The Reshaping of Conventional Farming: A North American Perspective

Debates over the future of agriculture in North Americaestablish a dialectical opposition between conventional,industrial agriculture and alternative, sustainable agriculture.This opposition has roots that extend back to the 18th century inthe United States, but the debate has taken a number ofsurprising turns in the 20th century. Originally articulated as aphilosophy of the left, industrial agriculture has utilitarianmoral foundations. In the US and Canada, the articulation of analternative to industrial agriculture has drawn upon threecentral themes: the belief that agriculture is, in some way, tiedto democracy; the belief that complex bureaucratic organizationsare inherently opposed to human interests; and the belief thatthe family farms characteristic of 19th century North Americatend to produce people of superior moral character. It has proveddifficult to weave these themes into a coherent vision ofagriculture for the 21st century. Often, risk and health-basedconcerns are the basis for public criticism of conventionalagriculture, but these do not conflict with the utilitarianorientation of the industrial model, and are easily incorporatedinto it. If there is to be a philosophical debate over the futureof agriculture, we must find some way to rehabilitate thequasi-Aristotelean view of agriculture that emerges from thethree critical themes noted above.     

Simulated Responses of a Forest-Interior Bird Population to Forest Management Options in Central Hardwood Forests of the United States

I used estimates of carrying capacity, survival, fecundity, and edge effects to simulate the responses of a forest-interior bird population to selection cutting clearcutting, and no timber harvest. I also modeled population sensitivity to changes in fecundity, survival, K , and edge relationships. Because model parameters are based on scant data, results should he regarded as hypotheses to be further investigated or measures of the relative impact or sensitivity (given model assumptions). Simulated population size was greater with no timber harvest than with clearcutting and greater with clearcutting than with group selection when edge effects were included in the model. Without edge effects, population levels were only slightly lower under group selection than under no timber harvest, and greater than clearcutting. Edge effects had only a small impact on population levels under clearcutting. Clearcut size did not have much effect on population levels, but longer and shorter rotation ages resulted in higher and lower population levels, respectively. The model was very sensitive to declines in mean fecundity and survival, suggesting that factors affecting mean demographic rates could be more important than local edge effects. Some methods of timber harvest may be compatible with the conservation of forest-interior birds, but better demographic data and information on habitat suitability of selectively cut forests and young even-aged stands is needed to adequately evaluate management options.     

Distribution and abundance of choanoflagellates (Acanthoecidae) in the coastal cold ocean of Newfoundland, Canada

Water samples from six bays were taken over a 5-year period (1988 to 1992) to determine the distribution and abundance of loricate choanoflagellates in coastal Newfoundland, and to assess the impact that these organisms might have on this cold ocean food web. Scanning electron microscopy was used to study the morphology of these flagellates, allowing us to identify 11 species of loricate choanoflagellates. Parvicorbicula socialis (Meunier) Deflandre was the most abundant species (80 × 10³ cells l⁻¹), particularly during the spring diatom bloom. Single-cell species, such as Bicosta spini fera (Throndsen) Leadbeater and Calliacantha natans (Grontved) Leadbeater, were found more commonly after the spring diatom bloom in the summer months. Many of the single-cell choanoflagellates were attached to bacteria-rich microaggregates and debris in the water column and in unpoisoned sediment traps. The P. socialis cell flux was calculated to be 5.3 × 10⁶ cells m⁻² d⁻¹ in late May sediment traps. P. socialis in the upper 100 m of the water column was removing 0.3% of the standing crop of bacteria each day (April/May), and the equivalent of 7.4% of the daily bacterial production over the water column. Diel studies of P. socialis in Conception Bay suggest that the sharp decline in population numbers observed in midnight samples may be related to the high number of grazing zooplankton observed during the same period. Pelagic tunicate and zooplankton fecal pellets were found to contain large numbers of choanoflagellate costae, thus providing a direct link from the microbial loop to the macrozooplankton. Received: 17 March 1997 / Accepted: 9 May 1997     

Measurement of filtration rates by infaunal bivalves in a recirculating flume

A flume system and protocol for measuring the filtration rate of infaunal bivalves is described. Assemblages of multi-sized clams, at natural densities and in normal filter-feeding positions, removed phytoplankton suspended in a unidirectional flow of water. The free-stream velocity and friction velocity of the flow, and bottom roughness height were similar to those in natural estuarine waters. Continuous variations in phytoplankton (Chroomonas salinay) cell density were used to measure the filtration rate of the suspension-feeding clam Potamocorbula amurensis for periods of 2 to 28 h. Filtration rates of P. amurensis varied from 100 to 580 liters (gd)^-1 over a free-stream velocity range of 9 to 25 cm s^-1. Phytoplankton loss rates were usually constant throughout the experiments. Our results suggest that suspension-feeding by infaunal bivalves is sensitive to flow velocity.     

Ultraviolet irradiation of municipal wastewater: Evaluation of effects on organic constituents

A comparison of chromatograms derived from the UV-absorbing and oxidizable constituents present in primary and secondary municipal wastewater effluents indicates that exposure to UV irradiation at disinfection levels results in only slight chemical changes. The most pronounced chemical effects to nonvolatile organic constituents in wastewater effluents have been observed at irradiation levels in excess of those necessary for disinfection. Aliquots of effluents before and after exposure to varying levels of UV irradiation were concentrated by lyophilization prior to liquid chromatographic (LC) analysis. Anion-exchange chromatographic techniques utilizing a modified ultraviolet detector coupled in series with a cerate oxidative monitor provided excellent resolution and sensitivity in the determination of chemical changes occurring in the effluents as a result of exposure to different irradiation levels. The total coliform counts for each irradiated effluent were determined by the membrane-filter technique to evaluate the effectiveness of UV irradiation as a disinfection process for municipal wastewaters. Changes in biochemical oxygen demand (BOD), chemical oxygen demand (COD), total organic carbon (TOC), and total Kjeldahl nitrogen (TKN) at different levels of exposure to UV irradiation are presented. The results of these determinations and the gas chromatography/mass spectrometry data characterizing the observed chemical changes are discussed.     

The environmental regulator and industrial development

Environmental regulatory agencies' administrative procedures have a significant impact on plant location. The authors review the basic reasons why companies build new plants and the constraints they operate under during site searches. The relationship between these issues and the regulatory agencies' administrative procedures is then shown, as well as the manner in which these procedures influence the site search. On the basis of this discussion, recommendations are made about how state environmental protection agencies can assist site seekers in a manner consistent with their regulatory responsibilities.     

Reduction of Urban Runoff Through Economic Incentives: Boulder,Colorado1

ABSTRACT: The problems of increased surface runoff which follow in step with urbanization can be conceptualized in terms of environmental economics. The private transformation of land from a permeable to an impermeable surface imposes the externality of increased surface runoff upon society as a whole and especially on those downstream. The city of Boulder, Colorado, has enacted an ordinance which attempts to internalize some of these external costs and at the same time decrease surface runoff from the urban environment.     

Vinyl Chloride Marine Risk Assessment with Special Reference to the Osparcom Region: North Sea

This risk assessment on vinyl chloride was carried out specifically for the marine environment, according to the methodology laid down in the European Union (EU) risk assessment Regulation (1488/94) and the Technical Guidance Documents for New and Existing Substances (TGD, 1996). Vinyl chloride is used for the production of polyvinyl chloride (PVC). The study consisted of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programmes in large rivers and estuaries in the North Sea area. The risk is indicated by the ratio of the Predicted Exposure Concentration (PEC) and the Predicted No-Effect Concentration (PNEC) for the marine aquatic environment. In total 6 studies for fish, 3 studies for invertebrates and one for algae have been evaluated. The appropriate assessment factors have been used to calculate a PNEC of 210 microg/l based on short-term exposure. For coastal waters and estuaries a worst case PEC of 0.15 microg/l is derived. For river waters a typical and worst case PEC of <0.008 and 0.4 microg/l is derived, respectively. These concentrations, which do not take into account any dilution within the sea, correspond to safety margins from 500 to 250,000 between the aquatic effect and the exposure concentration. Vinyl chloride is not a 'toxic, persistent and liable to bioaccumulate' substance sensu the Oslo and Paris Conventions for the Prevention of Marine Pollution (OSPAR-DYNAMEC). It can be concluded that the present use of vinyl chloride does not present a risk to the marine aquatic environment.     

Interlaboratory trial to determine the analytical state-of-the-art of bromate determination in drinking water

The new European Directive for water intended for human consumption has established a regulatory level for bromate at 10 microg L(-1). This Maximum Admissible Concentration requires analytical methods with detection limits of a least 2.5 microg L(-1). A project funded by the Standards, Measurements and Testing Programme of the European Commission has enabled the improvement and/or development of methods for the determination of bromate at such concentration levels. This collaborative work was concluded by the organisation of an interlaboratory trial involving 26 European laboratories, which enabled the testing of both a draft ISO Standard method and alternative methods. This paper presents the results of this interlaboratory trial, along with results of a bromate stability study. The progress made with respect to the analytical state-of-the-art for bromate will greatly benefit the quality of measurements carried out in water quality monitoring.     

1,1,1-Trichloroethane Marine Risk Assessment with Special Reference to the Osparcom Region: North Sea

This risk assessment on 1,1,1-trichloroethane was carried out specifically for the marine environment, accordingly to the methodology laid down in the EU risk assessment Regulation (1488/94) and the Guidance Document of the EU New and Existing Substances Regulation (TGD, 1996). 1,1,1-trichloroethane is being phased out of most uses because of its ozone depletion potential (ODP) under the Montreal Protocol. Production for emissive uses has already been phased out end 1995 in Europe and 1996 in the United States, Japan and other industrial countries. The risk assessment study consists of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programmes in large rivers and estuaries in the North Sea area. The risk is indicated by the ratio of the Predicted Environmental Concentration (PEC) and the Predicted No-Effect Concentration (PNEC) for the marine aquatic environment. In total 14 studies for fish, 7 studies for invertebrates and 9 studies for algae have been evaluated. Both acute and chronic studies have been taken into account and the appropriate assessment factors have been used to calculate a PNEC value of 21 microg/l based on long term exposure. The PEC was derived from monitoring data. The PEC was set at 0.206 microg/l (worst case) and 0.024 microg/l (typical case) for coastal waters and estuaries and 0.6 microg/l (worst case) and <0.1 microg/l (typical case) for river waters. The calculated PEC/PNEC ratios, which do not take into account any dilution factor within the sea, correspond to a safety margin of 35 to 1000 between the aquatic effect and the exposure concentration. 1,1,1-trichloroethane is not a 'toxic, persistent and liable to bioaccumulate' substance according to the criteria as mentioned by the Oslo and Paris Conventions for the Prevention of Marine Pollution (OSPAR-DYNAMEC). It can be concluded that the present use of 1,1,1-trichloroethane does not present a risk to the marine aquatic environment.