Comparative study of cadmium levels of shellfish and finfish species

This study indicates that the concentration of cadmium in shellfish species may often be higher than it is in their environment as a result of formation of stable biological chelate complexes. This study also indicates that the concentration of cadmium in finfish species is less than the shellfish species. It was found that cadmium levels in shellfish were relatively higher in oysters and shrimps, moderately high in scallops and squids, and less in crabs and clams. It seems that cadmium levels are surprisingly elevated in shellfish than other saltwater finfish. It also seems that larger shellfish had higher Cd content levels than the smaller shellfish of the same species.     

Policies towards proposals for large-scale natural resource projects: Attenuation versus postponement

The authors examine the problem of dealing with the environmental impact of uranium mining in Australia and consider its wider implications. Government, faced with unknown environmental and social damage from the initiation of uranium mining in northern Australia, has initiated an environmental impact assessment procedure. This requires the appellant company to provide information about the proposed project and its alternatives and is often followed by a period of ‘postponement’. This is compared with an alternative procedure, ‘attenuation’, allowing the project to proceed on a reduced scale in order to obtain information. Comparisons are made between the information which might be obtained by the two alternative procedures and the expected relative benefits and costs from a postponed project and an attenuated project.     

Weekend–weekday aerosols and geographic variability in cloud-to-ground lightning for the urban region of Atlanta, Georgia, USA

We characterized the differences in warm-season weekday and weekend aerosol conditions and cloud-to-ground (CG) flashes (1995–2008) for an 80,000 square kilometer region around Atlanta, Georgia, a city of 5.5 million in the humid subtropics of the southeastern United States. An integration of distance-based multivariate techniques (hierarchical agglomerative clustering, multiresponse permutation procedures, fuzzy kappa statistics, and Mantel tests) indicated a greater concentration of CG flash activity within a 100 km radius around Atlanta under weekday aerosol concentrations. On weekends, these effects contracted toward the city. This minimized any weekly anthropogenic cycle over the more densely populated urban center even though this location had a higher flash density, a higher percentage of days with flashes, and stronger peak currents over the course of a week compared to the surrounding region. The sharper contrasts in weekday and weekend lightning regime developed outside the perimeter of the city over nonurban land uses. Here, lightning on weekend and weekdays differed more in its density, frequency, polarity, and peak current. Across the full extent of the study region, weekday peak currents were stronger and flash days more frequent, suggesting that weekly CG lightning signals have a regional component not tied to a single city source. We integrate these findings in a conceptual model that illustrates the dependency of weekly anthropogenic weather signals on spatial and temporal extent.     

Field Exposure Study of Polylactic Acid (PLA) Plastic Films in the Banana Fields of Costa Rica

For use by the banana industry of Costa Rica, polylactic acid (PLA) plastic ropes and banana finger shrouds must remain operational for 14 to 16 weeks, and they also must be able to break down in the soil after serving their purposes. The banana field at La Rebusca Farm (Costa Rica) and the experiment station at University of Costa Rica were selected for a field exposure study of Cargill EcoPla Generation II (GII) and Cargill EcoPla monolayer (Ca-I) PLA films. The average monthly temperature, relative humidity, and cumulative rainfall of the La Rebusca Farm and the University of Costa Rica site were 26 and 22°C, 92 and 84%, and 352 and 177 in., respectively. The PLA plastic films at the La Rebusca Farm lost their mechanical properties earlier than at the University of Costa Rica site because of the higher temperature and relative humidity of the banana farm. The Ca-I film meets the 14-week operational time frame and it is recommended for further studies as ropes and banana shrouds.     

Controls on leaching of N species in upland moorland catchments

Spatial and temporal changes in mobility of N species have been studied for three UK upland river networks, the Etherow in the South Pennines, the Nether Beck in the Lake District and the Dee in NE Scotland. The catchments are subject to N deposition at 35.1, 22.0 and 10.8–15.6 kg N ha^?1 yr^?1, respectively. The NH⁺ ₄ leaching appears to be predominantly regulated by flow path in more polluted upland catchments. It is greatest where water draining acidified peaty soils contributes more to total discharge. Soluble organic matter may provide the dominant counter anion. In the Etherow and Dee catchments, which are dominated by acid mineral and organic soils, at high discharge NO^? ₃ also appears to be associated with greater input of water from acidified soils. In contrast, for the Nether Beck, higher NO^? ₃ concentrations are associated with tributaries draining soils contributing water with higher alkalinity, suggesting nitrification is important. For the Etherow and Dee, dissolved organic N (DON) appears to originate predominantly from acidified, peaty soils. Spiking experiments with peat soil from the Etherow catchment confirmed the limited capacity of these soils to utilize inorganic N inputs, favouring equilibration with NH⁺ ₄ inputs and leaching losses of inorganic N throughout the year.     

The Application of the Ecological Footprint: a case of passenger transport in Merseyside

The release of carbon dioxide from the burning of fossil fuels is believed to be responsible for climate change. In the UK, road transport emits 22% of the total output of carbon dioxide. This study applies the ecological footprint to Merseyside to ascertain the global environmental impact of passenger transport (expressed in hectares). Results show that car travel has a footprint of 704 000 hectares, which is 87% of the total footprint. It is demonstrated in scenarios that Policy initiatives involving the Local Transport Plan will cause the footprint to increase. It is also shown that individual behaviour could be influenced when highlighting the impacts of different modes of transport along the same route. By using the ecological footprint in educational programmes, the effect can be shown of carbon emissions and land appropriation on the 'school run'; these issues could be promoted alongside others such as health, safety, congestion, global equity and fairness.     

Sustainable public/private partnerships for public service delivery

This article defines three kinds of public/private partnership, lists their potential benefits and explains common issues and problems in their operation with examples from developing countries. It then defines and discusses the concepts of social sustainability and financial sustainability in relation to public/private partnerships, and emphasizes the importance of applying sustainability criteria to each partner. It is argued that essentially the same criteria apply to non-profit NGOs as to for-profit firms, despite their differences in goals and values. The article concludes with some suggested strategies for effective international technical co-operation in the establishment of public/private partnerships.     

Uptake of cadmium in tropical marine lamellibranchs,and effects on physiological behaviour

The effect of cadmium introduced as inorganic salts (chloride, nitrate, sulfate, carbonate, acetate and iodide) or organic chelates (with EDTA, NTA and humic acid) on the physiological behaviour of six species of tropical lamellibranchs — arcid blood clamsAnadara granosa andA. rhombea, venerid clamsMeretrix casta andKatelysia opima, and mytilid musselsPerna viridis andP. indica, collected from various intertidal areas in southern India from 1986 to 1989 — was evaluated. Inorganic salts of Cd are reported to completely ionize upon introduction to full-strength sea water and form predominantly (97%) chloride complexes. Some inorganic Cd salts, therefore, would hardly affect physiological parameters. However, bioaccumulation of Cd was greatest upon exposure to Cd introduced as sulfate, followed by iodide, acetate, chloride, nitrate and carbonate; 96-h LC₅₀'s also varied, but in a different order, being highest for chloride (3.5µg ml^–1), followed by nitrate, acetate, iodide and sulfate (1.8µg ml^–1). Furthermore, Cd levels increased linearly with time of exposure and levels in medium, and were species-specific, being highest in the arcid clams, followed by the venerid clams and mytilid mussels. The presence of other metals such as Zn reduced bioaccumulation of Cd significantly (P < 0.001), but the reverse was not true. Upon exposure to Cd in the presence of Cu, on the other hand, accumulation of both metals was reduced by 15 to 20%. In the presence of organic chelators — EDTA, NTA and reduced glutathione (GSH) — Cd accumulation was significantly inhibited, by 1/2 to 1/3. Humic acid, on the other hand, had no effect. Cd levels in soft tissues were inversely related to ambient salinity in the range of 12 to 32. However, both Zn and Cu significantly inhibited Cd accumulation irrespective of salinity. Cd increased the rate of filtration inAnadara granosa over the first 24 h by 28%, but on prolonged exposure (96 h) that rate decreased significantly, by 50%. Zn alone and in the presence of Cd, on the contrary, initially reduced filtration activity, which subsequently increased to control levels upon continued exposure. Cu alone and in combination with Cd and Zn also significantly (P < 0.001) inhibited filtration relative to controls. This combination also progressively reduced respiratory activity with time, the maximum decrease being 80% after 96 h of exposure. Furthermore, impact of all three metals on both filtration rate and oxygen consumption was initially synergistic, but changed to antagonistic upon prolonged exposure up to 96 h.Deceased. Please send all correspondence and requests for reprints to Dr. S. Patel at the same address