Lee Blaney

Organoarsenicals in poultry litter: Detection, fate, and toxicity

Arsenic contamination in groundwater has endangered the health and safety of millions of people around the world. One less studied mechanism for arsenic introduction into the environment is the use of organoarsenicals in animal feed. Four organoarsenicals are commonly employed as feed additives: arsanilic acid, carbarsone, nitarsone, and roxarsone. Organoarsenicals are composed of a phenylarsonic acid molecule with substituted functional groups. This review documents the use of organoarsenicals in the poultry industry, reports analytical methods available for quantifying organic arsenic, discusses the fate and transport of organoarsenicals in environmental systems, and identifies toxicological concerns associated with these chemicals. In reviewing the literature on organoarsenicals, several research needs were highlighted: advanced analytical instrumentation that allows for identification and quantification of organoarsenical degradation products; a greater research emphasis on arsanilic acid, carbarsone, and nitarsone; identification of degradation pathways, products, and kinetics; and testing/development of agricultural wastewater and solid treatment technologies for organoarsenical-laden waste.

Detection of a wide variety of human and veterinary fluoroquinolone antibiotics in municipal wastewater and wastewater-impacted surface water

As annual sales of antibiotics continue to rise, the mass of these specially-designed compounds entering municipal wastewater treatment systems has also increased. Of primary concern here is that antibiotics can inhibit growth of specific microorganisms in biological processes of wastewater treatment plants (WWTPs) or in downstream ecosystems. Growth inhibition studies with Escherichia coli demonstrated that solutions containing 1-10 μg/L of fluoroquinolones can inhibit microbial growth. Wastewater samples were collected on a monthly basis from various treatment stages of a 30 million gallon per day WWTP in Maryland, USA. Samples were analyzed for the presence of 11 fluoroquinolone antibiotics. At least one fluoroquinolone was detected in every sample. Ofloxacin and ciprofloxacin exhibited detection frequencies of 100% and 98%, respectively, across all sampling sites. Concentrations of fluoroquinolones in raw wastewater were as high as 1900 ng/L for ciprofloxacin and 600 ng/L for ofloxacin. Difloxacin, enrofloxacin, fleroxacin, moxifloxacin, norfloxacin, and orbifloxacin were also detected at appreciable concentrations of 9-170 ng/L. The total mass concentration of fluoroquinolones in raw wastewater was in the range that inhibited E. coli growth, suggesting that concerns over antibiotic presence in wastewater and wastewater-impacted surface water are valid. The average removal efficiency of fluoroquinolones during wastewater treatment was approximately 65%; furthermore, the removal efficiency for fluoroquinolones was found to be negatively correlated to biochemical oxygen demand removal and positively correlated to phosphorus removal.

Systematic optimization of an SPE with HPLC-FLD method for fluoroquinolone detection in wastewater

This paper describes a selective and ultra-sensitive analytical method for simultaneous determination of 11 fluoroquinolone (FQ) antibiotics in environmental and wastewater samples. The method employs offline solid-phase extraction (SPE) and reversed-phase high performance liquid chromatography with fluorescence detection (HPLC-FLD). A weak cation exchange SPE protocol was developed with a novel loading volume optimization algorithm and a methanol cleanup step to remove background organic matter. Various parameters were optimized to recover FQs from water/wastewater and analyte recovery was generally greater than 80%. Chromatographic separation of the 11 FQs was achieved on a 150 mm pentafluorophenyl column using a gradient elution scheme with methanol, acetonitrile, and 20mM phosphate buffer (pH=2.4). Excitation and emission wavelengths were individually optimized for each FQ using fluorescence spectroscopy; the excitation and emission wavelengths were 276-296 nm and 444-506 nm, respectively. Instrumental quantitation limits were 20-100 pg of mass injected. Of the 11 FQs investigated, seven (i.e., ciprofloxacin, difloxacin, enrofloxacin, fleroxacin, norfloxacin, moxifloxacin, and ofloxacin) were detected during a four-month sampling campaign of wastewater and wastewater-impacted surface water. Concentrations of FQs in raw wastewater, wastewater effluent, and wastewater-impacted surface water were 5-1292, 2-504, and 4-187ng/L, respectively.

Emerging contaminants in landfill leachate and their sustainable management

Abstract Emerging contaminants (ECs) are compounds that recently have been shown to occur widely in the environment and identified as being a potential environmental or public health risk, but yet adequate data do not exist to determine their risk. This review article focuses on ECs including pharmaceuticals, personal care products, surfactants, plasticizers, fire retardants, pesticides and nanomaterials. Their source, fate and transport in landfill leachate and adjacent environments have been discussed. Furthermore, state-of-the-art control and treatment techniques for ECs in landfill leachate have been presented. Sustainable management efforts for screening and control of ECs have been discussed. Molecular biology techniques to enumerate microbes capable of degrading ECs in landfills and their leachate are introduced. The article also presents future perspectives on the management of ECs in landfill leachate.

A novel approach to modeling the reaction kinetics of tetracycline antibiotics with aqueous ozone

Tetracycline antibiotics represent one of the most successful classes of pharmaceuticals and are extensively used around the world for human and veterinary health. Ozone-based processes have emerged as a selective water treatment process for many pharmaceuticals. The primary objective of this study was to determine the reaction kinetics for transformation of five tetracycline antibiotics (i.e., chlortetracycline, doxycycline, oxytetracycline, rolitetracycline, and tetracycline) by ozone across the pH2 to 9 range. The apparent second-order rate constant for tetracycline was on the order of 1-6 × 10(4) M(-1) s(-1) at low pH, and 0.6-2.0 × 10(6) M(-1) s(-1) at near neutral pH. The apparent second-order rate constants did not fit a conventional pKa-based model, presumably due to the complex acid/base speciation of tetracycline antibiotics. A model that considers the net charge on tetracycline molecules in solution provided a nice fit to experimental data for all five tetracyclines. The five tetracycline antibiotics demonstrated similar reaction kinetics with ozone, and a cumulative analysis of all kinetics data provides a baseline model for other tetracycline compounds. The ozone exposure required for complete transformation of tetracycline antibiotics (10(-5) M-s) is well below that achieved during ozone disinfection processes (10(-3) M-s), indicating that ozone is an effective treatment for tetracycline antibiotics.

An aggregate analysis of personal care products in the environment: Identifying the distribution of environmentally-relevant concentrations.

Over the past 3-4 decades, per capita consumption of personal care products (PCPs) has steadily risen, resulting in increased discharge of the active and inactive ingredients present in these products into wastewater collection systems. PCPs comprise a long list of compounds employed in toothpaste, sunscreen, lotions, soaps, body washes, and insect repellants, among others. While comprehensive toxicological studies are not yet available, an increasing body of literature has shown that PCPs of all classes can impact aquatic wildlife, bacteria, and/or mammalian cells at low concentrations. Ongoing research efforts have identified PCPs in a variety of environmental compartments, including raw wastewater, wastewater effluent, surface water, wastewater solids, sediment, groundwater, and drinking water. Here, an aggregate analysis of over 5000 reported detections was conducted to better understand the distribution of environmentally-relevant PCP concentrations in, and between, these compartments. The distributions were used to identify whether aggregated environmentally-relevant concentration ranges intersected with available toxicity data. For raw wastewater, wastewater effluent, and surface water, a clear overlap was present between the 25th-75th percentiles and identified toxicity levels. This analysis suggests that improved wastewater treatment of antimicrobials, UV filters, and polycyclic musks is required to prevent negative impacts on aquatic species.

Direct Photolysis of Fluoroquinolone Antibiotics at 253.7 nm: Specific Reaction Kinetics and Formation of Equally Potent Fluoroquinolone Antibiotics

Three fluoroquinolone-to-fluoroquinolone antibiotic transformations were monitored during UV-C irradiation processes. In particular, the following reactions were observed: enrofloxacin-to-ciprofloxacin, difloxacin-to-sarafloxacin, and pefloxacin-to-norfloxacin. The apparent molar absorptivity and fluence-based pseudo-first-order rate constants for transformation of the six fluoroquinolones by direct photolysis at 253.7 nm were determined for the pH 2-12 range. These parameters were deconvoluted to calculate specific molar absorptivity and fluence-based rate constants for cationic, zwitterionic, and anionic fluoroquinolone species. For a typical disinfection fluence of 40 mJ/cm(2), the apparent transformation efficiencies were inflated by 2-8% when fluoroquinolone products were not considered; moreover, the overall transformation efficiencies at 400 mJ/cm(2) varied by up to 40% depending on pH. The three product antibiotics, namely ciprofloxacin, sarafloxacin, and norfloxacin, were found to be equally or more potent than the parent fluoroquinolones using an Escherichia coli-based assay. UV treatment of a solution containing difloxacin was found to increase antimicrobial activity due to formation of sarafloxacin. These results highlight the importance of considering antibiotic-to-antibiotic transformations in UV-based processes.

Antibiotic Residues in Animal Waste: Occurrence and Degradation in Conventional Agricultural Waste Management Practices

The presence of antibiotics in animal manure represents a significant concern with respect to the introduction of antibiotic residues to the environment and the development of antibiotic-resistant pathogens. In this review, we have (1) compiled reported detections of antibiotics in poultry litter, swine manure, and cattle manure; and (2) discussed the treatment of antibiotics during conventional agricultural waste management practices. The most reported antibiotics in animal manure were fluoroquinolones, sulfonamides, and tetracyclines, all of which the World Health Organization has listed as critically important for human health. Relatively high treatment efficiencies were observed for antibiotics in composting, anaerobic digestion, and aerobic/anaerobic lagooning. Interestingly, active management of compost piles did not demonstrate a significant increase in antibiotic degradation; however, low- and high-intensity compost systems exhibited high treatment efficiencies for most antibiotics. Anaerobic digestion was not effective for some key antibiotics, including lincosamides and select sulfonamides and fluoroquinolones. Given the potential for energy recovery during anaerobic digestion of agricultural waste, efforts to optimize antibiotic degradation represent an important area for future research. Lagoons also exhibited fairly high levels of antibiotic treatment, especially for aerobic systems; however, the operational costs/complexity of these systems inhibit utilization at the full-scale. No overall trends in antibiotic treatment efficiency during these three agricultural waste management practices were observed. Finally, we posit that increased efforts to include analysis of antibiotic residues in animal manure in national surveillance programs will provide important information to address concerns over the continued use of antimicrobials in animal feeding operations.

Ozonation of the oxybenzone, octinoxate, and octocrylene UV-filters: Reaction kinetics, absorbance characteristics, and transformation products

UV-filters (UVFs) are active ingredients in personal care products that protect skin from exposure to UV light. Environmentally-relevant concentrations of UVFs have recently been linked to toxicity in aquatic organisms, necessitating research into improved UVF removal in water/wastewater treatment. Here, we investigated ozonation of the three most commonly employed UVFs: octinoxate (OMC), octocrylene (OC), and oxybenzone (OXY). Specific second-order rate constants for UVF reaction with ozone were identified as follows: OMC, 5.25×104M-1s-1; OC, 1.58M-1s-1; OXY (neutral), 3.80×102M-1s-1; and, OXY (anion), 1.51×106M-1s-1. These kinetic parameters indicated that OMC and OXY undergo significant (2-log or greater) transformation for typical ozone exposures in disinfection processes; however, minimal oxidation is expected for OC. UV absorbance mapping was employed to characterize the loss of UVF activity (i.e., absorbance across the UV-A, UV-B, and UV-C ranges) during ozonation. These 4-dimensional maps also confirmed ozone attack mechanisms, namely reaction at phenolate (OXY) and olefin (OMC, OC) groups. Primary transformation products from these reactions were identified for all three UVFs of concern. For OC and OXY, the benzophenone structure is conserved, suggesting that transformation products retain toxicity concerns.

PARAFAC modeling of irradiation- and oxidation-induced changes in fluorescent dissolved organic matter extracted from poultry litter

Parallel factor analysis (PARAFAC) applied to fluorescence excitation emission matrices (EEMs) allows quantitative assessment of the composition of fluorescent dissolved organic matter (DOM). In this study, we fit a four-component EEM-PARAFAC model to characterize DOM extracted from poultry litter. The data set included fluorescence EEMs from 291 untreated, irradiated (253.7 nm, 310-410 nm), and oxidized (UV-H2O2, ozone) poultry litter extracts. The four components were identified as microbial humic-, terrestrial humic-, tyrosine-, and tryptophan-like fluorescent signatures. The Tuckers congruence coefficients for components from the global (i.e., aggregated sample set) model and local (i.e., single poultry litter source) models were greater than 0.99, suggesting that the global EEM-PARAFAC model may be suitable to study poultry litter DOM from individual sources. In general, the transformation trends of the four fluorescence components were comparable for all poultry litter sources tested. For irradiation at 253.7 nm, ozonation, and UV-H2O2 advanced oxidation, transformation of the humic-like components was slower than that of the tryptophan-like component. The opposite trend was observed for irradiation at 310-410 nm, due to differences in UV absorbance properties of components. Compared to the other EEM-PARAFAC components, the tyrosine-like component was fairly recalcitrant in irradiation and oxidation processes. This novel application of EEM-PARAFAC modeling provides insight into the composition and fate of agricultural DOM in natural and engineered systems.