Canadian perspectives on aluminum

Summary The multi-media approach to aluminum exposure will allow a more informed decision on the inclusion or exclusion of various exposure media in future epidemiological studies.Knowledge of the types of Al (speciation) and their respective bioavailability will enable interpretation of the importance of specific media.     

Prenatal diagnostic testing for familial dysautonomia using linked genetic markers

Familial dysautonomia (FD), a recessively inherited disease, has been mapped to chromosome 9q31. Highly polymorphic dinucleotide repeat markers flanking the genetic locus and at the same genetic location have been identified. We describe the prenatal diagnosis of FD using linkage and linkage disequilibrium analyses with these markers. Twelve families were analysed for informativeness and of these, seven went on to have prenatal testing (a total of eight fetuses tested). All of these fetuses were predicted to be heterozygous unaffected (FD carriers). Seven fetuses have come to term and are normal. In the absence of a recombinant proband, a panel of three proximal and three distal markers is sufficient to provide informative flanking markers and an 87–96 per cent likelihood of a highly predictive test. In an additional family at 1:4 risk for FD, no DNA was available from the propositus. This family was analysed using linkage disequilibrium to the #18 allele of the tightly linked marker D9S58 in conjunction with linkage analysis using data from two unaffected children. Prenatal diagnosis in this family indicated an affected fetus.     

Management strategies for rural water development

Non-sustainability of programmes and projects has become an overriding concern for the water supply and sanitation sector. Poor programme conceptualization, unimaginative planning, use of inappropriate technologies and rigid management approaches have contributed to high rates of programme failure. Five major water supply programmes undertaken during the UN Water Decade in the Western Sudan were analysed for their management approaches, appropriateness and sustainability. Results prompt the conclusion that sustainable projects need to adopt an adaptive and flexible management approach and to employ a conceptual framework which emphasizes community management, the empowerment of women, selection of appropriate low cost technologies, built in operation and maintenance strategies, cost recovery and institutional support to government.     

EFFICIENTLY REDUCING NONPOINT PHOSPHORUS LOADS TO LAKES AND RESERVOIRS1

ABSTRACT: Several problems that make it difficult to deal with water pollution from cropland are identified. The most immediate need is for a rational framework for determining where conservation programs can make an impact on eutrophication problems in reservoirs draining rural watersheds. This includes estimating the level of control that would be required for each local farm situation and the economic impacts for the planning area. A modeling approach is suggested for a planning area in Southeastern Pennsylvania.     

EFFECT OF “WHITING” ON OPTICAL PROPERTIES AND TURBIDITY IN OWASCO LAKE,NEW YORK1

ABSTRACT: The effects “whiting” (CaCO₃ precipitate) had on the optical properties and turbidity of the epilimnion of Owasco Lake, New York, were studied during the summer of 1985. Turbidity was partitioned according to “whiting” and non-“whiting” components utilizing a simple acidification procedure. Diffuse light attenuation was partitioned according to the attenuating processes of absorption and scattering. “Whiting” was present most of the summer. Two major “whiting” events occurred that caused major increases in turbidity and the attenuation of light. “Whiting” was the principle regulator of turbidity during the study; it caused increases in light attenuation by increasing light scattering. “Whiting” events can easily be mistaken by the public for phytoplankton blooms.     

Aggregation pheromone ofCarpophilus freemani (Coleoptera: Nitidulidae): A blend of conjugated triene and tetraene hydrocarbons

Summary Males ofCarpophilus freemani Dobson (Coleoptera: Nitidulidae) produce an aggregation pheromone to which both sexes fly in a wind-tunnel bioassay. The major pheromone component (ca. 30 ng per male per day in volatile collections) was identified as (2E,4E,6E)-5-ethyl-3-methyl-2,4,6-nonatriene. A minor component, (2E,4E,6E,8E)-7-ethyl-3,5-dimethyl-2,4,6,8-undecatetraene, was 3–10% as abundant as the major triene and was 5–20% as active when compared at relative doses ranging from natural proportions to 1:1. These compounds act synergistically: a mixture of major and minor components in natural proportions attracted more than twice as many beetles as the major component alone, and the mixture fully accounted for the activity of male-derived volatile collections. Six other male-derived conjugated hydrocarbons, ranging from 2% down to 0.04% as abundant as the major component, were also identified. These are (in order of decreasing bioassay activity when compared on an equal-weight basis): (3E,5E,7E)-6-ethyl-4-methyl-3,5,7-decatriene, (2E,4E,6E)-5-ethyl-3-me-thyl-2,4,6-octatriene, (3E,5E,7E,9E)-8-ethyl-4,6-dimethyl-3, 5,7,9-dodecatetraene, (2E,4E,6E,8E)-3,5,7-trimethyl-2,4,6, 8-undecatetraene, (3E,5E,7E)-5-ethyl-7-methyl-3,5,7-undecatriene, and (2E,4E,6E)-3,5-dimethyl-2,4,6-nonatriene. All structure identifications were confirmed by synthesis. In the wind tunnel, the pheromone acted synergistically with host-type volatiles such as propyl acetate, valeric acid, and ethanol. This concept was verified by fields tests in California, in which there was dramatic synergism between the pheromone and fermenting host materials. Pheromone biosynthesis is discussed.     

The spatiotemporal expression pattern of trypsinogen and bile salt-activated lipase during the larval development of red porgy (<Emphasis Type="Italic">Pagrus pagrus</Emphasis>, Pisces,Sparidae)

A restoration programme was introduced in the Mondego Estuary (Portugal) to recover seagrass beds of Zostera noltii endangered by eutrophication. A long-term survey of 10 years was used to assess the development of the processes involved, focusing one of the key species (Cyathura carinata, Isopoda). The mitigation measures implemented since 1998 (nutrient loading reduction, freshwater circulation improvement and seagrass bed protection) enhanced water quality and seagrass recovery, thus preventing the development of macroalgal blooms. C. carinata was resilient to the occurrence of floods and macroalgal blooms, although both events caused dispersion of individuals. This isopod was not much influenced by the changes occurring in the estuary, showing an unalterable population structure during the entire study period. After 1998, its density and biomass became more stable at an inner unvegetated sand flat area, where this isopod was most abundant; its population slightly increased in a bare mud flat at the middle section of the estuary; but it could not establish successfully in a downstream Z. noltii bed, contrarily to other common estuarine species. Apart from other unknown reasons, the disrupted balanced between trematodes and their hosts, caused by the eutrophication processes, may have an important role in the discontinuity of C. carinata at the Z. noltii bed. If the intertidal areas become fully restored to the original seagrass coverage, high prevalence and intensity trematodes may prevent this isopod and other crustaceans from recovering within the intervened areas, by enhancing host mortality and recruitment failure. In order to avoid this kind of situation, it may be necessary to survey the levels of parasite infestation within the target hosts and safeguard areas where crustaceans present healthy populations.     

Analysis of anaerobic BTX biodegradation in a subarctic aquifer using isotopes and benzylsuccinates

In situ biodegradation of benzene, toluene, and xylenes in a petroleum hydrocarbon contaminated aquifer near Fairbanks, Alaska was assessed using carbon and hydrogen compound specific isotope analysis (CSIA) of benzene and toluene and analysis of signature metabolites for toluene (benzylsuccinate) and xylenes (methylbenzylsuccinates). Carbon and hydrogen isotope ratios of benzene were between -25.9 per thousand and -26.8 per thousand for delta13C and -119 per thousand and -136 per thousand for delta2H, suggesting that biodegradation of benzene is unlikely at this site. However, biodegradation of both xylenes and toluene were documented in this subarctic aquifer. Biodegradation of xylenes was indicated by the presence of methylbenzylsuccinates with concentrations of 17-50 microg/L in three wells. Anaerobic toluene biodegradation was also indicated by benzylsuccinate concentrations of 10-49 microg/L in the three wells with the highest toluene concentrations (1500-5000 microg/L toluene). Since benzylsuccinate typically accounts for a very small fraction of the toluene present in groundwater (generally <1 mol%), the signature metabolite approach works best at higher toluene concentrations when it is not constrained by detection limits. In wells with lower toluene concentrations (410-640 microg/L), carbon and hydrogen isotopic values were enriched by up to approximately 2 per thousand for delta13C and approximately 70 per thousand for delta2H. This evidence of isotopic fractionation verifies the effects of biodegradation in these low concentration wells where metabolites may already be below detection limits. The combined use of signature metabolite and CSIA data is particularly valuable given the challenge of verifying biodegradation in subarctic environments where degradation rates are typically much slower than in temperate environments.     

The relationship between ecology and the incidence of cooperative breeding in Australian birds

Summary Australia has many cooperatively breeding species of birds. These tend to occur in eucalypt and semi-arid woodlands rather than in rainforests or deserts. They tend to be insectivores that pursue rather than sit and wait for their prey, and tend to forage on the ground rather than above it. We propose that environments where resources do not show marked seasonal fluctuations are those in which cooperative breeding is most likely to evolve. Under these conditions birds might experience difficulty acquiring the extra food necessary to breed, especially if inexperienced. When adult survival was high, young and inexperienced birds could delay breeding. Unpredictable environments may also favor cooperative breeding, but our data do not strongly support this. Groupliving would be favored further if young birds are particularly vulnerable to predators when alone. They should therefore remain in the family group and delay their dispersal unitl a suitable breeding vacancy becomes available. These hypotheses are not mutually exclusive, but are complementary. Both may be required to ensure that at least some year-old birds do not breed and also do not disperse. We believe that they give rise to predictions, which can be tested in future field studies.     

Relationship between different size classes of particulate matter and meteorology in three European cities

Evidence on the correlation between particle mass and (ultrafine) particle number concentrations is limited. Winter- and spring-time measurements of urban background air pollution were performed in Amsterdam (The Netherlands), Erfurt (Germany) and Helsinki (Finland), within the framework of the EU funded ULTRA study. Daily average concentrations of ambient particulate matter with a 50% cut off of 2.5 microm (PM2.5), total particle number concentrations and particle number concentrations in different size classes were collected at fixed monitoring sites. The aim of this paper is to assess differences in particle concentrations in several size classes across cities, the correlation between different particle fractions and to assess the differential impact of meteorological factors on their concentrations. The medians of ultrafine particle number concentrations were similar across the three cities (range 15.1 x 10(3)-18.3 x 10(3) counts cm(-3)). Within the ultrafine particle fraction, the sub fraction (10-30 nm) made a higher contribution to particle number concentrations in Erfurt than in Helsinki and Amsterdam. Larger differences across the cities were found for PM2.5(range 11-17 microg m(-3)). PM2.5 and ultrafine particle concentrations were weakly (Amsterdam, Helsinki) to moderately (Erfurt) correlated. The inconsistent correlation for PM2.5 and ultrafine particle concentrations between the three cities was partly explained by the larger impact of more local sources from the city on ultrafine particle concentrations than on PM2.5, suggesting that the upwind or downwind location of the measuring site in regard to potential particle sources has to be considered. Also, relationship with wind direction and meteorological data differed, suggesting that particle number and particle mass are two separate indicators of airborne particulate matter. Both decreased with increasing wind speed, but ultrafine particle number counts consistently decreased with increasing relative humidity, whereas PM2.5 increased with increasing barometric pressure. Within the ultrafine particle mode, nucleation mode (10-30 nm) and Aitken mode (30-100 nm) had distinctly different relationships with accumulation mode particles and weather conditions. Since the composition of these particle fractions also differs, it is of interest to test in future epidemiological studies whether they have different health effects.