An Evaluation of Selenium Concentrations in Water, Sediment, Invertebrates, and Fish from the Republican River Basin: 1997–1999

The Republican River Basin of Colorado,Nebraska, and Kansas lies in a valley which contains PierreShale as part of its geological substrata. Selenium is anindigenous constituent in the shale and is readily leached intosurrounding groundwater. The Basin is heavily irrigated throughthe pumping of groundwater, some of which is selenium-contaminated, onto fields in agricultural production. Water,sediment, benthic invertebrates, and/or fish were collected from46 sites in the Basin and were analyzed for selenium to determinethe potential for food-chain bioaccumulation, dietary toxicity,and reproductive effects of selenium in biota. Resultingselenium concentrations were compared to published guidelines orbiological effects thresholds. Water from 38% of the sites (n = 18) contained selenium concentrations exceeding 5 g L^-1, which is reported to be a high hazard for selenium accumulation into the planktonic food chain. An additional 12 sites (26% of the sites) contained selenium in water between 3–5 g L^-1, constituting a moderate hazard. Selenium concentrations in sedimentindicated little to no hazard for selenium accumulation fromsediments into the benthic food chain. Ninety-five percent ofbenthic invertebrates collected exhibited selenium concentrationsexceeding 3 g g^-1, a level reported as potentially lethal to fish and birds that consume them. Seventy-five percent of fish collected in 1997, 90% in 1998, and 64% in 1999 exceeded 4 g g^-1selenium, indicating a high potential for toxicity andreproductive effects. However, examination of weight profilesof various species of collected individual fish suggestedsuccessful recruitment in spite of selenium concentrations thatexceeded published biological effects thresholds for health andreproductive success. This finding suggested that universalapplication of published guidelines for selenium may beinappropriate or at least may need refinement for systems similarto the Republican River Basin. Additional research is needed todetermine the true impact of selenium on fish and wildliferesources in the Basin.     

Efficiency of perchlorate consumption in road flares, propellants and explosives

When an explosive detonates or a propellant or flare burns, consumption of the energetic filler should be complete but rarely is, especially in the presence of large amounts of non-combustible materials. Herein we examine three types of perchlorate-containing devices to estimate their potential as sources of contamination in their normal mode of functioning. Road flares, rocket propellants and ammonium nitrate (AN) emulsion explosives are potentially significant anthropogenic sources of perchlorate contamination. This laboratory evaluated perchlorate residue from burning of flares and propellants as well as detonations of ammonium nitrate emulsion explosives. Residual perchlorate in commercial products ranged from 0.094 mg perchlorate per gram material (flares) to 0.012 mg perchlorate per gram material (AN emulsion explosives). The rocket propellant formulations, prepared in this laboratory, generated 0.014 mg of perchlorate residue per gram of material.     

Modular containers for microcosm and process model studies on the fate and effects of aquatic contaminants

Container modules are described for the laboratory simulation of selected processes and ecosystems that are representative of lentic environments. Emphasis is placed on design features permitting mass balance accountability of contaminant residues and procedural cautions required for the proper use of the described systems in environmental simulations. Experiments on the efficiency of container modules for microbial mineralization studies were conducted using ¹⁴CNaHCO₃, and acidification resulted in a ¹⁴CCO₂ recovery of $\text{97.3 ± 4.7\% (}\text{x}\text{?}\text{± SD}\text{)}$. The trapping efficiency of pesticides volatilized from water and glass surfaces was investigated using the same module and the mean recoveries of ¹⁴C-fonofos and ¹⁴C-trifluralin were 114.2 ± 3.2% and 95.2 ± 3.5%, respectively. The mass balance capabilities of the system was also demonstrated for extended microcosm exposures to ¹⁴C-trifluralin.     

Sequestration of priority pollutant PAHs from sediment pore water employing semipermeable membrane devices

Semipermeable membrane devices (SPMDs) were employed to sample sediment pore water in static exposure studies under controlled laboratory conditions using (control pond and formulated) sediments fortified with 15 priority pollutant polycyclic aromatic hydrocarbons (PPPAHs). The sediment fortification level of 750 ng/g was selected on the basis of what might be detected in a sediment sample from a contaminated area. The sampling interval consisted of 0, 4, 7, 14, and 28 days for each study. The analytical methodologies, as well as the extraction and sample cleanup procedures used in the isolation, characterization, and quantitation of 15 PPPAHs at different fortification levels in SPMDs, water, and sediment were reported previously (Williamson, M.S. Thesis, University of Missouri-Columbia, USA; Williamson et al., Chemosphere (This issue--PII: S0045-6535(02)00394-6)) and used for this project. Average (mean) extraction recoveries for each PPPAH congener in each matrix are reported and discussed. No procedural blank extracts (controls) were found to contain any PPPAH residues above the method quantitation limit, therefore, no matrix interferences were detected. The focus of this publication is to demonstrate the ability to sequester environmental contaminants, specifically PPPAHs, from sediment pore water using SPMDs and two different types of fortified sediment.     

Dynamics of isopropylphenyl diphenyl phosphate in fathead minnows

The fate of a triaryl phosphate (ring-UL-¹⁴C-2-isopropylphenyl diphenyl phosphate) was examined in fathead minnows. Diphenyl phosphate was identified as a major metabolite in whole body fish samples. A significant portion of the radioactive residues appeared to be associated with biogenic compounds, indicating “in vivo” reactions of biochemicals with ¹⁴C-metabolites or ¹⁴C-ring cleavage of 2-isopropylphenyl diphenyl phosphate and subsquent incorporation into biochemical pathways.     

A HYBRID COMPUTER PROGRAM FOR PREDICTING THE CHEMICAL QUALITY OF IRRIGATION RETURN FLOWS1

ABSTRACT. A hybrid computer program was developed to predict the water and salt outflow from a river basin in which irrigation is the major user of water. The model combines a chemical model which predicts the quality of water percolated through a soil profile with a general hydrologic model. The chemical model considers the reactions that occur in the soil, including the exchange of calcium, magnesium, and sodium cations on the soil complex, and the dissolution and precipitation of gypsum and lime. The chemical composition of the outflow is a function of these chemical processes within the soil, plus the blending of undiverted inflows, evaporation, transpiration, and the mixing of sub surface return flows with groundwater. The six common ions of western waters, namely calcium (Ca⁺⁺), magnesium (Mg⁺⁺), sodium (Na⁺), sulfate (SO₄⁼), chloride (Cl^?), and bicarbonate (HCO₃^?) were considered in the study. Total dissolved solids (TDS) outflow was obtained by adding the individual ions. The overall model operates on a monthly time unit. The model was tested on a portion of the Little Bear River basin in northern Utah. The model successfully simulated measured outflows of water and each of the six ions for a 24-month period. The usefulness of the model was demonstrated by a management study of the prototype system. For example, preliminary results indicated that the available water supply could be used to irrigate additional land without unduly increasing the salt outflow from the basin. With minor adjustments the model can be applied to other hydrologic areas.     

EIA — Its potential application to appropriate technology in developing countries

Summary Many developed countries in the Western world employ some form of Environmental Impact Assessment (EIA). A number of sophisticated procedures are used for the assessment of the impact of large- scale developments upon the environment. In developing countries there are both large-scale schemes that are often financed by foreign aid, and small-scale projects in which technology is less sophisticated but more appropriate to human needs. Standard EIA procedures are followed for large-scale developments but assessment of the impact of small-scale projects is often ignored.This paper attempts to define appropriate technology and to describe some of the often less apparent adverse effects of such technology upon society and the environment. The need for assessment of small-scale projects is established and the possibility of applying current EIA procedures to such developments is considered. The final paragraphs refer to the advantages and disadvantages of environmental impact assessment of small-scale technology.Dr Pamela M. Goode and Alastair I. Johnstone are both members of staff at the Environmental Institute, University of Salford, UK.     

Defining disaster resilience: comparisons from key stakeholders involved in emergency management in Victoria,Australia

Three years after the introduction of the National Strategy for Disaster Resilience there remains no unanimously adopted definition of disaster resilience within Australia's emergency management sector. The aim of this study is to determine what the concept means to key stakeholders in the emergency management sector in the Australian State of Victoria, and how these conceptualisations overlap and diverge. Via an online survey, 113 people were asked how they define disaster resilience in their work in the emergency management sector. A data mining software tool, Leximancer, was employed to uncover the relationships between the definitions provided. The findings show that stakeholders see resilience as an ‘ability’ that encompasses emergency management activities and personal responsibility. However, the findings also highlight some possible points of conflict between stakeholders. In addition, the paper outlines and discusses a number of potential consequences for the implementation and the success of the resilience‐based approach in Australia.     

Developing fuzzy signal detection theory for workers’ hazard perception measures on subway operations

The ability to perceive hazards has been suggested as being an important factor in determining safety risk. By measuring the ability to perceive hazard, at-risk workers could be identified and provided with additional training. This can reduce knowledge-based human errors and thereby help to avoid accidents. This paper proposes the use of fuzzy signal detection theory (FSDT), which combines fuzzy logic and conventional signal detection theory (SDT) to measure hazard perception. The flexibility of the proposed method allows multiple forms of qualitative and quantitative information to be used, including expert opinions and workers’ responses when quantitative data are lacking or when only qualitative aspects are known. Details have been provided on the basic postulates, formulas, and steps involved in FSDT analysis. A real-world example demonstrates the feasibility of the proposed framework. The results of a case study show that the participating workers had a medium level of hazard perception. This means that these workers were sensitive to the difference between hazard and safety. But there were still opportunities for improvement. Of the workers surveyed, five workers expressed conservative views regarding risk while the other workers expressed risky views. FSDT increases the applicability of conventional SDT analysis to many real-world settings, where the definition of a signal is less dichotomous than in a controlled laboratory environment.     

Visibility-related fatalities related to construction equipment

The construction industry annually experiences one of the highest fatality rates among the industrial sectors in the United States. The factors that contribute to this reputation include the nature of the work, human behavior, the tools and equipment involved, and also the compact work zones. Industrial fatalities are investigated by the Occupational Safety and Health Administration (OSHA). While OSHA groups the causes of fatalities into a few general categories, too little information is gleaned to effectively target specific problem areas.To improve safety performance in the construction industry, it is necessary to understand the underlying causes of accidents. With targeted analysis, patterns emerge and causal factors can be identified. These findings may then be used to form the basis for recommendations that will help to improve construction worker safety. Little research has been conducted in this area.Research was conducted that isolated fatalities in which vision or lack of good visibility was the principle factor or contributing cause. The objective of examining the details surrounding these fatalities was to uncover the contributing factors and to identify the agents that compromised visibility. The study identified 659 fatality accidents from a data pool of 13511 OSHA-investigated cases. It was discovered that blind spots, obstructions and lighting conditions were the most common factors contributing to vision-related fatalities. This research also analyzed the specific conditions associated with particular pieces of construction equipment.