Understanding the sorption behavior of per- and poly-fluoroalkyl substances (PFAS) in soils are essential for assessing their mobility and risk in the environment. Heavy metals often coexist with PFAS depending on the source and history of contamination. In this study, we investigated the effect of heavy metal co-contaminants (Pb2+, Cu2+ and Zn2+) on the sorption of 13 anionic PFAS with different perfluorocarbon chain length (C3-C9) in two soils with different properties. Results revealed that Pb2+, Cu2+ and Zn2+ had little effect on the sorption of most short-chain compounds, while the presence of these heavy metals enhanced the sorption of long-chain PFAS in two soils. The distribution coefficients (Kd) of several long-chain PFAS linearly increased with increasing concentrations of heavy metal, especially in the presence of Pb2+ (ΔKd/Δ [Pb2+] > 3 for PFOS and PFNA vs <1 for PFPeS and PFHxS). While several mechanisms may have contributed to the enhancement of sorption of PFAS, the heavy metals most likely contributed through enhanced hydrophobic interactions of PFAS by neutralizing the negative charge of adsorption surfaces in soils and thus making it more favorable for their partitioning onto the solid phase. Moreover, the increase in the concentrations of heavy metals led to a decrease in the pH of the system and promoted sorption of long-chain compounds, especially in soil with lower organic carbon content. Overall, this study provides evidence that the presence of co-existing heavy metal cations in soils can significantly enhance the sorption of long-chain PFAS onto soil, thereby potentially limiting their mobility in the environment.

Historical use of aqueous film forming foams (AFFF) containing per- and poly-fluoroalkyl substances (PFAS) for fire-fighting activities has contributed to widespread contamination of infrastructure which can represent an ongoing source of PFAS to the surrounding environment. A concrete fire training pad with historical use of Ansulite and Lightwater AFFF formulations had PFAS concentrations measured to quantify spatial variability of PFAS within the pad. Surface chips and whole cores of concrete through to the underlying aggregate base were collected over the 24 × 9 m concrete pad and depth profiles of PFAS concentrations in nine cores were analysed. PFOS and PFHxS dominated the PFAS for surface samples, along the depth profile of cores and in the underlying plastic and aggregate material, with substantial variability in the concentrations of PFAS in the samples. Although there was variability of individual PFAS along the depth profile, higher surface concentrations of PFAS generally followed the designed movement of water across the pad. Total oxidisable precursor (TOP) assessments of one core indicated additional PFAS were present along the entire length of the core. This study highlights concentrations of PFAS (up to low μg/kg) from historical use of AFFF can occur throughout concrete, with the variable concentrations throughout the profile.

Spills of hydraulic fracturing (HF) fluids and of produced water during unconventional gas extraction operations may cause soil contamination. We studied the degradation and microbial toxicity of selected HF chemical components including two biocides (methylisothiozolinone- MIT, chloromethylisothiozolinone- CMIT), a gel-breaker aid (triethanolamine -TEA), and three geogenic chemicals (phenol, m-cresol and p-cresol) in ultrapure water, HF fluid and produced water in five different soil types (surface and subsurface soils). The degradation of the two biocides (in soils treated with HF fluid or ultrapure water) and of the three geogenic chemicals (in soils treated with produced water) was rapid (in all cases DT50 values < 2 days in surface soils). In contrast, the loss of TEA was much slower in soils, especially in those treated with HF fluid (DT50 > 30 days). Sorption coefficients (Koc in L/Kg) in these soils ranged from 71 to 733 for TEA, 64-408 for MIT and 11-72 for CMIT. In terms of soil microbial toxicity, exposure to HF fluid and produced water reduced microbial respiration, albeit temporarily. The overall microbial activities in surface soils contaminated with produced water had fully recovered in most soils. In contrast, the HF fluid addition to soils completely inhibited the nitrification in all soils, with little recovery over the 60 day experimental period. In the case of produced water exposure, three out of five surface soils showed complete recovery in nitrification during the study period. The functional genes for nitrogen fixation (nifH) and carbon cycling (GA1) and microbial community composition (16 S rRNA) were significantly affected by HF fluid in some soils. Overall, the study shows that the HF fluid can have significant detrimental impact on soil microbial functions, especially on nitrogen cycling. More work is needed to identify the exact cause of microbial toxicity in soils contaminated with HF fluid.

The effect of soluble cations on sorption in soils of a range of anionic PFAS is not well studied. We investigated the role of three common cations (Na+, Ca2+, and Mg2+) at varying solution concentrations on the sorption coefficients (K-d) of 18 anionic PFAS in two contrasting soils. The effective charge of the soil suspension (Zeta potential) became less negative as the concentration of these cations increased in the soil solutions. Perfluorinated compounds showed greater sorption than polyfluorinated compounds, with sulfonates of comparable chain lengths showing higher sorption than the carboxylates. We observed that the K-d values of several PFAS in the two soils were positively correlated with the concentration of cations in solution, especially in the presence of polyvalent cations (Ca2+ and Mg2+). The changes in sorption with cation concentration were more prominent for long-chain PFAS, with C > 10 PFAS being completely removed from solution at higher cation concentrations. The emerging PFAS (replacement compounds GenX and ADONA) showed negligible or little sorption (K-d < 0.6 L/kg). While several mechanisms contribute towards sorption of PFAS in the presence of cations, we conclude that the primary effect of cations is through screening of negative charges on head groups of PFAS and reorientation of molecules at the interface between organic matter surfaces and soil solution as well as charge neutralisation at soil solid surface. Screening of negative charges allows for greater hydrophobic interaction between hydrophobic tails of PFAS and soil surfaces resulting in greater sorption. Increasing cation concentrations in soil solutions could thus reduce mobility of PFAS through a soil profile.

The legacy use of aqueous film-forming foam (AFFF) has led to the generation of large volumes of per- and poly-fluoroalkyl substances (PFAS)-contaminated asphalt materials, especially at airports and fire training areas. The management of such PFAS-contaminated asphalt materials requires an understanding of PFAS concentrations in these materials. This study, therefore, aimed to develop a suitable extraction methodology for the analysis of 22 target PFAS (i.e., carboxylic acids, sulfonic acids and fluorotelomers) in asphalt materials. A series of experiments was conducted to optimise extraction solvent composition, as well as to assess the performance of the chosen method under various conditions (i.e., sonication temperature, PFAS contamination level, asphalt core composition and timing of stable isotope addition used as internal standard). The methanol-based extractants performed best due to their accuracy and precision, which were within the acceptable range (extraction efficiency between 70 and 130% and RSD < 20%). The method which involved three successive extractions with methanol/1% NH3 by ultrasonication at 25 °C was selected due to its performance and ease of operation. The mean recovery of a vast majority of PFAS was found to be in the acceptable range. Tests on the timing of addition of stable isotope (SI)-labelled PFAS internal standards indicate that the recoveries obtained, regardless of when the stable isotopes were added, were within the acceptable range for PFAS. The accuracy and precision of PFAS recoveries were not affected by PFAS spike level (2 μg kg-1 and 200 μg kg-1), as well as sample composition (based on the location of asphalt material in the field). Low RSDs were achieved for asphalt cores collected from a contaminated site covering a wide range of concentrations (from LOQ to 2135 mg kg-1), demonstrating the suitability of the sample preparation method for real-world samples. The results from the interlaboratory testing were also in good agreement and validated the proposed PFAS extraction and analytical approach.

Measurement uncertainty (MU) is associated with analytical methods; it enhances the confidence of the method and helps in improving the quality of the analytical results. The present study aims to estimate MU of an analytical method used for analyzing the pharmaceutical residues in river water by using solid-phase extraction (SPE) followed by auto injector port silylation coupled with gas chromatography-tandem mass spectrometry (IPS-GC-MS/MS) system. The SPE conditions were optimized by using design of experiments approach (Plackett-Burman Design and Central Composite Design); top-down and bottom-up approaches were used for the estimation of MU. The calibration curves of all pharmaceutical residues showed dynamic linearity in the concentration range of 10-2000 ng/L with coefficient of determination (R-2) ranging between 0.985 and 0.999. The limit of detection, limit of quantification, and recovery were found to be in the range of 2.52-7.31 ng/L, 8.33-24.12 ng/L and 81.82-114.14%, respectively. The method robustness was found within acceptation limit (<15% RSD) for system suitability. The expanded uncertainty was estimated in the range of 1.28-32.96% for the SPE method. Precision and recovery were identified as major uncertainty sources of SPE-IPS-GC-MS/MS method for the analysis of pharmaceutical residues in river water.

We studied sorption potential for a range of herbicides using eleven waste materials (mill muds) containing organic matter (47.6 to 65.1%) produced by sugar mills and applied as soil conditioners by farmers. Sorption/desorption behaviour of five herbicides commonly used in sugarcane production (imazapic, atrazine, hexazinone, diuron and metribuzin) was studied on these mill muds, as is and after adding these to three soils at different rates (5-25%, dry weight basis). All mill muds had significant sorption capacity, especially for diuron, atrazine and metribuzin which was 6 to 26 times higher than the soil with 3.5% organic carbon (OC). Generally, sorption of the five herbicides assessed in all mill muds followed the order diuron > atrazine = metribuzin > hexazinone = imazapic. Eight out of 11 mill muds had similar sorption capacity for any given herbicides. Amending soils with selected mill muds significantly enhanced their sorption efficiency, depending on the rate of application especially in soil with low OC. Generally, application of mill muds at 5% w/w or 40 tons/ha increased sorption of studied herbicides by 2 to 10 folds. Soil amendment with mill muds also reduced the rate and extent of desorption of herbicides- especially mobile herbicides like metribuzin. Nearly 79% release of metribuzin was observed after three desorption steps in amended soil (at 5% w/w), whereas in unamended soil, 100% of metribuzin was released during first desorption step. The study demonstrates that wastes produced by sugar mills may have recycling use in enhancing the retention of mobile herbicides in soils with low OC content.

The pharmaceutical benzodiazepine diazepam and its metabolite oxazepam have been detected in wastewater treatment plants effluents, surface water and treated drinking water, but their transformation during chlorination process is not well understood. We investigated the reactions of diazepam and oxazepam with free available chlorine using a high-resolution mass analyzer and theoretical calculation to elucidate the fate of benzodiazepines during water chlorination process. The obtained apparent second-order rate constants (k(app)) for chlorine reaction with diazepam and oxazepam varied from 0.01 to 1.7 M-1 s(-1) and 0.7 to 31.6 M-1 s(-1) in the pH range of 5.5-10.0, respectively. Under typical wastewater disinfection conditions of neutral pH values, free chlorine concentrations of 5 mg L-1 and contact times of up to 2 h, the corresponding half-lives for diazepam (similar to 180 min) and oxazepam (similar to 61 min) suggest that diazepam will be partly transformed during disinfection. Conversely, oxazepam will be considerably transformed during wastewater disinfection. The pH-dependency of k(app) for diazepam could be explained by the reactions between neutral diazepam and HClO species. The kinetic pattern for oxazepam can be well described by species-specific reactions involving oxazepam or Cl-2 and Cl2O species. In total, fifteen and eight transformation products were identified for chlorination of diazepam and oxazepam, respectively. The C-3 of 1,4-benzodiazepine structure was the main site of attack, leading predominantly to the oxidation and then cleavage of the C(3)-N(4) bond, as well as diazepine ring contractions. Based on mass balance estimation, the main chlorination product for diazepam and oxazepam are 7-chloro-1-methyl-5-phenyl-1,3-dihydro- 2H-1,4-benzodiazepin-2,3-dione and 6-chloro-4-phenyl-2(1H)-quinazolinone, respectively.

The use of pyrethroid and neonicotinoid insecticides has increased in Australia over the last decade, and as a consequence, increased concentrations of the neonicotinoid insecticide imidacloprid have been measured in Australian rivers. Previous studies have shown that non-target crustaceans, including commercially important species, can be extremely sensitive to these pesticides. Most shrimp farms in Australia are predominantly located adjacent to estuaries so they can obtain their required saline water, which support multiple land uses upstream (e.g. sugar-cane farming, banana farming, beef cattle and urbanisation). Larval and post-larval shrimp may be most susceptible to the impacts of these pesticides because of their high surface area to volume ratio and rapid growth requirements. However, given the uncertainties in the levels of insecticides in farm intake water and regarding the impacts of insecticide exposure on shrimp larvae, the risks that the increased use of new classes of pesticide pose towards survival of post-larval phase shrimp cannot be adequately predicted. To assess the potential for risk, toxicity in 20day past hatch post-larval Black Tiger shrimp (Penaeus monodon) to modern use insecticides, imidacloprid, bifenthin, and fipronil was measured as decreased survival and feeding inhibition. Post-larval phase shrimp were sensitive to fipronil, bifenthrin, and imidacloprid, in that order, at concentrations that were comparable to those that cause mortality other crustaceans. Bifenthrin and imidacloprid exposure reduced the ability of post-larval shrimp to capture live prey at environmentally realistic concentrations. Concentrations of a broad suite of pesticides were also measured in shrimp farm intake waters. Some pesticides were detected in every sample. Most of the pesticides detected were measured below concentrations that are toxic to post-larval shrimp as used in this study, although pesticides exceed guideline values, suggesting the possibility of indirect or mixture-related impacts. However, at two study sites, the concentrations of insecticides were sufficient to cause toxicity in shrimp post larvae, based on the risk assessment undertaken in this study.

The application of fixed bed high rate nitrifying trickling filters (NTFs) for the removal of track organic chemicals of concern (CoC) is less well known than their application to nutrient removal in water treatment. Particularly, the effect of exogenous organic carbon substrate (sucrose) loading on the performance of NTFs is not well understood. A laboratory-scale NTF system was operated in recirculation mode, with the objective of removing ammonia and CoC simultaneously. The efficiency of a high rate NTF for removal both of low concentration of ammonia (5 mg NH4-N L(-1)) and different concentrations of CoC in the presence of an exogenous organic carbon substrate (30 mg total organic carbon (TOC) L(-1)) was investigated. In the presence of exogenous organic carbon, the results demonstrated that the high rate NTF was able to successfully remove most of the CoCs investigated, with the removal ranging from 20.2% to 87.54%. High removal efficiencies were observed for acetaminophen (87.54%), bisphenol A (86.60%), trimethoprim (86.24%) and 17α-ethynylestradiol (80.60%). It was followed by the medium removal efficiency for N, N-diethyl-m-toluamide (61.31%) and atrazine (56.90%). In contrast, the removal of caffeine (28.43%) and benzotriazole (20.20%) was poorer in the presence of exogenous organic carbon. The removal efficiency for CoC was also compared with the results obtained in our previous study in the absence of exogenous organic carbon. The results showed that the addition of exogenous organic carbon was able to improve the removal of some of the CoC. Significant TOC percentage removals (45.68%-84.43%) and ammonia removal rate (mean value of 0.44 mg NH4-N L(-1) h(-1)) were also achieved in this study. The findings from this study provide valuable information for optimising the efficiency of high rate NTF for the removal of ammonia, CoC and TOC.

Ferrate(VI) (Fe(VI)) has been known to react with emerging organic contaminants containing electron-rich organic moieties, such as phenols, anilines, olefins, reduced sulfur and deprotonated amines. Oxidation of fluoroquinolone antibiotics, ciprofloxacin (CIP) and enrofloxacin (ENR), by Fe(VI) were investigated for their reaction products and toxicity changes as well as biodegradability of these products. Ten products were identified for both CIP and ENR reactions with Fe(VI) using a high-resolution accurate-mass Orbitrap mass analyzer. Structural changes to the CIP and ENR molecule included dealkylation, formation of alcohols and amides in piperazine ring and oxygen transfer to the double bond in quinolone structure. An enamine formation mechanism was tentatively proposed to facilitate the interpretation of CIP and ENR oxidation pathways. Toxicity evaluation using Microbial Assay for toxicity Risk Assessment (MARA) bioassay indicated that Fe(VI) oxidation products of CIP and ENR contributed negligible antibacterial potency and Fe(VI) oxidation treatment can remove the residual toxicity of CIP and ENR impacted source waters. The Fe(VI) oxidation treatment resulted in formation of relatively more biodegradable products (based on in silico assessment) than their corresponding parent compounds. The results showed that Fe(VI) has a good potential to degrade fluoroquinolone antibiotics and their antimicrobial potency in natural waters.

BACKGROUND: The nitrifying trickling filter (NTF) is a process commonly used in wastewater treatment to remove ammonia. What is less clear is its ability to remove emerging organic contaminants. This study evaluated the potential of NTF to remove eight trace organic chemicals of concern (CoCs), with initial concentration of caffeine, bisphenol A, benzotriazole, trimethoprim and acetaminophen 1 mg L-1, atrazine 2 mg L-1, 17 alpha-ethynylestradiol 5 mg L-1 and N, N-diethyl-m-toluamide 10 mg L-1, using a laboratory-scale NTF system. The impact of initial nitrification rate on chemicals' removal and the impact of chemicals on nitrification rate were investigated.RESULTS: The removal efficiency of a recirculating NTF for CoC removal was in the following order: caffeine (98%)> acetaminophen and N, N-diethyl-m-toluamide (58.6%)> atrazine (48.7%)> 17 alpha NTF-ethynylestradiol (48.3%)> benzotriazole (42.8%)> bisphenol A (26.2%)> trimethoprim (17.9%). In NTFs, biodegradation was the dominant process. In this study, the removal of caffeine was found to be the most effective, and removal of trimethoprim the least. The removal efficiency of most chemicals increased, except for benzotriazole, with increasing nitrification. The presence of CoCs might negatively affect nitrification in NTFs.CONCLUSION: The research demonstrated that recirculating high rate NTF is potentially an efficient approach for removal of trace organic contaminants. (C) 2016 Society of Chemical Industry

Removal of a persistent antiepileptic drug carbamazepine (CBZ) in aqueous solutions was investigated by using solar photolysis combined with free available chlorine (FAC). The combination of chlorination with simulated or natural sunlight markedly enhanced removal of CBZ in 10 mM phosphate buffer solution (pH 7.0) and river water (pH 7.0) compared with sunlight or FAC alone. Further analysis indicated that the observed enhancements in CBZ removal can be attributed to the in situ hydroxyl radical (HO) and ozone (O3) production during FAC photolysis. During 70 min simulated sunlight photolysis combined with FAC treatment, HO reaction contributed to 35.8% removal of CBZ and O3 reaction contributed to 40.6% removal, while only 5.3% of CBZ was removed by HOCl reaction. The oxidation products of CBZ, epoxide CBZ, 10,11-dihydro-10,11-dihydroxy CBZ, 1-(2-benzaldehyde)-4-hydro-(1H,3H)-quinazoline-2-one (BQM), 1-(2-benzaldehyde)-(1H,3H)-quinazoline-2,4-dione (BQD) and 4-aldehyde-9-acridone, were mainly formed from the HO and O3 attack at the double bond on the central heterocyclic ring of CBZ. Formation of these oxidation products did not cause any increase or decrease in toxicity to microbial species tested through Microbial Assay for Toxicity Risk Assessment (MARA). The initial FAC concentration and pH had a major influence on the removal process of CBZ during FAC photolysis, while temperature had a minor effect only. The combination of chlorination with natural sunlight could provide an effective approach for removal of CBZ and other contaminants during water treatment.

Perfluoroalkyl substances (PFASs) have received great attention from the public and scientific community due to their potential adverse impacts on the ecosystem and human health. We investigated the occurrence and distribution of 16 PFASs from 2 classes of PFASs—perfluoroalkyl carboxylic acids and perfluoroalkane sulfonic acids—in the archived surface sediments of five major rivers (Yellow River, Hai River, Liao River, Zhujiang River, and Dongjiang River) in northern and southern China. The study was also performed during the wet and dry seasons. Perfluorooctanoic acid and perfluorooctane sulfonic acid were the most frequently detected (detection frequency = 100 and 63 %, respectively) in the sediments of the five rivers; the concentrations ranged from 0.08 to 0.99 ng/g dry weight (dw) and were lower than the limit of detection (<LOD), which is 3.89 ng/g dw for both. Perfluorodecanoic acid and perfluoroundecanoic acid were moderately detected (detection frequency = 42 and 44 %, respectively) with concentrations ranging from less than their limit of detection (<LOD) to 0.69 ng/g dw and <LOD to 0.22 ng/g dw, whereas 12 other target analytes were lower than their limit of quantification at most of the sampling sites. Greater concentrations of the PFASs were found at those sites located in urban areas compared with rural areas. Sediment organic content was found to be an important factor influencing the distribution of PFASs in the riverine environment. The results provided first-hand national data of PFASs in the sediments of major rivers in China.

Owing of their wide-range of commercial applications, fullerene (C-60) nanoparticles, are likely to reach environments through the application of treated sludge (biosolids) from wastewater treatment plants to soils. We examined the release behaviour of C-60 from contaminated biosolids added to soils with varying physicochemical characteristics. Incubation studies were carried out in the dark for up to 24 weeks, by adding biosolids spiked (1.5 mg/kg) with three forms of C-60 (suspended in water, in humic acid, and precipitated/particulate) to six contrasting soils. Leaching of different biosolids + soil systems showed that only small fractions of C-60 (<5% of applied amount) were released, depending on incubation time and soil properties (particularly dissolved organic carbon content). Release of C-60 from unamended soils was greater (at least twice as much) than from biosolids-amended soils. The form of C-60 used to spike the biosolids had no significant effect on the release of C-60 from the different systems. Contact time of C-60 in these systems only slightly increased the apparent release up to 8 weeks, followed by a decrease to 24 weeks. Mass balance analysis at the completion of the experiment revealed that 20-60% of the initial C-60 applied could not be accounted for in these systems; the reasons for this are discussed. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.