Carter G. Naylor

Alkylphenol ethoxylates in the environment

A comprehensive monitoring study, sponsored by the Chemical Manufacturers Association and designed in cooperation with the Environmental Protection Agency (EPA), measured the levels of nonylphenol (NP) and its ethoxylates (NPE) in 30 rivers. The sites, all receiving municipal or industrial wastewater, were selected at random from EPA’s United States river reach database by a statistical procedure. Water column and bottom sediment samples were collected along a perpendicular transect at each site. All samples were assayed for NP and NPE1, and the higher ethoxylates (NPE2 to NPE17) were determined in the water samples. Analysis was by high-performance liquid chromatography (HPLC) with fluorescence detection of microgram quantities of NPE obtained by extractive steam distillation (NP and NPE1) or a dualcolumn extraction procedure (NPE2 to NPE17). Sample collection and analytical procedures were validated according to rigorous EPA guidelines, and quality assurance standards were met throughout the study. NP and NPE concentrations in river water were mostly (60 to 75% of the samples) below their detection limits (about 0.1 ppb for NP, NPE1, and NPE2; 1.6 ppb for NPE3–17). The highest levels found were about 1 ppb for NP, NPE1, and NPE2, 15 ppb for NPE3–17. A majority of sediment samples contained detectable amounts of NP and NPE1, ranging up to 3000 ppb for NP and 170 ppb for NPE1. Sediment interstitial water concentrations of NP were estimated to be similar to concentrations in the water column.

Trace analysis of alkylphenol ethoxylates

A method for quantitative determination of trace amounts of alkylphenol ethoxylates (APE) in environmental water is described. Levels of 1 to 3 μg/L can be detected and resolved into their complete oligomer distribution (1EO to 18EO) while maintaining integrity of the oligomer distribution. This is a major improvement over previous methods; for the first time distortion of oligomer distribution due to work-up conditions of earlier methods has been prevented.Isolation of the APE from water is achieved using a simple and rapid dual-column procedure. The first column removes interfering ionic materials, the second traps the APE on alkyl-bonded silica. Assay of the extract employs HPLC with a fluorescence detector.The method was used for analyzing treated waste-water and river water. A much better picture of the biodegradation behavior of APE in the environment has emerged as a result of keeping APE oligomer distribution intact during sample extraction. There is no accumulation of alkylphenol and the low EO oligomers during wastewater treatment, although the oligomer distribution may become skewed toward these species. Concentrations in the receiving waters examined were very low, in the range of 1–2 μg/L total APE species (OEO to 18EO).

Biodegradation of nonionic surfactants containing propylene oxide

Insertion of oxypropylene groups into the polyoxyethylene chain of fatty and oxo alcohol ethoxylates decreased the rate and extent of biodegradation. The magnitude of the effects was proportional to the PO-block size and the extent of branching in the alcohol. Data are presented from a series of PO-containing nonionic surfactants in semi-continuous activated sludge reactors over test periods of up to 12 weeks. Bioassays performed on effluents from the SCAS units showed little or no toxicity due to residual degradation metabolities towardPimephales promelas andDaphnia pulex and a stimulatory effect onSelenastrum capricornutum growth rate.

C8- and C9-Alkylphenols and Ethoxylates: I. Identity, Physical Characterization, and Biodegradation Pathways Analysis

ABSTRACT C8- and C9-alkylphenols (AP) and their ethoxylates (APE) are widely used commercial products mainly used in industrial applications, in the formulation of crop protection chemicals, and in industrial and household cleaners. These compounds have been the subject of considerable regulatory scrutiny regarding their potential to pose environmental risks. Recent regulatory focus on these compounds has included an assessment of their potential to meet criteria for persistent, bioaccumulative, and toxic compounds (PBTs). To facilitate the evaluation of the environmental behavior of APE and an assessment of their PBT characteristics, a review of the physical-chemical properties and environmental degradation pathways was performed. The most widely used commercial APE are highly water soluble and non-volatile. Nonylphenol (NP) and octylphenol (OP) are relatively low solubility compounds that are more hydrophilic and volatile than the ethoxylates. Properties of ethoxylate degradation intermediates such as APE1,2 are between values for the commercial APE and the AP building blocks in terms of solubility and partitioning characteristics and are non-volatile at ambient temperatures. The ether carboxylate intermediates are ionic in neutral water solution; hence, they are non-volatile and less prone to partitioning to organic matter. Under aerobic conditions, commercial APE undergo rapid degradation to short chain ethoxylates and ether carboxylates, which in turn degrade ultimately to carbon dioxide and water. Under anaerobic conditions, APE degrade more slowly, and may result in some accumulation of AP. Degradation half-lives and the potential for these compounds to bioaccumulate will be examined in a companion article.

Exposure Analysis of C8- and C9-Alkylphenols, Alkylphenol Ethoxylates, and Their Metabolites in Surface Water Systems within the United States

ABSTRACT This study was conducted to develop a statistical understanding of exposures to C8- and C9-alkylphenol ethoxylates (APEO) and their metabolites (APEM) in U.S. surface waters. Concentrations of APEO/APEM (all analytes) in freshwater have been reported by 19 investigations over the past 15 years. Only limited data are available for sediments and marine ecosystems. Based on the frequency of detection in surface waters, 67% of all analytes were below their detection limits. Although maximum reported concentrations varied with time, the average and 90th centile concentrations have remained relatively constant. Examination of frequency distributions for nonylphenol (NP) concentrations indicated that 99% of the levels in fresh surface waters are below the U.S. Environmental Protection Agencys Aquatic Life Ambient Chronic Water Quality Criteria for NP (6.6 μg/L). A conservative evaluation of aggregated NPEO/NPEM concentrations suggested that 97% of the samples contained aggregate NP equivalent concentrations that are also below 6.6 μg/L. These results suggest that on a nationwide basis, the likelihood of surface water concentrations exceeding the chronic USEPA Water Quality Criterion for NP is low.

Nonionic surfactants containing propylene oxide

Physical and surface active properties of ethoxylates are altered by the inclusion of propylene oxide (PO) groups. The location of PO within the ethoxylate (EO) chain can be as important a factor as the relative amounts of PO and EO. The optimum position of the PO was shown to be a single discrete block of PO located in approximately the middle of the ethoxylate chain. The influence of PO on surfactant properties was assessed for several alcohol ethoxylates and nonyl-phenol ethoxylates. Pour points and gelling tendencies were lowered at the expense of detergency, foaming and wetting power.

Occurrence of nonylphenol ethoxylates and their metabolites in municipal wastewater treatment plants and receiving waters.

Nonylphenol ethoxylates (NPEs) are surfactants often used in applications that result in their disposal and treatment in wastewater treatment plants (WWTPs). In this study, three municipal activated sludge WWTPs, receiving primarily residential wastewater, were monitored, with their receiving waters, to determine the occurrence of NPEs and their biodegradation metabolites, including nonylphenol (NP), low-mole and higher-mole nonylphenol ethoxylates (NPE1, NPE2-8, and NPE > or =9), and nonylphenol ether carboxylates (NPECs). The facilities were moderately sized and operating normally when influent and effluent samples were taken. Treatment efficiencies, taking into account concentrations of the parent ethoxylate and metabolites, ranged from 97.2 to 99.8%. Samples of receiving stream water, sediment, and pore water were collected upstream, downstream at the end of the mixing zones, and farther downstream from the WWTP discharges, to determine the occurrence of NPE and their metabolites and to assess the potential effect on the receiving stream ecosystems. Concentrations of nonylphenol or total nonylphenol equivalents measured upstream (<0.02 to 1.29 microg/L), at the end of the mixing zone (0.2 to 3.15 microg/L), and farther downstream (<0.02 to 1.84 microg/L) were compared with the recently established national ambient water quality chronic criteria of 6.6 mcirog/L. On the basis of this analysis, the likelihood of adverse effects on aquatic species within the three receiving streams is low.

C8- and C9-Alkylphenols and Ethoxylates: II. Assessment of Environmental Persistence and Bioaccumulation Potential

ABSTRACT C8- and C9-alkylphenols and their ethoxylates (APE) are widely used commercial products mainly used in industrial applications, in the formulation of crop protection chemicals, and in industrial and household cleaners. Recent regulatory focus on these compounds has included an assessment of their potential to meet criteria for persistent, bioaccumulative, and toxic compounds (PBT). To fully evaluate either the relative persistence or bioaccumulation potential of any APE, degradation intermediates and metabolic by-products of these compounds should also be considered. To facilitate the evaluation of the ultimate fate of APE in the environment, a review of the degradation pathways and identification of degradation intermediates was performed (part I of a two-part series). In part II of this series, the relative persistence of APE as indicated by degradation half-lives was examined based on a review of abiotic and biological degradation data. To assess the bioaccumulation potential of APE, the relevant literature was also reviewed. The available data for C8- and C9-APE show that the commercial products and their degradation intermediates do not meet any national or international criteria for identifying these compounds as PBT substances.