The effect of additives on the aerosolization of JP-5 jet fuel

The May spinning top aerosol generator was used to generate aerosols from neat Navy jet fuel and selected dispersions of three types of polymer additives in the jet fuel. The additives selected were Oppanol B-200, a Vistanex Series, and a proprietary antimisting additive designated as FM-9. The mass median diameter (MMD) of the droplets produced was studied as a function of additive concentration and spinning top velocity for each additive. In the case of each additive, the MMD significantly increased with concentration at constant RPS. The effect of the Oppanol B-200 was comparable with that of FM-9 with respect to its influence on the MMD.     

Assessment of dermal absorption and penetration of components of a fuel mixture (JP-8)

Occupational and environmental multi-chemical exposures are extremely common. Methods for assessment of the risks from dermal exposures to complex mixtures vary depending on the information available. The composition of a volatile mixture (such as JP-8 jet fuel) can change radically, depending on the phase of the mixture - vapor, liquid or aerosol. Assessing the absorption (into the skin) and penetration (through the skin) of components of the mixture can reduce uncertainty in the risk assessment process. Permeability coefficients of the 12 individual components that could be detected to penetrate the skin could be used to assess the toxicity of each individual component in the JP-8. The penetration of each of these components is related to and can be predicted from molecular weight and octanol water partition coefficients of that component. The composition of the components that penetrate the skin would be different from the composition of JP-8 because the permeability of the components differs by two orders of magnitude. Concentrations of the aliphatic chemicals found in the skin correlated well with carbon number. The JP-8 jet fuel is used as an example of how component data on absorption and penetration can be integrated into an assessment (McDougal et al., Toxicol Sci 2000; 55: 247-255). The component approach shows promise for estimating systemic toxicity of mixtures. Local toxicity (irritation, sensitization, etc.) may be better understood in the future when quantitative information becomes available about the duration and magnitude of chemical exposures required to cause local effects.     

The toxicity of jet fuels to fish—II: The toxicity of JP-8 to flagfish (Jordanella floridae) and rainbow trout (Salmo gairdneri) and golden shiners (Notemigonus chysoleucas)

JP-8 is a widely-used commercial and military jet fuel which may reach the aquatic environment by several avenues. The toxicity of JP-8 to cold and warm water fish was investigated to help define the impact on fresh water species. Fish were exposed to the water soluble fraction (WSF) of JP-8 in static acute bioassays and continuous-flow bioassays of approx. 4 months duration. The goal was to determine the 96-h LC₅₀ and the long-term no effect level on the life cycle. The acute toxicity to a warm water fish was found to be unaffected by pH in the range of 7.3–9.1. The no effect level with respect to growth was lower in rainbow trout than in flagfish. Fuel accumulation and depuration from fish tissues are compared for the two species, as are the effects on egg hatching. The relative toxicity of JP-8 and JP-9 (previously reported) is discussed.     

Effects of inorganic metal toxicity on bod—I methods for the estimation of bod parameters—II

Metal toxicity: In this study, the effects of HgCl₂, HgSO₄, K₂Cr₂O₇, CuSO₄, ZnSO₄ and Al₂(SO₄)₃ on BOD were investigated using a respirometer. When these inorganic metal compounds were added to a synthetic medium, respirometric BOD values and bacterial growth in an aeration system were affected. Parameter estimation: Some new solutions of the first order equation are time saving alternatives to the existing ones. Ultimate BOD values obtained from the second order equation are significantly higher than those produced from the first order equation. There is linear relationship between first and second order BOD parameters using crude sewage samples, but not when synthetic medium is used.     

Mathematical analysis of the chemical system “cyanide-heavy metals” in water—determination of components and toxicity of the system—II. Solution by computer

An essentially new method of chemical analysis was developed and named “the non-experimental chemical analysis”. The subject of the method is the qualitative and quantitative analysis of chemical properties of the system of complex forming reagents and central atoms. The method is based on the application of the general system equation. An application of the general system equation for the toxic system “cyanide-heavy metals” in water solutions is advanced.     

The ecology of a land drainage channel—I. Oxygen balance

In shallow land drainage channels day-time solar heating during the summer produced vertical temperature and density gradients. These facilitated the development of marked gradients of dissolved oxygen, with maximum sub-surface values exceeding 300% air saturation and deoxygenated water near the sediments. Night-time cooling promoted mixing of the water column. Rates of community photosynthesis and respiration, calculated from dissolved oxygen distributions by two methods, were high.     

Dynamics of the ozonation of phenol—I. Experimental observations

This first paper presents the results of an experimental investigation of the ozonation of phenol in a semi-batch reactor, in which mass-transfer kinetics of ozone into solution and the kinetics of the reaction between molecular ozone and phenol are considered separately. Attention has been given to distinguishing between direct and indirect reaction pathways involving ozone. Intermediates and final products of the reaction have been measured as a function of time using high pressure liquid chromatography.     

Utilisation de l''algue oocystis sp. pour le traitement tertiaire des eaux usées—I. Culture en vrac de cellules préalablement conditionnées en cyclostat

With the aim of developing an efficient and economic method for the tertiary treatment of wastewater, a two-phased culture system of Oocystis alga is presented. During the first phase, a unialgal strain grows in a cyclostat supplied with secondary effluents diluted to a low concentration (50 μM NH₄⁺, i.e. 0.7 mg N 1⁻¹) of inorganic ions. Once the equilibrium is reached (i.e. the cell population is conditioned and the nutrient concentration is zero), in a second phase, the starved cells are mixed with a secondary effluent which has a higher nutrient content (200–400 μM NH₄⁺, i.e., 2.8–5.6 mg N 1⁻¹). Ion depletion (NH₄⁺, NO₃^-, NO₂^- and PO₄^3-) follows specific kinetics; successive identifiable stages related to photoperiod lead to a complete stripping of nutrients. In addition to ion concentrations, pH and cell population were determined every 2 h during the experiment. Results and conclusions are presented.     

Construction of the Seikan undersea tunnel—I. General scheme of execution

The Seikan Tunnel, which is distinguished by the fact that it passes under the sea and is very long, consists of three tunnels: the main tunnel, a pilot tunnel, and a service tunnel. The paper describes the execution of those portions of the undersea section of the Seikan Tunnel that were executed by contractors—i.e. the main tunnel and the service tunnel in the Tappi Section (Honshu end) and the Yoshioka Section (Hokkaido end). The general scheme of execution of these tunnels under the distinctive conditions peculiar to the works is described, with emphasis on excavation by blasting; mechanical excavation; grouting; temporary facilities; and the labor system.     

The effect of reactor hydraulics on the performance of activated sludge systems—I. The traditional modelling approach

The traditional modelling approach involving only overall substrate and biomass parameters and a Monod-type of a rate expression was used to investigate the effect of reactor hydraulics on the substrate removal efficiencies of activated sludge systems. The traditional kinetics was observed to give a useful, although not a completely accurate picture of performances of different types of reactors: it showed basically that the relative performance of a given hydraulic configuration was significantly affected by the kinetic constants as well as by operating parameters. The results of model simulations indicated that most experimental studies in this area, were designed to operate at a range which should secure complete removal of the growth limiting substrate; therefore, the related experimental data so far available, do not necessarily provide conclusive evidence on the effect of reactor hydraulics.     

Persistence of some phenylamide pesticides in the aquatic environment—I. Hydrolysis

Phenylamide pesticides are a group of closely related compounds namely, phenylcarbamates, phenylureas and anilides. Their hydrolysis in aqueous solutions and the kinetic of the reaction were investigated. The observed reactivity of phenylamides and their susceptibility for nucleophilic attack by OH⁻ ions are mainly linked with the polarity of the carbonyl carbon atom. Hydrolysis at measurable rates was only affected in high alkaline solutions. At pH values which dominate in natural surface waters, these compounds are liable to maintain their stability and chemical hydrolysis will be a minor route for their degradation in the aquatic environment.     

Eutrophication in peel inlet—I. The problem-defining behavior and a mathematical model for the phosphorus scenario

The utilization of a mathematical model at an early stage of research on an environmental problem, the causes of which are poorly understood, is usually infeasible because of a lack of data. If the problem of interest is generically similar to others that have been reported in the literature however, a considerable amount of applicable information may be available and, if so, the parameters of a simulation model may be specified via a priori statistical distributions. Monte Carlo experiments can then be utilized to examine whether the model is able to simulate the salient qualitative aspects of the problem-defining behavior. The ultimate objective of such an approach is to identify areas of critical uncertainty in knowledge of the system and thereby to derive information that may be useful in focusing the next phase of research. The problem of cultural eutrophication in Peel Inlet, Western Australia, where the system behavior of interest is the excessive growth of the alga Cladophora, is amenable to such treatment. A phosphorus-based model provides one feasible explanation of this nuisance algal problem.     

Mathematical analysis of the chemical system “cyanide-heavy metals” in water—determination of components and toxicity of the system—I. The theoretical solution

A mathematical analysis of the chemical system “cyanide-heavy metals” in water is described. It allows to determine the type, number, and concentration of the system components to be computed. This mathematical analysis replaces chemical analysis, both qualitative and quantitative. The former is replaced by mathematical testing of the chemical properties of the system; the latter is replaced by solution of the equations for calculating the components concentrations in the system.     

The treatment of woolscour effluent—I removal of colloidal dirt

A small group of synthetic polymeric flocculants have been found which are capable of flocculating colloidal dirt in woolscour effluent. Their effectiveness has been tested in both laboratory and fullscale experiments. It has been found that up to 80% of the dirt in the liquor may be removed, as a 20 w/v% solids sludge, which is readily de-waterable, using a solid bowl centrifuge, to 45–50% solids. Use of the flocculants in a recycle process had no deleterious effect on grease recovery or wool quality, but allowed a constant low discharge flow of liquor to be maintained, independent of the wool throughput or dirt content.     

Investigating the Social Dimensions of Transport Disadvantage—I. Towards New Concepts and Methods

This article is the first of two papers that engage critically and productively with the relationship between the socio-economic transformations of cities, the differentiation of vulnerable groups within urban space and the distribution of transport services. This article undertakes a comprehensive review of the major conceptual and methodological approaches by which scholars and policy researchers have sought to address the connection between social disadvantage and access to transport. The article critically assesses the relative merits of various spatial analytical methodologies in illuminating social-transport links. The study finds that there is a need for greater sophistication in the use of analytical methods in transport research as well as an imperative for greater sensitivity to social differentiation within urban areas and relative to infrastructure and services. The article concludes by developing a method for combining spatial social and transport service data that is then deployed in the empirical case study reported in the second paper.     

Study of flowthrough couette flocculators—I. Design for uniform and tapered flocculation

Based on published hydrodynamic data for Couette apparatuses, two flocculators were designed consisting of co-axial cylinders. The annular gap between the cylinders constituted the flocculation chamber, in one case of uniform width, and in the other tapering from a narrow to a wider gap by a taper on the inner cylinder. For best hydrodynamic stability the outer cylinder only rotated, creating a velocity gradient across the annular gap. A novel feature of the apparatuses were inflow and outflow connections allowing flocculation to be studied on a flowthrough basis, which is more realistic in water treatment, rather than as a batch process. In this flowthrough condition the tapered flocculator reduced the velocity gradient in the direction of flow reducing the shear on flocs as they grew in size. Visual studies of the flow stability, using dye, of the two flocculators used both in batch and continuous flow processes, revealed the presence of currents along the cylinder boundaries, attributed to end effects. Residence time distribution tests, using lithium tracer, indicated some short circuiting varying with velocity gradient in the tapered flocculator, but independent of velocity gradient in the uniform flocculator.     

Automatic control of the activated sludge process—I. Development of a simplified dynamic model

A set of simplified dynamic models was developed for the activated sludge process (primary settler, biological reactor, and final settler). The models incorporate variable gains, variable time constants, and fixed dead times. Because the parameters may be easily evaluated on site, the models will be particularly useful for process analysis, control system design, and automatic control of a particular plant. Two different cases were studied; one for a plant in which the steady state concentration of suspended solids in the final effluent is directly proportional to the mixed liquor suspended solids, and one in which it is inversely proportional. Due to this difference in steady state gains the final performance of the system is quite different for the two cases although the dynamics are very similar. Therefore, care should be taken in characterizing the final settler.     

The chronic toxicity of molybdate to freshwater organisms. I. Generating reliable effects data

The European Union regulation on Registration, Evaluation, Authorization and Restriction of Chemical substances (REACH) (EC, 2006) requires the characterization of the chronic toxicity of many chemicals in the aquatic environment, including molybdate (MoO₄²⁻). Our literature review on the ecotoxicity of molybdate revealed that a limited amount of reliable chronic no observed effect concentrations (NOECs) for the derivation of a predicted no-effect concentration (PNEC) existed. This paper presents the results of additional ecotoxicity experiments that were conducted in order to fulfill the requirements for the derivation of a PNEC by means of the scientifically most robust species sensitivity distribution (SSD) approach (also called the statistical extrapolation approach). Ten test species were chronically exposed to molybdate (added as sodium molybdate dihydrate, Na₂MoO₄·2H₂O) according to internationally accepted standard testing guidelines or equivalent. The 10% effective concentrations (EC10, expressed as measured dissolved molybdenum) for the most sensitive endpoint per species were 62.8-105.6 (mg Mo)/L for Daphnia magna (21 day-reproduction), 78.2 (mg Mo)/L for Ceriodaphnia dubia (7 day-reproduction), 61.2-366.2 (mg Mo)/L for the green alga Pseudokirchneriella subcapitata (72 h-growth rate), 193.6 (mg Mo)/L for the rotifer Brachionus calyciflorus (48 h-population growth rate), 121.4 (mg Mo)/L for the midge Chironomus riparius (14 day-growth), 211.3 (mg Mo)/L for the snail Lymnaea stagnalis (28 day-growth rate), 115.9 (mg Mo)/L for the frog Xenopus laevis (4 day-larval development), 241.5 (mg Mo)/L for the higher plant Lemna minor (7 day-growth rate), 39.3 (mg Mo)/L for the fathead minnow Pimephales promelas (34 day-dry weight/biomass), and 43.2 (mg Mo)/L for the rainbow trout Oncorhynchus mykiss (78 day-biomass). These effect concentrations are in line with the few reliable data currently available in the open literature. The data presented in this study can serve as a basis for the derivation of a PNEC_aquatic that can be used for national and international regulatory purposes and for setting water quality criteria. Using all reliable data that are currently available, a HC_5,50% (median hazardous concentration affecting 5% of the species) of 38.2 (mg Mo)/L was derived with the statistical extrapolation approach.