Characterization of 1,4-dioxane degrading microbial community enriched from uncontaminated soil.

1,4-Dioxane is a contaminant of emerging concern that has been commonly detected in groundwater. In this study, a stable and robust 1,4-dioxane degrading enrichment culture was obtained from uncontaminated soil. The enrichment was capable to metabolically degrade 1,4-dioxane at both high (100 mg L-1) and environmentally relevant concentrations (300 µg L-1), with a maximum specific 1,4-dioxane degradation rate (qmax) of 0.044 ± 0.001 mg dioxane h-1 mg protein-1, and 1,4-dioxane half-velocity constant (Ks) of 25 ± 1.6 mg L-1. The microbial community structure analysis suggested Pseudonocardia species, which utilize the dioxane monooxygenase for metabolic 1,4-dioxane biodegradation, were the main functional species for 1,4-dioxane degradation. The enrichment culture can adapt to both acidic (pH 5.5) and alkaline (pH 8) conditions and can recover degradation from low temperature (10°C) and anoxic (DO < 0.5 mg L-1) conditions. 1,4-Dioxane degradation of the enrichment culture was reversibly inhibited by TCE with concentrations higher than 5 mg L-1 and was completely inhibited by the presence of 1,1-DCE as low as 1 mg L-1. Collectively, these results demonstrated indigenous stable and robust 1,4-dioxane degrading enrichment culture can be obtained from uncontaminated sources and can be a potential candidate for 1,4-dioxane bioaugmentation at environmentally relevant conditions. KEY POINTS: •1,4-Dioxane degrading enrichment was obtained from uncontaminated soil. • The enrichment culture could degrade 1,4-dioxane to below 10 µg L-1. •Low Ks and low cell yield of the enrichment benefit its application in bioremediation.

The Need for Testing Isomer Profiles of Perfluoroalkyl Substances to Evaluate Treatment Processes.

Many environmentally relevant poly-/perfluoroalkyl substances (PFASs) including perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) exist in different isomeric (branched and linear) forms in the natural environment. The isomeric distribution of PFASs in the environment and source waters is largely controlled by the source of contamination and varying physicochemical properties imparted by their structural differences. For example, branched isomers of PFOS are relatively more reactive and less sorptive compared to the linear analogue. As a result, the removal of branched and linear PFASs during water treatment can vary, and thus the isomeric distribution in source waters can influence the overall efficiency of the treatment process. In this paper, we highlight the need to consider the isomeric distribution of PFASs in contaminated matrices while designing appropriate remediation strategies. We additionally summarize the known occurrence and variation in the physicochemical properties of PFAS isomers influencing their detection, fate, toxicokinetics, and treatment efficiency.

Microbial generation of elemental mercury from dissolved methylmercury in seawater.

Elemental mercury (Hg0) formation from other mercury species in seawater results from photoreduction and microbial activity, leading to possible evasion from seawater to overlying air. Microbial conversion of monomethylmercury (MeHg) to Hg0 in seawater remains unquantified. A rapid radioassay method was developed using gamma-emitting 203Hg as a tracer to evaluate Hg0 production from Hg(II) and MeHg in the low pM range. Bacterioplankton assemblages in Atlantic surface seawater and Long Island Sound water were found to rapidly produce Hg0, with production rate constants being directly related to bacterial biomass and independent of dissolved Hg(II) and MeHg concentrations. About 32% of Hg(II) and 19% of MeHg were converted to Hg0 in 4 d in Atlantic surface seawater containing low bacterial biomass, and in Long Island Sound water with higher bacterial biomass, 54% of Hg(II) and 8% of MeHg were transformed to Hg0. Decreasing temperatures from 24°C to 4°C reduced Hg0 production rates cell-1 from Hg(II) 3.3 times as much as from a MeHg source. Because Hg0 production rates were linearly related to microbial biomass and temperature, and microbial mercuric reductase was detected in our field samples, we inferred that microbial metabolic activities and enzymatic reactions primarily govern Hg0 formation in subsurface waters where light penetration is diminished.

Bioaccumulation of methylmercury in a marine diatom and the influence of dissolved organic matter.

The largest bioconcentration step of most metals, including methylmercury (MeHg), in aquatic biota is from water to phytoplankton, but the extent to which dissolved organic matter (DOM) affects this process for MeHg largely remains unexplored in marine systems. This study investigated the influence of specific sulfur-containing organic compounds and naturally occurring DOM on the accumulation of MeHg in a marine diatom Thalassiosira pseudonana. Initial uptake rate constants and volume concentration factors (VCFs) of MeHg were calculated to evaluate MeHg enrichment in algal cells in the presence of a range of organic compound concentrations. At environmentally realistic and higher concentrations, the addition of glycine and methionine had no effect on algal MeHg uptake, but thiol-containing compounds such as cysteine and thioglycolic acid reduced MeHg accumulation in algal cells at high added concentrations (> 100 times higher than naturally occurring concentrations). However, environmentally realistic concentrations of glutathione, another thiol-containing compound as low as 10 nM, resulted in a decline of ~ 30% in VCFs, suggesting its possible importance in natural waters. Humic acid additions of 0.1 and 0.5 mg C/L also reduced MeHg VCFs by ~ 15% and ~ 25%, respectively. The bioaccumulation of MeHg for T. pseudonana in coastal waters with varying levels of dissolved organic carbon (DOC) was inversely correlated with bulk DOC concentrations. Generally, naturally occurring DOM, particularly certain thiol-containing compounds, can reduce MeHg uptake by phytoplankton.

Methylmercury uptake by diverse marine phytoplankton.

Phytoplankton may serve as a key entry for methylmercury (MeHg) into aquatic food webs however very few studies have quantified the bioconcentration of MeHg in marine phytoplankton from seawater, particularly for non-diatoms. Experiments using 203Hg to measure MeHg uptake rates and concentration factors in six marine phytoplankton species belonging to different algal classes were conducted and the influence of light, temperature, and nutrient conditions on MeHg bioaccumulation were determined. All algal species greatly concentrated MeHg out of seawater, with volume concentration factors (VCFs) ranging from 0.2 × 105 to 6.4 × 106. VCFs were directly related to cellular surface area-to-volume ratios. Most of the cellular MeHg was found in the cytoplasm. Temperature, light, and nutrient additions did not directly affect MeHg uptake in most species, with the exception that the dinoflagellate Prorocentrum minimum displayed significantly greater uptake per cell at 18°C than at 4°C, suggesting an active uptake for this species. Passive transport seemed to be the major pathway for most phytoplankton to acquire MeHg and was related to the surface area-to-volume ratio of algal cells. Environmental conditions that promoted cell growth resulted in more total MeHg associated with cells, but with lower concentrations per unit biomass due to biodilution. The very high bioconcentration of MeHg in marine phytoplankton is by far the largest bioconcentration step in marine food chains and variations in algal uptake may account for differences in the amount of MeHg that ultimately builds up in different marine ecosystems.

Declining Mercury Concentrations in Bluefin Tuna Reflect Reduced Emissions to the North Atlantic Ocean.

Tunas are apex predators in marine food webs that can accumulate mercury (Hg) to high concentrations and provide more Hg (∼40%) to the U.S population than any other source. We measured Hg concentrations in 1292 Atlantic bluefin tuna (ABFT, Thunnus thynnus) captured in the Northwest Atlantic from 2004 to 2012. ABFT Hg concentrations and variability increased nonlinearly with length, weight, and age, ranging from 0.25 to 3.15 mg kg-1, and declined significantly at a rate of 0.018 ± 0.003 mg kg-1 per year or 19% over an 8-year period from the 1990s to the early 2000s. Notably, this decrease parallels comparably reduced anthropogenic Hg emission rates in North America and North Atlantic atmospheric Hg0 concentrations during this period, suggesting that recent efforts to decrease atmospheric Hg loading have rapidly propagated up marine food webs to a commercially important species. This is the first evidence to suggest that emission reduction efforts have resulted in lower Hg concentrations in large, long-lived fish.

Cationic surfactant-assisted foam fractionation enhances the removal of short-chain perfluoroalkyl substances from impacted water.

Several studies have demonstrated that air-bubbling and foam fractionation techniques can efficiently remove long-chain PFAS from contaminated water. However, removing short-chain PFAS is challenging due to its lower surface activity and inability to form self-assembly structures at the air-water interface. In this study, we tested various additives, including salts, surfactants, and polymers, to improve short-chain PFAS (e.g., perfluorobutanesulfonic acid (PFBS) and perfluorobutanoic acid (PFBA)) removal in non-foaming solutions using a bench-scale system. We found that in the presence of cetyltrimethylammonium chloride (CTAC) and salt, air-bubbling can significantly remove 0.5 µg L-1 of PFBS and PFBA in deionized water by >99% (15 min) and 81% (60 min), respectively. The decline of surface tension and the formation of thin foam-like layers during bubbling, controlled by the concentration of CTAC, significantly improved the removal of short-chain PFAS. Adding anionic and neutral surfactants showed no removal of short-chain PFAS during bubbling, suggesting the importance of the electrostatic interactions between short-chain PFAS and the cationic CTAC. We observed a 1:1 M ratio between CTAC and PFBS removed from the solution, suggesting the formation of ion pairs in the solution and enhancing the surface activity of the overall neutral (PFAS-CTAC) complex. A mass balance of the system revealed that the primary mechanism by which PFAS was removed from non-foaming waters was through aerosol generation (70-100%). Using the optimized condition, PFAS mixtures (short- and long-chain PFAS, including five recently regulated PFAS by USPEA, 2 nM each) in deionized water and natural groundwater were successfully removed to below detection (>99% removal; <2 ng L-1), except for PFBA (25-73% removal). These results provide an improved understanding of the mechanism by which PFAS is removed during foam fractionation and highlight the need for capturing aerosols enriched with PFAS to prevent secondary contamination.

Application of electron beam technology to decompose per- and polyfluoroalkyl substances in water.

The widespread detection of per- and polyfluoroalkyl substances (PFAS) in environmental compartments across the globe has raised several health concerns. Destructive technologies that aim to transform these recalcitrant PFAS into less toxic, more manageable products, are gaining impetus to address this problem. In this study, a 9 MeV electron beam accelerator was utilized to treat a suite of PFAS (perfluoroalkyl carboxylates: PFCAs, perfluoroalkyl sulfonates, and 6:2 fluorotelomer sulfonate: FTS) at environmentally relevant levels in water under different operating and water quality conditions. Although perfluorooctanoic acid and perfluorooctane sulfonic acid showed >90% degradation at <500 kGy dose at optimized conditions, a fluoride mass balance revealed that complete defluorination occurred only at/or near 1000 kGy. Non-target and suspect screening revealed additional degradation pathways differing from previously reported mechanisms. Treatment of PFAS mixtures in deionized water and groundwater matrices showed that FTS was preferentially degraded (∼90%), followed by partial degradation of long-chain PFAS (∼15-60%) and a simultaneous increase of short-chain PFAS (up to 20%) with increasing doses. The increase was much higher (up to 3.5X) in groundwaters compared to deionized water due to the presence of PFAS precursors as confirmed by total oxidizable precursor (TOP) assay. TOP assay of e-beam treated samples did not show any increase in PFCAs, confirming that e-beam was effective in also degrading precursors. This study provides an improved understanding of the mechanism of PFAS degradation and revealed that short-chain PFAS are more resistant to defluorination and their levels and regulation in the environment will determine the operating conditions of e-beam and other PFAS treatment technologies.

1,4-Dioxane removal in nitrifying sand filters treating domestic wastewater: Influence of water matrix and microbial inhibitors.

1,4-Dioxane is a recalcitrant pollutant in water and is ineffectively removed during conventional water and wastewater treatment processes. In this study, we demonstrate the application of nitrifying sand filters to remove 1,4-dioxane from domestic wastewater without the need for bioaugmentation or biostimulation. The sand columns were able to remove 61 ± 10% of 1,4-dioxane on average (initial concentration: 50 µg/L) from wastewater, outperforming conventional wastewater treatment approaches. Microbial analysis revealed the presence of 1,4-dioxane degrading functional genes (dxmB, phe, mmox, and prmA) to support biodegradation being the dominant degradation pathway. Adding antibiotics (sulfamethoxazole and ciprofloxacin), that temporarily inhibited the nitrification process during the dosing period, showed a minor effect in 1,4-dioxane removal (6-8% decline, p < 0.05), suggesting solid resilience of the 1,4-dioxane-degrading microbial community in the columns. Columns amended with sodium azide significantly (p < 0.05) depressed 1,4-dioxane removal in the early stage of dosing but followed by a gradual increase of the removal over time to >80%, presumably due to a shift in the microbial community toward azide-resistant 1,4-dioxane degrading microbes (e.g., fungi). This study demonstrated for the first time the resilience of the 1,4-dioxane-degrading microorganisms during antibiotic shocks, and the selective enrichment of efficient 1,4-dioxane-degrading microbes after azide poisoning. Our observation could provide insights into designing better 1,4-dioxane remediation strategies in the future.

Sodium Alginate-Aldehyde Cellulose Nanocrystal Composite Hydrogel for Doxycycline and Other Tetracycline Removal.

A novel composite hydrogel bead composed of sodium alginate (SA) and aldehyde cellulose nanocrystal (DCNC) was developed for antibiotic remediation through a one-step cross-linking process in a calcium chloride bath. Structural and physical properties of the hydrogel bead, with varying composition ratios, were analyzed using techniques such as BET analysis, SEM imaging, tensile testing, and rheology measurement. The optimal composition ratio was found to be 40% (SA) and 60% (DCNC) by weight. The performance of the SA-DCNC hydrogel bead for antibiotic remediation was evaluated using doxycycline (DOXY) and three other tetracyclines in both single- and multidrug systems, yielding a maximum adsorption capacity of 421.5 mg g-1 at pH 7 and 649.9 mg g-1 at pH 11 for DOXY. The adsorption mechanisms were investigated through adsorption studies focusing on the effects of contact time, pH, concentration, and competitive contaminants, along with X-ray photoelectron spectroscopy analysis of samples. The adsorption of DOXY was confirmed to be the synergetic effects of chemical reaction, electrostatic interaction, hydrogen bonding, and pore diffusion/surface deposition. The SA-DCNC composite hydrogel demonstrated high reusability, with more than 80% of its adsorption efficiency remaining after five cycles of the adsorption-desorption test. The SA-DCNC composite hydrogel bead could be a promising biomaterial for future antibiotic remediation applications in both pilot and industrial scales because of its high adsorption efficiency and ease of recycling.

Monitoring of over-the-counter (OTC) and COVID-19 treatment drugs complement wastewater surveillance of SARS-CoV-2.

BACKGROUND: The application of wastewater-based epidemiology to track the outbreak and prevalence of coronavirus disease (COVID-19) in communities has been tested and validated by several researchers across the globe. However, the RNA-based surveillance has its inherent limitations and uncertainties. OBJECTIVE: This study aims to complement the ongoing wastewater surveillance efforts by analyzing other chemical biomarkers in wastewater to help assess community response (hospitalization and treatment) during the pandemic (2020-2021). METHODS: Wastewater samples (n = 183) were collected from the largest wastewater treatment facility in Suffolk County, NY, USA and analyzed for COVID-19 treatment drugs (remdesivir, chloroquine, and hydroxychloroquine (HCQ)) and their human metabolites. We additionally monitored 26 pharmaceuticals including common over-the-counter (OTC) drugs. Lastly, we developed a Bayesian model that uses viral RNA, COVID-19 treatment drugs, and pharmaceuticals data to predict the confirmed COVID-19 cases within the catchment area. RESULTS: The viral RNA levels in wastewater tracked the actual COVID-19 case numbers well as expected. COVID-19 treatment drugs were detected with varying frequency (9-100%) partly due to their instability in wastewater. We observed a significant correlation (R = 0.30, p < 0.01) between the SARS-CoV-2 genes and desethylhydroxychloroquine (DHCQ, metabolite of HCQ). Remdesivir levels peaked immediately after the Emergency Use Authorization approved by the FDA. Although, 13 out of 26 pharmaceuticals assessed were consistently detected (DF = 100%, n = 111), only acetaminophen was significantly correlated with viral loads, especially when the Omicron variant was dominant. The Bayesian models were capable of reproducing the temporal trend of the confirmed cases. IMPACT: In this study, for the first time, we measured COVID-19 treatment and pharmaceutical drugs and their metabolites in wastewater to complement ongoing COVID-19 viral RNA surveillance efforts. Our results highlighted that, although the COVID-19 treatment drugs were not very stable in wastewater, their detection matched with usage trends in the community. Acetaminophen, an OTC drug, was significantly correlated with viral loads and confirmed cases, especially when the Omicron variant was dominant. A Bayesian model was developed which could predict COVID-19 cases more accurately when incorporating other drugs data along with viral RNA levels in wastewater.

Associations between total mercury, trace minerals, and blood health markers in Northwest Atlantic white sharks (Carcharodon carcharias).

The ecology and life-histories of white sharks make this species susceptible to mercury bioaccumulation; however, the health consequences of mercury exposure are understudied. We measured muscle and plasma total mercury (THg), health markers, and trace minerals in Northwest Atlantic white sharks. THg in muscle tissue averaged 10.0 mg/kg dry weight, while THg in blood plasma averaged 533 µg/L. THg levels in plasma and muscle were positively correlated with shark precaudal length (153-419 cm), and THg was bioaccumulated proportionally in muscle and plasma. Nine sharks had selenium:mercury molar ratios in blood plasma >1.0, indicating that for certain individuals the potential protective effects of the trace mineral were diminished, whereas excess selenium may have protected other individuals. No relationships between plasma THg and any trace minerals or health markers were identified. Thus, we found no evidence of negative effects of Hg bioaccumulation, even in sharks with very high THg.

Hydroxyl-radical based advanced oxidation processes can increase perfluoroalkyl substances beyond drinking water standards: Results from a pilot study.

Advanced oxidation processes (AOPs) are popular technologies employed across the U.S. for wastewater reclamation and drinking water treatment of recalcitrant chemicals. Although there is consensus about the ineffectiveness of AOPs to treat perfluoroalkyl substances (PFASs; not polyfluoro compounds by definition here), there is a lack of field data demonstrating their impact on the transformation of unknown PFAS precursors during groundwater treatment. In this study, the fate of PFASs in seven pilot-scale AOPs, including four different technologies (UV/H2O2, UV/Cl2, UV/TiO2, and O3/H2O2), was assessed at four drinking water systems across New York State (NYS), USA. Seven of 18 PFASs were detected in the influent at concentrations ranging from below method detection to 64 ng/L. Across all systems, all detected PFASs showed an increase in concentration after treatment presumably due to unknown precursor transformation with specific increases for perfluorobutane sulfonate (PFBS), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorohexane sulfonate (PFHxS), perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and perfluorononanoic acid (PFNA) averaging 405 (range: 0 - 1220) %, 1.0 (-7 - 9) %, 3.8 (0 - 9.5) %, 3.3 (-11 - 13) %, 14 (0 - 48) %, 13 (3 - 25) %, and 2 (0 - 5.2) %, respectively. The increase in PFAS concentration was dependent on UV and oxidant dose, further confirming that transformation reactions were occurring due to AOPs similar to a total oxidizable precursor assay. At one of the sites, PFOA levels exceeded the current NYS drinking water standard of 10 ng/L after, but not before treatment, highlighting the importance of considering the potential impact of AOP on treated water quality when designing treatment systems for regulatory compliance. The increase in PFAS concentration in the AOP systems positively correlated (r = 0.91) with nitrate levels in groundwater, suggesting that onsite septic discharges may be an important source of PFAS contamination in these unsewered study areas. Results from this pilot-scale demonstration reveal that hydroxyl radical-based AOPs, although ineffective in treating PFASs, can help to reveal the true extent of PFAS contamination in source waters.

Risk assessment for seafood consumers exposed to mercury and other trace elements in fish from Long Island, New York, USA.

We determined concentrations of Hg, Pb, Cd, Cr, As, Ni, Ag, Se, Cu, and Zn in muscle tissue of six commonly consumed Long Island fish species (black seabass, bluefish, striped bass, summer flounder, tautog, and weakfish, total sample size = 1211) caught off Long Island, New York in 2018 and 2019. Long-term consumption of these coastal fish could pose health risks largely due to Hg exposure; concentrations of the other trace elements were well below levels considered toxic for humans. By combining the measured Hg concentrations in the fish (means ranging from 0.11 to 0.27 mg/kg among the fish species), the average seafood consumption rate, and the current US EPA Hg reference dose (0.0001 mg/kg/d), it was concluded that seafood consumption should be limited to four fish meals per month for adults for some fish (bluefish, tautog) and half that for young children. Molar ratios of Hg:Se exceeded 1 for some black seabass, bluefish, tautog, and weakfish.

The invasive red seaweed, Dasysiphonia japonica, forms harmful algal blooms: Mortality in early life stage fish and bivalves and identification of putative toxins.

In recent decades, the rate of introduction of non-indigenous macroalgae has increased. While invasive seaweeds often outcompete native species for substrata, their direct effects on marine life are rarely described. Here, we describe 'red water' events caused by the decay of blooms of the invasive red seaweed, Dasysiphonia japonica, in Great South Bay, NY, USA, and the ability of water from such events to induce rapid and significant mortality in larval and juvenile fish (Menidia beryllina, Menidia menidia, and Cyprinodon variegatus) and larval bivalves (Mercenaria mercenaria and Crassostrea virginica). All species studied experienced significant (p<0.05) reductions in survival when exposed to macroalgae in a state of decay, seawater in which the alga was previously decayed, or both. Both bivalve species experienced 50-60% increases in mortality when exposed to decaying D. japonica for ∼ one week, despite normoxic conditions. Among fish, significant increases (40-80%) in mortality were observed after 24 h exposure to decayed D. japonica and one-week exposures caused, on average, 90% mortality in larval M. beryllina, 50% mortality in juvenile (∼3 cm) M. menidia, and 50% mortality in larval C. variegatus. All fish and bivalve mortality occurred under normoxic conditions (dissolved oxygen (DO) >7 mg L-1) and low ammonium levels (< 20 µM), with the exception of C. variegatus, which expired under conditions of decayed D. japonica coupled with reduced DO caused by the alga. Screening of water with decayed D. japonica using liquid chromatography-mass spectrometry revealed compounds with mass-to-charge ratios matching caulerpin, a known algal toxin that causes fish and shellfish mortality, and several other putative toxicants at elevated levels. Collectively, the high levels of mortality (50-90%) of larval and juvenile fish and bivalves exposed to decaying D. japonica under normoxic conditions coupled with the observation of 'red water' events in estuaries collectively indicate the red seaweed, D. japonica, can create harmful algal blooms (HABs).

Effects of methylmercury on the early life stages of an estuarine forage fish using two different dietary sources.

Marine fish accumulate methylmercury (MeHg) to elevated concentrations, often higher than in freshwater systems. As a neurotoxic compound, high MeHg tissue concentrations could affect fish behavior which in turn could affect their populations. We examined the sublethal effects of MeHg on larvae of the Sheepshead minnow (Cyprinodon variegatus), an estuarine fish, using artificial or natural diets with varying MeHg concentrations (0-4.8 ppm). Larvae were fed control and MeHg-contaminated diets at low or normal (10% of their body mass) daily food rations from 7 to 29 days when they reached juvenile stage. Growth, respiration, swimming activity and prey capture ability were assessed. Food ration affected Hg toxicity in our study. Natural diets containing 3.2 ppm MeHg had no impacts on growth and swimming in fish that were fed normal food rations but depressed growth and swimming at low food rations. MeHg toxicity did not differ between artificial and natural foods, however fish accumulated more MeHg from the former. Artificial food containing 4.8 ppm MeHg only affected prey capture after 21 days of exposure. Sheepshead minnows, a forage fish species occupying a low trophic level in coastal waters, can be MeHg tolerant, especially when food is abundant, and can serve as an enriched Hg source for higher trophic level predators.

Occurrence and removal of PPCPs from on-site wastewater using nitrogen removing biofilters.

The presence of pharmaceuticals and personal care products (PPCPs) in the environment is primarily the result of discharge of waste, including from onsite wastewater treatment systems (OWTSs) which are employed by 25% of homes in the United States. However, the occurrence and removal of PPCPs in OWTSs is not well understood, particularly given the large diversity in PPCP compounds as well as in OWTS designs. In this study, we monitored 26 different PPCPs in 13 full-scale nitrogen removing biofilters (NRBs), an innovative/alternative type of OWTS that utilizes an overlying sand layer and an underlying woodchip/sand layer to simultaneously remove nitrogen and other wastewater-derived contaminants. The specific objectives of this study were (i) to measure the occurrence of PPCPs in septic tank effluent (STE) that served as an influent to NRBs, (ii) to quantify PPCP removal in three types of NRB configurations (n = 13), and (iii) to evaluate PPCP removal with depth and environmental conditions in NRBs. Aqueous samples were taken during 42 separate sampling events during 2016 - 2019 and analyzed by liquid chromatography tandem mass spectrometry. Analysis of the STE samples yielded detection of 23 of the 26 PPCPs, with caffeine being the most abundant and frequently detected compound at 52,000 ng/L (range: 190 - 181,000 ng/L), followed by acetaminophen and paraxanthine at 47,500 ng/L (190 - 160,000 ng/L), and 34,300 ng/L (430 - 210,000 ng/L), respectively. Cimetidine, fenofibrate, and warfarin were the only compounds not detected. The average removal of PPCPs by NRBs ranged from 58% to >99% for the various compounds. PPCP removal as a function of depth in the systems showed that 50 to >99% of the observed removal was achieved within the top oxic layer (0 - 46 cm) of the NRBs for 19 analytes. Seven of the compounds had >85% removal by the same depth. These results indicate that NRBs are effective at removing PPCPs and that a large portion of the removal is achieved within the oxic nitrifying layer of the NRBs. Overall, the removal of PPCPs in NRBs was comparable (n = 8) or better (n = 15) than that observed for conventional wastewater treatment plants.

Removal of 1,4-dioxane during on-site wastewater treatment using nitrogen removing biofilters.

The presence and release of 1,4-dioxane to groundwater from onsite-wastewater treatment systems (OWTS), which represent 25% of the total wastewater treatment in the U.S., has not been studied to date. In this study we monitored 1,4-dioxane in six septic tank effluents (STE) and receiving OWTS installed at residences on Long Island (LI), NY, for a period of 15 months. We specifically evaluated the performance of Nitrogen Removing Biofilters (NRBs) as an innovative/alternative-OWTS, consisting of a top sand layer and a bottom woodchip/sand layer, to simultaneously remove nitrogen and 1,4-dioxane. 1,4-Dioxane levels in STE (mean: 1.49 µg L-1; range: 0.07-8.45 µg L-1; n = 37) were on average > 15 times higher than tap water from these residences, demonstrating that 1,4-dioxane primarily originated from the use of household products. NRBs were effective in removing both 1,4-dioxane and total nitrogen with an overall removal efficiency of 56 ± 20% and 88 ± 12%, respectively. The majority of 1,4-dioxane removal (~80%) occurred in the top oxic layer of the NRBs. The detection of functional genes (dxmB, prmA, and thmA), which encode for metabolic and co-metabolic 1,4-dioxane degradation, in NRBs provides the first field evidence of aerobic microbial degradation of 1,4-dioxane occurring in a wastewater system. Given that there are ~500,000 conventional OWTS on LI, the 1,4-dioxane discharge to groundwater from residential wastewater was estimated at 195 ± 205 kg yr -1, suggesting high risk of contamination to shallow aquifers. The results also demonstrate that installation of NRBs can reduce 1,4-dioxane to levels even lower than the NY State drinking water standard of 1 µg L-1.

Metal concentrations in coastal sharks from The Bahamas with a focus on the Caribbean Reef shark.

Over the last century anthropogenic activities have rapidly increased the influx of metals and metalloids entering the marine environment, which can bioaccumulate and biomagnify in marine top consumers. This may elicit sublethal effects on target organisms, having broad implications for human seafood consumers. We provide the first assessment of metal (Cd, Pb, Cr, Mn, Co, Cu, Zn, As, Ag, and THg) and metalloid (As) concentrations in the muscle tissue of coastal sharks from The Bahamas. A total of 36 individual sharks from six species were evaluated, spanning two regions/study areas, with a focus on the Caribbean reef shark (Carcharhinus perezi), and to a lesser extent the tiger shark (Galeocerdo cuvier). This is due their high relative abundance and ecological significance throughout coastal Bahamian and regional ecosystems. Caribbean reef sharks exhibited some of the highest metal concentrations compared to five other species, and peaks in the concentrations of Pb, Cr, Cu were observed as individuals reached sexual maturity. Observations were attributed to foraging on larger, more piscivorous prey, high longevity, as well a potential slowing rate of growth. We observed correlations between some metals, which are challenging to interpret but may be attributed to trophic level and ambient metal conditions. Our results provide the first account of metal concentrations in Bahamian sharks, suggesting individuals exhibit high concentrations which may potentially cause sublethal effects. Finally, these findings underscore the potential toxicity of shark meat and have significant implications for human consumers.

Impact of groundwater quality and associated byproduct formation during UV/hydrogen peroxide treatment of 1,4-dioxane.

In this study, a semi-batch, bench-scale UV/hydrogen peroxide (UV/H2O2) advanced oxidation process system was used to investigate how typical groundwater quality parameters (pH, alkalinity, natural organic matter (NOM), nitrate, and iron) influence the treatment of 1,4-dioxane. Deionized (DI) water spiked with 1,4-dioxane (100 µg L-1), treated using H2O2 (10 mg L-1) in a commercially available UV system (40 W low-pressure lamp) showed an UV fluence-based first-order rate constant (k') and electrical energy-per-order (EEO) of 4.32✕10-3 cm2-mJ-1 and 0.15 kWh-m-3-order-1, respectively. The most abundant byproduct generated in spiked-DI water was oxalic acid (up to 55 µg L-1), followed by formic and acetic acids. The k' showed no significant difference at pH ranging from 5 to 7 and at low alkalinity concentrations (<20 mg-CaCO3 L-1), typical of sandy aquifers. The k' declined by up to 85% with increasing NOM concentration. Elevated production (up to ∼400% increase) of aldehydes and organic acids was observed in NOM-spiked water, implying that NOM is a significant byproduct precursor during UV/H2O2 treatment. High NO3- concentration (10 mg-N L-1) in source water reduced the k' by 25%, while no significant impact was observed at lower concentrations (<2 mg-N L-1). Addition of Fe(II) at 0.5 mg-L-1 resulted in an instantaneous Fenton-reaction-assisted removal of ∼10% 1,4-dioxane in the presence of H2O2, but did not enhance the performance of UV/H2O2 treatment over time. In contrast, both Fe(II) and Fe(III) addition lowered the k' by 15-27%. The decline of k' observed in these experiments was attributed to reduced UVT (Fe), .OH radical scavenging (pH), or both (NO3-, NOM). Treatment of groundwater samples collected from three 1,4-dioxane-contaminated wells located in Long Island, NY, showed k' values of 13-40% lower than what was observed for DI water due to radical scavenging from a combination of high NO3- and NOM in the samples. A multiple linear-regression model, developed using water quality data as model input, showed good agreement with field observations (paired t-test: p > 0.05) in predicting k' for the removal of 1,4-dioxane from groundwater. This study provides the first systematic evaluation of the impacts of groundwater quality on UV/H2O2 process to remove environmentally relevant levels of 1,4-dioxane and reports standardized performance-related parameters to aid in the design and evaluation of full-scale systems.