Characterization and phosphate stabilization of dusts from the vitrification of MSW combustion residues

The use of soluble PO₄³⁻ as a heavy metal chemical stabilization agent was evaluated for a dust generated from melting or vitrification of municipal solid waste combustion residues. Vitrification dusts contain high concentrations of volatile elements such as Cl, Na, K, S, Pb, and Zn. These elements are present in the dusts largely as simple salts (e.g. PbCl₂, ZnSO₄) which are highly leachable. At an experimental dose of 0.4 moles of soluble PO₄³⁻ per kg of residue, the pH-dependent leaching (pH 5,7,9) showed that the treatment was able to reduce equilibrium concentrations by factors of 3 to 100 for many metals; particularly Cd, Cu, Pb and Zn. Bulk and surface spectroscopies showed that the insoluble reaction products are tertiary metal phosphate [e.g. Zn₃(PO₄)₂] and apatite [e.g. Pb₅(PO₄)₃Cl] family minerals. Geochemical thermodynamic equilibrium modeling showed that apatite family and tertiary metal phosphate phases act as controlling solids for the equilibrium concentrations of Ca²⁺, Zn²⁺, Pb²⁺, Cu²⁺, and Cd²⁺ in the leachates during pH-dependent leaching. Both end members and ideal solid solutions were seen to be controlling solids. Soluble phosphate effectively converted soluble metal salts into insoluble metal phosphate phases despite the relatively low doses and dry mixing conditions that were used. Soluble phosphate is an effective stabilization agent for divalent heavy metals in melting dusts where leachable metals are present in high concentrations.     

Identification of abnormal chromosomal complement in formalin-fixed,paraffin-embedded placental tissue

The objective of this project was to assess the efficacy of fluorescence in situ hybridization (FISH) with chromosome-specific DNA probes to identify chromosome number in formalin-fixed, paraffin-embedded placental specimens. Using this approach, 75 per cent of the karyotypes in 20 formalin-fixed placental samples (comprising aneuploids, triploids, and normals) were correctly identified. As this technology improves, the ability to obtain information regarding chromosomal abnormalities in formalin-fixed, paraffin-embedded placental tissue should improve as well. This technology can potentially provide important cytogenetic information even when fresh tissue is not available for standard karyotypic analysis.     

First-trimester aneuploidy screening using serum human chorionic gonadotropin (hCG), free ahCG,and progesterone

Immunochemical serum assays for human chorionic gonadotropin (hCG), the free ohCG subunit, and progesterone (P) were considered separately and in combination for their ability to screen for chromosomally abnormal pregnancies in the first trimester. Maternal serum was collected from 141 women undergoing chorionic villus sampling at 9–12 menstrual weeks. Trisomy 21 pregnancies had significantly higher hCG levels, while trisomy 18 and 13 pregnancies had markedly lower hCG and progesterone levels than those of chromosomally normal pregnancies. However, the discrimination of normal from aneuploid pregnancies was poor with either hCG alone, progesterone alone, or free ahCG alone. Much improved discrimination was obtained by combining hCG, free ahCG, and P into an aneuploidy index [(P/hCG)(free ahCG/hCG)]. This index distinguished 9 out of 17 (53 per cent) of the trisomy 21 pregnancies, while only misidentifying 5 out of 112 (4.5 per cent) of the normal pregnancies. The aneuploidy index thus appears promising as a first-trimester biochemical screen for aneuploid pregnancies.     

The costs and benefits of cooperation between the Australian lycaenid butterfly,Jalmenus evagoras,and its attendant ants

Summary The larvae and pupae of the Australian lycaenid butterfly, Jalmenus evagoras associate mutualistically with ants in the genus Iridomyrmex. Four ant exclusion experiments in three field sites demonstrated that predation and parasitism of J. evagoras are so intense that individuals deprived of their attendant ants are unlikely to survive. Larvae and pupae of J. evagoras aggregate, and the mean number of attendant ants per individual increases with larval age and decreases with group size. Field observations showed that young larvae could gain more attendant ants per individual by joining the average size group of about 4 larvae than by foraging alone. Aggregation behaviour is influenced by ant attendance: young larvae and pupating fifth instars aggregated significantly more often on plants with ants than on plants where ants had been excluded. In return for tending and protecting the larvae, ants were rewarded by food secretions that can amount to as much as 409 mg dry biomass from a single host plant containing 62 larvae and pupae of J. evagoras over a 24 h period. Larval development in the laboratory lasted approximately a month, and larvae that were tended by ants developed almost 5 days faster than larvae that were not tended. However, tended individuals, particularly females, pupated at a significantly lower weight than their untended counterparts, and the adults that eclosed from these pupae were also lighter and smaller. On average, pupae that were tended by ants lost 25% more weight than untended pupae, and in contrast with larvae, they took longer to eclose than pupae that were not tended. These experimental results are discussed in terms of costs and benefits of association for both partners, and of aggregation for the lycaenids.     

Latitudinal patterns of diversity and abundance in North Atlantic intertidal boulder-fields

In order to study taxon richness, biodiversity and abundance patterns in the North Atlantic from temperate latitudes through Arctic to high Arctic latitudes, we recorded the faunas (at ELWS level) colonizing 20 cobbles from three sites at each of seven boulder-field localities (south-west England, 50°N; Wales, 51°N; west Scotland, 56°N; Iceland, 64°N; Tromsø, 70°N; Svalbard, 77°N, 79°N). Inverse correlations were found between latitude and all measures of richness (species, orders, and phyla numbers) and biodiversity (S–W, P). However, these correlations were driven mostly by the consistently impoverished Arctic sites; an even cline of decreasing diversity from south to north did not exist. Multidimensional scaling revealed two communities, temperate–subarctic species-rich and high arctic species-poor. Evenness as measured by Pielou’s index was similar across all latitudes. Abundance data exhibited a similar trend to the species richness and diversity data with a significant negative correlation with latitude, but when Arctic data were excluded the correlation vanished.     

Analysis of volatile fatty acids by ion-exclusion chromatography,with special reference to marine pore water

A method for measuring volatile fatty acids using ion-exclusion chromatography is presented. The system was found to be applicable to samples with high salt concentrations (e.g. seawater and marine pore water) when coupled with a vacuum distillation procedure. The method is straightforward, with no sample preconcentration and no introduction of external contamination. Calibration was found to be linear, with good reproducibility (coefficient of variation normally less than 5%) and the system was sufficiently sensitive to operate at the sub-ppm level (minimum detection limit for acetate and propionate was approximately 0.02 and 0.05 ppm, respectively). This technique was used to investigate the distribution of volatile fatty acids with sediment depth at Station E70 in Loch Eil, Scotland (sample was collected in March, 1983) and the results were in good agreement with recent publications. Although the system, at present, is limited in marine pore water to acetate and propionate, it has certain advantages over alternative systems and these are described.     

Interaction between peat, humic acid and aqueous metal ions

Analysis of peat samples from four regions of the British Isles indicates that the concentrations of Al, Pb and common transition metals tend, as expected, to be higher in regions subject to industrial pollution, but that the concentrations of the nontransition metals Na, K, Mg, Ca and Zn tend to be higher in regions remote from industrial pollution. Humic acids were extracted from the most polluted and least polluted of the peat samples and some characteristics of these acids were compared with those of two commercial acids. Values for stability constants of complexes formed between humic acids extracted from peat and Cu²⁺, Zn²⁺ or Pb²⁺ have been obtained by an ionexchange equilibrium method. Of the three metal ions examined, Pb²⁺ was found to form the most stable humic acid complexes, followed by Cu²⁺: this order agrees with the findings of Irving and Williams and of Bunzl. Implications to the binding of actinide and other heavy metal ions in aqueous humic acid are discussed.     

Comparative study of the effects of temperature,salinity and oxygen tension on the rates of oxygen consumption of nauplii of different strains of Artemia

The effects of temperature, salinity and oxygen tension on the rates of oxygen consumption of three different strains of Artemia nauplii have been studied. When acclimated to a salinity of 30, nauplii from each of the three strains were able to maintain approximately constant rates of oxygen consumption over a wide range of oxygen tension. The ability to maintain respiratory independence during hypoxia was reduced, however, with an increase in either temperature or salinity. Nauplii of two of the strains (parthenogenetic diploid and tetraploid) showed a progressive increase in the rate of oxygen consumption with increasing temperature up to 35°C. Nauplii of the bisexual strain appeared to be less tolerant of exposure to temperatures >30°C, since at higher temperatures their oxygen consumption declined slightly. The differences between the nauplii of the different strains in their physiological responses to changing environmental conditions appear to correlate well with their seasonal occurrence in the field.