Recent developments in planning the settlement hierarchy of Barbados: Implications concerning the debate on urban primacy

The topic of big-city growth is receiving increasing attention from geographers, economists, planners and environmentalists, particularly in relation to the likely social and economic impact of urban primacy, and the theoretical and practical implications of optimal city size. This short paper examines these issues in the context of Barbados, where Bridgetown, the chief port and capital city houses some 42% of the island's total population. Initially, the recommendations of the Physical Development Plan for Barbados, published in 1970 with United Nations technical assistance, are presented. In essence, the plan advocated the creation of a hierarchy of settlements within the island by the 1980s, in order to counter the perceived supremacy of Bridgetown. Subsequently, recent progress in promoting the decentralization of population and facilities from Bridgetown is reviewed; and in conclusion, the original proposals and recent developments are critically evaluated.     

Analysis of Petroleum-Contaminated Water by GC/FID with Direct Aqueous Injection

A direct aqueous injection capillary gas chromatography/flame ionization (GC/FID) procedure for the analysis of petroleum-contaminated water was developed and applied to seven water samples saturated with different petroleum products. Separation of C₁ to C₄ alcohols, C₆ to C₉ monoaromatics, MTBE, phenol, aniline, and other compounds, and the detection of BTEX compounds at concentrations at or below their maximum contaminant levels (MCLs) is reported. Among the test compounds analyzed, the only pair found to coelute were 1-butanol and benzene. A method for confirmation of alcohols and polar compounds in the presence of dissolved petroleum hydrocarbons was also evaluated. In this case, water samples were analyzed before and after purging. Polar compounds were found to be significant components of the water soluble fractions of commercial petroleum products.     

Blue-green algal blooms and the commercial fishery of a large Australian estuary

Massive increases in macroalgae (Cladophora and Chaetomorpha spp.) in the large Peel-Harvey Estuary during the 1970s, resulting from increased nutrient run-off from surrounding agricultural land, were accompanied by a marked increase in catch per unit effort (CPUE) and therefore apparently fish abundance. Despite the additional presence since the late 1970s of seasonal and extremely dense blooms of a potentially detrimental blue-green alga (Nodularia spumigena) in the Harvey Estuary, the CPUE for the whole system has also risen over recent years. However, the dense blooms of Nodularia in the Harvey Estuary greatly reduce water clarity, and also apparently fish abundance. When this occurs, Harvey Estuary fishermen shift their activities to the Peel Inlet where water clarity is far greater and they can switch from gill to haul netting, which relies on the visual detection of schools of fish.     

A commentary on the recent CO2-climate controversy

Suggestions have persisted over the past few years that, contary to conventional estimates, increasing levels of atmospheric carbon dioxide will produce negligible warming of the earth's surface, or might even result in surface cooling. In the present paper we reexamine several aspects of these suggestions and illustrate that they are either founded in various violations of the first law of thermodynamics, or that they are based upon misinterpretations of historical data.     

Kilometer-wave type III burst: Harmonic emission revealed by direction and time of arrival

A type III solar burst was observed at seven frequencies between 3.5 MHz and 80 kHz by the Michigan experiment aboard the IMP-6 satellite. From the data we can determine burst direction-of-arrival as well as time-of-arrival. We predict these quantities using simple models whose parameters we vary to obtain a good fit to the observations. We find that between 3.5 MHz and 230 kHz the observed radiation was emitted at the fundamental of the local plasma frequency while below 230 kHz it was emitted at the second harmonic. The exciter particles that produced the burst onset and burst peak have velocities of 0.27 and 0.12, respectively, in units of the velocity of light.     

The biology of the catfish Cnidoglanis macrocephalus (Plotosidae) in an Australian estuary

This paper describes the age structure, growth, diet and aspects of gonadal development in the cobbler, Cnidoglanis macrocephalus (Valenciennes), in the large Swan estuary in south-western Australia between August 1982 and June 1984. Analysis of otolith annuli showed that while the 0+ to 3+ age classes were regularly represented in monthly samples, the 4+ and more particularly the 5+ and 6+ were much less abundant. The weighted means for the back calculated lengths at the end of the first to fourth years of life were 181 mm (≡ 26 g), 314 mm (≡ 156 g), 418 mm (≡ 410 g) and 518 mm (≡ 833 g) respectively. The mean length at the end of the second year of life was similar to the minimum legal size for capture by commercial fishermen (320 mm). The von Bertlanffy growth curve calculated from the back calculated lengths was L_t = 917 [1 − e^{−0·20(t + 0·11)}]. The relative weight of mulluscs, crustaceans and polychaetes in the intestine varied markedly between small and large fish, apparently reflecting differences in the size of these prey. The large mean diameter of mature eggs ( ) was correlated with a low mean absolute fecundity (2078). Trends shown by egg size, gonadosomatic index and time of appearance of spent females indicate that spawning takes place between October and December. The attainment of sexual maturity is both age- and size-dependent. Although sexually maturing and occasionally spent fish were found in the lower estuary, meristic values, commercial catch statistics and other data indicate that the cobbler found in the Swan estuary are part of a population which typically spawns at sea.     

Observations of metallic species in Mercury’s exosphere

From observations of the metallic species sodium (Na), potassium (K), and magnesium (Mg) in Mercury’s exosphere, we derive implications for source and loss processes. All metallic species observed exhibit a distribution and/or line width characteristic of high to extreme temperature - tens of thousands of degrees K. The temperatures of refractory species, including magnesium and calcium, indicate that the source process for the atoms observed in the tail and near-planet exosphere are consistent with ion sputtering and/or impact vaporization of a molecule with subsequent dissociation into the atomic form. The extended Mg tail is consistent with a surface abundance of 5-8% Mg by number, if 30% of impact-vaporized Mg remains as MgO and half of the impact vapor condenses. Globally, ion sputtering is not a major source of Mg, but locally the sputtered source can be larger than the impact vapor source. We conclude that the Na and K in Mercury’s exosphere can be derived from a regolith composition similar to that of Luna 16 soil (or Apollo 17 orange glass), in which the abundance by number is 0.0027 (0.0028) for Na and 0.0006 (0.0045) for K.     

Benthic macroinvertebrates as indicators of environmental deterioration in a large microtidal estuary

This study tested the hypothesis that, during recent years, the benthic macroinvertebrate fauna of the large basin of the Swan-Canning Estuary has changed in ways consistent with deteriorating environmental conditions in that estuary. Between 1986/7 and 2003/4, the compositions of that fauna altered markedly at the species and even family levels. Thus, the densities and number of species of molluscs, and especially of crustaceans, which are particularly susceptible to environmental stress, declined, while those of the more tolerant polychaetes increased. However, taxonomic distinctness declined consistently only at one of the four widely-spaced sampling sites and the dispersion of samples did not differ markedly between periods, indicating that the benthic fauna has not undergone such extreme changes as in the nearby Peel-Harvey Estuary. It is thus proposed that benthic macroinvertebrates can act as important indicators of the severity of environmental degradation in microtidal estuaries in regions where such perturbations are increasing.     

The use of benthic macroinvertebrates to establish a benchmark for evaluating the environmental quality of microtidal, temperate southern hemisphere estuaries

Establishment of a benchmark against which deleterious changes to an estuary can be evaluated requires validating that it has not been subjected to detrimental anthropogenic perturbations and then identifying the biological features which are indicative of a pristine condition and can thus be employed as indicators for detecting and monitoring departures from the natural state. The characteristics of the benthic macroinvertebrate fauna of an essentially pristine, seasonally-open estuary in Western Australia (Broke Inlet) have been determined and compared with those previously recorded for a nearby eutrophic, seasonally-open estuary (Wilson Inlet). Density was far lower in Broke than Wilson. Compositions differed radically at all taxonomic levels, with polychaetes contributing less, and crustaceans more, to the abundance in Broke. Average taxonomic distinctness was greater for Broke than both Wilson and 16 other temperate southern hemisphere estuaries, whereas the reverse was true for variation in taxonomic distinctness, emphasizing that Broke Inlet is pristine.