Analyzing interdependent impacts of resource sustainability

Quantifying the impact of the shortage of a scarce resource requires a systemic account of the interdependent nature of several industry and infrastructure sectors that rely either directly or indirectly on that resource. An ability to quickly and easily quantify such an impact provides policymakers with a useful measure of the efficacy of discovering, designing, or developing a sustainable alternative. Discussed in this paper is a methodological approach for measuring the broader interdependent impacts of a resource shortage. The dynamic inoperability input–output model (DIIM) is used to illustrate both the economic effects of resource shortages over a period of time and the time-dependent recovery of industry sectors. Extensions to the DIIM are introduced to produce an accessible tool for policymakers and industry decision makers. Case studies using publicly available data illustrate the usefulness of the model for describing local oil production shortages and global rare earth metals supply shortages, highlighting the industries that will need to adapt to changes in resource availability, as well as those industries that will remain relatively unaffected. Above all, the model presented in this paper is an effective means of communicating the impact and importance of resource shortages to assist in the design and development of a sustainable future.     

Design and risk assessment tool for vegetative treatment areas receiving agricultural wastewater: Preliminary results

Vegetative treatment areas (VTAs) are commonly being used as an alternative method of agricultural process wastewater treatment. However, it is also apparent that to completely prevent discharge of pollutants to the surrounding environment, settling of particulates and bound constituents from overland flow through VTAs is not sufficient. For effective remediation of dissolved agricultural pollutants, VTAs must infiltrate incoming wastewater. A simple water balance model for predicting VTA soil saturation and surface discharge in landscapes characterized by sloping terrain and a shallow restrictive layer is presented and discussed. The model accounts for the cumulative effect of successive rainfall events and wastewater input on soil moisture status and depth to water table. Nash–Sutcliffe efficiencies ranged from 0.65 to 0.81 for modeled and observed water table elevations after calibration of saturated hydraulic conductivity. Precipitation data from relatively low, average, and high annual rainfall years were used with soil, site, and contributing area data from an example VTA for simulations and comparisons. Model sensitivity to VTA width and contributing area (i.e. barnyard, feedlot, silage bunker, etc.) curve number was also investigated. Results of this analysis indicate that VTAs should be located on steeper slopes with deeper, more-permeable soils, which effectively lowers the shallow water table. In sloping landscapes (>2%), this model provides practitioners an easy-to-use VTA design and/or risk assessment tool that is more hydrological process-based than current methods.     

Value chain for next-generation biofuels: resilience and sustainability of the product life cycle

Multiple factors including climate change, price uncertainties, and geopolitical instability have prompted many industries to investigate the feasibility of replacing traditional petroleum-based fuels with biofuel alternatives. However, to make this transition successful, these new biofuels must be environmentally sustainable and the necessary support infrastructure must be in place to make the production, distribution, and storage of these biofuels technologically feasible and cost effective. Developing a value chain, spanning from feedstock production to distribution to end users, requires garnering buy-in from multiple stakeholders by demonstrating environmental, economic, and social benefits and incentives. Two critical factors are the environmental benefits achieved from the use of the biofuel technology and the degree of resilience of the value chain to emergent conditions to ensure steady supply to consumers. Moreover, different biofuel pathways have different costs, benefits, and risks which must be compared. In this paper, we describe how environmental sustainability can be modeled using life cycle assessment (LCA) and how the resilience of value chain initiatives can be modeled using a scenario-based decision model. We then describe how sustainability and resilience assessments can be integrated in an iterative, anticipatory LCA framework. These assessments can be used as the basis for a business case for various investments, as well as a means for promoting responsible innovations, with the aviation industry used as a case study.     

Effects of feeding history on the growth characteristics of a reef fish at settlement

A feeding experiment was conducted on the pelagic stages of the tropical goatfish Upeneus tragula (family Mullidae) to examine how food quantity affects growth characteristics and potential success at settlement. Pelagic goatfish were collected from aggregation rafts 3 nautical miles west of Lizard Island on the northern Great Barrier Reef during December 1990. Three tanks in each of four feeding regimes were stocked with 25 pelagic goatfish between 20 and 23 mm standard length (SL). The four feeding regimes were: fed ad lib. (fed): fed once per day (f1pd); starved every second day (stld); starved for 3 d and re-fed (st3d). Fishes were fed 36 to 48 h old Artemia sp. nauplii (Ocean Star strain). Fish were removed from tanks when they underwent metamorphosis, changed pigmentation and settled to the bottom of the tanks. Morphology, muscle development, time taken to settle and biochemical condition were examined. Growth attributes of the treated fish were compared to fish which settled within 24 h of capture (field). All attributes examined were significantly influenced by the feeding treatments. Fish within the fed and st3d treatments were significantly larger and heavier than fish in the less well-fed treatments (f1pd, st1d). Similarly, concentrations of total lipid, carbohydrate and protein in the settled fish were significantly higher in the fed and st3d treatments compared with the st1d and f1pd treatments. For all these morphological and biochemical attributes the st1d and f1pd fish did not significantly differ from the field fishes, but did differ from the fed and st3d fishes. Water content was significantly higher in the f1pd, st1d and field fishes compared with the fed and st3d fish. Furthermore, the average time taken to settle followed the pattern: fed (14d)U. tragula are physiologically well suited to exploiting a patchy food source, and that food availability within the pelagic stages can have a major influence on the growth characteristics of this reef fish at settlement. The ramifications of this finding are discussed in relation to survival and success once fish have recruited to the reef population.     

Idle emissions from heavy-duty diesel and natural gas vehicles at high altitude

Idle emissions of total hydrocarbon (THC), CO, NOx, and particulate matter (PM) were measured from 24 heavy-duty diesel-fueled (12 trucks and 12 buses) and 4 heavy-duty compressed natural gas (CNG)-fueled vehicles. The volatile organic fraction (VOF) of PM and aldehyde emissions were also measured for many of the diesel vehicles. Experiments were conducted at 1609 m above sea level using a full exhaust flow dilution tunnel method identical to that used for heavy-duty engine Federal Test Procedure (FTP) testing. Diesel trucks averaged 0.170 g/min THC, 1.183 g/min CO, 1.416 g/min NOx, and 0.030 g/min PM. Diesel buses averaged 0.137 g/min THC, 1.326 g/min CO, 2.015 g/min NOx, and 0.048 g/min PM. Results are compared to idle emission factors from the MOBILE5 and PART5 inventory models. The models significantly (45-75%) overestimate emissions of THC and CO in comparison with results measured from the fleet of vehicles examined in this study. Measured NOx emissions were significantly higher (30-100%) than model predictions. For the pre-1999 (pre-consent decree) truck engines examined in this study, idle NOx emissions increased with model year with a linear fit (r2 = 0.6). PART5 nationwide fleet average emissions are within 1 order of magnitude of emissions for the group of vehicles tested in this study. Aldehyde emissions for bus idling averaged 6 mg/min. The VOF averaged 19% of total PM for buses and 49% for trucks. CNG vehicle idle emissions averaged 1.435 g/min for THC, 1.119 g/min for CO, 0.267 g/min for NOx, and 0.003 g/min for PM. The g/min PM emissions are only a small fraction of g/min PM emissions during vehicle driving. However, idle emissions of NOx, CO, and THC are significant in comparison with driving emissions.     

Towards a more appropriate water based extraction for the assessment of organic contaminant availability

This study correlated extractabilities of 37 d aged phenanthrene residues in four dissimilar soils with the fraction that was available for earthworm (Lumbricus rubellus) accumulation and microorganism (Pseudomonas sp.) mineralisation. Extractability was determined using two established techniques, namely, (1) a water based extraction using CO(2) equilibrated water and (2) an aqueous based hydroxypropyl-beta-cyclodextrin (HPCD) extraction. Results showed no relationship between earthworm accumulation and phenanthrene extractability using either HPCD (r(2)=0.07; slope=-4.76; n=5) or the water based extraction (r(2)=0.31; slope=-5.34; n=5). Earthworm accumulation was overestimated by both techniques. In contrast, the fraction of phenanthrene extractable using both the HPCD technique and the water based extraction correlated strongly with microbial mineralisation. However, the slopes of these linear relationships were 0.48 (r(2)=0.96; n=10), and 0.99 (r(2)=0.88; n=10) for the water based extraction and HPCD, respectively. Thus, the HPCD extraction provided values that were numerically close to the mineralisation values, whilst the water based extraction values were approximately half the mineralisation values. It is submitted that HPCD extraction provided an appropriate method of assessing the fraction of contaminant available for microbial mineralisation in these dissimilar soils.     

Social learning of predators by coral reef fish: does observer number influence acquisition of information?

Prey that are capable of continuously learning the identity of new predators whilst adjusting the intensity of their responses to match their level of risk, are often at a substantive advantage. Learning about predators can occur through direct experience or through social learning from experienced individuals. Social learning provides individuals with an effective means of acquiring information while reducing the costs associated with direct learning. Under a natural setting, social learning is likely to occur between more than two individuals. As such, investigating the effect that group size has on the ability of individuals to acquire information is vital to understanding social learning dynamics. Given the characteristics of coral reefs and the biology of coral reef fishes, these habitats are an ideal medium to test whether group size affects the transmission of information. Using newly settled damselfish (Pomacentrus amboinensis), we examined whether the number of observers present influences transmission of information. We showed that: (1) predator recognition is socially transmitted from predator-experienced to predator-naïve individuals regardless of group size, and that (2) the level of response displayed by the observer does not differ following learning in different sized groups. Our study highlights that information on predator identities is able to be passed onto group members quickly without a dilution of information content.