Spencer M. Steinberg

A review of environmental applications of bioluminescence measurements

This review of the recent literature on environmental applications of bioluminescence systems will focus on in vivo and in vitro bioluminescence methods that have been utilized to elucidate properties of chemicals, toxic and mutagenic effects, and to estimate biomass. The unifying theme was the applications of bioluminescence to environmental monitoring, remedial investigations, toxicity assessments, and field methods. In addition to standard analytical laboratory methods and emerging field methods used for environmental monitoring, there currently exist a need for rapid and cost-effective methods to determine toxicity and bioavailability of pollutants in contaminated environmental samples. The U. S. Environmental Protection Agency (EPA) has continuing interest in innovative technologies for environmental monitoring applications such as those provided by bioluminescence methods.

Volatile aromatic hydrocarbons and dicarboxylic acid concentrations in air at an urban site in the Southwestern US

Concentrations of benzene, toluene, ethylbenzene, o-xylene, and m- and p-xylene were measured at an urban sampling site in Las Vegas, NV by sorbent sampling followed by thermal desorption and determination by GC-PID. Simultaneously, measurements of oxalic, malonic, succinic, and adipic acids were made at the same site by collection on quartz filters, extraction, esterification, and determination by GC-FID. For the period from April 7, 1997 to June 11, 1997, 201 sets of hydrocarbon measurements and 99 sets of acid measurements were made. Additional measurements of dicarboxylic acids were made on samples that represented potential direct sources, e.g. green plants and road dust. Correlations between the hydrocarbon and CO concentrations (measured by the Clark County Health District at a nearby site) were highly significant and a strong negative correlation of hydrocarbon concentration with ozone concentration (also from the county site) was observed under quiescent atmospheric conditions. In general, dicarboxylic acid concentrations were well correlated with one another (with the exception of adipic acid) but not well correlated with hydrocarbon, CO, and ozone concentrations. Multiple sources and complex formation processes are indicated for the dicarboxylic acids.

The sorption of selenite on various cement formulations

Abstract Twenty-seven cementitious formulations containing three levels of water/solids ratio (0.45, 0.50, and 0.55), three concentrations of silica fume (0, 10, and 20%), and three concentrations of clay (0, 3, and 5%) were evaluated for their ability to effectively sorb selenite (SeO32-) from an alkaline solution. A batch sorption procedure was utilized to determine distribution coefficients (Kd) for selenite between water and each cement formulation. Experimental Kd values obtained ranged from 250 to 930 l kg−1. The results indicated that varying the water and clay content of the mixes had little effect on selenite sorption, while adding increasing amounts of silica fume in a cement mix tended to decrease selenite sorption. A sorption/desorption study using several concentrations of selenium ranging from 6.5 to 1510 ppb was also conducted on cement formulations at one water/solids ratio (0.50), no silica fume, and three concentrations of clay (0, 3, and 5%). Freundlich isotherms were fitted to the sorption and desorption data. Results indicated that selenite sorption was irreversible under these conditions.

Sorption of benzene and trichloroethylene (TCE) on a desert soil: Effects of moisture and organic matter

Sorption of Trichlorethylene (TCE) and Benzene onto a desert soil has been investigated, at two different temperatures and various moisture contents, using a gas chromatographic method. Sorption of these two VOCs to the unmodified soil was compared to sorption onto the same soil that was alternately treated with hydrogen peroxide (to remove organic carbon) or with humic acids (to add organic carbon) in order to examine the role of soil organic matter in vapor phase sorption. Results from this study indicate that organic carbon plays only a minor role in sorption at low moisture contents.

The concentration, apparent molecular weight and chemical reactivity of silica from groundwater in Southern Nevada

Sorption of radionuclides, metals and organic compounds to colloidal particles has been suggested to increase the mobility of these pollutants in groundwater. Because silicates and alumino-silicates can be important components of groundwater colloids, we have conducted a study to characterize the nature of silica in various springs and wells in Southern Nevada and to determine the extent that silica may be associated with colloidal particles that can participate in pollutant transport. The total silica content was measured using inductively coupled plasma emission spectroscopy (ICP). In addition, reactive silica was measured using the silica molybdate colorimetric technique. The apparent molecular weight of the silica was investigated using split-flow-lateral-transport-thin-cell-fractionation (SPLITT) which can readily distinguish between colloidal and low molecular weight associations. This study indicates that silica does not tend to form stable inorganic colloids in Southern Nevada groundwaters but exists as low molecular weight species. However, water from one of the test facilities on the Nevada Test Site (NTS) did contain stable siliceous colloids that could have important implications for the modeling the transport of radionuclides at this site.

A Versatile One‐Pot Synthesis of Dialkyl Disulfides and Sulfides

Abstract Conversions of monofluoroalkyl and alkyl bromides to the corresponding dialkyl disulfides in a one‐pot synthesis using thiourea followed by basic hydrogen peroxide are described. Modified methods afford access to unsymmetrical disulfides and sulfides.

Paradoxical anaerobism in desert pupfish

ABSTRACT In order to estimate metabolic demands of desert pupfish for conservation purposes, we measured oxygen consumption in fish acclimated to the ecologically relevant temperatures of 28 or 33°C. For these experiments, we used fish derived from a refuge population of Devils Hole pupfish (Cyprinodon diabolis). Measurement of routine oxygen consumption (V̇O2,routine) revealed some 33°C-acclimated fish (10% of 295 assayed fish) periodically exhibited periods of no measurable oxygen consumption despite available ambient oxygen tensions that were above the critical PO2. We call this phenomenon paradoxical anaerobism. The longest observed continuous bout with no oxygen consumption was 149 min, although typical bouts were much shorter. Fish maintained normal posture and ventilation rate (>230 ventilations per minute) during paradoxical anaerobism. Fish rarely demonstrated a compensatory increase in oxygen use following a period of paradoxical anaerobism. In contrast, only one out of 262 sampled fish acclimated at 28°C spontaneously demonstrated paradoxical anaerobism. Muscle lactate concentration was not elevated during periods of paradoxical anaerobism. However, the amount of ethanol released by the 33°C-acclimated fish was 7.3 times greater than that released by the 28°C acclimation group, suggesting ethanol may be used as an alternative end product of anaerobic metabolism. Exposure to exogenous ethanol, in concentrations as low as 0.1%, produced periods of paradoxical anaerobism even in 28°C-acclimated fish. Highlighted Article: Pupfish acclimated to warm but ecologically relevant temperatures experience extended periods of anaerobism despite the availability of ambient oxygen.

Persistence of several volatile aromatic and halogenated hydrocarbons in a low organic carbon calcareous soil

Abstract Incubation of soil samples with volatile organic solvents at part-per-thousand (PPT) concentrations leads to the formation of a residual firmly bound fraction that resists evaporation. The concentration of this firmly bound fraction increases with temperature and solvent concentration. Formation of the firmly bound fraction is not greatly effected by the water concentration in the soil. The dynamic head space concentration method (purge and trap) is inadequate for recovery of this firmly bound material.

A review of applications of luminescence to monitoring of chemical contaminants in the environment

The recent analytical literature on the application of luminescence techniques to the measurement of various classes of environmentally significant chemicals has been reviewed. Luminescent spectroscopy based methods are compared to other current techniques. Also, examples of recently developed applications of luminescence to environmental monitoring are provided. The advantages and disadvantages of luminescence measurements for field screening measurements are discussed.

On-line dechlorination-hydrogenation of chlorinated paraffin mixtures using GC and GC/MS.

Chlorinated paraffins (CPs) are straight chain hydrocarbons that are produced as complex mixtures and are used as flame retardants and paint additives. These mixtures are extremely difficult to characterize using conventional chromatographic methods, as conventional gas chromatography results in unresolved complex chromatograms that preclude the identification and quantification of individual congeners or any reasonable assessment of the average carbon chain length. Carbon chain length is an important parameter for assessing physical properties and the toxicity of these materials. We have modified and improved a previously published gas chromatography–flame ionization detector method that uses Pd catalyst held in the gas chromatograph injector to simultaneously dechlorinate the CPs and separate the resulting alkanes. In addition, we have adapted this method to gas chromatography–mass spectrometry. Dehalogenation of other compounds was also studied with this system to investigate potential application to other complex halogenated mixtures.