A low cost instrument based on a solid state sensor for balloon-borne atmospheric O(3) profile sounding

The design of an instrument based on a solid state tungsten oxide sensor for making profile measurements of atmospheric ozone from balloon platforms is described. The sensor is operated at a constant temperature, typically 530 [degree]C. The importance of a detailed consideration of the electronic design is demonstrated, with particular reference to the circuit to control the sensor heater. Calibration methods which are straightforward to implement are illustrated, and the results of a test flight alongside an electrochemical ozonesonde are shown. Quantitative agreement within 25% for most of the profile demonstrates the potential of this type of sensor for ozone sounding. Future improvements from manufacture to analysis are expected to improve on this.     

The effects of acid precipitation-long term ecological measurements in loch vale watershed,Rocky Mountain National Park

Contribution from Fourth World Wilderness Congress-Acid Rain Symposium, Denver (Estes Park), Colorado, September 11–18, 1987.     

Membrane Bioreactor Model for Removal of Organics from Wastewater

Abstract

The persistence of trace organics in wastewater effluent is a major environmental concern. Possible use of fixed microbial films in wastewater treatment processes is currently an active area of research that may be able to address many of these problems. In the waste effluent, the persistence of trace organics is attributed, in part, to the inability of microbial populations to extract energy from dilute environments at a rate fast enough to sustain themselves. To address this problem, a novel wastewater treatment scheme is considered. On the basis of previous hollow fiber biomass growth studies, we believe that an anaerobic biofilm supported by hollow fibers could achieve greater biomass density than a film grown on traditional impermeable supports. This in turn could lead to improved substrate removal efficiency in a reactor of a given volume. Using this concept, we developed a mathematical model to test the potential of hollow fiber membrane reactors for biodegradation of acetate solution. A computer simulation has shown that it would be possible to remove about 90% from feed solutions containing 0.1 mg-cm^-3 acetate with biomass density 25 mg-cm^-3 in the hollow fiber supported biofilm. More concentrated feeds could be effectively treated if sufficiently high biomass density could be attained. This process, therefore, shows promise in wastewater treatment. The advantages of hollow fiber membrane bioreactors are their high surface-to-volume ratio, separation of cells from flow, and high cell concentration. All of these are essential requirements for optimum utilization of biomass in wastewater treatment. The hollow fiber membrane bioreactor concept, therefore, may provide a new and unique approach to treating organics.     

Effects of Disturbance on Nitrogen Export from Forested Lands of the Chesapeake Bay Watershed

The objective of this research project is to develop, test, validate, and demonstrate an analytical framework for assessing regional-scale forest disturbance in the mid-Atlantic region by linking forest disturbance and forest nitrogen export to surface waters at multiple spatial scales. It is hypothesized that excessive nitrogen (N) leakage (export) from forested watersheds is a potentially useful, integrative "indicator" of a negative change in forest function which occurs in synchrony with changes in forest structure and species composition. Our research focuses mainly on forest disturbance associated with recent defoliations by the gypsy moth larva (Lymantria dispar) at spatial scales ranging from small watersheds to the entire Chesapeake Bay watershed. An approach for assessing the magnitude of forest disturbance and its impact on surface water quality will be based on an empirical model relating forest N leakage and gypsy moth defoliation that will be calibrated using data from 25 intensively-monitored forested watersheds in the region and tested using data from more than 60 other forested watersheds in Virginia. Ultimately, the model will be extended to the region using spatially-extensive data describing: 1) the spatial distribution of dominant forest types in the mid-Atlantic region based on both remote sensing imagery and plot-scale vegetation data; 2) the spatial pattern of gypsy moth defoliation of forested areas from aerial mapping; and 3) measurements of dissolved N concentrations in streams from synoptic water quality surveys.     

Inter- and Intra-Annual Chemical Variability During the ice-Free Season in Lakes with Different Flushing Rates and Acid Deposition Histories

Quantifying chemical variability in different lake types is important for the assessment of both chemical and biological responses to environmental change. For monitoring programs that emphasize a large number of lakes at the expense of frequent samples, high variability may influence how representative single samples are of the average conditions of individual lakes. Intensive temporal data from long-term research sites provide a unique opportunity to assess chemical variability in lakes with different characteristics. We compared the intra- and inter-annual variability of four acidification related variables (Gran alkalinity, pH, sulphate concentration, and total base cation concentration) in four lakes with different flushing rates and acid deposition histories. Variability was highest in lakes with high flushing rates and was not influenced by historic acid deposition in our study lakes. This has implications for the amount of effort required in monitoring programs. Lakes with high flushing rates will require more frequent sampling intervals than lakes with low flushing rates. Consideration of specific lake types should be included in the design of monitoring programs.     

A Knowledge-Based Approach to the Assessment of Watershed Condition

The Ecosystem Management Decision Support (EMDS) system is an application framework for knowledge-based decision support of ecological assessments. EMDS integrates geographic information system and knowledge base system technologies to provide an analytical tool for environmental assessment and monitoring. The basic objective of EMDS is to improve the quality and completeness of environmental assessments and the efficiency with which they are performed. The USDA Forest Service and the U.S. Environmental Protection Agency have cooperatively developed an EMDS knowledge base for watershed condition assessment. Specifically, this knowledge base evaluates watershed processes, patterns, general effects of human activity, and fisheries habitat suitability. Such assessments are based on spatially explicit input data concerning current conditions and reference conditions which are subsequently interpreted by user-defined "fuzzy" membership functions. In this paper we describe basic components of our knowledge base for assessing watershed condition and illustrate its application within northern Idaho and northwestern Montana.     

Larval salivary glands are a source of primer and releaser pheromone in honey bee (Apis mellifera L.)

A brood pheromone identified in honeybee larvae has primer and releaser pheromone effects on adult bees. Using gas chromatography–mass spectrometry (GC–MS) to evaluate fatty acid esters—the pheromonal compounds—in different parts of the larvae, we have localized the source of the esters as the larval salivary glands. A histochemical study describes the glands and confirms the presence of lipids in the glands. Epithelial cells of the gland likely secrete the fatty acids into the lumen of the gland. These results demonstrate the salivary glands to be a reservoir of esters, components of brood pheromone, in honeybee larvae.     

Diagnosis of polyhydramnios in early gestation: Indication for prenatal diagnosis?

Previously published reports have indicated that idiopathic polyhydramnios may be associated with trisomies 18 and 21 and that chromosomal analysis is indicated. Furthermore, the natural history and fetal outcome of polyhydramnios diagnosed in early gestation have not been well delineated. We identified 138 pregnancies with polyhydramnios prior to 26 weeks' gestation. Of 131 complete cases, 21 were diagnosed as severe, 18 as moderate, and 92 as mild polyhydramnios. Congenital abnormalities were noted in 18 of 21 severe cases (86 per cent). Two of the remaining three cases were twin-to-twin transfusion. Thirteen of 18 cases with moderate polyhydramnios (72 per cent) were associated with anomalies; six of the remaining cases were twin-to-twin transfusion. Sixteen of 92 cases of mild polyhydramnios (17 per cent) were associated with congenital abnormalities. In 69 of 76 cases of mild hydramnios not associated with anomalies (91 per cent), the hydramnios resolved prior to delivery. Only 2 of 16 (13 per cent) associated with anomalies resolved. In 4 of 5 cases (80 per cent) with moderate hydramnios and no anomalies, the amniotic fluid volume was normal on subsequent ultrasound. No case of moderate polyhydramnios associated with anomalies or maternal conditions nor any case of severe polyhydramnios resolved. There were seven cases of chromosomal abnormalities in this series; all were associated with sonographic findings in addition to the presence of polyhydramnios. On the basis of these data, we doubt the benefit of amniocentesis following the early diagnosis of idiopathic polyhydramnios in the absence of other ultrasound findings.