Interacting pressure and temperature effects on enzymes of marine poikilotherms: Catalytic and regulatory properties of FDPase from deep and shallow-water fishes

At low temperature (3°C), and in the absence of substrate and cofactor, the enzyme, fructose diphosphatase (FDPase), extracted from liver of the benthic fishCoryphaenoides acrolepis, is reversibly inactivated by exposure to relatively low pressures (5,000 psi). At pressures of 20,000 psi at 3°C the native enzyme is irreversibly denatured. When the cofactor and the substrate are present, the enzyme is protected against pressure denaturation; hence, catalysis is insensitive to at least 10,000 psi at 3°C. Similarly, interactions between FDPase and its negative modulator adenosine monophosphate (AMP), are largely pressure insensitive. Pressure sensitivity of the native enzyme and of the catalytic process is much reduced at temperatures above about 9°C. The homologous enzyme from a surface fish,Pimelometopon pulchrum, is strikingly more sensitive to pressure, particularly at low temperatures.     

Carbon flux to seabirds in waters with different mixing regimes in the southeastern Bering Sea

The southeastern Bering Sea is characterized by three mixing regimes, separated by fronts associated with the 50, 100, and 200 m isobaths. Phytoplankton to zooplankton transfer-rates are high in waters over the outer shelf and slope (seaward of the 100 m front) relative to transfer in waters over the middle shelf (between the 50 and 100 m fronts). To see whether this difference is reflected at a higher trophic level, we computed carbon flux to the 11 commonest seabird species. Bird-density data (for the period 1975 through 1979) were combined with daily caloric requirement, which is an allometric function of body size in this endothermic group. Minimum transfer to seabirds over a 153 d period (April–August) was 30 mg C m^-2 for the middle shelf and 48 mg C m^-2 for outer shelf and slope waters. Trophic transfer to subsurface-feeding birds (shearwaters, murres and auklets) differed little between regions. In contrast, trophic transfer to surface-feeding birds (fulmars, petrels, and kittiwakes) in the outer shelf and slope waters was 3 times greater than in the waters of the middle shelf. Thus, for seabirds as a whole, pathways of energy transfer differed more between regions than did total carbon flux.     

Using computer graphics to reveal temporal changes in urban population density patterns

Population distributions change substantially over time in major metropolitan areas. Knowledge of these variations by time of day, day of the week and other time periods can be helpful to disaster planners who need to prepare response plans to earthquakes and other disasters that will injure and kill large numbers of people. Computer graphics can display data that describe these changing population patterns in ways that can be more easily comprehended than page after page of printed numbers. Several different illustrations of 3-D population density maps drawn by the ASPEX computer program are presented. Each illustrates a guideline that can be used to prepare maps that deal with the many ways of looking at urban population density distributions and their temporal changes. Those maps can help disaster planners gain a realistic perception of population density distributions by enabling them to see what cannot be seen from the actual physical structure of a large metropolitan region.     

PLANNING DIFFUSE POLLUTION CONTROL: AN ANALYTICAL FRAMEWORK1

ABSTRACT: Determination of an optimal nonpoint pollution control strategy demands information relating to (1) costs of pollutant reduction, (2) transport of pollutants, (3) water quality impact of pollutants, and (4) the economic impact of water quality changes. This paper briefly reviews the literature in each of these areas and suggests an analytical framework useful in the development of an optimal nonpoint pollutant control strategy.     

GROUNDWATER MANAGEMENT ON THE TEXAS HIGH PLAINS1

ABSTRACT The effects of major water management practices on the pumping requirement from the Ogallala aquifer are discussed. Demand on the aquifer may be reduced as much as 15 percent by recycling irrigation runoff, 25 percent by recycling irrigation runoff and irrigating with water from playas, and 29 percent by recycling irrigation water in combination with irrigation from playas and artificial recharge of playa water to the aquifer. Other practices that can result in more efficient use of precipitation and groundwater are limited irrigation, land forming, soil profile modification, and improved irrigation systems, thereby reducing the pumping demand on the Ogallala. Additional water supplies can possibly be obtained by water harvesting, weather modification, and water importation. Conclusions reached were that the overdraft on the aquifer can be reduced by the application of sound water management practices on an area-wide basis.     

Environmental hazards,neighbourhood quality,and neighbourhood environmental activism

summary This article presents a study of the association of perceived neighbourhood hazards, neighbourhood quality, and resident behavioural responses in two New Jersey, USA, communities that contain multiple technological hazards and populations that are relatively poor and racially homogeneous. The number of neighbourhood problems was highest among residents who engaged in activities to protect their neighbourhood and perceived that their neighbourhood was of poor or fair quality. These respondents perceived three to five times as many hazards as their counterparts who were passive and perceived that their neighbourhood was of excellent or good quality. Respondents' age, education, gender, type of residential unit occupied, and length of residence in the neighbourhood, were not associated with their evaluation of neighbourhood hazards. The authors argue that multiple-hazard neighbourhoods are excellent environments to learn about perception of hazards.Professor Michael Greenberg is Head of the Department of Urban Studies and Community Health where Professor Dona Schneider and Jim Parry are associates.     

Rieselfelder

Soils of the large sewage farm area south of Berlin are contaminated with heavy metals such as Cd, Cr, Cu, Hg, Ni, Pb, Zn. Based on earlier studies the total amount and the bioavailable proportions of heavy metals in soil samples were analysed. In some samples very high levels of total heavy metal concentrations were detected. For Pb, Cd, Cu and Hg the maximum values were 1360, 29.7, 817 and 40.8 mg/kg soil dry matter, respectively. The biovailable fractions of heavy metals which were found primarily in the acetate and EDTA fractions and to a lesser degree in the water extract account for about 50 % (Pb, Ni), 70 % (Cd) or 90% (Zn) of their total amount and may therefore pose a considerable environmental risk.