Short-term changes in mobile dunes at Port Alfred,South Africa

Development along the western beachfront of Port Alfred, which is situated along a sandy shoreline, increased markedly in the 1960s as the coastal town became a popular holiday resort. This development included the removal of coastal vegetation, which resulted in the destabilization of dunes and migration of sand westerly onto the road, West Beach parking lot, and lawns of the cabanas. Sand traps were constructed to collect sand blowing across the dunes over set periods, and the net sand movement along the mobile dune belt was calculated using Hunter's equation. The dunes show an easterly movement of sand at a rate of 3.5 m/yr, which is comparable with figures recorded along other areas of this coastline. Considering the wind regime and amount of sand movement along this coast, it is inappropriate to clear vegetation and develop within the dune region.     

The International Drinking Water Supply and Sanitation Decade in retrospect and implications for the future

In global terms this paper reviews the progress made during the International Drinking Water Supply and Sanitation Decade. There has been considerable progress. In terms of percent receiving water services, the urban areas made good progress: 77% in 1980 to 82% in 1990. In the rural areas progress was even greater, 30% had water services in 1980 versus 63% in 1990. There was also considerable progress in institutional terms. A positive trend towards better linkage betweeen authorities dealing with water supply and sanitation and those dealing with economic development, was one. Another was the awareness of the need for community involvement. In some cases progress was hampered by fragmentation of governmental authorities dealing with water and sanitation at the rural and/or urban level. In the 1990s an important issue will be financing the infrastructure needed to bring water and sanitation services to those not already covered and to an increasing population. Institutional issues will continue to be important as well.     

Microbial degradation of poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in compost

The microbial degradation of tensile test pieces made of poly(3-hydroxybutyrate) [P(3HB)] or copolymers with 10% [P(3HB-co-10%3HV)] and 20% [P(3HB-co-20%3HV)] 3-hydroxyvaleric acid was studied in small household compost heaps. Degradation was measured through loss of weight (surface erosion) and changes in molecular weight and mechanical strength. It was concluded, on the basis of weight loss and loss of mechanical properties, that P(3HB) and P(3HB-co-3HV) plastics were degraded in compost by the action of microorganisms. No decrease inM _w could be detected during the degradation process. The P(3HB-co-20%3HV) copolymer was degraded much faster than the homopolymer and P(3HB-co-10%3HV). One hundred nine microbial strains capable of degrading the polymersin vitro were isolated from the samples used in the biodegradation studies, as well as from two other composts, and identified. They consisted of 61 Gram-negative bacteria (e.g.,Acidovorax facilis), 10 Gram-positive bacteria (mainlyBacillus megaterium), 35Streptomyces strains, and 3 molds.     

Against idealistic beliefs in the problem-solving capacities of integrated resource management

Integrated resource management (IRM) is currently implemented in many parts of the world. This article promotes a pragmatic interpretation and suggests that idealistic beliefs in the problem-solving capacities of IRM are not justified. Successful implementation and performance of IRM are primarily a function of the historical context into which a project is placed. A comparative analysis of several case studies in Western Canada provides evidence for this argument, and the results can be summarized in a conceptual model about integration in resource management. IRM is interpreted as a process of constructing an objective reality of integration for sectorial management decisions, and this construction involves the transformations of power structures. This article suggests several pragmatic conclusions for IRM practice.     

Evaluation of Material Biodegradability in Real Conditions–Development of a Burial Test and an Analysis Methodology Based on Numerical Vision

This work validated a burial protocol for in situ testing and presents a robust, repeatable and time-saving technique to measure degraded areas in the sample, i.e. an image analysis method. 1440 specimens of degraded samples have been compiled in a data base. To this end, twenty samples presenting different levels of biodegradability (i.e. PHBV/HV, PLA, PCL, PCL-Starch, paper, PE, PE-Starch) were buried at 4 different locations and then disinterred at 4, 6, 9, 12, 18, and 24-month intervals. The biodegradation levels of these samples were determined by computing weight and area loss. Weight loss was measured after careful cleaning, whereas area loss was quantified using image analysis. Image analysis gives reliable information on visual pollution while only requiring a rudimentary and thus quicker cleaning of the samples.     

Existing oxidant/ozone standards in OECD countries

This paper describes the historical development and current legislation to control photochemical oxidant pollution in OECD countries. Policies for implementing, attaining, and maintaining ambient air quality standards or goals are discussed, problems associated with the various steps are highlighted, and the possibility of international policy guidelines which could control pollution across national frontiers is considered. To date, only a few countries have formulated ambient air quality standards for ozone/ oxidants; these standards are usually short-term averages over 1 h, ranging from 0.06 ppm (μL/L) in Japan to 0.12 ppm (μL/L) in the United States. The current interest in air quality management on an international scale leads to the conclusion that successful control of photochemical oxidant pollution would be best accomplished through the establishment of internationally acceptable standards or goals for oxidants/ozone based on health effects and other relevant environmental impacts, in combination with control strategies developed and implemented on an international level.     

Preliminary ecotoxicological characterization of a new energetic substance, CL-20

A new energetic substance hexanitrohexaazaisowurtzitane (or CL-20) was tested for its toxicities to various ecological receptors. CL-20 (epsilon-polymorph) was amended to soil or deionized water to construct concentration gradients. Results of Microtox (15-min contact) and 96-h algae growth inhibition tests indicate that CL-20 showed no adverse effects on the bioluminescence of marine bacteria Vibrio fischeri and the cell density of freshwater green algae Selenastrum capricornutum respectively, up to its water solubility (ca. 3.6 mg l(-1)). CL-20 and its possible biotransformation products did not inhibit seed germination and early seedling (16-19 d) growth of alfalfa (Medicago sativa) and perennial ryegrass (Lolium perenne) up to 10,000 mg kg(-1) in a Sassafras sandy loam soil (SSL). Indigenous soil microorganisms in SSL and a garden soil were exposed to CL-20 for one or two weeks before dehydrogenase activity (DHA) or potential nitrification activity (PNA) were assayed. Results indicate that up to 10,000 mg kg(-1) soil of CL-20 had no statistically significant effects on microbial communities measured as DHA or on the ammonium oxidizing bacteria determined as PNA in both soils. Data indicates that CL-20 was not acutely toxic to the species or microbial communities tested and that further studies are required to address the potential long-term environmental impact of CL-20 and its possible degradation products.     

Radon-222 signatures of natural ventilation regimes in an underground quarry

Radon-222 activity concentration has been monitored since 1999 in an underground limestone quarry located in Vincennes, near Paris, France. It is homogeneous in summer, with an average value of 1700 Bq m(-3), and varies from 730 to 1450 Bq m(-3) in winter, indicating natural ventilation with a rate ranging from 0.5 to 2.4 x 10(-6) s(-1) (0.04-0.22 day(-1)). This hypothesis is supported by measurements in the vertical access pit where, in winter, a turbulent air current produces a stable radon profile, smoothly decreasing from 700 Bq m(-3) at 20 m depth to 300 Bq m(-3) at surface. In summer, a thermal stratification is maintained in the pit, but the radon-222 concentration jumps repeatedly between 100 and 2000 Bq m(-3). These jumps are due to atmospheric pressure pumping, which induces ventilation in the quarry at a rate of about 0.1 x 10(-6) s(-1) (0.009 day(-1)). Radon-222 monitoring thus provides a dynamical characterisation of ventilation regimes, which is important for the assessment of the long-term evolution of underground systems.     

Response of Organic and Inorganic Carbon and Nitrogen to Long-Term Grazing of the Shortgrass Steppe

We investigated the influence of long-term (56 years) grazing on organic and inorganic carbon (C) and nitrogen (N) contents of the plant–soil system (to 90 cm depth) in shortgrass steppe of northeastern Colorado. Grazing treatments included continuous season-long (May–October) grazing by yearling heifers at heavy (60–75% utilization) and light (20–35% utilization) stocking rates, and nongrazed exclosures. The heavy stocking rate resulted in a plant community that was dominated (75% of biomass production) by the C₄ grass blue grama (Bouteloua gracilis), whereas excluding livestock grazing increased the production of C₃ grasses and prickly pear cactus (Opuntia polycantha). Soil organic C (SOC) and organic N were not significantly different between the light grazing and nongrazed treatments, whereas the heavy grazing treatment was 7.5 Mg ha^–1 higher in SOC than the nongrazed treatment. Lower ratios of net mineralized N to total organic N in both grazed compared to nongrazed treatments suggest that long-term grazing decreased the readily mineralizable fraction of soil organic matter. Heavy grazing affected soil inorganic C (SIC) more than the SOC. The heavy grazing treatment was 23.8 Mg ha^–1 higher in total soil C (0–90 cm) than the nongrazed treatment, with 68% (16.3 Mg ha^–1) attributable to higher SIC, and 32% (7.5 Mg ha^–1) to higher SOC. These results emphasize the importance in semiarid and arid ecosystems of including inorganic C in assessments of the mass and distribution of plant–soil C and in evaluations of the impacts of grazing management on C sequestration.