A Comparison of the Size Distribution of Particulates Emitted from Air,Mechanical, and Steam Atomized Oil Fired Burners

Particulate size distributions were obtained in the effluent gases from three steam generating boilers of a power station employing mechanical, steam, and air systems for heavy fuel atomization. Samples were obtained with an eight-stage cascade impactor. The air atomized burner produced the lowest particulate loading, the greatest percentage of particulates by weight in the submicron range, and particulates with the lowest combustible content.     

The influence of gill and liver metabolism on the predicted bioconcentration of three pharmaceuticals in fish

The potential for xenobiotic compounds to bioconcentrate is typically expressed through the bioconcentration factor (BCF), which has gained increased regulatory significance over the past decade. Due to the expense of in vivo bioconcentration studies and the growing regulatory need to assess bioconcentration potential, BCF is often calculated via single-compartment models, using K(OW) as the primary input. Recent efforts to refine BCF models have focused on physiological factors, including the ability of the organism to eliminate the compound through metabolic transformation. This study looks at the ability of in vitro biotransformation assays using S9 fractions to provide an indication of metabolic potential. Given the importance of the fish gill and liver in metabolic transformation, the metabolic loss of ibuprofen, norethindrone and propranolol was measured using rainbow trout (Oncorhynchus mykiss) and channel catfish (Ictalurus punctatus) gill and liver S9 fractions. Metabolic transformation rates (k(M)) were calculated and integrated into a refined BCF model. A significant difference was noted between BCF solely based on K(OW) and BCF including k(M). These studies indicate that the inclusion of k(M) in BCF models can bring predicted bioconcentration estimates closer to in vivo values.     

Limestone Dissolution in Flue Gas Scrubbing: Effect of Sulfite

Batch limestone dissolution experiments were carried out in a pH stat apparatus at 55°C with CO2 sparging and dissolved sulfite. Particle size distribution, utilization, sulfite in solution, limestone type, and the approach to calcite equilibrium were all found to contribute to the limestone reactivity. In the absence of sulfite, limestone dissolution was controlled solely by mass transfer. For a given stone under mass transfer control, film thickness was found to be independent of pH. The dissolution rate in the presence of sulfite was controlled by a combined surface kinetics/mass transfer regime. SEM micrographs supported this conclusion. A surface rate correlation was developed which accounted for observed inhibition by an inverse dependence on calcium sulfite concentration at the limestone surface. While the form of the rate expression was applicable to all stones, the surface rate constant was stone dependent. A computer code which accounted for mass transfer with surface kinetics was tested against experimental observations of four limestone types. Changes in pH and the concentrations of calcium, carbonate, sulfite, sulfate, and adipic acid were accurately modeled.     

IDENTIFICATION OF SOLUTE LOADING SOURCES TO A SURFACE STREAM1

ABSTRACT: A study was performed to identify sources of solute loading to the Dirty Devil River and its major tributaries, in southeastern Utah. A primary goal was to determine the contribution of gypsum dissolution to total dissolved solids concentration, and its potential increase in the future if salinity control measures are instituted. Synoptic field data were collected during the low flow period in October 1983. Data were analyzed using the geochemistry models WATEQF and BALANCE to postulate mineral reactions leading to solute loading. Three known sources of solute loading, involving two different geochemical mechanisms, were clearly discernable. Two additional areas of possible gypsum dissolution were located.     

RELATIONSHIP BETWEEN ANNUAL RUNOFF AND WATERSHED AREA FOR THE EASTERN UNITED STATES1

ABSTRACT: As part of the U.S. Environmental Protection Agency's effort to determine the long-term effects of acidic deposition on surface water chemistry, annual runoff was estimated for about 1000 ungaged sites in the eastern U.S. using runoff contour maps. One concern in using contour maps was that a bias may be introduced in the runoff estimates due to the size of the 1000 ungaged sites relative to the size of the watersheds used in developing the maps. To determine if a bias was present the relationship between the annual runoff (expressed as depth) and the watershed area for the Northeast (NE) and Southern Blue Ridge Province (SBRP) was tested using five regional data bases. One short-term data base (1984 Water Year, n = 531) and two long-term data bases (1940–57, n = 134 and 1951–80, n = 342) were used in the NE. In the SBRP one short-term database (1984 Water Year, n = 531) and one long-term data base (1951–80, n = 60) were used. For the NE and the SBRP, runoff was not directly correlated with watershed area using the five regional databases. Also, runoff normalized by precipitation was not related to watershed area.     

A Call for Urgent Monitoring of Food and Water Security Based on Relevant Indicators for the Arctic

This perspective paper argues for an urgent need to monitor a set of 12 concrete, measurable indicators of food and water security in the Arctic over time. Such a quantitative indicator approach may be viewed as representing a reductionist rather than a holistic perspective, but is nevertheless necessary for actually knowing what reality aspects to monitor in order to accurately understand, quantify, and be able to project critical changes to food and water security of both indigenous and non-indigenous people in the Arctic. More relevant indicators may be developed in the future, taking us further toward reconciliation between reductionist and holistic approaches to change assessment and understanding. However, the potential of such further development to improved holistic change assessment is not an argument not to urgently start to monitor and quantify the changes in food and water security indicators that are immediately available and adequate for the Arctic context.     

Comparative audit of booking and mid-trimester ultrasound scans in the prenatal diagnosis of congenital anomalies

During 1988 and 1989, 3565 women booked under consultants who performed an ultrasound scan at booking, whilst 4984 booked under consultants who performed a formal mid-trimester scan between 16 and 18 weeks. All significant anomalies diagnosed prenatally and in the neonatal period were recorded, the incidence in each group being 12.9/1000 and 9.83/1000, respectively (NS). The sensitivity of diagnosis before 20 weeks was 45 per cent in the ‘mid-trimester’ group (kappa 0.62) compared with 30 per cent in the ‘booking’ group (kappa 0.46), overall sensitivity of prenatal diagnosis, however, being similar in both groups (63 vs. 65 per cent, kappa 0.77 vs. 0.79). Cardiac anomalies were the single largest group which were not detected equally prenatally in both groups. This study shows that formal mid-trimester scanning leads to anomalies being detected significantly earlier in the antenatal period. Although not statistically significant, three lethal anomalies were missed prenatally in the ‘booking’ group which we would have expected to diagnose on a mid-trimester scan. These figures are discussed in the light of previous reports.     

Modelling reactions between cement pore fluids and rock: implications for porosity change

The migration of groundwater equilibrated with cement from a deep geological disposal facility for radioactive wastes will perturb the chemical, minerological and physical properties of the geosphere in advance of the migration of radionuclides. Preliminary modelling of a simplified scenario has been conducted to assess these changes using appropriate data for mineral dissolution kinetics, the chemical composition of cement pore fluids, and the hydrogeological characteristics of fractured crystalline rock. Chemical exchanges between rock immediately adjacent to the engineered barriers of a waste disposal facility and pore fluids were evaluated using the speciation-reaction path code. which revealed rapid loss of Ca, and gains in Na and Si of the evolved fluids, with little change in pH. Secondary minerals show a sequence of calcium silicate hydrates, and zeolites. Precise definition of the overall mass balance is uncertain due to the absence of both thermodynamic data for many zeolites and kinetic data for the precipitation of feldspars. Modelling has demonstrated that reaction kinetics will be important in governing chemical exchanges for length scales up to 20 m. Radionuclide retardation will be enhanced by the growth of zeolites and calcium silicate hydrates.     

Placental biopsy in the third trimester of pregnancy

Forty-two women with abnormal ultrasound findings after 27 weeks' gestation underwent a placental biopsy. In 39 cases, a karyotype was obtained from a direct preparation within 48 h, five abnormal karyotypes being detected (four trisomies and a triploidy). One confirmed placental mosaic was also detected. In one case, a small terminal deletion of chromosome 7 was not detected at the time due to the quality of the preparation. A karyotype can be obtained from a direct preparation in the third trimester in over 90 per cent of cases, the quality of the preparation allowing the reliable detection of abnormalities of chromosome number. We believe that this technique may be usefully, reliably, and safely employed in the third trimester of pregnancy by those with an interest in antenatal ultrasound diagnosis who do not have immediate access to a cytogenetics laboratory and who feel that cordocentesis is inappropriate for their situation.