Occurrence and Fate of Benzophenone-Type UV Filters in a Tropical Urban Watershed.

The study investigated the occurrence and fate of seven benzophenone-type UV filters (i.e., 2,4-dihydroxybenzophenone (2,4OH-BP), 2,2',4,4'-tetrahydroxybenzophenone (2,2',4,4'OH-BP), 2-hydroxy-4-methoxybenzophenone (2OH-4MeO-BP), 2,2'-Dihydroxy-4,4'-dimethoxybenzophenone (2,2'OH-4,4'MeO-BP), 2,2'-dihydroxy-4-methoxybenzophenone (2,2'OH-4MeO-BP), 4-hydroxybenzophenone (4OH-BP), and 4,4'-dihyroxybenzophenone (4DHB)) in a tropical urban watershed consisting of five major tributaries that discharge into a well-managed basin. Total benzophenone concentrations (∑CBPs) varied from 19-230.8 ng L-1 in overlying bulk water, 48-115 ng L-1 in pore water, 295-5813 ng g-1 dry weight (d.w.) in suspended solids, and 6-37 ng g-1 d.w. in surficial sediments, respectively. The tributaries (∑CBPs: 19-231 ng L-1) were the main source of benzophenone compounds entering the basin (∑CBPs: 20-81 ng L-1). In the water column, the vertical concentration profile in the aqueous phase was uniform while concentrations in the suspended solids decreased with depth. Different distribution profiles were also identified for benzophenones in suspended solids and sediments. A preliminary risk assessment suggested that the seven BPs were unlikely to pose ecotoxicological risks to local aquatic organisms except for 2OH-4MeO-BP in the case of an intermittent release.

Environmental and health impacts of artificial turf: a review.

With significant water savings and low maintenance requirements, artificial turf is increasingly promoted as a replacement for natural grass on athletic fields and lawns. However, there remains the question of whether it is an environmentally friendly alternative to natural grass. The major concerns stem from the infill material that is typically derived from scrap tires. Tire rubber crumb contains a range of organic contaminants and heavy metals that can volatilize into the air and/or leach into the percolating rainwater, thereby posing a potential risk to the environment and human health. A limited number of studies have shown that the concentrations of volatile and semivolatile organic compounds in the air above artificial turf fields were typically not higher than the local background, while the concentrations of heavy metals and organic contaminants in the field drainages were generally below the respective regulatory limits. Health risk assessment studies suggested that users of artificial turf fields, even professional athletes, were not exposed to elevated risks. Preliminary life cycle assessment suggested that the environmental impacts of artificial turf fields were lower than equivalent grass fields. Areas that need further research to better understand and mitigate the potential negative environmental impacts of artificial turf are identified.

Magnesium deficiency phenotypes upon multiple knockout of Arabidopsis thaliana MRS2 clade B genes can be ameliorated by concomitantly reduced calcium supply.

Plant MRS2 membrane protein family members have been shown to play important roles in magnesium uptake and homeostasis. Single and double knockouts for two Arabidopsis thaliana genes, AtMRS2-1 and AtMRS2-5, have previously not shown significant phenotypes even under limiting Mg(2+) supply although both are strongly expressed already in early seedlings. Together with AtMRS2-10, these genes form clade B of the AtMRS2 gene family. We now succeeded in obtaining homozygous AtMRS2-1/10 double and AtMRS2-1/5/10 triple knockout lines after selection under increased magnesium supply. Although wilting early, both new mutant lines develop fully and are also fertile under standard magnesium supply, but show severe developmental retardation under limiting Mg(2+) concentrations. To investigate nutrient dependency of germination and seedling development under various conditions, including variable supplies of Mg(2+), Ca(2+), Zn(2+), Mn(2+), Co(2+), Cd(2+) and Cu(2+), in a reproducible and economical way, we employed a small-scale liquid culturing system in 24-well plate set-ups. This allowed the growth and monitoring of individual plantlets of different mutant lines under several nutritional conditions in parallel, and the scoring and statistical evaluation of developmental stages and biomass accumulation. Detrimental effects of higher concentrations of these elements were similar in mutants and the wild type. However, growth retardation phenotypes seen upon hydroponic cultivation under low Mg(2+) could be ameliorated when Ca(2+) concentrations were concomitantly lowered, supporting indications for an important interplay of these two most abundant divalent cations in the nutrient homeostasis of plants.

Effects of chlorine exposure conditions on physiochemical properties and performance of a polyamide membrane--mechanisms and implications.

Understanding the effects of chlorine exposure on polyamide (PA) based membranes is essential in membrane lifespan improvement. In this study, NF90 nanofiltration membrane was treated with sodium hypochlorite at different concentrations, pHs and durations. The changes in membrane elemental composition and bonding chemistry obtained from XPS and ATR-FTIR revealed the impacts of two competing mechanisms: N-chlorination and chlorination-promoted hydrolysis. More chlorine was incorporated into the PA matrix at pH <7, at which HOCl is dominant, while chlorine-promoted hydrolysis was more favorable at pH >7 with abundant hydroxyl groups. The membrane surface became more hydrophobic when chlorination was dominant, which in turn caused the water permeability of chlorinated membrane to decrease. Meanwhile, membrane became more hydrophilic and less cross-linked when hydrolysis effects were governing, which made the membrane more permeable for water. Rejection of charged solutes [NaCl, As(V)] improved in most chlorinating conditions due to increased charge density. However, when hydrolysis was severe (≥ 1000 ppm, pH 7 and 9), the enhanced charge repulsion effect could not compensate for the extensive amide bond cleavage, resulting in declined rejection. The lower rejection of neutral boric acid provided strong evidence of a less cross-linked separation layer.

Degradation of polyamide nanofiltration and reverse osmosis membranes by hypochlorite.

The degradation of polyamide (PA) nanofiltration and reverse osmosis membranes by chlorine needs to be understood in order to develop chlorine-resistant membranes. Coated and uncoated fully aromatic (FA) and piperazine (PIP) semi-aromatic PA membranes were treated with hypochlorite solution and analyzed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR). XPS results showed that in chlorine treated FA PA membranes the ratio of bound chlorine to surface nitrogen was 1:1 whereas it was only 1:6 in the case of PIP PA membranes. Surface oxygen of uncoated FA and PIP membranes increased with increasing hypochlorite concentration whereas it decreased for coated FA membranes. High resolution XPS data support that chlorination increased the number of carboxylic groups on the PA surface, which appear to form by hydrolysis of the amide bonds (C(O)-N). FTIR data indicated the disappearance of the amide II band (1541 cm(-1)) and aromatic amide peak (1609 cm(-1)) in both coated and uncoated chlorinated FA membranes, consistent with the N-chlorination suggested by the XPS results. Furthermore, the surface charge of chlorinated membranes at low pH (<6) became negative, consistent with amide-nitrogen chlorination. Chlorination appeared to both increase and decrease membrane hydrophobicity depending on chlorination exposure conditions, which implied that N-chlorination and hydrolysis may be competing processes. The effects of property changes on the membrane performance were also observed for NF90, BW30, and NF270 membranes.

Critical review of Pd-based catalytic treatment of priority contaminants in water.

Catalytic reduction of water contaminants using palladium (Pd)-based catalysts and hydrogen gas as a reductant has been extensively studied at the bench-scale, but due to technical challenges it has only been limitedly applied at the field-scale. To motivate research that can overcome these technical challenges, this review critically analyzes the published research in the area of Pd-based catalytic reduction of priority drinking water contaminants (i.e., halogenated organics, oxyanions, and nitrosamines), and identifies key research areas that should be addressed. Specifically, the review summarizes the state of knowledge related to (1) proposed reaction pathways for important classes of contaminants, (2) rates of contaminant reduction with different catalyst formulations, (3) long-term sustainability of catalyst activity with respect to natural water foulants and regeneration strategies, and (4) technology applications. Critical barriers hindering implementation of the technology are related to catalyst activity (for some contaminants), stability, fouling, and regeneration. New developments overcoming these limitations will be needed for more extensive field-scale application of this technology.

Occurrence, fate, and fluxes of perfluorochemicals (PFCs) in an urban catchment: Marina Reservoir, Singapore.

A study was carried out to characterize the occurrence, sources and sinks of perfluorochemicals (PFCs) in the Marina Catchment and Reservoir, Singapore. Salinity depth profiles indicated the reservoir was stratified with lower layers consisting of sea water (salinity ranging from 32 to 35 g L(-1)) and a brackish surface layer containing approximately 14-65% seawater. The PFC mixture detected in catchment waters contained perfluoroalkyl carboxylates (PFCAs), particularly perfluorooctanoate (PFOA), perfluorohexanoate (PFHpA), perfluorooctane sulfonate (PFOS) and PFC transformation products. PFC concentrations in storm runoff were generally higher than those in dry weather flow of canals and rivers. PFC concentration profiles measured during storm events indicated 'first flush' behavior, probably because storm water is leaching PFC compounds from non-point sources present in the catchment area. Storm runoff carries high concentrations of suspended solids (SS), which suggests that PFC transport is via SS. In Marina Bay, PFCs are deposited in the sediments along with the SS. In sediments, the total PFC concentration was 4,700 ng kg(-1), approximately 200 times higher than in the bottom water layers. Total perfluoroalkyl sulfonates (PFSAs), particularly PFOS and 6:2 fluoro telomer sulfonate (6:2 FtS) were dominant PFCs in the sediments. PFC sorption by sediments varied with perfluorocarbon chain length, type of functional group and sediment characteristics. A first approximation analysis based on SS transport suggested that the annual PFC input into the reservoir was approximately 35 ± 12 kg y(-1). Contributions of SS, dry weather flow of river/canals, and rainfall were approximately 70, 25 and 5%, respectively. This information will be useful for improving strategies to protect the reservoir from PFC contamination.

An Assist for Cognitive Diagnostics in Soccer: Two Valid Tasks Measuring Inhibition and Cognitive Flexibility in a Soccer-Specific Setting With a Soccer-Specific Motor Response.

In professional soccer, players, coaches, and researchers alike recognize the importance of cognitive skills. Research addressing the relevance of cognitive skills has been based on the cognitive component skills approach (i.e., general cognitive processes) or the expert performance approach (i.e., sport-specific cognitive processes). Our project aimed to combine the strengths of both approaches to develop and validate cognitive tasks measuring inhibition and cognitive flexibility in a soccer-specific setting with a soccer-specific motor response. In the main study 77 elite youth soccer players completed a computerized version of the standard flanker and number-letter tasks as well as flanker and number-letter tasks requiring a soccer-specific motor response (i.e., pass) in a soccer-specific setting (i.e., the SoccerBot360). Results show good reliability for both tasks. For the SoccerBot360 number-letter task, switch effects for response times and accuracy and acceptable convergent validity were shown. A flanker effect for response time but not accuracy was apparent. Due to no acceptable convergent validity, the flanker task was revised (i.e., adaptation of stimuli) and 63 adult soccer players participated in a follow-up validation study in the SoccerBot100. The revised flanker task showed the flanker effect for response time, but not for accuracy. However, acceptable convergent validity for response time was present. Thus, the soccer-specific number-letter and to some extent the soccer-specific flanker task show potential to be used as a valid cognitive diagnostic tool by soccer clubs.

One planet: one health. A call to support the initiative on a global science-policy body on chemicals and waste.

The chemical pollution crisis severely threatens human and environmental health globally. To tackle this challenge the establishment of an overarching international science-policy body has recently been suggested. We strongly support this initiative based on the awareness that humanity has already likely left the safe operating space within planetary boundaries for novel entities including chemical pollution. Immediate action is essential and needs to be informed by sound scientific knowledge and data compiled and critically evaluated by an overarching science-policy interface body. Major challenges for such a body are (i) to foster global knowledge production on exposure, impacts and governance going beyond data-rich regions (e.g., Europe and North America), (ii) to cover the entirety of hazardous chemicals, mixtures and wastes, (iii) to follow a one-health perspective considering the risks posed by chemicals and waste on ecosystem and human health, and (iv) to strive for solution-oriented assessments based on systems thinking. Based on multiple evidence on urgent action on a global scale, we call scientists and practitioners to mobilize their scientific networks and to intensify science-policy interaction with national governments to support the negotiations on the establishment of an intergovernmental body based on scientific knowledge explaining the anticipated benefit for human and environmental health.

Novel perspectives on the bioaccumulation of PFCs--the concentration dependency.

The effects of exposure concentration on the bioaccumulation of four perfluorinated chemicals (PFCs): perfluorooctanesulfonate (PFOS), perfluoroocanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA), was investigated using green mussels, Perna viridis. Mussels were exposed to concentrations of 1 µgL(-1) and 10 µgL(-1) of each PFC for 56 days, and the bioaccumulation factors (BAF) were found to range from 15 to 859 L/kg and from 12 to 473 L/kg at 1 µgL(-1) and 10 µgL(-1), respectively. For all compounds, the BAF was larger at the lower dosage. Results suggest that the bioaccumulation of PFCs is concentration dependent. This concentration dependency can be explained by a nonlinear adsorption mechanism, which was further supported by the experimental results. The sensitivity of BAF to exposure concentration was found to be positively related to perfluorinated chain length and the binding affinity of the compounds. Bioaccumulation of long chain carboxylates and sulfonates are more easily affected by concentration changes. The validity of the conventional kinetic method was examined by comparing the results with the fundamental steady-state method: in addition to the above-mentioned batch test, mussels were also subject to 24-day exposure (1 µgL(-1) and 10 µgL(-1)) followed by 24-day depuration. Contradictions were found in the resulting kinetic BAF and model curving fittings. A new kinetic model based on adsorption mechanism was proposed, which potentially provide more accurate description of the bioaccumulation process of PFCs.

Biotransformation of halogenated nonylphenols with sphingobium xenophagum bayram and a nonylphenol-degrading soil-enrichment culture.

When discharged in chlorinated wastewater, alkylphenol ethoxylate metabolites (APEMs) are often discharged in halogenated form (XAPEMs, X = Cl, or Br). The potential environmental impact of XAPEM release was assessed by studying the biotransformation of halogenated nonylphenol by Sphingobium xenophagum Bayram and a soil-enrichment culture. S. xenophagum Bayram transformed chlorinated nonylphenol (ClNP) slowly and nearly completely to form nonyl alcohol; the monobrominated nonylphenol (BrNP) and dibrominated nonylphenol were transformed cometabolically with nonylphenol (NP) as the primary substrate. The presence of either ClNP or BrNP in the S. xenophagum Bayram cultures retarded the transformation of nonhalogenated NP. NP-degrading soil cultures transformed nonhalogenated NP to a mixture of nonyl alcohols but were not capable of transforming either ClNP or BrNP. The presence of either ClNP or BrNP retarded the transformation of nonhalogenated NP in the soil cultures, as was observed in S. xenophagum Bayram cultures. Predicting the environmental fate of alkylphenol ethoxylate residues requires considering APEM halogenation during effluent chlorination and inhibitory effects as well as the refractory nature of halogenated metabolites.

Occurrence of herbicides and pharmaceutical and personal care products in surface water and groundwater around Liberty Bay, Puget Sound, Washington.

Organic contaminants, such as pharmaceuticals and personal care products (PPCPs), pose a risk to water quality and the health of ecosystems. This study was designed to determine if a coastal community lacking point sources, such as waste water treatment plant effluent, could release PPCPs, herbicides, and plasticizers at detectable levels to their surface water and groundwater. Research was conducted in Liberty Bay, an embayment within Puget Sound, where 70% of the population (-10,000) uses septic systems. Sampling included collection of groundwater and surface water with grab samples and the use of polar organic chemical integrative samplers (POCIS). We analyzed for a broad spectrum of 25 commonly used compounds, including PPCPs, herbicides, and a flame retardant. Twelve contaminants were detected at least once; only N,N-diethyl-meta-toluamide, caffeine, and mecoprop, a herbicide not attributed to septic systems, were detected in more than one grab sample. The use of POCIS was essential because contaminants were present at very low levels (nanograms), which is common for PPCPs in general, but particularly so in such a small community. The use of POCIS allowed the detection of five compounds that were not present in grab samples. Data suggest that the community is contaminating local water with PPCPs; this effect is likely to increase as the population and product usage increase. The results presented here are a first step toward assessing the transport of herbicides and PPCPs into this coastal system.

A sensitive and accurate method for simultaneous analysis of algal toxins in freshwater using UPLC-MS/MS and 15N-microcystins as isotopically labelled internal standards.

The development of analytical methods for the detection and accurate quantification of algal toxins is of importance to assess the health risk of exposure to algal toxins in freshwater sources. This study established a sensitive and accurate analytical method for the quantification of 13 algal toxins (microcystins and nodularin) based on solid phase extraction (SPE) coupled with UPLC-MS/MS, in which 15N-microcystins were used as surrogate/internal standards. SPE method was optimized to extract the target algal toxins in freshwater samples. Good SPE efficiencies (84-96%) were achieved for the overwhelming majority of the investigated algal toxins when SPE was performed using HLB (500 mg, 6 mL) under alkaline conditions (pH 11). An accurate quantitative analysis of the algal toxins in real freshwater samples was performed by using 15N-labelled microcystins as isotopically labelled internal standards (ILISs), which compensated for the loss of target toxins during the whole analytical process. In addition, ILISs also helped to correct the effects of environmental matrices and instrument fluctuation in UPLC-MS/MS analysis. The limit of method quantification (MQL) for the algal toxins was <2.0 ng/L that is sensitive enough to quantify extremely low levels of target toxins in freshwater samples.

Quantification of cylindrospermopsin, anatoxin-a and homoanatoxin-a in cyanobacterial bloom freshwater using direct injection/SPE coupled with UPLC-MS/MS.

Analytical methods based on direct injection (DI) and solid phase extraction (SPE) coupled with ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC- MS/MS) were developed for the determination of anatoxin-a (ATX-a), cylindrospermopsin (CYN), and homoanatoxin-a (HATX-a) in freshwater samples impacted with cyanobacterial blooms. The presence of CYN in freshwater samples was detected and quantified based on direct injection method, while ATX-a and HATX-a could be determined by both DI and SPE-based methods. Matrix effects (ME) on the signal intensity of the cyanotoxins were systematically evaluated for both direct injection and SPE extract samples. CYN, ATX-a, and HATX-a suffered a significant suppression during UPLC-MS/MS. The selection of internal standards (ISs) for compensating/correcting the losses of target cyanotoxins during sample preparation and matrix effects in UPLC-MS/MS analyses were systematically evaluated. Acetaminophen-d4 (an isotopically labelled acetaminophen) is a suitable internal standard for correcting the ME on the signal intensity of ATX-a and HATX-a, while the use of L-phenylalanine-d5 or caffeine-d9 as IS for correcting ME of these toxins was not efficient, as expected. The method detection limit (MDL) for the target cyanotoxins ranged from 0.6 to 15 ng/L, which is sensitive enough to detect the presence of these toxins in cyanobacterial bloom freshwater. The developed methods were successfully applied for routine monitoring of the occurrence of these cyanotoxins in a local water body. Monitoring results depicted that ATX-a, CYN and HATX-a were ubiquitously detected in water samples, at concentrations ranging from 70 to 24,600 ng/L.

Controlled field studies on soil aquifer treatment in a constructed coastal sandfill.

A controlled artificial recharge experiment was conducted to investigate the effect of soil aquifer treatment during percolation of secondary and tertiary (ultrafiltered) treated wastewater through the shallow vadoze zone of a newly constructed coastal sandfill. The sandfill is a reclaimed land constructed from marine sand dredged from the seabed. To obtain 1-D flow, a stainless steel column was driven to a depth of 2.5 m, penetrating the phreatic surface. Wastewater was percolated through the column under fully-saturated and unsaturated conditions. Infiltration rates, dissolved organic carbon (DOC) and ultra-violet absorption (UVA) were monitored. The wastewaters were recharged at similar infiltration rates of approximately 5.5 m/day and 3.5 m/day under fully-saturated and unsaturated conditions, respectively. In both cases, clogging occurred 40 days after the start of recharge, under saturated conditions. For secondary treated wastewater, DOC concentration (mg/l) reduced by 28% and 13% under unsaturated and saturated conditions, respectively. The corresponding UVA reduction was 19.4% and 14.1%. Similar reductions in DOC were observed for the tertiary treated wastewater; however, the reduction in UVA was higher; 28% and 22% under unsaturated and saturated conditions, respectively. On an mass removal (mg/m(2) DOC) basis, DOC reduction appeared to be more significant under unsaturated conditions. This is attributed to the presence of interstitial oxygen.

Multi-compartment distribution of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in an urban catchment system.

Ecotoxicological risks of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in surface waters are difficult to model because data on PFASs distribution in multiple compartments (sediments, suspended particles and aqueous phase) are difficult to predict. This study quantified the distribution of 21 PFASs including PFCAs: C6-C13 perfluoroalkyl carboxylates, C4, C6, C8 and C10 perfluoroalkane sulfonates, 5 perfluorooctane sulfonamide substances (FOSAMs, including EtFOSA, FOSA, MeFOSAA, EtFOSAA, FOSAA), 2 N-alkyl perfluoroalkane sulfonamidoethanols (MeFOSE and EtFOSE), bis (perfluorooctyl) phosphinic acid (C8/C8 PFPIA), and 5:3 fluorotelomer carboxylic acid (5:3 acid) between bulk water and suspended particles in water column, and pore water and benthic sediments from a tropical urban water body. The distribution of PFASs between sorbed and dissolved phase was largely dependent on the perfluoroalkyl chain length (NCF2). PFCAs with NCF2 > 11 and perfluorodecane sulfonate (PFDS, NCF2 = 10) were found predominantly in the suspended particles and sediments. By contrast, short-chain PFASs (NCF2 ≤ 7) were detected predominantly in the dissolved phase. Sediment acts as a sink for long-chain PFASs while short-chain PFASs are more easily transported via the aqueous phase. Compared with benthic sediments, suspended particles, especially those in the top water layer, carried much higher concentrations of PFASs (by a factor of >100), indicating the stronger sorption capability of suspended particles. The wide variation in PFAS concentrations in suspended particles (∑PFASs concentrations: < 26.8-1,284 ng/g d.w.) suggests that some suspended particles were preloaded with different concentrations of PFASs in the water column which could highly affect the distribution of PFASs in the aquatic environment. Pore water contained 1-2 times higher concentrations of PFASs (∑PFASs: <20.25-159.34 ng/L) than overlying bulk water (∑PFASs: <14.2-79.98 ng/L), indicating the accumulation of PFASs in pore water. Distribution coefficients (KD) were calculated using paired solids concentration and dissolved concentration in both water and sediment column (KD-SP and KD-SED respectively) and were compared with values derived from a laboratory batch experiment. The averaged Log KD-SP/Log KD-SED showed significant positive correlation with NCF2, except for short-chain PFASs (NCF2 <5) which presented higher Log KD values than estimated. The discrepancies found between KD (Log KD-SP > Log KD -desorption > Log KD -sorption > Log KD-SED) suggest that the distribution of PFASs in the field, especially between suspended particles and bulk water could not be well represented by lab results and that using the water concentrations in the bottom layer for estimation of pore water concentrations could lead to bias results.

Emerging contaminants in wastewater, stormwater runoff, and surface water: Application as chemical markers for diffuse sources.

Diffuse sources of pollution such as sewer leakages, sewer overflows, illicit discharges and stormwater runoff affect the urban surface water quality but often remain unknown. Therefore, the development of chemical markers for identifying and characterizing the origin of diffuse sources of pollution in urban surface waters is a requisite for protecting and managing urban water resources. In this study, the occurrence of 31 emerging contaminants (ECs) in untreated wastewater, treated wastewater, urban stormwater runoff, agricultural stormwater runoff, and freshwater bodies was investigated. Artificial sweeteners (ASs), pharmaceuticals and personal care products (PPCPs) were more frequently detected in the collected water samples. In raw wastewater, 21 target ECs were detected 100% in the collected samples with median concentrations ranging from 49.6 to 77,721 ng/L, while in freshwater bodies, only 13 compounds were found with detection frequency >50%. The median concentration of the majority of detected ECs in freshwater samples was below 100 ng/L. The suitability of ECs as chemical markers of diffuse sources in an urban watershed was assessed using a suite of criteria, including the detection frequency (DF), detection ratio (DR) (i.e. the ratio between median concentration and method quantification limit of a compound) and attenuation rates (i.e., biodegradation, sorption and abiotic degradation) in wastewater treatment processes. In addition, we propose a new key criterion, the concentration ratio (CR) of labile to conservative compounds, to evaluate the applicability of suitable chemical markers for source tracking. Using this new set of criteria (i.e. CR, DF, DR and attenuation rates), our analysis showed that among the investigated ECs, only acesulfame (ACE), acetaminophen (ACT), cyclamate (CYC), saccharin (SAC) were suitable as chemical markers of diffuse sources in surface waters. For caffeine (CF), N,N-diethyl-meta-toluamide (DEET), crotamiton (CTMT), triclocarban (TCC) and triclosan (TCS), their median concentration ratio to sucralose (SUC) in water bodies was consistently higher than that in raw wastewater, suggesting that these compounds might be unsuitable as chemical markers of sewage leakage in surface waters for this study area.

N-nitrosodimethylamine (NDMA) removal by reverse osmosis and UV treatment and analysis via LC-MS/MS.

N-nitrosodimethylamine (NDMA) is a probable human carcinogen found in ng/l concentrations in chlorinated and chloraminated water. A method was developed for the determination of ng/l levels of NDMA using liquid chromatography-tandem mass spectrometry (LC-MS/MS) preceded by sample concentration via solid-phase extraction with activated charcoal. Recoveries were greater than 90% and allowed a method reporting limit as low as 2ng/l. Using this method, the removal of NDMA was determined for the Interim Water Purification Facility (IWPF), an advanced wastewater treatment facility operated by the Orange County Water District (OCWD) in Southern California. The facility treats effluent from an activated sludge treatment plant with microfiltration (MF), reverse osmosis (RO), and an ultraviolet-hydrogen peroxide advanced oxidation process (UV-AOP). Six nitrosamines were surveyed: NDMA, N-nitrosomethylethylamine (NMEA), N-nitrosodiethylamine (NDEA), N-nitrosodi-n-propylamine (NDPA), N-nitrosopiperidine (NPip), and N-nitrosopyrrolidine (NPyr). Only NDMA was detected and at all treatment steps in the IWPF, with influent concentrations ranging from 20 to 59 ng/l. Removals for RO and UV ranged from 24% to 56% and 43% to 66%, respectively. Overall, 69+/-7% of the original NDMA concentration was removed from the product water across the advanced treatment process and, in combination with blending, the final concentration did not exceed the California drinking water notification level of 10 ng/l. NDMA removal data are consistent with findings reviewed for other advanced treatment facilities and laboratory studies.

Perfluorochemicals in water reuse.

Faced with freshwater shortages, water authorities are increasingly utilizing wastewater reclamation to augment supplies. However, concerns over emerging trace contaminants that persist through wastewater treatment need to be addressed to evaluate potential risks. In the present study, perfluorinated surfactant residues were characterized in recycled water from four California wastewater treatment plants that employ tertiary treatment and one that treats primary sewage in a wetland constructed for both treatment and wildlife habitat. Effluent concentrations were compared with surface and groundwater from a creek where recycled water was evaluated as a potential means to augment flow (Upper Silver and Coyote Creeks, San Jose, CA). In the recycled water, 90-470 ng/l perfluorochemicals were detected, predominantly perfluorooctanoate (PFOA; 10-190 ng/l) and perfluorooctanesulfonate (PFOS; 20-190 ng/l). No significant removal of perfluorochemicals was observed in the wetland (total concentration ranged 100-170ng/l across various treatment stages); in this case, 2-(N-ethylperfluorooctanesulfonamido) acetic acid (N-EtFOSAA), perfluorodecanesulfonate (PFDS), and PFOS were dominant. Though there is currently no wastewater discharge into the creeks, perfluorochemicals were found in the surface water and underlying groundwater at a total of 20-150 ng/l with PFOS and PFOA again making the largest contribution. With respect to ecotoxicological effects, perfluorochemical release via recycled water into sensitive ecosystems requires evaluation.

Degradation of organic compounds during the corrosion of ZVI by hydrogen peroxide at neutral pH: Kinetics, mechanisms and effect of corrosion promoting and inhibiting ions.

The corrosion of zero valent iron (ZVI) by hydrogen peroxide (H2O2) generates hydroxyl (⋅OH) and other radical oxygen species (ROS) that degrade organic materials. To better understand the factors that govern the ROS formation during the H2O2-induced corrosion, we investigated the degradation of an organic probe compound (acesulfame (ACE)) in slurries of ZVI powder in unbuffered laboratory water at pH 6.5 ±â€¯0.5. Chloride ions accelerated the corrosion of ZVI by H2O2 and the formation ROS and, therefore, the degradation of organic materials. Conversely, slowing corrosion by phosphate buffer inhibited ROS formation and the degradation of organic compounds. The rate of H2O2 decomposition was correlated with the liberation of Fe2+(aq) and the ACE degradation rate. The kinetics of H2O2 decomposition was pseudo-first-order and zero-order at low (<0.04 mM/mg) and high [H2O2]/[ZVI] initial ratios, respectively, and was consistent with Langmuir kinetics. The H2O2 decomposition rate was proportional to the ZVI reactive surface area (SA) and nearly independent of the extent of ZVI oxidation, the presence of a Fe2+(aq) chelating agent, and ⋅OH quenchers (methanol and tert-butanol). Kinetic data suggest a mechanism involving rapid cathodic reduction of H2O2 at the metallic ZVI surface which causes the liberation of Fe2+(aq) that generate ⋅OH via the homogeneous Fenton reaction. The stoichiometric efficiency (SE) of organics degradation ranged from 0.0008% to 0.014% and increased with decreasing H2O2 decomposition rate.