A technique for collection of particulate organic matter in situ

A technique is described for concentrating and collecting particulate organic matter from water with minimal disturbance. This involves exposing in situ the surface of a Millipore^® filter monitor mounted on a simple vacuum flask assembly.     

Systems approaches to integrated solid waste management in developing countries

Solid waste management (SWM) has become an issue of increasing global concern as urban populations continue to rise and consumption patterns change. The health and environmental implications associated with SWM are mounting in urgency, particularly in the context of developing countries. While systems analyses largely targeting well-defined, engineered systems have been used to help SWM agencies in industrialized countries since the 1960s, collection and removal dominate the SWM sector in developing countries. This review contrasts the history and current paradigms of SWM practices and policies in industrialized countries with the current challenges and complexities faced in developing country SWM. In industrialized countries, public health, environment, resource scarcity, climate change, and public awareness and participation have acted as SWM drivers towards the current paradigm of integrated SWM. However, urbanization, inequality, and economic growth; cultural and socio-economic aspects; policy, governance, and institutional issues; and international influences have complicated SWM in developing countries. This has limited the applicability of approaches that were successful along the SWM development trajectories of industrialized countries. This review demonstrates the importance of founding new SWM approaches for developing country contexts in post-normal science and complex, adaptive systems thinking.     

Effects of oxidants on soybean growth and yield in the Pakistan Punjab.

Plants of soybean (Glycine max L.) were grown with and without the ozone protectant EDU (N-[2-(2-oxo-1-imidazolidinyl)ethyl]-n2 phenylurea) at a suburban site, a remote rural site and a rural roadside site around the city of Lahore, Pakistan. The development and yield of the plants was determined in two experiments--one immediately post-monsoon and one in the following spring (pre-monsoon). Concentrations of nitrogen dioxide and photochemical oxidants were measured at each site. The effect on yield of EDU at the suburban site (47 and 113% increase in seed weight per plant relative to the untreated plants in the post- and pre-monsoon experiments, respectively) was similar to the effects of filtration on yield on soybean in a parallel open-top chamber study at the same site (77% increase relative to plants subjected to unfiltered air for the pre-monsoon experiment). Effects of EDU on yield were greater at both rural sites than at the suburban site in both experiments, and greater in the spring experiment (182% at the remote rural site and 285% at the rural roadside site) than in the post-monsoon experiment (94% at the remote rural site and 170% at the rural roadside site); oxidant concentrations were also greater at the rural sites than at the suburban site, and greater in the spring experiment than the post-monsoon experiment. The results imply that ozone may be causing significant crop losses in rural areas around Lahore; however, the geographical extent of the problem, and the implications for peri-urban agriculture around other cities of south Asia are uncertain.     

Using social resilience and resource dependency to increase the effectiveness of marine conservation initiatives in Salum,Egypt

The social and economic ramifications of marine conservation strategies such as marine protected areas (MPAs) are important to consider prior to their implementation to ensure that they do not exceed the resilience of resource-users and that resource protection might be maximised through compliance and low resistance. This paper presents a framework in which the human dimensions can be more easily and usefully integrated into the design and delivery of conservation initiatives. The framework espouses quantifying (1) the level of dependency on the resource; (2) perceptions towards conservation initiatives; and (3) social resilience. The framework is applied in Salum, Egypt, which is the site of a prospective MPA.     

Preliminary comparison of alternative designs for soil remediation by bioventilation

Computer simulation provides a powerful tool for comparing alternative designs of remediation processes. The software package FLUENT copes successfully with subsurface three-dimensional flow fields, multiple and directional permeabilities, wide spatial variations in subsurface gas velocities, and the presence of surface structures. FLUENT can provide an invaluable method for comparing remediation efficiencies among competing design alternatives. This article features case studies to illustrate the benefits that simulation studies provide before and during the initiation of remedial actions using bioventing.     

Toxicant-induced fecundity compensation: A model of population responses

A mathematical model widely applied in population studies and in assessment of the impact of exploitation on fish populations was applied to assess cadmium toxicity in laboratory populations ofDaphnia galeata mendotae. Over a range of toxicant concentrations, the birth rate of the population increased to balance the death rate and the population compensated for the increased mortality. The model describes the relation between toxicant concentration, toxicant-induced mortality, and equilibrium population size. Compensation for increased mortality is described in terms of the decrease in population size necessary to produce an increase in the birth rate that will balance the increased death rate. The relative capacity of different aquatic organisms to compensate for toxicant-induced mortality is examined and a relation between compensatory capacity and the innate capacity for increase is developed.     

The acid rain debate in North America “Where you stand depends on where you sit”

Summary An analysis of the recent acid rain debate in North America reveals that the policies and priorities of the various interested bodies with regard to this issue directly reflect their vested interests and in many instances their geographical location.Dr Marshall E. Wilcher is Assistant Professor in Political Science at the New Kensington Campus of Pennsylvania State University.     

Estimates of total polychlorinated biphenyl (PCB) compounds in soils/sediments by hydrogenolysis to dicyclohexyl

A method to determine the total PCB content by hydrogenolysis (hydrodechlorination and hydrogenation) of chlorinated biphenyl compounds was extended to natural particulate matrices (soil and sediment). The contaminated soil was suspended in hexane in the presence of Pd/gamma-Al2O3 in a hydrogen atmosphere then permitted to react for one hour at 65 degrees C. Dicyclohexyl, recovered in the hexane, was quantified by gas chromatography mass spectrometry. The reaction was very efficient for soil/sediment in hexane suspension and virtually complete provided that excess catalyst was added to samples that were burdened with higher PCB loadings prior to reaction otherwise some partial hydrogenation of biphenyl was also observed. The proposed method was validated with the analysis of five certified reference materials.     

Long-term phytoplankton trends and related water quality trends in the lower Chesapeake Bay,Virginia, USA

Long-term trends (i.e., 1985 through 1999; 14 1/2 yrs) of the phytoplankton community in Chesapeake Bay indicated patterns of increasing phytoplankton abundance and biomass associated with mainly diatoms and chlorophytes, and to a lesser degree dinoflagellates. Decreasing trends in productivity rates above the pycnocline were present over a shorter time period (10 1/2 yrs.), with evidence for increasing nitrogen limitation is indicated. Reduced light availability is inferred due to decreasing trends of Secchi depths and increased suspended solids trends, which were associated with decreasing trends in productivity rates.