that water has a negative role in the ·OH-initiated degradation of TCPP by modifying the stabilities of prereactive complexes and transition states via forming hydrogen bonds, which unveils one underlying mechanism for the observed persistence of TCPP in the atmosphere. Water also influences secondary reaction pathways of selected TCPP radicals formed from the primary H-abstraction. These results demonstrate the importance of water in the evaluation of the atmospheric fate of newly synthesized chemicals and emerging pollutants.

Integrated Framework for Identifying Toxic Transformation Products in Complex Environmental Mixtures

Complex environmental mixtures consist of hundreds to thousands of unknown and unregulated organic compounds that may have toxicological relevance, including transformation products (TPs) of anthropogenic organic pollutants. Non-targeted analysis and suspect screening analysis offer analytical approaches for potentially identifying these toxic transformation products. However, additional tools and strategies are needed in order to reduce the number of chemicals of interest and focus analytical efforts on chemicals that may pose risks to humans and the environment. This brief review highlights recent developments in this field and suggests an integrated framework that incorporates complementary instrumental techniques, computational chemistry, and toxicity analysis, for prioritizing and identifying toxic TPs in the environment.