Antioxidant alteration ofGlycine max (Fabaceae) defensive chemistry: Analogy to herbivory elicitation

Summary The water-soluble antioxidant, L-ascorbic acid (vitamin C), proved elicitory to alterable anti-herbivory inGlycine max againstTrichoplusia ni larvae. Elicitation by vitamin C was influenced especially by dose, time after elicitation and space in the plant. Results allow an analogy between antioxidant and herbivory elicitation. Elicitation apparently involves a sulfhydryl-protein-dependent redox mechanism which can be significantly affected by antioxidants. Findings would also support a proposed common redox-based mechanism, involving the plasma membrane, for communication between plant and animal cells and their environments.     

Direct analysis of polycyclic aromatic hydrocarbons in cloud-water aerosol filtrates using laser desorption mass spectrometry

A novel technique for the rapid screening of polyaromatic hydrocarbons (PAHs) in atmospheric particulates is presented. Two-step laser desorption laser photoionisation time-of-flight mass spectrometry was used to assay for PAHs in cloud-water particulates collected near Peebles in southern Scotland. The particulates were examined in situ on their host filters removing the requirement for time-consuming sample extraction and separation. The mass spectra obtained from a single filter are shown. The principal components of these are assigned to PAH contaminants and phthalate contaminants. A distribution of PAHs was observed using 193 nm laser photoionisation. The mass spectrum obtained on using 248 nm laser photoionisation exhibits a different intensity distribution demonstrating an ionisation wavelength dependence. The utility of the technique for rapid screening of PAHs and other polyaromatic species is discussed.     

Anion mobility in soils: Relevance to nutrient transport from forest ecosystems

Nutrient transport from forest ecosystems is strongly regulated by the availability of anions in soil solution. Each of the major anions in forest soil solutions has some unique properties which affect its production and mobility. The production of bicarbonate, one of the most common anions, is regulated by soil CO₂ pressure and pH. The mobility of phosphate is most strongly affected by adsorption reactions. The mobility of nitrate is regulated almost solely by biological processes, whereas chloride is relatively uninvolved in either biological or inorganic chemical reactions. Sulfate is intermediate, being involved in both biological and inorganic chemical reactions.Knowing these properties of the major anions, it is possible to assess and to predict the effects of several diverse site manipulations on soil leaching rates. Case studies from a site in Washington State consistently demonstrate the importance of accounting for bicarbonate transformations following site manipulations.Although organic anions are frequently dominant in cold-region soil solutions, very little information on the complex factors affecting their mobilities is available. Further research into organic anion mobility and futher attention to bicarbonate mobility should add greatly to the body of knowledge on nutrient transport processes in forest soils.     

An Evaluation of Emissions and Control Technologies for the Metal Decorating Process

Data are reported on a number of controlled and uncontrolled sources from various metal decorating operations. Emission levels are related to process variables such as ink coverage, coater speed, sheet size, and applied coating film weight. Results are presented depicting variation of organic emission levels from a coating process line with elapsed process time. For controlled sources employing either catalytic or thermal incineration, conversion efficiencies are reported as a function of temperature. Operational curves are presented for each control system studied indicating the dependence of carbon dioxide, NO_x, and organic output on incineration temperatures.     

Strategies for Testing the “Irritation-signaling” Model for Chronic Lung Effects of Fine Acid Particles

The “irritation signaling” model proposed that a long term contribution to chronic bronchitis might result from the repeated delivery of “signals” resulting from temporary localized acidification of the bronchial epithelium by the action of Individual particles. This led to a prediction that the effectiveness of particles in inducing changes in mucus secreting cell numbers/types should depend on the number of particles deposited that contained a particular amount of acid—implying that particles below a certain size cutoff (and therefore lacking a minimum amount of acid) should be ineffective; and that particle potency per unit weight should be greatest at the cutoff and decline strongly above the cutoff.

Since the development of this hypothesis both epidemiologlcal observations and some experimental studies have tended to reinforce the notion that acid particles can make a contribution to relatively long lasting bronchitic-like changes, and enhance the desirability of more direct testing of the model. In this paper we develop a general theoretical framework for the contributions of environmental agents to chronic obstructive lung disease, and a series of alternative hypotheses against which the predictions of the “Irritant signaling” model can be compared. Based on this, we suggest a research program that could be used to further develop and test the model and reasonable alternatives.     

Development of a field method for measuring manganese in welding fume

Workers who perform routine welding tasks are potentially exposed to fume that may contain manganese. Manganese may cause respiratory problems and is implicated in causing the occurrence of Parkinson-like symptoms. In this study, a field colorimetric method for extracting and measuring manganese in welding fume was developed. The method uses ultrasonic extraction with an acidic hydrogen peroxide solution to extract welding fume collected on polyvinyl chloride filters. Commercially available pre-packaged reagents are used to produce a colored solution, created by a reaction of manganese(ii) with 1-(2-pyridylazo)-2-naphthol. Absorbance measurements are then made using a portable spectrophotometer. The method detection limit and limit of quantification (LOQ) were 5.2 microg filter(-1) and 17 microg filter(-1), respectively, with a dynamic range up to 400 microg filter(-1). When the results are above the LOQ for the colorimetric method, the manganese masses are equivalent to those measured by the International Organization for Standardization Method 15202-2, which employs a strong acid digestion and analysis using inductively coupled plasma-optical emission spectrometry.     

FRESH-WATER LENS FORMATION IN AN UNCONFINED BARRIER-ISLAND AQUIFER1

ABSTRACT: Cone-penetrometer testing and computer modeling were utilized to investigate factors controlling fresh-water lens formation at Grand Isle, Louisiana. Measurements of tip resistance, sleeve friction, and electrical conductivity were recorded with depth to permit classification of sediment type and to determine thickness of the fresh-water lens and transition zone. Cone-penetrometer testing provided virtually continuous determinations of change in sediment type and ground-water salinity at a resolution rarely achieved using conventional drilling and water sampling techniques. Three sand bodies are present, each separated by a clay layer. The fresh-water lens is thinner in the center of the island than on the flanks. Fresh-water lens thickness is limited by a clay layer which prohibits downward movement of significant volumes fresh water. The transition zone from fresh water to salt water varies in thickness, being thinnest near the Gulf of Mexico and thickest where silt and clay interfinger with the upper sand. Both the thickness of the fresh-water lens and the shape of the transition zone differ from that predicted by theoretical models. Calibration of STJTRA, a variable-density solute-transport model, indicates that permeability variations are the dominant control on formation of the fresh-water lens.     

Assessing drought-related ecological risk in the Florida Everglades

In the winter-spring of 2001, South Florida experienced one of the worst droughts in its recorded history. Out of a myriad of ecological concerns identified during this time, the potential for catastrophic peat fire and negative impacts to wading bird reproduction emerged as critical issues. Water managers attempted to strike a balance between the environment and protection of water supplies for agriculture and urban interests. It became evident, however, that a broad-scale, integrated way to portray and prioritise ecological stress was lacking in the Florida Everglades, despite this being considered a necessary tool for addressing issues of environmental protection. In order to provide a framework for evaluating various water management operations using real-time information, we developed GIS-based indices of peat-fire risk and wading bird habitat suitability. These indices, based on real physical, chemical, and biological data, describe two ecological conditions that help define the physical and biological integrity of the Everglades. In addition to providing continuous, updated assessments throughout the drought period, we incorporated predictive models of water levels to evaluate how various water management alternatives might exacerbate or alleviate ecological stress during this time.     

Evaluation of a standardized method for determining soluble silver in workplace air samples

Several occupational exposure limits and guidelines exist for silver, but the values for each depend on the chemical form of the silver compound in question. In the past, it generally was not possible, without prior knowledge of the work process, to distinguish soluble silver from insoluble silver compounds collected in workplace air samples. Therefore, analytical results were historically reported as total silver. In this study, work was conducted to evaluate a method to differentiate between the quantities of water-soluble silver compounds and total silver collected on filters. The investigation entailed an evaluation of an International Organization for Standardization method to determine soluble silver in airborne particulate matter. The study design incorporated laboratory experiments to evaluate analytical figures of merit, such as selection of appropriate filter media and extraction solution, analytical recovery, and sample stability during storage. Polytetrafluoroethylene (PTFE) filters (2 microm, 37 mm) in opaque cassettes were either spiked with known amounts of silver nitrate or contained a known mass of solid silver nitrate. Results showed that over 90% of the silver was recovered from PTFE filters. Also, field studies were conducted in which workplace air samples were collected in two silver refineries. Some of these samples were analyzed only for soluble silver while others were sequentially extracted and analyzed, first, for soluble silver, then for total silver. The mass fractions of soluble silver, as compared to total silver, were approximately 2% or less. This investigation served to validate an international standard procedure for the determination of soluble silver in workplace air samples.