Excretion of polybrominated diphenyl ethers and AhR activation in breastmilk among firefighters.

Excretion of toxicants accumulated from firefighter exposures through breastmilk represents a potential hazard. We investigated if firefighting exposures could increase the concentration of polybrominated diphenyl ethers (PBDEs) and aryl hydrocarbon receptor (AhR) activation in excreted breastmilk. Firefighters and non-firefighters collected breastmilk samples prior to any firefighting responses (baseline) and at 2, 8, 24, 48, and 72 hours after a structural fire (firefighters only). Five PBDE analytes (BDEs 15, 28, 47, 99, and 153) detected in at least 90% of samples were summed for analyses. The AhR in vitro DR CALUX® bioassay assessed the mixture of dioxin-like compounds and toxicity from breastmilk extracts. Baseline PBDEs and AhR response were compared between firefighters and non-firefighters. Separate linear mixed models assessed changes in sum of PBDEs and AhR response among firefighters over time and effect modification by interior or exterior response was assessed. Baseline PBDE concentrations and AhR responses did not differ between the 21 firefighters and 10 non-firefighters. There were no significant changes in sum of PBDEs or AhR response among firefighters over time post-fire, and no variation by interior or exterior response. Plots of sum of PBDEs and AhR response over time demonstrated individual variation but no consistent pattern. Currently, our novel study results do not support forgoing breastfeeding after a fire exposure. However, given study limitations and the potential hazard of accumulated toxicants from firefighter exposures excreted via breastfeeding, future studies should consider additional contaminants and measures of toxicity by which firefighting may impact maternal and child health.

Formation of nitrogenous disinfection byproducts in MP UV-based water treatments of natural organic matters: The role of nitrate.

UV-based water treatment processes have been reported to induce genotoxicity during the treatments of surface water, drinking water and artificial water with natural organic matters (NOMs), causing genotoxicity concerns for the drinking water safety. Nitrogenous disinfection byproducts (N-DBPs) were generally reported to be much more genotoxic than their non-nitrogenous analogues, and might be responsible for the genotoxicity in UV processes. Although nitrate-rich water was getting attention for the possibility of genotoxicity and N-DBPs during UV treatments, the impact mechanism of nitrate on the degradation of NOMs, the formation of N-DBPs and genotoxicity has not been explicated. Here simulation experiments of NOM degradation under medium-pressure (MP) UV and MP UV/H2O2 treatments were conducted to explore the effect of nitrate on the molecular characteristics of NOM, the nitrate-derived N-DBPs and the potential genotoxicity through non-targeted analysis and CALUX® reporter gene assays. The results showed that nitrate can accelerate the degradation of NOMs in the MP UV process but inhibit the degradation of NOMs in the MP UV/H2O2 process. During the degradation of NOMs, the molecular compositions varied by the effect of nitrate on oxygen atoms, molecule analogs, and saturation. A total of 105 and 374 nitrate-derived N-DBPs were identified in the MP UV and MP UV/H2O2 treatment, respectively. Most of these N-DBPs contain one nitrogen atom, and the representative features are nitro-, methoxy- (or hydroxyl-) and ester- groups on benzene. No genotoxicity was observed without nitrate spiking, whereas genotoxicity was induced after both MP UV and MP UV/H2O2 treatments when nitrate was spiked, which is worthy of attention for the drinking water safety management.

Development and optimization of analytical methods for the detection of 18 taste and odor compounds in drinking water utilities.

Taste and odor (T&O) issues have been a major concern among drinking water utilities as source waters are becoming increasingly vulnerable to compounds released during algal blooms as well as non-algal compounds. While most of the literature focuses on the two most common T&O compounds - 2-MIB and geosmin, there are other compounds that have the potential to cause T&O events. The aim of this study was to develop an advanced analytical method using solid phase microextraction (SPME) and gas chromatography-tandem mass spectrometry (GC-MS/MS) to identify 18 T&O compounds belonging to various odor classes. The developed method was optimized for the 18 analytes and implemented to determine the holding time of the compounds in raw and treated (distribution system point-of-entry or PoE) drinking water matrices. Compounds belonging to certain classes such as pyrazines and anisoles were found to be "stable" (< 30% loss) in all tested waters for up to two weeks, while aldehydes, ketones, esters and alkyl sulfides showed > 30% loss within 96 h in raw water. Preservation of samples at low pH (< 2) using hydrochloric acid increased the holding times and reduced losses within 96 h for aldehydes, ketones and esters. The paper also discusses the occurrence of these compounds with water utilities from the Midwest and Eastern US during the summer months. The study detected eight T&O compounds - 2-MIB, geosmin, ß-cyclocitral, ß-ionone, hexanal, indole, dimethyl disulfide and dimethyl trisulfide. While five compounds were detected above their threshold concentrations in the raw water, two of them (2-MIB and geosmin) were detected above threshold in the PoE samples.

Evaluation of fireground exposures using urinary PAH metabolites.

BACKGROUND: Firefighters have increased cancer incidence and mortality rates compared to the general population, and are exposed to multiple products of combustion including known and suspected carcinogens. OBJECTIVE: The study objective was to quantify fire response exposures by role and self-reported exposure risks. METHODS: Urinary hydroxylated metabolites of polycyclic aromatic hydrocarbons (PAH-OHs) were measured at baseline and 2-4 h after structural fires and post-fire surveys were collected. RESULTS: Baseline urine samples were collected from 242 firefighters. Of these, 141 responded to at least one of 15 structural fires and provided a post-fire urine. Compared with baseline measurements, the mean fold change of post-fire urinary PAH-OHs increased similarly across roles, including captains (2.05 (95% CI 1.59-2.65)), engineers (2.10 (95% CI 1.47-3.05)), firefighters (2.83 (95% CI 2.14-3.71)), and paramedics (1.84 (95% CI 1.33-2.60)). Interior responses, smoke odor on skin, and lack of recent laundering or changing of hoods were significantly associated with increased post-fire urinary PAH-OHs. SIGNIFICANCE: Ambient smoke from the fire represents an exposure hazard for all individuals on the fireground; engineers and paramedics in particular may not be aware of the extent of their exposure. Post-fire surveys identified specific risks associated with increased exposure.

Evaluation of a recirculating hydroponic bed bioreactor for removal of contaminants of emerging concern from tertiary-treated wastewater effluent.

Tertiary-treated effluent from a municipal wastewater treatment plant in Tucson, AZ, was added to recirculating hydroponic bed bioreactors filled with light expanded clay aggregate (LECA) and recirculated for 10 days. Bioreactors were planted with high and low densities of sorghum (Sorghum bicolor), switchgrass (Panicum virgatum) and Bacillus thuringiensis cotton (Gossypium sp.). The experiment also included a non-planted bioreactor treatment and a control bioreactor with neither plants nor substrate medium. Of 46 contaminants of emerging conern assayed with liquid chromatography tandem mass spectrometry (LC-MS/MS), 16 were initially identified at detectable levels in the effluent. After one day, concentrations of Ibuprofen and Diphenhydramine fell below detection limits in all treatments as well as the control. After five days, initial concentrations of atenolol, benzotriazole, carbamazepine, hydrochlorothiazide, iohexol, iopamidol iopromide, primidone, sulfamethoxazole and tris TCPP were reduced by greater than 80% in all treatments, while the control exhibited little to no removal. Diclofenac, simazine and sucralose exhibited variable removal rates among treatments ranging from 44 to 84% after five days. After 10 days, concentrations of DEET, diclofenac, iopromide, primidone and simazine were all below detection levels, while there was near zero removal in the control. Bioreactors planted with cotton had significantly more removal of sulfamethoxazole than unplanted bioreactors by 16-19% after five days and by an additional 18-20% removal after 10 days. The percentage uptake of benzotriazole by every planted treatment was significantly higher than the non-planted treatment after five and 10 days. Significant contaminant removal occurred in the media substrate, likely through adsorption to LECA or microbial degradation. More research is needed to examine specific pathways of degradation and removal by various microbials and plants.

Evaluation of Interventions to Reduce Firefighter Exposures.

OBJECTIVE: Evaluate the effectiveness of firefighter exposure reduction interventions. METHODS: Fireground interventions included use of self-contained breathing apparatus by engineers, entry team wash down, contaminated equipment isolation, and personnel showering and washing of gear upon return to station. Urinary polycyclic aromatic hydrocarbon metabolites (PAH-OHs) were measured after structural fire responses before and after intervention implementation. Separately, infrared sauna use following live-fire training was compared to standard postfire care in a randomized trial. RESULTS: The fireground interventions significantly reduced mean total urinary postfire PAH-OHs in engineers (-40.4%, 95%CI -63.9%, -2.3%) and firefighters (-36.2%, 95%CI -56.7%, -6.0%) but not captains (-11.3% 95%CI -39.4%, 29.9%). Sauna treatment non-significantly reduced total mean PAH-OHs by -43.5% (95%CI -68.8%, 2.2%). CONCLUSIONS: The selected fireground interventions reduced urinary PAH-OHs in engineers and firefighters. Further evaluation of infrared sauna treatment is needed.

Assessment of the toxicity of firefighter exposures using the PAH CALUX bioassay.

Firefighters can be exposed to a complex set of contaminants while at a fire scene. Identifying new ways to monitor and assess exposure, particularly relating to toxicity is essential to determine the effectiveness of intervention techniques to reduce exposure. This study investigated the use of the polycyclic aromatic hydrocarbon (PAH) CALUX® bioassay for the assessment of exposure and associated toxicity firefighters might encounter. This was done through analysis of extracts of dermal wipes and urine samples collected from firefighters before and after a controlled fire. An increased bioassay response was observed from post-fire neck and calf samples, indicating a greater concentration of PAH-like compounds on the skin. The use of a baby wipe to clean the face and neck during rehab resulted in the attenuation of the observed bioassay response from the neck post-fire. Though a correlation was observed between the bioassay response and hydroxylated PAH concentrations found in the urine, the increased bioassay response from the post-fire urine samples was likely due to unknown compounds other than the hydroxylated PAHs tested. Our results suggest that this bioassay provides a useful measure of firefighter exposure, particularly relating to the potential toxicity of contaminants.

DEET occurrence in wastewaters: Seasonal, spatial and diurnal variability - mismatches between consumption data and environmental detection.

DEET (N, N-diethyl-m-toluamide) is one of the most frequently detected trace organic contaminants (TOrC) in wastewaters and is used primarily as an insect repellent. It was introduced for use in the general public in 1957. It is ubiquitously present in the environment and DEET concentrations are usually among the highest reported for TOrCs. Due to recent concerns about possible analytical interferences in detection methods being reported, this study focused on possible artifacts caused by seasonal, spatial, and diurnal variations in wastewater influent concentration of DEET. We also compared usage data to observed wastewater concentrations of seven wastewater treatment plants (WWTPs) in four different regions in the US monitored from November 2014 to November 2016. Consumption data obtained reveal patterns of consumption according to climatic regions and season. During the summer DEET usage accounts for almost 60% of all usage during a year, while during the winter months DEET usage accounts for <5%. Concerning spatial distribution, while per capita consumption of DEET in Florida is three times higher than the one observed in Arizona (44 g vs 14 g), DEET concentrations in wastewater tend to be much higher in Arizona. Regardless of WWTPs or monitoring period, concentrations as high as 15,200 ng/L were observed during the month of October 2016. While DEET has a diurnal variation in the wastewater influent, with a maximum at 18:00, the diurnal variability is not enough to explain the great discrepancies between consumption of DEET versus occurrence in wastewaters. Although LC-MS/MS analysis of isobaric and structural mimics suggests some possibility of interferences, NMR spectroscopy analysis of environmental samples does not support the presence of such mimics in real samples.

Formation of Haloacetonitriles, Haloacetamides, and Nitrogenous Heterocyclic Byproducts by Chloramination of Phenolic Compounds.

The potential formation of nitrogenous disinfection byproducts (N-DBPs) was investigated from the chloramination of nitrogenous and non-nitrogenous aromatic compounds. All molecules led to the formation of known N-DBPs (e.g., dichloroacetonitrile, dichloroacetamide) with various production yields. Resorcinol, a major precursor of chloroform, also formed di/trichloroacetonitrile, di/trichloroacetamide, and haloacetic acids, indicating that it is a precursor of both N-DBPs and carbonaceous DBPs (C-DBPs) upon chloramination. More detailed experiments were conducted on resorcinol to understand N-DBPs formation mechanisms and to identify reaction intermediates. Based on the accurate mass from high resolution Quadrupole Time-of-Flight GC-MS (GC-QTOF) and fragmentation patterns from electronic impact and positive chemical ionization modes, several products were tentatively identified as nitrogenous heterocyclic compounds (e.g., 3-chloro-5-hydroxy-1H-pyrrole-2-one with dichloromethyl group, 3-chloro-2,5-pyrroledione). These products were structurally similar to the heterocyclic compounds formed during chlorination, such as the highly mutagenic MX (3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone) or halogenated pyrroles. To our knowledge, this is the first time that the formation of halogenated nitrogenous heterocyclic compounds is reported from chloramination process. The formation of these nitrogenous byproducts during chloramination might be of concern considering their potential toxicity.

Sonochemical degradation of perfluorinated chemicals in aqueous film-forming foams.

Aqueous film-forming foams (AFFFs) are complex mixtures containing 1-5% w/w fluorocarbons (FCs). Here, we have investigated degradation of two commercial AFFF formulations, 3M and Ansul, using sound field at 500kHz and 1MHz, with varying initial concentrations ranging from 200 to 930× dilution. The foams were readily degraded by 1MHz, with percentage of defluorination ranging from 11.1±1.4% (200× dilution of 3M) to 47.1±5.8% (500× dilution of Ansul). Removal of total organic carbon (TOC) ranged from 16.0±1.4% (200× dilution Ansul) to 39.0±7.2% (500× dilution Ansul). Degradation of AFFF was affected by sound frequency with rates of defluorination 10-fold greater when the frequency was 1MHz than when it was 500kHz. Mineralization of TOC was 1.5- to 3.0-fold greater under 1MHz than 500kHz. Rate of fluoride release was 60% greater for the greatest initial concentration of FC in Ansul compared to the least initial concentration. While the rate of mineralization of AFFF was directly proportional to the initial concentration of Ansul, that was not the case for 3M, where the rates of mineralization were approximately the same for all three initial concentrations. Results of the study demonstrate that sonolysis is a promising technology to effectively treat AFFFs.

Attenuation of trace organic compounds (TOrCs) in bioelectrochemical systems.

Microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) are two types of microbial bioelectrochemical systems (BESs) that use microorganisms to convert chemical energy in wastewaters into useful energy products such as (bio)electricity (MFC) or hydrogen gas (MEC). These two systems were evaluated for their capacity to attenuate trace organic compounds (TOrCs), commonly found in municipal wastewater, under closed circuit (current generation) and open circuit (no current generation) conditions, using acetate as the carbon source. A biocide was used to evaluate attenuation in terms of biotransformation versus sorption. The difference in attenuation observed before and after addition of the biocide represented biotransformation, while attenuation after addition of a biocide primarily indicated sorption. Attenuation of TOrCs was similar in MFCs and MECs for eight different TOrCs, except for caffeine and trimethoprim where slightly higher attenuation was observed in MECs. Electric current generation did not enhance attenuation of the TOrCs except for caffeine, which showed slightly higher attenuation under closed circuit conditions in both MFCs and MECs. Substantial sorption of the TOrCs occurred to the biofilm-covered electrodes, but no consistent trend could be identified regarding the physico-chemical properties of the TOrCs tested and the extent of sorption. The octanol-water distribution coefficient at pH 7.4 (log DpH 7.4) appeared to be a reasonable predictor for sorption of some of the compounds (carbamazepine, atrazine, tris(2-chloroethyl) phosphate and diphenhydramine) but not for others (N,N-Diethyl-meta-toluamide). Atenolol also showed high levels of sorption despite being the most hydrophilic in the suite of compounds studied (log DpH 7.4 = -1.99). Though BESs do not show any inherent advantages over conventional wastewater treatment, with respect to TOrC removal, overall removals in BESs are similar to that reported for conventional wastewater systems, implying the possibility of using BESs for energy production in wastewater treatment without adversely impacting TOrC attenuations.

Start-up performance of a full-scale riverbank filtration site regarding removal of DOC, nutrients, and trace organic chemicals.

The performance of a full-scale riverbank filtration facility in Colorado was evaluated from initial start-up over a period of seven years including the impact of seasonal variations to determine whether sustainable attenuation of various chemical constituents could be achieved. Both, annual and seasonal average concentrations were determined for several wastewater-derived constituents including dissolved organic carbon (DOC), ultraviolet absorbance at 254 nm, nitrate, phosphate for the years 2006, 2009, 2010, 2012, and trace organic chemicals (TOrC) for years 2009, 2010, and 2012. ANOVA analyses and Student's t-tests were performed to evaluate the consistency of contaminant attenuation at the site. Findings revealed no significant statistical differences for any of the bulk parameters with the exception of phosphate suggesting a highly reliable attenuation of DOC and nitrate from start-up to full-scale performance. Phosphate attenuation, however, exhibited a steady decline, which was likely attributed to exhaustion of sorption sites in the subsurface porous media. The river's flow regime influenced both occurrence levels and attenuation of TOrC during riverbank filtration, i.e. less river discharge resulted in higher TOrC concentrations and lower proportion of river water in the recovered groundwater. Differences in removal performance between annual data sets for caffeine, trimethoprim, sulfamethoxazole, and carbamazepine were caused by variations in the source; concentrations in riverbank filtrate remained similar over several years. The seasonal assessment for TOrC revealed steady or improving removal between winter and summer seasons based on the statistical analysis with atenolol being the only exception likely due to an increased microbial activity at elevated temperatures.

The occurrence of emerging trace organic chemicals in wastewater effluents in Saudi Arabia.

Emerging trace organic chemicals (TOrCs) released into the environment via discharge of wastewater effluents have been detected in rivers and lakes worldwide, raising concerns due to their potential persistence, toxicity and bioaccumulation. This study provides the first reconnaissance of TOrC occurrence in wastewater effluents within Saudi Arabia. Four wastewater treatment plants (WWTPs 1-4) located in Western Saudi Arabia were sampled hourly over twelve-hour periods, for a total of six sampling events. All samples were analyzed for a wide range of TOrC encompassing pharmaceuticals, personal care products and household chemicals. Treatment and capacities of the plants varied from non-nitrifying to full biological nutrient removal providing a representative cross section of different types of plants operational within the country. A comparison of TOrC occurrence in effluents in Saudi Arabia with respective effluent qualities in the United States revealed similar levels for most TOrC. Overall, the occurrence of TOrC was higher at two of the plants. The higher TOrC concentrations at WWTP 1 are likely due to the non-nitrifying biological treatment process. The unique TOrC occurrence observed in the WWTP 3 effluent was unlike any other plant and was attributed to the influence of a large number of international visitors in its sewershed. The occurrence of TOrC in this plant was not expected to be representative of the occurrence elsewhere in the country. Bimodal diurnal variation expected for a range of TOrC was not observed, though some hourly variation in TOrC loading was noted for WWTP 3. Since water reclamation and reuse have received increasing interest in Saudi Arabia within the last few years, results from this study provide a good foundation in deciding whether advanced treatment is necessary to attenuate TOrC deemed to be of concern in effluents, or if natural treatment such as managed aquifer recharge provides sufficient protection to public health.

Results of an interlaboratory comparison of analytical methods for contaminants of emerging concern in water.

An evaluation of existing analytical methods used to measure contaminants of emerging concern (CECs) was performed through an interlaboratory comparison involving 25 research and commercial laboratories. In total, 52 methods were used in the single-blind study to determine method accuracy and comparability for 22 target compounds, including pharmaceuticals, personal care products, and steroid hormones, all at ng/L levels in surface and drinking water. Method biases ranged from <10% to well over 100% in both matrixes, suggesting that while some methods are accurate, others can be considerably inaccurate. In addition, the number and degree of outliers identified suggest a high degree of variability may be present between methods currently in use. Three compounds, ciprofloxacin, 4-nonylphenol (NP), and 4-tert-octylphenol (OP), were especially difficult to measure accurately. While most compounds had overall false positive rates of ≤5%, bisphenol A, caffeine, NP, OP, and triclosan had false positive rates >15%. In addition, some methods reported false positives for 17ß-estradiol and 17α-ethynylestradiol in unspiked drinking water and deionized water, respectively, at levels higher than published predicted no-effect concentrations for these compounds in the environment. False negative rates were also generally <5%; however, rates were higher for the steroid hormones and some of the more challenging compounds, such as ciprofloxacin. The elevated false positive/negative rates of some analytes emphasize the susceptibility of many current methods to blank contamination, misinterpretation of background interferences, and/or inappropriate setting of detection/quantification levels for analysis at low ng/L levels. The results of both comparisons were collectively assessed to identify parameters that resulted in the best overall method performance. Liquid chromatography-tandem mass spectrometry coupled with the calibration technique of isotope dilution were able to accurately quantify most compounds with an average bias of <10% for both matrixes. These findings suggest that this method of analysis is suitable at environmentally relevant levels for most of the compounds studied. This work underscores the need for robust, standardized analytical methods for CECs to improve data quality, increase comparability between studies, and help reduce false positive and false negative rates.

The role of microbial adaptation and biodegradable dissolved organic carbon on the attenuation of trace organic chemicals during groundwater recharge.

It is widely recognized that efficient biological attenuation of bulk organic matter and trace organic chemicals (TOrC) can occur in managed aquifer recharge (MAR) systems receiving reclaimed water. The heterotrophic microbial activity in these subsurface systems is a function of the availability of biodegradable dissolved organic carbon (BDOC) present in reclaimed water. This study examined the influence of environmental factors, such as BDOC-rich (>1.6 mg/L) and BDOC-starving (<1mg/L) conditions and microbial adaptation, on the attenuation of TOrC, including clofibric acid, dichlorprop, gemfibrozil, ibuprofen, ketoprofen, mecoprop, and naproxen, within soil-columns mimicking groundwater recharge. Under conditions that were characterized by a lack of BDOC and a biocommunity that was not yet adapted to these conditions, attenuation of biodegradable TOrC was less than 15%. After a three-month adaptation period, biotransformation increased to more than 80% for the biodegradable TOrC. This suggests that adaptation likely initiates enzyme expressions that eventually results in TOrC transformations even under seemingly less favorable conditions (i.e., lack of biodegradable carbon). For both non-adapted (stressed) and adapted conditions in the presence of higher concentrations of BDOC and travel times of 7 days, the degree of biotransformation was variable across compounds but generally exceeded 25%. This suggests that BDOC above a minimum level (>1.6 mg/L) can provide favorable microbial conditions resulting in TOrC removal, even for non-adapted systems. However, it is noteworthy that adapted MAR systems that were fed with low BDOC levels performed similarly or better with respect to TOrC biotransformation than systems that received BDOC levels above 1.6 mg/L. These findings are important for field-scale applications. They suggest that MAR facilities that are microbiologically active and are fed with highly treated water with effluent concentrations of less than 1 mg/L (i.e., nanofiltration permeate) can still attenuate biodegradable TOrC.

Dissolved organic carbon influences microbial community composition and diversity in managed aquifer recharge systems.

This study explores microbial community structure in managed aquifer recharge (MAR) systems across both laboratory and field scales. Two field sites, the Taif River (Taif, Saudi Arabia) and South Platte River (Colorado), were selected as geographically distinct MAR systems. Samples derived from unsaturated riverbed, saturated-shallow-infiltration (depth, 1 to 2 cm), and intermediate-infiltration (depth, 10 to 50 cm) zones were collected. Complementary laboratory-scale sediment columns representing low (0.6 mg/liter) and moderate (5 mg/liter) dissolved organic carbon (DOC) concentrations were used to further query the influence of DOC and depth on microbial assemblages. Microbial density was positively correlated with the DOC concentration, while diversity was negatively correlated at both the laboratory and field scales. Microbial communities derived from analogous sampling zones in each river were not phylogenetically significantly different on phylum, class, genus, and species levels, as determined by 16S rRNA gene pyrosequencing, suggesting that geography and season exerted less sway than aqueous geochemical properties. When field-scale communities derived from the Taif and South Platte River sediments were grouped together, principal coordinate analysis revealed distinct clusters with regard to the three sample zones (unsaturated, shallow, and intermediate saturated) and, further, with respect to DOC concentration. An analogous trend as a function of depth and corresponding DOC loss was observed in column studies. Canonical correspondence analysis suggests that microbial classes Betaproteobacteria and Gammaproteobacteria are positively correlated with DOC concentration. Our combined analyses at both the laboratory and field scales suggest that DOC may exert a strong influence on microbial community composition and diversity in MAR saturated zones.

Attenuation of total organic carbon and unregulated trace organic chemicals in U.S. riverbank filtration systems.

There is increasing concern regarding the presence of unregulated trace organic chemicals in drinking water supplies that receive discharge from municipal wastewater treatment plants. In comparison to conventional and advanced drinking water treatment, riverbank filtration represents a low-cost and low-energy alternative that can attenuate total organic carbon (TOC) as well as trace organic chemicals (TOrC). This study examined the role of predominant redox conditions, retention time, biodegradable organic carbon, and temperature to achieve attenuation of TOC and TOrC through monitoring efforts at three full-scale RBF facilities in different geographic areas of the United States. The RBF systems investigated in this study were able to act as a reliable barrier for TOC, nitrogen, and certain TOrC. Temperature (seasonal) variation played an important role for the make-up of the river water quality and performance of the RBF systems. Temperatures of less than 10 degrees C did not affect TOC removal but resulted in diminished attenuation of nitrate and select TOrC.