Evaluating the respiratory bioaccessibility of nickel in soil through the use of a simulated lung fluid

Simulated lung fluids are solutions designed to mimic the composition of human interstitial lung fluid as closely as possible. Analysis of mineral dusts using such solutions has been used to evaluate the respiratory bioaccessibility of various elements for which solubility in the lungs is a primary determinant of reactivity. The objective of this study was to employ simulated lung fluid analysis to investigate the respiratory bioaccessibility of nickel in soils. Current occupational guidelines in Australia regulate nickel compounds in terms of water solubility, though this may not be an accurate estimation of the total nickel that will dissociate in the lungs. Surface soils were collected from the city of Kalgoorlie in Western Australia, the site of an operational nickel smelter and metal mining activities. The fraction of the samples less than 10 μm was extracted from the soil, and it was this sub-10-μm fraction that was found to hold most of the total nickel present in the soil. The fine fraction was analyzed using a simulated lung fluid (modified Gamble’s solution) to isolate the nickel phases soluble in the lungs. In addition, a sequential extraction was employed to compare the bioaccessible fraction to those dissolved from different binding forms in the soil. In all samples, the simulated lung fluid extracted more nickel than the two weakest leaches of the sequential extraction combined, providing a more representative nickel bioaccessibility value than the current water leach method.     

Multiple structural modifications to dendritic ecological networks produce simple responses

Structural modifications to landscapes affect the ability of organisms to access different habitat patches. There exist, however, very few general methods by which to relate modifications to expectations of effects, and even fewer that enable understanding of how multiple modifications may interact. In the absence of any guiding principles, ecologists have assumed that interactions will result in complex landscape-scale effects. One way of understanding such effects is through rendering a landscape as a graph or network, among the simplest of which are dendritic networks typified by stream systems. Yet even for stream networks, there are no known general principles concerning the nature of interactions between multiple modifications. We developed a model to describe the ability of fish to access and use different habitat patches within dendritic networks. We used mathematical and numerical analyses of the model to investigate how the habitat value of a network is affected by changes in connectivity and habitat quality, and then to examine interactions between multiple modifications. Rather than showing complex interactions, our analytic and simulation-based results show that the combined effect of multiple modifications approximately equals the sum of individually predicted effects. Dendritic networks thus appear to respond far more simply to multiple modifications than has previously been assumed. These results have implications for stream management planning, and offer a firm foundation from which to better understand population processes within dendritic networks.     

Learning about knowledge management for improving environmental impact assessment in a government agency: the Western Australian experience

How does knowledge management (KM) by a government agency responsible for environmental impact assessment (EIA) potentially contribute to better environmental assessment and management practice? Staff members at government agencies in charge of the EIA process are knowledge workers who perform judgement-oriented tasks highly reliant on individual expertise, but also grounded on the agency’s knowledge accumulated over the years. Part of an agency’s knowledge can be codified and stored in an organizational memory, but is subject to decay or loss if not properly managed. The EIA agency operating in Western Australia was used as a case study. Its KM initiatives were reviewed, knowledge repositories were identified and staff surveyed to gauge the utilisation and effectiveness of such repositories in enabling them to perform EIA tasks.     

Source term characterisation using concentration trends and geochemical associations of Pb and Zn in river sediments in the vicinity of a disused mine site: Implications for contaminant metal dispersion processes

River sediment at a disused lead-zinc mine was analysed to provide an understanding of the chemical nature of the source term for contaminated sediment exported from the site. Changes in concentration and geochemical associations of Pb and Zn were measured using aqua regia digestion and the BCR sequential extraction procedure. Sediment in the immediate vicinity of the mine was highly contaminated with Pb (max. c. 11,000 mg kg⁻¹) and Zn (max. c. 30,000 mg kg⁻¹), but these values declined rapidly within 1 km of the mine due to dilution and hydraulic sorting. Lead fractionation changed from being predominantly in the reducible fraction to being in the acetic acid-extractable fraction, whereas Zn was predominantly in the residual fraction. This material is transported as fine sediment in the river system.     

Lessons from a microfinance recapitalisation programme

Following a major disaster, microfinance institutions (MFIs) often face high levels of bad debt, which may require the institutions to be recapitalised. This paper describes a recapitalisation programme implemented by the SANASA movement of Sri Lanka in 390 microfinance societies following the December 2004 tsunami, and highlights lessons for other similar programmes. MFI recapitalisation is a good use of funds in post‐disaster situations. To create successful programmes, donors should expect to relax some of their usual project requirements and MFIs should focus on maintaining credit discipline.     

Effects of bridge construction on songbirds and small mammals at Blennerhassett Island, Ohio River, USA

Construction of man-made objects such as roads and bridges may have impacts on wildlife depending on species or location. We investigated songbirds and small mammals along the Ohio River, WV, USA at a new bridge both before and after construction and at a bridge crossing that was present throughout the study. Comparisons were made at each site over three time periods (1985–1987 [Phase I] and 1998–2000 [Phase II] [pre-construction], 2007–2009 [Phase III] [post-construction]) and at three distances (0, 100, 300 m) from the bridge or proposed bridge location. Overall, 70 songbirds and 10 small mammals were detected during the study. Cliff swallows (Petrochelidon pyrrhonota) and rock pigeons (Columba livia) showed high affinity for bridges (P?<?0.05). Combined small mammal abundances increased between Phases I and II (P?<?0.05), but did not differ between Phases II and III (P?>?0.05). Species richness and diversity for songbirds and small mammals did not differ before and after bridge construction (P?>?0.05). We found that most species sampled did not respond to the bridge crossing, and believe that the bridge is not causing any measurable negative density impacts to the species we investigated. The new bridge does provide habitat for exotic rock pigeons that are adjusted to man-made structures for nesting.     

Investigation of organic matter dynamics during in-vessel composting of an aged coal-tar contaminated soil using fluorescence excitation-emission spectroscopy

In-vessel composting of an aged coal-tar contaminated soil from a manufactured gas plant site was investigated over 98days using laboratory-scale in-vessel composting reactors. The composting reactors were operated at 18 different operational conditions using a logistic three-factor factorial design with three temperatures (T=38, 55 and 70 degrees C), four soil to green waste ratios (S:GW; 0.6:1, 0.7:1, 0.8:1 and 0.9:1 on a dry weight basis) and three moisture contents (MC; 40%, 60% and 80%). Excitation-emission matrix (EEM) fluorescence spectroscopy was used to investigate organic matter dynamics in the composting mixture. The results of this investigation indicated that formation of humic substances can be monitored by fluorescence excitation-emission matrix, and provided evidence of progressive mineralization or humification of the composting mixture. Peak excitation wavelength shifts and peak fluorescence intensity can both be used as indicators to monitor the humification or maturation of compost. Finally, the fluorescence index can be applied to investigate the origin of humic substances and fulvic acids, and the humification or maturation of compost.     

In vitro approaches to assess bioavailability and human gastrointestinal mobilization of food-borne polychlorinated biphenyls (PCBs)

This study reports on the potential for gastrointestinal (GI) mobilization and bioavailability of food-borne PCBs in humans. The development and validation of a GI simulator and operational protocols, developed in compliance with the requirements of German DIN 19738 risk assessment test procedure, are presented. Food, naturally contaminated with PCBs, was homogenized with simulated saliva fluid and shaken in the GI simulator with simulated gastric fluids (containing pepsin, mucine) for 2 h at 37 degrees C. Afterwards, the simulated intestinal fluids (containing pepsin, mucine, trypsin, pancreatin, bile) were added and the mixture shaken for a further 6 h prior to centrifugation and filtration using Buchner funnels to separate the undigested GI residues from GI fluids. PCBs were recovered from GI residues and fluids by Soxhlet and liquid-liquid extraction respectively, cleaned up using silica-SFE, and analyzed by gas chromatography mass spectrometry detection (GC-MSD). Detailed studies with fish indicate variations in mobilization and bioavailability of Sigma PCBs (28, 52, 101, 118, 153, 138 and 180). For example, the bioavailable fractions (fractions mobilized) in mackerel, salmon, crab and prawn were 0.77, 0.60, 0.54, and 0.72 respectively of the Sigma PCBs initially present in these food samples. The bioavailable fraction was dependent on the physicochemical characteristics of the PCBs. In mackerel bioavailable fractions for individual PCB congeners ranged from 0.47-0.82, from 0.30-0.70 in salmon, 0.44-0.64 in crab and in prawn from 0.47-0.77. Future studies will focus on understanding better, the variability in bioavailable fractions to be expected for different foodstuffs, in addition to tissue culture techniques using human gut cell lines to investigate a simultaneous mobilization and absorption of food-borne PCBs.     

The use of invertebrates to detect small-scale habitat heterogeneity and its application to restoration practices

Recent conceptual and technological solutions to biodiversityassessment allow large numbers of invertebrate specimens to beprocessed rapidly and provide researchers and practitioners with a unique tool for characterizing habitats. One applicationof these advances is the ability to detect and monitor small-scale habitat heterogeneity and so provide a measure of ecosystem restoration. This case study presents a test of theefficacy of using invertebrates to assess and monitor ecologicalrestoration following bush regeneration. Eight contiguous habitatpatches within a suburb of northern Sydney, Australia, were selected to represent areas that had undergone different bushregeneration techniques. A nearby and relatively undisturbed area of bushland was also sampled. A total of 57 806 ground-active invertebrate specimens from 35 different orders were collected in pitfall traps. 1 246 ant (Formicidae) specimens were further sorted into 46 ant morphospecies from20 genera. Analyses of the three taxonomic data sets, includingtwo different data transformations, demonstrated that: (i) invertebrate communities successfully characterized different sites, providing a high degree of differentiation among sites;(ii) ordinations of the sites allowed visual assessment of theimpact of each management technique on the habitat relativeto undisturbed habitats; and (iii) characterization of sitescould be achieved using abundance classes or binary countsof ant morphospecies, representing potential cost and timesavings. The project duration was a total of three personweeks and cost less than US$3,000 (1999 prices) to complete.Measurement of invertebrate assemblages will provide a toolfor both rapid assessment of management decisions and ameans by which to implement adaptive management and restoration.