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Per- and polyfluoroalkyl substances (PFAS) constitute a large class of toxic manmade compounds that have been used in many industrial and household products. Dispersion of PFAS in the environment has raised concerns because of their persistence and toxicity for living organisms. Both terrestrial and aquatic plants have been shown to take up PFAS from contaminated soil and groundwater, and to accumulate these compounds inside their tissues. Although PFAS generally exert a low toxicity on plants at environmentally relevant concentrations, they frequently impact biomass growth and photosynthetic activity at higher levels. Uptake, translocation, and toxicity of PFAS in plants have been well covered in literature. Although less attention has been given to the molecular mechanisms underlying the plant response to PFAS, recent studies based on -omics approaches indicate that PFAS affects the plant metabolism even a low concentration. The objective of this review is to summarize the current knowledge about the effects of PFAS on plants at the molecular level. Results from recent transcriptomics, proteomics, and metabolomics studies show that low levels of PFAS induce oxidative stress and affect multiple plant functions and processes, including photosynthesis and energy metabolism. These potentially harmful effects trigger activation of defense mechanisms.

Although the uptake, translocation, and toxicity of per- and polyfluoroalkyl substances (PFAS) in plants have been well covered in literature, less attention has been given to the molecular mechanisms underlying the plant response to PFAS. Using results from recent transcriptomics, proteomics, and metabolomics studies, this review article aims to summarize the current knowledge about the effects of PFAS on plants at the molecular level. Several reviews have been published on the effects of PFAS on plants, however, none have focused specifically on the molecular mechanisms of PFAS phytotoxicity.

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The objective of this study is to investigate the fate and transport of per-polyfluoroalkyl substances (PFAS) through a high-density polyethylene (HDPE) geomembrane (GM) that is commonly used in landfill composite liner systems. Tests were conducted to measure the sorption and diffusion of per-polyfluoroalkyl substances (PFAS) with varying number of carbons in chain and functional groups on HDPE GM. Perfluoroalkyl carboxyl acids (PFCAs), perfluoroalkyl sulphonic acids (PFSAs), alkyl-sulfonamidoacetic acids (FOSAAs), fluorotelomer sulfonic acids (FtSAs), alkane sulfonamides (FOSA) and ether carboxylic acids (Gen X) were investigated in this study. The partition coefficients (Kd) on HDPE GM ranged from 3.8 to 98.3 L/kg. PFAS with amide and sulfonic functional groups showed stronger sorption than that of PFAS with carboxylic acid functional groups. Molecular weight directly affected the Kd for long-chained PFAS whereas the Kd of short-chained PFAS was not sensitive to molecular weight. The diffusion coefficients (Dg) of PFCAs and PFSAs through 0.1-mm HDPE GM were found to be in the orders of 10-18 to 10-17 m2/s. The Dg decreased with increasing molar mass and were also observed to be dependent on the functional group. Dg of PFSAs was lower than that of PFCAs for similar number of carbons in the chain. The estimated mass flux for PFAS in an intact 1.5-mm HDPE GM varied from 38.7 to 2080.8 ng/m2/year whereas the estimated diffusive breakthrough time for PFAS in intact 1.5-mm HDPE was 1526 years or longer.

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Selected pharmaceutical chemicals, steroids and xenoestrogens (PCSXs) consisting of 29 endocrine modulators, therapeutic drugs, pesticides, detergents, plastics, and active ingredients in household products were measured in water, riverbed sediments and fish collected in a tributary embayment of the Potomac River (Hunting Creek, Alexandria, VA, USA) in the vicinity of wastewater discharge. A total of 17 PCSXs were found in the Hunting Creek samples, with steroid hormones (e.g., progesterone and 17α-ethinylestradiol), triclosan, dextromethorphan and bisphenol A being the most prominent micropollutants detected.The geospatial distribution of the PCSXs in Hunting Creek indicated that the steroids correlated with wastewater treatment plant discharge in all matrices, but such an association is tentative in Hunting Creek given the complex nature of urban sources of PCSXs and hydrodynamics in an urban tidal river. The sediment PCSX concentrations correlated with sediment total organic carbon content at all sampling sites. For the most part, the PCSXs showed an enrichment in fish tissue relative to sediments when concentrations were normalized to lipids and sediment organic carbon contents, but the influence of endogenous steroids is also an important consideration for these chemicals.

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The goal of this study was to develop a robust method of analyzing surface water samples for S-triazine herbicides, chloroacetanilide herbicides, and their transformation products (TPs) using solid-phase extraction (SPE) followed by liquid chromatograph-mass spectrometry (LC-MS) with electrospray ionization (ESI) by in-source collision-induced dissociation (ISCID) capability of an orthogonal electrospray ionization probe on a single quadrupole LC-MS system. The method developed here met the goals of the study and yielded estimated method detection limits (EMDLs) averaging 0.3 ± 0.1 ng L(-1) for S-triazines and their TPs and 0.7 ± 0.4 ng L(-1) for chloroacetanilides and TPs. Spiked filtered river water yielded SPE recoveries ranging from 94.2 % ± 4.8 % for S-triazines and TPs after eliminating three compounds with less that 65 % recovery from analysis and 95.9 % ± 19 % for chloroacetanilides and their TPs. The method was field-tested with filtered water samples collected from four sites over a four-month period. Detectible values of S-triazines and TPs ranged from 0.3 to 1540 ng L(-1) with a mean of 79.3 and a median of 19.4 ng L(-1). Detectible values for chloroacetanilides and TPs ranged from 0.31 to 3780 ng L(-1) with a mean of 252 and a median of 25.6 ng L(-1). An additional goal was to determine if the method was useful for microbial degradation studies using native bacterial communities. The bacteria transformed atrazine (2-chloro-4-ethylamino-6-isopropylamino-S-triazine) solely into 2-hydroxy atrazine (2-hydroxy-4-ethylamino-6-isopropylamino-S-triazine) with concentrations of 78.4, 63.3 and 32.5 ng L(-1) after 12 days of incubation compared with 6.3 and 7.1 ng L(-1) for control dark and control sunlight respectively.

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Pharmaceuticals and domestic-use chemicals (PDCs) are classes of emerging chemical contaminants thought to enter the aquatic environment primarily through wastewater treatment plant (WTP) discharges. The intent of this study was to quantify loadings of PDCs in an urban watershed. The watershed has two major branches but with wastewater discharge occurring in only one of the two major branches. Surface water from the Anacostia River (Washington, DC) was collected in base-flow and storm-flow regimes. Surface water was filtered to separate water and particles, and the PDCs were extracted from water with Oasis HLB solid-phase extraction cartridges and extracted from sediments using microwave-assisted extraction. The PDCs in the extracts were quantified using gas chromatography-mass spectrometry in the form of the trimethylsilyl ether derivatives. The most frequently detected PDC with the highest concentration was bisphenol-A in both branches of the Anacostia River watershed and the least frequently detected PDC was diclofenac. The overall median concentrations for all measured PDCs in surface water ranged from nondetectable to 54.9 ng/l. Alternatively, in the collected WTPs samples, naproxen was observed, with the highest concentration and the median concentrations in WTP effluent ranging from nondetectable to 276 ng/l. Estimates of PDC loadings for February 2006 from WTP effluent showed that <2% of the downstream load in the NE Branch was derived from WTP discharge. PDC sources other than WTP effluent appear to influence surface water concentrations in the urban Anacostia River watershed.

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We conducted a series of phosphate adsorption experiments with alumina and hematite at a range of initial P concentrations and pH values. We found that at low initial P concentration of <323 micromol/L for alumina and <194 micromol/L for hematite, phosphate adsorption showed a plateau from pH 2.5 to pH 6.5, followed by an abrupt decrease at pH 6.5-7.0. However, as initial P concentration increased, adsorption on alumina displayed a sharp maximum at pH 4.0, while adsorption on hematite exhibited a steep increase with decreased pH but did not seem to reach a maximum even at pH<3.0. Using surface complexation theory, this study proves that the adsorption maximum at pH 4.0 for alumina results from (1) phosphate being adsorbed preferentially as protonated complexes at low pH and high surface P coverage and (2) surface electric potential approaching a plateau with decreased pH due to the absence of proton-reactive but phosphate-nonreactive triply coordinated hydroxyls at transformed surfaces of Al oxides. The absence of triply coordinated surface hydroxyls at the hydrated oxide surface seems to be the reason why the adsorption maximum appears on Al oxides but not on Fe oxides.

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PAHs and PCBs were measured in river sediments along a 226 km longitudinal transect that spanned rural to urban land use settings through Valley and Ridge, Piedmont Plateau and Coastal Plain physiographic provinces in the Potomac River basin (mid-Atlantic USA). A gradient in PAH concentrations was found in river bed sediments along the upstream transect in the Potomac and Shenandoah Rivers that correlated with population densities in the nearby sub-basins. Sediment PAH concentrations halved per each approximately 40 km of transect distance upstream (i.e., the half-concentration distance) from the urban center (Washington, DC) of the Potomac River basin in direct proportion to population density. The PAH molecular composition was consistent across all geologic provinces, revealing a dominant pyrogenic source. Fluoranthene to perylene ratios served as useful markers for urban inputs, with a ratio > 2.4 observed in sediments near urban structures such as roadways, bridges and sewer outfalls. PCBs in sediments were not well correlated with population densities along the river basin transect, but the highest concentrations were found in the urban Coastal Plain region near Washington, DC and in the Shenandoah River near a known industrial Superfund site. PAHs were moderately correlated with sediment total organic carbon (TOC) in the Shenandoah River and Coastal Plain Potomac River regions, but TOC was poorly correlated with PCB concentrations throughout the entire basin. Although both PAHs and PCBs are widely recognized as urban-derived contaminants, their concentration profiles and geochemistry in river sediments were uniquely different throughout the upper Potomac River basin.

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To investigate the loadings, solid-water partitioning, transport dynamics, and sources of polychlorinated biphenyls (PCBs) in urban stormwater runoff entering into the lower tidal Anacostia River, which flows south of Washington, DC, USA, storm and base flow samples were collected in six branches. Stormwater runoff contained elevated levels of PCBs (9.82 to 211 ng/L) higher than base flow by up to 80-fold. The present study suggests that input of PCBs from Lower Beaverdam Creek is likely to be greater than those from the two major branches (Northeast and Northwest Branches) that were believed as primary source areas. PCBs in storm flow were significantly enriched in the particle phase, which accounted for more than 90% of the total PCBs. Particles were the primary vector transporting PCBs into the Anacostia River, suggesting that removal of particles in stormwater runoff using best management practices (BMPs) such as post treatment system likely decrease PCBs significantly. PCB congener patterns found in stormwater samples clearly explain stormwater runoff is a major transport pathway adding substantial amount of PCBs to the tidal Anacostia River.

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Microwave-assisted extraction (MAE) was carried out for the determination of the fungicides thiophanate methyl [1.2-alpha-(3-methoxycarbonyl-2-thioureido)benzene] and carbendazim (methyl benzimidazol-2-ylcarbamate) in vegetable samples. Two vegetable samples, cabbage and tomatoes, were fortified with the two pesticides and subjected to MAE followed by cleanup to remove co-extractives prior to analysis by high-performance liquid chromatography (HPLC). Using the selected microwave exposure time and power setting, the recoveries of carbendazim ranged from 69 to 75%. But thiophanate methyl could not be recovered as the parent compound. It was converted and recovered as carbendazim. The conversion was quantitative as confirmed by high-performance liquid chromatography-mass spectrometry (HPLC-MS).

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Oxytetracycline (OTC) is a broad-spectrum antibiotic used in livestock production. The widespread use and relative persistence of OTC may encourage development of antibiotic-resistant bacteria. The objective of this study was to determine whether composting would substantially reduce the concentration of OTC found in manure from medicated animals. The effect of OTC on composting was also investigated. Five beef calves were medicated for 5 days with 22 mg/kg/day of OTC. Approximately 23% of the OTC fed to the calves was recovered in the manure. Manure samples collected from calves prior to and after medication were mixed with straw and woodchips, and aliquots of the subsequent mixtures were treated in laboratory composters for 35 days. In addition, aliquots of the OTC-containing mixture were incubated at 25 degrees C or sterilized followed by incubation at 25 degrees C. The presence of OTC did not appear to affect composting processes. Within the first six days of composting, levels of extractable OTC in the compost mixture decreased from 115+/-8 microg/g dry weight to less than 6+/-1 microg/g dry weight (a 95% reduction). In contrast, levels of extractable OTC in room temperature incubated and sterilized mixtures decreased only 12-25% after 37 and 35 days, respectively. Levels of total heterotrophic bacteria and OTC-resistant bacteria in the finished compost mixture were roughly 30-fold higher and 10-fold lower, respectively, than levels in the mixture prior to composting. Although the basis of the OTC disappearance during composting is not known, the preponderence of OTC-sensitive bacteria and the decrease of OTC-resistant bacteria in the finished compost suggests that OTC residues have been rendered biologically inactive or unavailable.

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To investigate the sources, fate, and transport dynamics of PAHs (polycyclic aromatic hydrocarbons) in stormwater runoff that is a leading source of pollution in urban watersheds, storm and base flow samples were collected in six branches along the lower Anacostia River. PAHs in storm flow (1510-12,500 ng/L) were significantly enriched in the particle phase, which accounted for 68-97% of the total PAHs. It suggests that reducing particles in stormwater using post-treatment system would decrease PAHs considerably. The solid-water distribution coefficients (KD) of PAHs in the storm flow samples were up to 340 times higher than predicted values. A greater portion of high molecular weight PAHs and their distribution patterns indicate higher contribution of automobile originated pyrogenic PAHs. Total suspended solids in storm flow had a positive relationship with flow rates and exceeded benchmark level for the protection of aquatic biota in some samples.

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Pharmaceuticals are a class of emerging contaminants whose fate in the wastewater treatment process has received increasing attention in past years. Acidic pharmaceuticals (ibuprofen, naproxen, mefenamic acid, ketoprofen, and diclofenac), caffeine, and the antibacterial triclosan were quantified at four different steps of wastewater treatment from three urban wastewater treatment plants. The compounds were extracted from wastewater samples on Waters Oasis hydrophilic-lipophilic balance solid-phase extraction columns, silylated, and analyzed by gas chromatography-mass spectrometry. For the chemicals studied, it was found that the majority of the influent load was removed during secondary treatment (51-99%), yielding expected surface water concentrations of 13 to 56 ng/L.

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Pharmaceuticals are a class of chemicals whose fate in the environment has received increasing attention in the past few years. A quantitative method was developed for the determination of acidic pharmaceuticals (ibuprofen, naproxen, ketoprofen, mefenamic acid, and diclofenac), caffeine and the antibacterial triclosan in wastewater effluent. The compounds were extracted from wastewater samples on Waters Oasis HLB solid-phase extraction columns, derivatized with N,O-bis [Trimethylsilyl] trifluoroacetamide (BSTFA) and analyzed using gas chromatography-mass spectrometry. Estimated method detection limits ranged from 6 to 45 ng/L based on replicate analyses (n = 10). This method was applied to the analysis of effluent from a wastewater treatment plant and compounds were detected at concentrations of 18-72 ng/L.

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Microwave-assisted extraction (MAE) was carried out for the simultaneous determination of the insecticides thiamethoxam [(EZ)-3-(2-chloro-1,3-thiazol-5-ylmethyl)-5-methyl-1,3,5-oxadiazinan-4-ylidene(nitro)amine], imidacloprid [1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine], and the fungicide carbendazim (methyl benzimidazol-2-ylcarbamate) in vegetable samples. Five crop samples consisting of cabbage, tomatoes, chilies, potatoes, and peppers were fortified with the three pesticides and subjected to MAE followed by cleanup to remove coextractives prior to analysis by high-performance liquid chromatography. Using the selected microwave exposure time and power setting, the recoveries of the three pesticides from the fortified vegetable samples ranged from 68.1 to 106%. The corresponding recoveries for samples processed simultaneously but without microwave exposure ranged from 37.2 to 61.4%. The recoveries by MAE were comparable to those obtained by the conventional blender extraction technique. The precision of the MAE method was demonstrated by relative standard deviations of <7% for the three pesticides. The cooked cabbage and tomato samples showed no breakdown of the parent compounds, and the recoveries of three pesticides were comparable to those obtained with the uncooked samples.

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Concentrations of current-use pesticides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine (OC) insecticides were determined above the reach of tide in the Chesterville Branch and Nanticoke River on the eastern shore of Chesapeake Bay during base-flow and storm-flow hydrologic regimes to evaluate mass transport to Chesapeake Bay. The two rivers monitored showed relatively high concentrations of atrazine, simazine, alachlor, and metolachlor in comparison to previously investigated western shore tributaries, and reflected the predominant agricultural land use in the eastern shore watersheds. The four current use pesticides showed the greatest seasonal contribution to annual loadings to tidal waters of Chesapeake Bay from the two rivers, and the relative order of annual loadings for the other contaminant classes was PAHs > PCBs > OC insecticides. Annual loadings normalized to the landscape areas of selected Chesapeake Bay watersheds showed correlations to identifiable source areas, with the highest pesticide yields (g/km2/yr) occurring in eastern shore agricultural landscapes, and the highest PAH yields derived from urban regions.

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The method describes a rapid and accurate procedure for the analysis of ethyl carbamate in wines. The separation of the ethyl carbamate (EC), the target analyte, from alcohol and the sample matrix is a challenge to many analytical chemists. After alcohol removal from the sample, EC was extracted and concentrated by solid-phase extraction. For analysis of EC, large-volume injection on a programmable temperature vaporization (PTV) inlet was used followed by multidimensional gas chromatography/mass spectrometry (MDGC/MS) using electron-impact ionization (EI). For quantitation, the ratio of ions produced during EI at m/z 62 (EC) and 64 (isotopically labeled EC) was monitored. The use of solid-phase extraction and MDGC/MS removes the majority of the matrix interference encountered in other methods. A linear dynamic range was established from 0.387 to 1160 ng/mL, with a limit of detection at 0.1 ng/mL and limit of quantitation at 1 ng/mL.

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White and black "niebe" beans [Vigna unguiculata (L.) Walp] from Senegal were treated with fenitrothion (O,O-dimethyl O-4-nitro-m-tolyl phosphorothioate), and the residues were determined by high-performance liquid chromatography (HPLC) and electron capture gas chromatography (EC-GC). Fenitrothion residues from the beans were extracted by Soxhlet extraction (SE) and microwave-assisted extraction (MAE). A column cleanup procedure was used to remove the coextractives in the extract before HPLC and EC-GC analyses. The overall mean recoveries of fenitrothion residues in the 0.19-1.90 microg/kg fortification range determined from extracts obtained by SE and MAE were 88.4 and 89.8%, respectively, with respective relative standard deviations of <4%. The results show that MAE is a viable alternative to the commonly used SE for the determination of fenitrothion residues in beans.

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Twelve suspected former secondary lead smelting sites were investigated. Ten of the sites were confirmed to be former secondary lead smelters or lead works by historical fire insurance maps and contemporaneous metal industry trade directories. At eight sites sampled, the ratio Sb:Pb was closer to ratios from 10 known lead smelting sites than were the As:Pb and Cd:Pb ratios. Data from the 10 known lead smelting sites showed that the Sb:Pb ratio is most characteristic of secondary lead smelting sites. This is because the primary alloy smelted at such sites is antimonial lead. Lead contamination at the eight sites investigated here can be attributed At least in part to the former smelters because of the association between Sb and Pb.

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