Geostatistical analysis of Palmerton soil survey data

This paper presents a literature review focused on predictive technique audits, one of the types of audit considered to have the greatest potential role in improving environmental impact assessment practice. The literature review is limited to US literature with the exception of a few UK audits, one undertaken by Tomlinson at the University of Aberdeen. The authors are, however, aware that literature from other countries exists on this subject, for example from Canada and South Africa.In the review, predictive technique audits performed for or by the US Bureau of Land Management, the Electric Power Research Institute, the US Nuclear Regulatory Commission, the US Corps of Engineers, together with the Wisconsin Power Plant Impact Study are described. In addition, articles describing the auditing of models designed to predict environmental change are reviewed, before details of auditing activity in the UK are presented.     

Mitochondrial DNA analysis of native and selectively inbred Chesapeake Bay oysters,Crassostrea virginica

Mitochondrial DNA (mtDNA) genotypes were examined in 1989 in threeCrassostrea virginica (Gmelin) populations native to Chesapeake Bay, USA, and in one population selectively inbred for rapid growth for ten generations. We wished to determine whether this character would be useful as a genetic marker for distinguishing between the inbred line and the native oysters and to determine whether detectable genetic differences exist among present-day native populations ofC. virginica. Thirty mtDNA haplotypes were identified. The average percentage nucleotide difference between native haplotypes was 1.8%. Inbred oysters were characterized by mtDNA haplotypes distinctly different from ancestral native oysters, indicating a high degree of genetic differentiation between the two groups (average percentage mtDNA nucleotide sequence divergence,=21.8%). The common native haplotype was not present in the selectively inbred sample, and six of the seven haplotypes detected in the inbred oysters were not found in the survey of native oysters. Chi-square tests on haplotype frequencies indicated that the native populations were not significantly different from one another. However, the distribution and relatedness of haplotypes suggest that significant change in the oyster gene pool may have occurred over the past few decades.     

Local agenda 21, compulsory competitive tendering and local environmental practices

This paper focuses on the issues arising from Local Agenda 21 where the role of local authorities is seen as vital in promoting and achieving sustainable development. The implications of the current forms of public sector restructuring for local authorities, and in particular the consequences of the requirement to contract out the delivery and management of traditional environmental services such as grounds maintenance are considered. The paper concludes that the ongoing processes of local government restructuring, together with the removal of many functions from local democratic control, are reducing the capacity of local communities to respond positively to the demands of Local Agenda 21.     

DEVELOPMENT AND EVALUATION OF A DIMENSIONLESS UNIT HYDROGRAPH1

ABSTRACT: A generalized unit hydrograph method is developed and evaluated for ungaged watersheds. A key component in this method is the value of a dimensionless storage coefficient. Procedures to estimate this coefficient are given using calibrated values from 142 rainfall-runoff events gaged in watershed located mainly in the Eastern US. Only limited success was obtained in predicting this storage coefficient. Thirty-seven, independent rainfall-runoff events were used to test the proposed technique. The generalized unit hydrograph predicted the observed runoff hydrographs fairly well with considerable improvement in accuracy over the SCS dimensionless unit hydrograph. Approximately one-half of test storms had percent errors in predicted peak flow rates that were less than 34 percent compared to percent error of 88 percent with the SCS method.     

EFFECTS OF PRECIPITATION AND LAND USE ON STORM RUNOFF1

ABSTRACT: Storm-runoff quantity and quality were studied in three watersheds located near St. Paul in Ramsey County, Minnesota, from April 15 through September 15 of 1984, 1985, and 1986 to qualitatively determine the effects of precipitation and selected land uses on storm runoff. In respect to precipitation effects, differences in stormrunoff quantity between years in an urban watershed that lacks wetlands appear to be related to the average storm size (amount of precipitation) during the study period of each year. In contrast, the differences in storm-runoff quantity from watersheds that contain wetlands appear to be related to total precipitation during study period of each year. In respect to land use, the differences in storm-runoff quantity appear to be related to the amounts of impervious and wetland area. The watershed that contains the largest amount of impervious area and smallest amount of wetland area has the largest amount of storm runoff. Differences in storm-runoff quality appear to be related to the amounts of wetland and lake area. The watershed that contains the largest amounts of wetland and lake area has the smallest storm-runoff loading of suspended solids, phosphorus, and nitrogen. The wetland and lake areas likely retain the loading and, subsequently, lower the amount of storm-runoff loading exported from a watershed.     

Assessing the human health effects of PCBs

Toxic effects can be induced in experimental animals by high doses of pure PCBs, and in man by PCDF-contaminated PCB. In order to assess the effects of ordinary, uncontaminated PCB on man, a group of capacitor workers who had direct occupational exposure to Aroclors 1254, 1242, and 1016 during the period 1946 to 1977 has been under medical surveillance since 1976. This group presented some indications of non-AhR-mediated microsomal enzyme induction during the period of direct exposure, but no chloracne or increased cancer mortality. Multiple regression studies revealed no significant associations between lipid PCB levels and clinical indicators of hepatotoxicity, hypertension, or pulmonary impairment.     

Modeling tracer diffusion in fractured and unfractured, unsaturated, porous media

A proposed tracer diffusion test for the Exploratory Shaft Facility at Yucca Mountain, NV, is modeled. For the proposed test, a solution containing conservative tracers will be introduced into a borehole in the geologic medium of interest. The tracers will diffuse and advect from the saturated source region into the unsaturated matrix in the surrounding tuff. After some time, the borehole is to be overcored, and tracer concentrations in the fluid will be measured in the core as a function of distance from emplacement. The data will be used to evaluate diffusive behavior and to derive effective diffusion coefficients for the tracers in the specific tuff. Numerical simulations are used to study the effects of effective diffusion coefficient, porosity, saturation, and fracturing on tracer transport. Results are reported for numerical simulations of tests in the Topopah Spring Member and the Tuff of Calico Hills, which have significantly different porosities and saturations. The simulations make the following predictions: The spread of tracer during the test will be sensitive to the effective diffusion coefficient of the tracer. Tracer will diffuse farther in the Topopah Spring Member than in the Tuff of Calico Hills because of the former's lower porosity and saturation. Tracer transport by advection into the Topopah Spring Member will be greater than that into the Tuff of Calico Hills because of capillary effects. While advection will be a significant mechanism for tracer penetration into the Topopah Spring tuff, it will be less significant for tracer penetration into the Calico Hills tuff. The proximity of a single vertical fracture to the source region determines its effects on tracer transport, especially if the fracture diverts fluid flowing from the source region into the matrix.     

Determination of time-dependent partition coefficients for several pesticides using diffusion theory

Diffusion-retarded partitioning of pesticides with aggregated soils results in a time-dependent partition coefficient (Kd') which is different at equilibrium from the partition coefficient derived from conventional 24-h batch studies (Kd) measured on dispersed soil. An experiment was undertaken to determine the importance of Kd' for the prediction of pesticide concentrations in solutions bathing artificial soil aggregates and to determine whether diffusion theory could accurately predict the concentrations. Two clay soils were mixed with polyacrylamide to create artificial aggregates of 0.8, 1.4 and 1.7 cm diameter when dry. After saturation, the aggregates were immersed in solutions containing isoproturon or a mixture of isoproturon, chlorotoluron and triasulfuron. The decline with time of the pesticide concentrations in the bathing solution was monitored and the results were compared with predictions from a diffusion-based model. The effective diffusion coefficients of the compounds were obtained by either fitting the non-linear diffusion model to the data (D(ef)) or by independent calculations based on the properties of the compounds and of the aggregates (D(ec)). The diffusion model was able to predict the temporal variation in pesticide concentrations in the bathing solution reasonably well whether D(ef) or D(ec) values were used. However, equilibrium concentrations in solution were sometimes overestimated due to increased sorption with time at the particle scale. Overall, the ratio between D(ef) and D(ec) ranged from 0.23 to 0.95 which was a reasonable variation when compared to the range of aggregate sizes used in the experiments and of the Kd values of the compounds.     

A study into the parameters affecting selected reaction monitoring of 2,3,7,8-TCDD

The use of high resolution (10,000 resolving power) coupled gas chromatography - mass spectrometry is a well established technique in the analysis of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) but in the case of heavily contaminated stack samples interferences can still occur. A complementary technique that offers high specificity is selected reaction monitoring (SRM).A study has been made into the effects that affect the metastable dissociation of 2,3,7,8-TCDD in the first field free region (FFR1) of a magnetic sector mass spectrometer, and monitored using SRM.Monatomic, diatomic and polyatomic gases have been investigated in the collision chamber of the mass spectrometer, as have the effects of electron energy, source temperature and trap current on the dissociation, and optima conditions determined for them.     

Genetic evidence for hybridisation between Haliotis rubra and H. laevigata

Seventeen abalone whose appearance was intermediate between the two commonly fished species in south-eastern Australia, blacklip (Haliotis rubra) and greenlip (H. laevigata), were collected between 1986 and 1989. Protein electrophoresis revealed that rare, morphologically intermediate abalone are predominantly F₁ hybrids; others are backcross individuals. There is also evidence of possible local introgression of H. rubra genes into H. laevigata and vice versa in sympatric populations. These two species exhibit marked morphological, behavioural and genetic differences, and yet hybridisation, although rare, occurs in at least several regions of sympatry. The commonly invoked explanations for the breakdown of species barriers, environmental disturbance and rarity of one of the parent species, do not appear applicable, unless microhabitat separation creates local rarity of one species. The frequency of hybridisation is discussed in relation to regional biogeography.