A near-infrared survey of IRAS sources in the South Galactic Cap

The paper describes the JHK colours of late-type stars which were investigated as part of a survey of South Galactic Cap (b < -30°) IRAS sources selected on the basis of their 12/25µm flux ratios as high mass-loss candidates. Near-infrared two-colour diagrams provide an effective technique for distinguishing between various groups of late-type stars. Such diagrams are also useful in indicating which stars are likely to be peculiar and worthy of more detailed study. The late-type stars isolated by this survey comprise: 61 Mira variables (3 of which are carbon stars with very thick shells), 3 young stellar objects, 4 interacting binaries, 2 semi-regular carbon variables and 154 oxygen-rich giants.     

Globular clusters and the Mira period–luminosity relation

A globular cluster distance scale based on Hipparcos parallaxes of subdwarfs has been used to derive estimates of M _K for cluster Miras, including one in the Small Magellanic Cloud (SMC) globular cluster NGC 121. These lead to a zero-point of the Mira infrared period–luminosity (PL) relation, PL( K ), in good agreement with that derived from Hipparcos parallaxes of nearby field Miras. The mean of these two estimates together with data on LMC Miras yields a Large Magellanic Cloud (LMC) distance modulus of     in evident agreement with a metallicity-corrected Cepheid modulus     .
The use of luminous asymptotic giant branch (AGB) stars as extragalactic population indicators is also discussed.     

Effects of hydrocarbon contamination on a free living marine nematode community: results from microcosm experiments

Anthropogenic inputs of crude and refined petroleum hydrocarbons into the sea require knowledge of the effects of these contaminants on the receiving assemblages of organisms. A microcosm experiment was carried out to study the influence of diesel on a free living nematode community of a Tunisian lagoon. Sediments were contaminated by diesel that ranged in concentration from 0.5 to 20 mg diesel kg⁻¹ dry weight (dw), and effects were examined after 90 days. Gradual changes in community structure were revealed depending on the quantity of diesel administrated. In the medium (1 mg diesel kg⁻¹ and 5 mg diesel kg⁻¹ (dw)) and high (10 mg diesel kg⁻¹, 15 mg diesel kg⁻¹ and 20 mg kg⁻¹ (dw)) treated microcosms, most univariate measures, including diversity and species richness, decreased significantly with increasing level of diesel contamination whereas nematode assemblage from the low treated microcosm (0.5 mg diesel kg⁻¹ (dw)) remained unaffected. Results from multivariate analyses of the species abundance data demonstrated that responses of nematode species to the diesel treatments were varied: Chaetonema sp. was eliminated at all doses tested and seemed to be intolerant species to diesel contamination; Pomponema sp. and Oncholaimus campylocercoïdes were significantly affected at all diesel contamination levels but they were not eliminated, these species were categorized as “diesel-sensitive”; Hypodontolaimus colesi, Daptonema trabeculosum and Daptonema fallax which significantly increased respectively at 0.5, 1 and 5 mg diesel kg⁻¹ (dw) concentrations and appeared to be “opportunistic” species at these doses whereas Marylynnia stekhoveni which increased at all high doses (10, 15 and 20 mg diesel kg⁻¹ (dw)) seemed to be a “diesel-resistant” species.     

Molluscs as multidisciplinary models in environment toxicology

The primary goal of this paper is to stimulate discussion and promote the use of mollusc models and multidisciplinary research approaches in the field of environmental toxicology. Molluscs are effective models because they are ubiquitous, have highly conserved control and regulatory pathways that are often homologous to vertebrate systems, and are extremely sensitive to anthropogenic inputs. We have attempted to provide initial references as an avenue into the literature and as a means for researchers to expand their thoughts to regions outside of their own area of expertise. The authors are particularly interested in developing multidisciplinary international collaborative efforts.     

Investigation of natural and anthropogenic hydrocarbon inputs in sediments using geochemical markers. I. Santos, SP--Brazil

A study on the inputs of organic matter to marine sediments of Santos Bay and Estuary, located in southeastern S?o Paulo State, Brazil, is presented here. The following geochemical markers were identified and quantified: aliphatic hydrocarbons (normal and isoprenoid alkanes), petroleum biomarkers, linear alkylbenzenes (LABs) and polycyclic aromatic hydrocarbons (PAHs). Sediment samples, collected at 15 sites in the bay and surrounding channels, were extracted and analyzed by gas chromatography with flame ionization and mass spectrometer detectors. Total concentrations varied from 0.17 to 107.80 microg g(-1) for aliphatics, from 47.2 to 2560.1 ng g(-1) for petroleum biomarkers, from 16.9 to 430.6 ng g(-1) for LABs and from 79.6 to 15389.1 ng g(-1) for PAHs. Anthropogenic contributions were apparent, indicating the influences of the Cubatao industrial complex, sewage outfalls along the area, the waste deposit of Santos city and storage facilities for petroleum and derivatives, based on the higher concentrations of geochemical markers detected.