Caribbean small-island tourism styles and sustainable strategies

This article focuses on developing a sustainable tourism in small Caribbean islands, defined here as those that have populations of fewer than 500,000. Such islands share a very fragile ecology and a high dependence on tourism. They differ in their degree of tourist penetration and visitor density and the related degree of environmental degradation. To explain the link between tourism intensity and ecological vulnerability, the so-called “destination life-cycle model” is presented. This suggests that islands pass through three primary stages of tourist development low-density exploration, rapid growth and consolidation, and high-density maturation involving the substitution of man-made for natural attractions. A broad empirical test of the model is performed through a quantitative examination of the tourism characteristics and visitor densities of a cross section of 23 small Caribbean islands. The three basic stages or tourism styles are identified: low-impact emerging areas, high-density mass-market mature destinations, and rapidly growing intermediate islands in between. Some broad strategies consistent with the systems framework for a sustainable tourism with moderate densitites are briefly explored. An earlier version of this article was presented to Caribbean Conservation Association Conference on Economics and the Environment. Barbados, West Indies, 6–8 November, 1989.     

Individual protein balance strongly influences δ<Superscript>15</Superscript>N and δ<Superscript>13</Superscript>C values in Nile tilapia,<Emphasis Type="Italic"> Oreochromis niloticus</Emphasis>

Although stable isotope ratios in animals have often been used as indicators of the trophic level and for the back-calculation of diets, few experiments have been done under standardized laboratory conditions to investigate factors influencing ¹⁵N and ¹³C values. An experiment using Nile tilapia [Oreochromis niloticus (L.)] was therefore carried out to test the effect of different dietary protein contents (35.4, 42.3, and 50.9%) on ¹⁵N and ¹³C values of the whole tilapia. The fish were fed the isoenergetic and isolipidic semi-synthetic diets at a relatively low level. ¹⁵N and ¹³C values of the lipid-free body did not differ between the fish fed the diets with different protein contents, but the trophic shift for N and C isotopes decreased with increasing protein accretion in the individual fish, for N from 6.5 to 4 and for C in the lipid-free body from 4 to 2.5. This is the first study showing the strong influence of the individual protein balance to the degree to which the isotopic signature of dietary protein was modified in tissue protein of fish. The extrapolation of the trophic level or the reconstruction of the diet of an animal from stable isotope ratios without knowledge of the individual physiological condition and the feeding rate may lead to erroneous results.     

Comparison of selected aerobic and anaerobic procedures for MSW treatment

This paper considers selected efficiency rates and process data of aerobic and anaerobic procedures for the treatment of municipal solid waste and residual waste. Data are exclusively related to mechanical-biological treatment (MBT) procedures for generating waste appropriate for landfilling. The following aspects are regarded: general framework conditions for the application of MBT, efficiency of decomposition and of stabilisation, air and water emissions and energy balances. The presented data can be used for more efficient planning. In comparison to aerobic processes, anaerobic digestion can be ecologically advantageous, particularly with regard to exhaust emissions and energy balances. On the other hand, the wastewater emissions and the wastewater treatment required must be regarded as disadvantageous. Due to the relatively short period of operational history of most anaerobic processes for mechanical-biological waste treatment and thus limited experiences, operational reliability of anaerobic processes is slightly lower. Extensive biological stability of the treated waste for low-emission disposal cannot be reached by anaerobic digestion alone, but only in combination with additional aerobic post-treatment. In connection with the utilisation of renewable energies and the rising relevancy of climate protection, it can be affirmed that anaerobic digestion for the treatment of municipal solid waste has a high potential for further development.     

Behavior of metals in ash melting and gasification-melting of municipal solid waste (MSW)

In this study, metal behavior in ash-melting and municipal solid waste (MSW) gasification-melting facilities were investigated. Eight ash-melting and three MSW gasification-melting facilities with a variety of melting processes and feedstocks were selected. From each facility, melting furnace fly ash (MFA) and molten slag were sampled, and feedstock of the ash-melting processes was also taken. For the ash melting process, the generation rate of MFA was well correlated with the ratio of incineration fly ash (IFA) in feedstock, and this was because MFA was formed mostly by mass transfer from IFA and a limited amount from bottom ash (BA). Distribution ratios of metal elements to MFA were generally determined by volatility of the metal element, but chlorine content in feedstock had a significant effect on Cu and a marginal effect on Pb. Distribution ratio of Zn to MFA was influenced by the oxidizing atmosphere in the furnace. High MFA generation and distribution ratio of non-volatile metals to MFA in gasification-melting facilities was probably caused by carry-over of fine particles to the air pollution control system due to large gas volume. Finally, dilution effect was shown to have a significant effect on metal concentration in MFA.     

Degradation of aqueous carbon tetrachloride by nanoscale zerovalent copper on a cation resin

Nanoscale zerovalent copper supported on a cation resin was successfully synthesized to enhance the removal of carbon tetrachloride (CCl(4)) from contaminated water. The use of the cation resin as a support prevents the reduction of surface area due to agglomeration of nanoscale zerovalent copper particles. Moreover, the cation resin recycles the copper ions resulting from the reaction between CCl(4) and Cu(0) by simultaneous ion exchange. The decline in the amount of CCl(4) in aqueous solution results from the combined effects of degradation by nanoscale zerovalent copper and sorption by the cation resin; thus the amount of CCl(4) both in aqueous solution and sorbed onto the resin were measured. The pseudo-first-order rate constant normalized by the surface-area and the mass concentration of nanoscale zerovalent copper (k(SA)) was 2.1+/-0.1 x 10(-2)lh(-1)m(-2), approximately twenty times that of commercial powdered zerovalent copper (0.04 mm). Due to the exchange between Cu(2+) and the strongly acidic ions (H(+) or Na(+)), the pH was between 3 and 4 in unbuffered solution and Cu(2+) at the concentration of less than 0.1 mg l(-1) was measured after the dechlorination reaction. In the above-ground application, resin as a support would facilitate the development of a process that could be designed for convenient emplacement and regeneration of porous reductive medium.     

Corer-reactors for contaminant flux measurement in sediments

Design details and operating instructions are provided for a sediment corer that can be converted into a reactor for the measurement of the fluxes of contaminants from sediments to overlying waters. The corer-reactor permits measurements, under controlled laboratory conditions, on intact, largely undisturbed sediment cores, without significantly perturbing the physical and chemical conditions found in the field. The design can be constructed in-house for around US dollar 240 (A dollar 400) (excluding motor and corer lid), making it a relatively inexpensive system.     

Vorläufige klinische Beobachtungen mit einem neuen N-Lost-Phosphamidester in der Tumortherapie

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