Inorganic mercury pharmacokinetics in man: a two-compartment model

Excreta data obtained from five human subjects and previously analyzed as part of a multicompartment model (Hall, L.L., P.V. Allen, H.L. Fisher, and B. Most. 1995. The kinetics of intravenously administered inorganic mercury in humans. In Kinetic models of trace element and mineral metabolism, ed. K.N.S. Subramanian and M.E. Wastney, 1-21. Boca Raton: CRC Press) were reanalyzed by means of a two-compartment model. The mobile compartment represents mercury of any form that is available for transport throughout the body. The immobile compartment represents mercury in forms that are not available for transport. The model simulates time profiles for body inorganic mercury and for fecal and urinary excretion. According to the model, intravenously administered mercury enters the body in the mobile form. Following administration, two distinct kinetic profiles were observed. In four of five subjects, mobile mercury in the body declined rapidly and the immobile form became dominant within 6 days. In these subjects, fecal excretion profiles were characterized by an initial phase dominated by excretion of mobile mercury lasting up to 6 days. This was followed by a slower phase during which mobile and immobile mercury were excreted in varying amounts. A similar pattern was seen in urinary profiles, but the initial phase is shorter and less pronounced. In each of these subjects, immobile mercury accounted for 84–94% of the total cumulative urinary excretion. The fifth subject showed a unique kinetic profile. Conversion of mobile to immobile mercury was slow and the two forms did not reach equivalence until approximately 70 days after dosing. Despite this fact, approximately 99% of fecally excreted mercury and 100% of urinary mercury originated in the immobile compartment. Possible explanations for the different profiles are discussed within the context of the model.     

Reproductive success in male savanna baboons

Summary Different techniques have been utilized to ascertain male savanna baboon reproductive success based upon behavioral data. A 19 month field study of the reproductive behavior of savanna baboons in Kenya revealed a high degree of concordance among five different measures of male baboon reproductive success. The number of ejaculations showed the highest correlation with time spent in consort. Male reproductive success was not correlated with the number of females mated with because most males mated with most females. Female baboons regularly undergo multiple cycles prior to conception and the penultimate cycle showed no behavioral or physiological differences from the conception cycle. In nearly one-third of conception cycles a single consort partner was responsible for almost two-thirds of ejaculations during the four day optimal conception period. One may be able to reasonably infer paternity in these cases, but the available data are insufficient to support the idea that the variance in male baboon reproductive success is greater than the variance in female baboon reproductive success. The variance in male savanna baboon reproductive success will remain uncertain until genetic paternity studies are undertaken. It is suggested that mate selectivity, longevity, and stochastic factors are important components influencing male baboon reproductive success.     

Ground flora trampling studies: Five years after closure

Trampling as an ecological factor is a major concern of the management of park, forest, nature preserves, and wilderness areas as recreational resources. Of particular importance to the management concept of carrying capacity is the relative resistance of native plant communities, to trampling and the resilience or the capacity of impacted communities to recover. This information can be used by management to establish seasonal use limits to prevent irreversible degradation of these resources. The purpose of this study was to follow the recolonizaton of experimental trail surfaces barren of vegetative cover and hiked at three levels of use intensity. Results of this study indicate that soil compaction as measured by soil penetration resistance increased progressively with use level while the total number of species, species diversity, and dominant index scores declined. A major finding was that the greatest degree of change occurred at the first level of hiking, indicating that major floristic measures were most affected by the least amount of hiking. Recolonization of impacted areas that received 100 trampling passes as measured by plant cover, dominant indices, floristic dissimilarity, and species diversity was similar to areas receiving four and eight times more trampling, despite major differences in soil penetration resistance. These data suggest limited use delivered at one time can be as damaging as increasing levels of use delivered at over time.     

Book reviews

Local Politics and Participation in Britain and France

Albert Mabileau, George Moyser, Gerraint Parry, Patrick Quantin. 1989. 281 pp. Price £30.00.

ISBN: 0 521 34576 6.

The Rural State?: Limits to Planning in Rural Society

Paul Cloke and Jo Little. 1990, Oxford University Press. 287 pp.

Price £30.00.

ISBN: 0 19 823287 X

Urbanisation in History: A Process of Dynamic Interactions. International Studies in Demography.

Edited by Ad van der Woude, Jan de Vries, and Akira Hayami. Clarendon Press, Oxford, 1990. 371 pp. Price £40.00.

Housing and Social Inequality

Jenny Morris and Martin Winn

Integrated Land‐Use and Transport Modelling — Decision Chains and Hierarchies

Tomas de la Barra

Beyond Green Belts — Managing Urban Growth in 21st Century

Regional Studies Association (1990). 64 pp. Price £9.95.

Learning from Rotterdam

M. J. Vroom and J. H. A. Meeus.

173 pp. Nichols, New York. Price £25.

Reviewing the Quality of Environmental Statements

N. Lee and R. Colley

EIA Centre, University of Manchester, 1990.

Occasional Paper 25, 46 pp. Price: £3.00.

Knowledge and Public Policy: the search for meaningful indicators

Judith Innes. Transaction Publishers, New Brunswick. 352 pp. Price: £16.95.

Urban Problems: An Applied Urban Analysis

Michael Pacione. Routledge, 1990.

Living with Inner City Policies: Two Essays on Inner City Life and Inner City Policies

Meryl Aldridge and John Edwards, Department of Social Policy, Royal Holloway and Bedford New College. Social Policy Papers No. 2, 1989.

Information Technology in Geography and Planning: including principles of GIS

Bracken and Webster, Routledge, London 1990. 444 pp.

Housing and Social Change in Europe and the USA

Michael Ball, Michael Harloe and Maartje Martens. Routledge, 222 pp. Price: £10.99.

Land and Property Development: Changing Context

Edited by Healey and Nabarro. 212 pp. Price: £39.50.     

Creating markets for combined heat and power and clean distributed generation in New York State

Combined heat and power (CHP) is the simultaneous production of electrical or mechanical power and thermal energy from in a single process. Because thermal output from the generation of electricity is captured and utilized onsite, CHP systems can achieve efficiencies from 60% to as high as 90%. In contrast generation of electric power at sites remote from the loads served often results in efficiencies of 33% or less due to losses in generation and transmission and distribution of the power to ultimate end users. A well designed CHP system is the essence of energy efficiency. It may also provide significant environmental benefits. However, the full promise of CHP for improving the efficiency and productivity of businesses and the quality of the environment is unlikely to be realized given the current market structure and regulatory environment in which CHP projects are forced to compete. This paper examines the market structure and regulatory obstacles that hinder the development of more robust markets for CHP in New York State.     

MULTISCALE INFLUENCES ON PHYSICAL AND CHEMICAL STREAM CONDITIONS ACROSS BLUE RIDGE LANDSCAPES1

ABSTRACT: Streams integrate biogeochemical processes operating at broad to local spatial scales and long term to short term time scales. Humans have extensively altered those processes in North America, with serious consequences for aquatic ecosystems. We collected data on Upper Tennessee River tributaries in North Carolina to: (1) compare landuse and landscape geomorphology with respect to their ability to explain variation in water quality, sedimentation measures, and large woody debris; (2) determine if landscape change over time contributed significantly to explaining present stream conditions; and (3) assess the importance of spatial scale in examining landuse influences on streams. Stream variables were related to both landuse and landscape geomorphology. Forest cover accounted for the most variation in nearly all models, supporting predictions of nutrient enrichment, thermal pollution, and sedimentation caused by landscape disturbance. Legacy effects from past catchment disturbance were apparent in sedimentation measures. Nitrogen and phosphorus concentrations, as well as stream temperature, were lower where riparian buffers had reforested. Models of stream physicochemistry fit better when predictors were catchment wide rather than more localized (i.e., within 2 km of a site). Cumulative impacts to streams due to changes in landuse must be managed from a watershed perspective with quantitative models that integrate across scales.     

RASTER-BASED HYDROLOGIC MODELING OF SPATIALLY-VARIED SURFACE RUNOFF1

ABSTRACT: The proliferation of watershed databases in raster Geographic Information System (GIS) format and the availability of radar-estimated rainfall data foster rapid developments in raster-based surface runoff simulations. The two-dimensional physically-based rainfall-runoff model CASC2D simulates spatially-varied surface runoff while fully utilizing raster GIS and radar-rainfall data. The model uses the Green and Ampt infiltration method, and the diffusive wave formulation for overland and channel flow routing enables overbank flow storage and routing. CASC2D offers unique color capabilities to display the spatio-temporal variability of rainfall, cumulative infiltrated depth, and surface water depth as thunderstorms unfold. The model has been calibrated and independently verified to provide accurate simulations of catchment response to moving rainstorms on watersheds with spatially-varied infiltration. The model can accurately simulate surface runoff from flashfloods caused by intense thunderstorms moving across partial areas of a watershed.     

LOCAL OPPOSITION TO THE TRANSFER OF WATER SUPPLIES:AN OKLAHOMA CASE STUDY1

Interregional conflicts over the allocation and transfer of water supplies have occurred with increasing frequency in the contemporary United States. This paper presents the results of a case study of citizen opposition to a proposal to transfer water supplies within Oklahoma. Residents of the area adjacent to Lake Tenkiller in eastern Oklahoma were surveyed concerning their reactions to a proposal of the City of Tulsa to transfer large volumes of water from the reservoir to the city. Results of the survey indicated that a community based concern for preserving local water levels transcended individual self-interests in maintaining Tenkiller's water levels. The results support the recently developed concept of “turf politics,” which suggests that regional and community based considerations tend to dominate interregional locational conflict resolution.