Philip B. Dorn

Degradation of bisphenol A in natural waters

Abstract In establishing chemical environmental safety a hazard assessment using environmental exposure and effects information is required. Environmental degradation information is factored into estimates of exposure. The environmental degradation of polycarbonate grade Bisphenol A 2,2′-Bis (p-hydroxyphenyl propane) CAS#80-05-7, used in the manufacture of plastics, was measured using local waters in the Houston Ship Channel. A spike of 3 mg/l BPA was added to four laboratory units containing fresh water (control), Houston Ship Channel water, Patricks Bayou water (200 yards downstream from a BPA chemical plant discharge), and the chemical plant treated process effluent. Greater than 90% degradation was observed in all treatments except the control within four days. The initiation of biodegradation in the units was in the following order: effluent> Patricks Bayou> Houston Ship Channel.

Temporal ecological assessment of oil contaminated soils before and after bioremediation

Ecotoxicity methods were used to assess different soil and oil combinations before, during and after laboratory bioremediation with associated hydrocarbon analysis. Heavy, medium and light crude oil (API gravity 14, 30, and 55) was spiked (ca. 5% w/w) into two sandy soils in the laboratory having organic carbon concentrations of 0.3 (Norwood) and 4.7% (Norwood/Baccto). The earthworm (Eisenia fetida) 14-d lethality assay, the modified Microbics Microtox Solid-Phase assay, and the 14-d plant seed germination and growth assays using corn, wheat and oats, were spiked and tested during a 360-d laboratory remediation. Eisenia was the most sensitive of the three methods utilized with survival increasing throughout bioremediation with fastest toxicity reduction in the high carbon Norwood/Baccto soils where LC50s were 100% or greater at the end of 90-d whereas, > 150-d were required to achieve a similar result in the low carbon soil. Analysis of the undiluted treatments with oily soil alone showed that earthworm survival was high after 90-d in all high organic carbon soils, and after eight months in the low carbon soils, except for the Norwood soil-light oil treatment, which required 360-d to achieve 100% survival. The Microtox assay was less sensitive with EC50s 100% or greater observed after 90-d in high carbon soils and after 240-d for all low carbon soils. After bioremediation, no effects on seed germination were observed, although some plant growth inhibition effects remained. There was no direct correlation between total petroleum hydrocarbon concentrations and toxicity.

Bisphenol A concentrations in receiving waters near US manufacturing and processing facilities

Bisphenol A (BPA) (CAS 80-05-7) was analyzed in receiving waters upstream and downstream of US manufacturers (1996 and 1997) and processors (1997) during seasonal low flow periods. BPA was not detected (< 1 microgram/l) in any surface water sample in 1996 or at six of seven sites in 1997. Concentrations near the seventh site ranged from 2 to 8 micrograms/l; however, its receiving stream had no measurable flow and concentrations represent undiluted effluent. All surface water concentrations from this and other studies were less than the freshwater predicted no effect concentration (PNEC) of 64 micrograms/l, suggesting that BPA discharges from manufacturing and processing facilities to surface water do not pose an environmental concern.

Assessment of the acute toxicity of crude oils in soils using earthworms, microtox®, and plants

The assessment of soil quality resulting from a chemical or oil spill and/or remediation effort may be obtained by evaluating the toxicity to soil organisms. To enhance our understanding of the soil quality resulting from laboratory and field oil spill remediation, we have assessed three soil toxicity test methods. Heavy, medium and light crude oils (API gravity 16–18, 30 and 53) were spiked into two soils in the laboratory. The earthworm (Eisenia foetida) 14-d lethality assay, the modified Microbics Microtox® Solid-Phase assay, and the 14-d plant seed germination and growth assays were tested with combinations of crude oils and soils. Earthworms were 1.4 to 14 times more sensitive than Microtox and 1.3 to >77 times more sensitive than plants to the oily soils. Light oil in the silty low organic carbon soil was generally the most toxic, while heavy oil in the sandy high organic carbon soil was least toxic. The bioassay techniques were demonstrated to be sensitive indicators of soil quality and may be used to evaluate the quality of remediated oily soils.

Transfers and transformations of zinc in constructed wetlands: mitigation of a refinery effluent.

Abstract Two pilot-scale wetlands were constructed to facilitate transfers and transformations of Zn in a secondary refinery wastewater effluent. The wetlands (6.1×30.5 m, width×length) were planted with Scirpus californicus and were operated with 24-h nominal hydraulic retention times (HRT). To evaluate wetland performance in terms of Zn removal at two water depths, one wetland was amended with a nominal concentration of 4.0 mg Zn/l as ZnCl2 for 144 days at an operational water depth of 0.3 m, and for an additional 22 days at a water depth of 1 m. The second wetland served as an unamended control. From wetland inflow to outflow, approximately 38% of total recoverable and 65% of soluble Zn was removed during the experiment at the 0.3-m water depth. During the flooded period (1.0-m water depth), approximately 18% of total recoverable and 66% of soluble Zn was removed from the effluent. Toxicity of effluent to Ceriodaphnia dubia Richard and Pimephales promelas Rafinesque decreased from inflow to outflow by ∼54 and 73%, respectively, at the 0.3-m water depth, and by at least 100% at the 1.0-m water depth. These data illustrate successful construction of wetlands for transfers and transformations of Zn from the water column and for decreases in associated toxicity.

Environmental Safety of the Use of Major Surfactant Classes in North America

This paper brings together over 250 published and unpublished studies on the environmental properties, fate, and toxicity of the four major, high-volume surfactant classes and relevant feedstocks. The surfactants and feedstocks covered include alcohol sulfate or alcohol sulfate (AS), alcohol ethoxysulfate (AES), linear alkylbenzene sulfonate (LAS), alcohol ethoxylate (AE), and long-chain alcohol (LCOH). These chemicals are used in a wide range of personal care and cleaning products. To date, this is the most comprehensive report on these substances chemical structures, use, and volume information, physical/chemical properties, environmental fate properties such as biodegradation and sorption, monitoring studies through sewers, wastewater treatment plants and eventual release to the environment, aquatic and sediment toxicity, and bioaccumulation information. These data are used to illustrate the process for conducting both prospective and retrospective risk assessments for large-volume chemicals and categories of chemicals with wide dispersive use. Prospective risk assessments of AS, AES, AE, LAS, and LCOH demonstrate that these substances, although used in very high volume and widely released to the aquatic environment, have no adverse impact on the aquatic or sediment environments at current levels of use. The retrospective risk assessments of these same substances have clearly demonstrated that the conclusions of the prospective risk assessments are valid and confirm that these substances do not pose a risk to the aquatic or sediment environments. This paper also highlights the many years of research that the surfactant and cleaning products industry has supported, as part of their environmental sustainability commitment, to improve environmental tools, approaches, and develop innovative methods appropriate to address environmental properties of personal care and cleaning product chemicals, many of which have become approved international standard methods.

Influence of hydrophobe type and extent of branching on environmental response factors of nonionic surfactants

A number of ethoxylated nonionic surfactants differing in hydrophobe branching and chainlengths have been evaluated for environmental responses. Screening biodegradation tests show that those nonionics having more than one methyl group per hydrophobe degrade considerably slower than those having less extensive branching. Continuous flow-through activated sludge tests, simulating actual waste treatment, show that the more highly branched nonionics biodegrade more slowly and less extensively than those with less hydrophobe branching. In addition, treated effluents originating from influents containing the more highly branched nonionics tend to be more surface active and more toxic to aquatic species than those originating from influents containing surfactants with less hydrophobe branching. Under conditions simulating plant stress, such as high surfactant concentrations in the influent or low temperature, biodegradation of the highly branched nonionics was considerably less extensive, while biodegradation of the linear nonionics was not affected to any measurable degree compared to more normal operating conditions.

Sorption of two model alcohol ethoxylate surfactants to sediments

Abstract We have examined the sorption of two radiolabeled alcohol ethoxylate surfactants (AE) (C13 alcohols with exactly 3 or 9 moles of ethylene oxide (EO) per mole of alcohol) to natural sediments. Formalin was included in the sediment/surfactant/water mixtures to prevent biodegradation. Four sediments with 0.3 to 2.2 % organic carbon content were used in equilibrium experiments to determine the effect of various sediment properties and EO chain length on the sorption process. The equilibrium sorption isotherms were determined to be non-linear and described by the Freundlich model, and distribution ratios (ratio of surfactant concentration on sediment to aqueous concentration) at 1 mg/L surfactant ranged from 110 to 590 L/kg. These distribution ratios indicated that the AEs did not sorb strongly to the tested sediments. The amount of sorption was better correlated to the percent clay content of the sediment than to the percent organic carbon content of the sediment.

An assessment of the ecological effects of a C9--11 linear alcohol ethoxylate surfactant in stream mesocosm experiments

The responses of stream mesocosm communities to a linear alcohol ethoxylate (LAE) surfactant were studied to (i) assess the relationship between laboratory and field-scale tests; (ii) develop NOECs for responding taxa; and (iii) provide data to develop an aquatic risk assessment for alcohol ethoxylates. The LAE was a mixture of C9--11 linear alcohols with an average of six ethylene oxide (EO) units per mole of alcohol. Twelve stream mesocosms were used to test the effects of five concentrations of the LAE on periphyton, aquatic macrophytes, invertebrates and fish during a 30-day exposure. Vascular plants were unaffected at 11.4 mg L−1, the highest surfactant concentration tested, but various periphyton parameters were altered at lower concentrations. The effects on periphyton were attributed to grazing by resident invertebrates. Invertebrate densities were affected at LAE concentrations above 2.0 mg L−1. Fathead minnows were particularly sensitive to LAE with a NOEC of 0.73 mg L−1 for egg production and larval survival. Bluegill were less sensitive than fathead minnows, with a NOEC for survival and growth of 5.7 mg L−1. The stream mesocosm results for fish and invertebrates were similar to those obtained using laboratory single-species tests

Responses of aquatic invertebrates to a C9–11 non-ionic surfactant in outdoor stream mesocosms

Abstract Responses of aquatic invertebrates to a C9–11 linear alcohol ethoxylate (LAE) non-ionic surfactant with an average of six ethylene oxide units per mole of alcohol were evaluated in 30-day exposures in 12 outdoor stream mesocosms by measuring changes in benthic invertebrate densities, invertebrate drift, and feeding rates of caged Hyalella azteca Saussure. Five surfactant concentrations were chosen for this study and the mean measured concentrations in duplicate streams were 0.73, 2.04, 4.35, 5.70, and 11.24 mg l−1 with two untreated streams as controls. Surfactant analyses showed that in-stream concentrations were similar to nominal values throughout the 30-day treatment period. There were statistically significant effects (P