Enhanced diapycnal mixing by salt fingers in the thermocline of the tropical Atlantic

Diapycnal mixing plays a significant role in the ocean's circulation and uptake of heat and carbon dioxide, but has not been quantified in salt finger-driven thermohaline staircases. We recently performed a tracer release experiment in the western tropical Atlantic staircase at approximately 400 m depth. The observed dispersion implies an effective diapycnal diffusivity for tracer and salt of 0.8 to 0.9 x 10(-4) m2/s. Temperature microstructure data interpreted in terms of a vertical production-dissipation balance yields a smaller effective diffusivity for heat of 0.45 (+/- 0.2) x 10(-4) m2/s, consistent with salt fingers and well above the mixing ascribable to mechanical turbulence.     

Atmospheric particulates: specific surface areas and densities

Suspended particulates in Pittsburgh air were collected on glass-fiber filters. The specific surface areas of particulates brushed from the filter surface varied from 1.55 to 4.51 square meters per gram when measured by the Brunauer-Emmett-Teller (BET) method with nitrogen and krypton, after 8-hour degassing of the samples at 25 degrees C. Specific surfaces of the same samples varied from 4.3 to 8.00 square meters per gram after 4-hour degassing at 200 degrees C. Bulk densities and densities of samples were 0.49 to 0.64 and 2.0 to 2.6 grams per cubic centimeter, respectively. These data provide some basis for explanation of unpredictable responses reported after inhalation of mixtures of pollutant gases and particles by animals and man; they should also assist in interpretation of gas-solid phase reactions in the atmosphere.     

The Genome sequence of the SARS-associated coronavirus

We sequenced the 29,751-base genome of the severe acute respiratory syndrome (SARS)-associated coronavirus known as the Tor2 isolate. The genome sequence reveals that this coronavirus is only moderately related to other known coronaviruses, including two human coronaviruses, HCoV-OC43 and HCoV-229E. Phylogenetic analysis of the predicted viral proteins indicates that the virus does not closely resemble any of the three previously known groups of coronaviruses. The genome sequence will aid in the diagnosis of SARS virus infection in humans and potential animal hosts (using polymerase chain reaction and immunological tests), in the development of antivirals (including neutralizing antibodies), and in the identification of putative epitopes for vaccine development.     

The impact of sett disturbance on badger Meles meles numbers; when does protective legislation work?

Considerable increases in badger Meles meles numbers have been reported from long-term studies on local populations and national surveys in Britain. One theory proposed to explain this population change, is that increased protective legislation has led to reduced levels of persecution, allowing the population to expand. In the present study, we show that the badger population in Northern Ireland has not increased in parallel with the British population, and investigate whether sustained high persecution levels are responsible. As legal protection of badgers in Northern Ireland was not increased at the same time as in Britain, a simultaneous decrease in persecution would not be expected. We test two hypotheses: (i) where there is no change in the level of sett disturbance, the number of social groups will remain unchanged and, (ii) if sett disturbance affects group size, those groups suffering from most disturbance will be smallest. We demonstrate that badger sett disturbance affects both social group size and the number of social groups, thus influencing overall badger density. We also show that high levels of sett disturbance are constraining the growth of the Northern Ireland badger population and discuss what lies behind the apparent failure of the protective legislation in this country.     

An appraisal of environmental conflict management provisions in New Zealand's Resource Management Act 1991

Abstract: Since the 1970s a body of literature has developed internationally which can be termed loosely as ‘environmental conflict management’ (ECM) theory and practice. When New Zealand's disparate environmental management framework was reformed during the 1980s a ‘superstatute’ known as the Resource Management Act (RMA), passed in 1991, was the major outcome. During the RMA policy formulation process in the late 1980s, known as Resource Management Law Reform (RMLR), calls were made for better integration of mediation and other alternative dispute resolution (ADR) approaches into the statutory framework. The final wording of the RMA includes specific clauses on mediation and the option of ‘pre‐hearing meetings’, suggesting that ECM and environmental dispute resolution (EDR) approaches have become part of the new decision‐making framework in New Zealand. Given such provisions, and the fact that it is now more than ten years since the RMA was passed, an appraisal of ECM/EDR progress to date within this statute seems justified. It is argued that to date very little emphasis has been placed upon early EDR intervention. This lack of emphasis, it is concluded, is due primarily to low levels of awareness and inadequate training and despite limitations on its usefulness in certain resource conflict settings we suggest that there is scope for greater promotion and implementation of EDR approaches in the local government context.     

Frequency and timing of stem removal influence Corylus americana resprout vigor in oak savanna

Shrubs are an important component of many ecosystems, contributing to spatial and resource heterogeneity and adding to life form and species diversity. Many shrub species have adapted to regular disturbances such as fire by resprouting after stem removal. The relative vigor with which shrubs resprout influences post-disturbance size and density of individuals and thus, can alter community structure. However, little is known about how disturbance frequency and seasonality influence resprouting. We studied resprout vigor of the native shrub American hazel (Corylus americana Walter) in oak savanna in Minnesota, USA. We measured resprout growth of individual shrubs in response to the frequency and timing of clipping in relatively open and shaded conditions. We hypothesized that resprouting of C. americana would be negatively related to clip frequency, due to more rapid depletion of stored resources necessary for resprouting, and positively related to light availability. In 12 weeks following a single clipping, shrubs recovered 82% of the lost stem biomass in open savanna, but only 17% in shaded forest. In both open and closed sites, shrubs clipped three times or more resprouted only 10-15% as much biomass as those clipped once. Moreover, the timing of clipping had as large an effect on resprout potential as the number of clipping events, and small differences in timing were important. Plants clipped once in mid or late June or in July regrew 57, 17, and 8% as much biomass, respectively in the six weeks following clipping as those clipped in early June. These results illustrate that both the timing and number of disturbance events within a growing season can strongly influence shrub growth, which can have important implications for ecosystem structure, function, and management.     

A mathematical model for removing volatile subsurface hydrocarbons by miscible displacement

A mathematical model is developed for analyzing the forced venting method of controlling hazardous vapors escaping from underground spills. Equations for predicting concentration profiles are derived from the fundamental laws governing the isothermal flow and dispersion of two-component, miscible, compressible fluids in a porous medium. The resulting equations are solved numerically by finite difference methods to predict concentration profiles for a two-dimensional venting process. Concentration profiles were found to be more sensitive to the dispersion coefficient than to porosity or permeability for the flow rates examined. A comparison of the model profiles with laboratory measurements indicated that realistic predictions are feasible.     

Softening cities

In the U.S. we stand somewhere about the halfway point in a major shift in the way we view city building, both the process and the product that results. We have been used to seeing urbanization as a production process. (This, in itself, replaced an earlier view of the city as a necessary condition of industrial production.) More and more we see metropolitan areas as distributions of people and their social relations, formal and informal. As this change occurs we lose interest in urban hardware as such. From single houses to new towns, from garden paths to freeways, the things we focused on when we saw cities as production questions dissolve. Things take on importance. only as we take them to be important, as settings for social interaction, not for any intrinsic qualities. We see enormous evidence of this change in the everyday world around us as needed facilities are vetoed in favor of social imperatives, freeways give way to expressions of neighborhood solidarity, and all the rest. The two views conflict and mutually exclude each other to a large extent. Within a decade the new view should be dominant throughout our country.