Yeast abundance in the sediments of 13 coastal sites in Massachusetts was quantified, and the potential of yeast isolates to biotransform polycyclic aromatic hydrocarbons (PAHs) was determined. Plate counts of yeasts varied between 102 to 107 CFU g (dry weight) of sediment-'. The most abundant genera isolated and identified included Candida, Cryptococcus, Rhodotorula, Torulopsis, and Trichosporon. More than 50% of the isolates from heavily contaminated sites transformed phenanthrene, as determined by spray-plate screening. The plate counts of phenanthrene-transforming yeasts correlated significantly to the sediment concentrations of phenanthrene. Transformation of [9-14C]phenanthrene and [12-14C]benz[ajanthracene by individual isolates varied greatly, ranging from 0.15 to 8.15 ,umol of PAH g-1 in 120-h incubations. Of the isolated yeasts,
Per‐ and polyfluoroalkyl substances (PFAS) are found in a variety of industrial and household products. Human and wildlife exposure to PFAS is widespread. Increasing evidence suggests adverse effects of PFAS to human health and the environment. Human health risks from exposure through drinking water and fish consumption are areas of concern. Therefore, understanding occurrence and exposure risk is important to protect water resources. PFAS was investigated in fish fillet from the Delaware River over a 15‐y period (2004–2018). The sample period coincided with actions to reduce or eliminate the release of certain PFAS to the environment. Elevated levels of perfluorononanoate (PFNA) and perfluoroundecanoate (PFUnA) were initially observed in tidal fish fillet. While significant decreases in PFNA and PFUnA concentrations were observed in fish fillet from the tidal river during the timeframe of the study, changes in concentrations of other PFAS in tidal and nontidal fish were less substantial. In 2018, fish fillet continued to be contaminated with perfluorooctanesulfonate (PFOS) at levels exceeding recommended regional risk advisory limits on fish consumption. Integr Environ Assess Manag 2021;17:411–421. © 2020 SETAC
The degradation of nitroguanidine (NQ) wastewater components was studied using continuous‐flow and perfusion soil columns. After 271 d of operation of the continuous‐flow columns and 84 d of operation of the perfusion columns, only some components of NQ wastewater were completely or partially removed. Guanidine nitrate and sulfate were the most readily transformed. NQ, however, was only partially removed. Carbon supplements enhanced the transformation of both sulfate and NQ. Transformation products included nitrosoguanidine and ammonia, but not cyanoguanidine or melamine. Microbial adaptation to wastewater components was not demonstrated. Based on test data, land application of untreated wastewater is not recommended.
The relative role of eukaryotic versus prokaryotic microorganisms in phenanthrene transformation was measured in slurries of coastal sediment by two different approaches: detection of marker metabolites and use of selective inhibitors on phenanthrene biotransformation. Phenanthrene biotransformation was measured by polar metabolite formation and CO2 evolution from [9-14C]phenanthrene. Radiolabeled metabolites were tentatively identified by high-performance liquid chromatography (HPLC) separation combined with UV/ visible spectral analysis of HPLC peaks and comparison to authentic standards. Both yeasts and bacteria transformed phenanthrene in slurries of coastal sediment. Two products of phenanthrene oxidation by fungi, phenanthrene trans-3,4-dihydrodiol and 3-phenanthrol, were produced in yeast-inoculated sterile sediment. However, only products of phenanthrene oxidation typical of bacterial transformation, 1-hydroxy-2-naphthoic acid and phenanthrene cis-3,4-dihydrodiol, were isolated from slurries of coastal sediment with natural microbial populations. Phenanthrene trans-dihydrodiols or other products of fungal oxidation of phenanthrene were not detected in the slurry containing a natural microbial population. A predominant role for bacterial transformation of phenanthrene was also suggested from selective inhibitor experiments. Addition of streptomycin to slurries, at a concentration which suppressed bacterial viable counts and rates of [methyl-3H] thymidine uptake, completely inhibited phenanthrene transformation. Treatment with colchicine, at a concentration which suppressed yeast viable counts, depressed phenanthrene transformation by 40%, and this was likely due to nontarget inhibition of bacterial activity. The relative contribution of eukaryotic microorganisms to phenanthrene transformation in inoculated sterile sediment was estimated to be less than 3% of the total activity. We conclude that the predominant degraders of phenanthrene in muddy coastal sediments are bacteria and not eukaryotic microorganisms.
Behavior of the antimicrobial triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) was investigated under laboratory chlorination conditions and in a wastewater treatment plant discharging 380 million liters daily to the Delaware River, USA. Reactions of triclosan with chlorine were investigated using concentrations and exposure time typical of municipal wastewater treatment plants, i.e., 1 h contact time and average 1–2 mg/L residual chlorine. In reagent water, triclosan reacted quickly, transforming into mono- and dichlorinated species and further into dichlorophenol and trichlorophenol. However, triclosan remained stable for up to 2 h in wastewater samples chlorinated under these conditions. To confirm observed behavior under field conditions, a liquid chromatography tandem mass spectrometry-based analytical method capable of monitoring triclosan and its transformation products in wastewater was developed. Qualitative and quantitative wastewater characterization before and after chlorination are presented. Triclosan was present at the same concentration (P > 0.05) in pre-chlorination and post-chlorination aqueous wastewater samples (mean 368 ng/L). This finding is consistent with the non-detection of specific triclosan transformation products above sample reporting limits (30.0–100 ng/L), but contrasts markedly with detection of chlorination transformation products reported in reagent water. These data suggest the importance of influent matrix components in chlorination reactions of triclosan in contaminated wastewater under treatment plant conditions.
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