Discrimination of flicker frequency rates in the reptile tuatara (Sphenodon )

By investigating the mechanisms that underlie the perception of environmental cues, we may begin to understand how the sensory system governs behavioral responses. This is the first empirical study to examine learning and visual sensitivity in a reptile species, the tuatara (Sphenodon punctatus). We established a non-intrusive psychophysical method by employing an instrumental paradigm in order to examine discrimination learning and the ability to distinguish different flicker frequencies in the tuatara. Seventeen tuatara were trained under an operant conditioning task to respond to various discriminative stimuli flickering between 2.65 and 65.09 Hz. Tuatara were able to learn the operant task and discriminate between a constant light and flicker frequency rates between 2.65 and 45.61 Hz, but not at 65.09 Hz. We demonstrated a reliable psychophysical method where these reptiles could learn a basic operant task and discriminate visual stimuli in the form of flicker frequency rates. The tuatara’s ability to perceive flickering light is comparable to that of avian, mammalian, and other reptilian species. This method is thus suitable for more comprehensive examinations of vision and additional sensory abilities in other reptiles. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Conceptions of vulnerability in adaptation projects: a critical examination of the role of development aid agencies in Timor-Leste

It is widely acknowledged that Small Island Developing States (SIDS) are particularly vulnerable to climate change and will continue to require external support to adapt to current and future impacts. The international development community plays an important role in supporting SIDS adapt to climatic changes, and calls for increased international commitment have been made. However, how the vulnerability of SIDS to climate change is being conceptualised and, subsequently, how adaptation programmes are conceived and designed by the international development community are yet to be critically explored. Using Timor-Leste as a case study, this study examines the conceptual trends underpinning 32 donor-led adaptation programmes implemented from 2010 to the present date. Results show that donor-led adaptation programmes continue to conceptualise climate change vulnerability as a biophysical issue rather than a consequence of the dynamic interactions between political, institutional, economic and social structures. Adaptation policy responses therefore have limited ability to target more nuanced and broader-scale structures affecting SIDS and may be falling short in their efforts to reduce the vulnerability of SIDS. We argue that it is critical that the international development community re-conceptualise its approach to vulnerability reduction in SIDS. We conclude by highlighting how the Paris Agreement, with its expanding understanding of vulnerability, can act as a useful instrument to promote such changes.     

Characterization and performance of nanofiltration membranes

The availability of clean water has become a critical problems facing the society due to pollution by human activities. Most regions in the world have high demands for clean water. Supplies for freshwater are under pressure. Water reuse is a potential solution for clean water scarcity. A pressure-driven membrane process such as nanofiltration has become the main component of advanced water reuse and desalination systems. High rejection and water permeability of solutes are the major characteristics that make nanofiltration membranes economically feasible for water purification. Recent advances include the prediction of membrane performances under different operating conditions. Here, we review the characterization of nanofiltration membranes by methods such as scanning electron microscopy, thermal gravimetric analysis, attenuated total reflection Fourier transform infrared spectroscopy, and atomic force microscopy. Advances show that the solute rejection and permeation performance of nanofiltration membranes are controlled by the composition of the casting solution of the active layer, cross-linking agent concentration, preparation method, and operating conditions. The solute rejection depends strongly on the solute type, which includes charge valency, diffusion coefficient, and hydration energy. We also review the analysis of the surface roughness, the nodule size, and the pore size of nanofiltration membranes. We also present a new concept for membrane characterization by quantitative analysis of phase images to elucidate the macro-molecular packing at the membrane surface.     

Dryland salinity and vector-borne disease emergence in southwestern Australia

Broad-scale clearing of native vegetation for agriculture in southwestern Australia has resulted in severe ecosystem degradation, which has been compounded by the subsequent development of large areas of dryland salinity; decreased transevaporation allows the water table to rise, dissolving ancient aeolian salt deposits and creating saline surface pools. The mosquito-borne disease Ross River virus has been noted as a potential adverse human health outcome in salinity-affected regions because the principal vector, Aedes camptorhynchus, is salt tolerant and thrives preferentially in such systems. To understand the geology and ecology underlying the relationship between land clearing and disease emergence, we examine the relationship between dryland salinity processes that determine the dissolved solids profile of saline pools in affected areas, the mosquito vectors and interactions with the human population within the disease cycle. Aedes camptorhynchus is able to survive in a wide range of salinities in pools created by dryland salinity processes. The link with disease emergence is achieved where population distribution and activity overlaps with the convergence of environmental and ecological conditions that enhance disease transmission.     

Coal mining and the resource community cycle: A longitudinal assessment of the social impacts of the Coppabella coal mine

Two social impact assessment (SIA) studies of Central Queensland's Coppabella coal mine were undertaken in 2002–2003 and 2006–2007. As ex post studies of actual change, these provide a reference point for predictive assessments of proposed resource extraction projects at other sites, while the longitudinal element added by the second study illustrates how impacts associated with one mine may vary over time due to changing economic and social conditions. It was found that the traditional coupling of local economic vitality and community development to the life cycle of resource projects—the resource community cycle—was mediated by labour recruitment and social infrastructure policies that reduced the emphasis on localised employment and investment strategies, and by the cumulative impacts of multiple mining projects within relative proximity to each other. The resource community cycle was accelerated and local communities forced to consider ways of attracting secondary investment and/or alternative industries early in the operational life of the Coppabella mine in order to secure significant economic benefits and to guard against the erosion of social capital and the ability to cope with future downturns in the mining sector.     

A GIS Approach to Model Sediment Reduction Susceptibility of Mixed Sand and Gravel Beaches

The morphological form of mixed sand and gravel beaches is distinct, and the process/response system and complex dynamics of these beaches are not well understood. Process response models developed for pure sand or gravel beaches cannot be directly applied to these beaches. The Canterbury Bight coastline is apparently abundantly supplied with sediments from large rivers and coastal alluvial cliffs, but a large part of this coastline is experiencing long-term erosion. Sediment budget models provide little evidence to suggest sediments are stored within this system. Current sediment budget models inadequately quantify and account for the processes responsible for the patterns of erosion and accretion of this coastline. We outline a new method to extrapolate from laboratory experiments to the field using a geographical information system approach to model sediment reduction susceptibility for the Canterbury Bight. Sediment samples from ten representative sites were tumbled in a concrete mixer for an equivalent distance of 40 km. From the textural mixture and weight loss over 40 km tumbling, we applied regression techniques to generate a predictive equation for Sediment Reduction Susceptibility (SRS). We used Inverse Distance Weighting (IDW) to extrapolate the results from fifty-five sites with data on textural sediment composition to field locations with no data along the Canterbury Bight, creating a continuous sediment reductions susceptibility surface. Isolines of regular SRS intervals were then derived from the continuous surface to create a contour map of sediment reductions susceptibility for the Canterbury Bight. Results highlighted the variability in SRS along this coastline.     

Conversion of calcium sulphide to calcium carbonate during the process of recovery of elemental sulphur from gypsum waste

The production of elemental sulphur and calcium carbonate (CaCO₃) from gypsum waste can be achieved by thermally reducing the waste into calcium sulphide (CaS), which is then subjected to a direct aqueous carbonation step for the generation of hydrogen sulphide (H₂S) and CaCO₃. H₂S can subsequently be converted to elemental sulphur via the commercially available chemical catalytic Claus process. This study investigated the carbonation of CaS by examining both the solution chemistry of the process and the properties of the formed carbonated product. CaS was successfully converted into CaCO₃; however, the reaction yielded low-grade carbonate products (i.e. <90 mass% as CaCO₃) which comprised a mixture of two CaCO₃ polymorphs (calcite and vaterite), as well as trace minerals originating from the starting material. These products could replace the Sappi Enstra CaCO₃ (69 mass% CaCO₃), a by-product from the paper industry which is used in many full-scale AMD neutralisation plants but is becoming insufficient. The insight gained is now also being used to develop and optimize an indirect aqueous CaS carbonation process for the production of high-grade CaCO₃ (i.e. >99 mass% as CaCO₃) or precipitated calcium carbonate (PCC).     

Efficient suspension freeze desalination of mine wastewaters to separate clean water and salts

Suspension freeze desalination is a promising technique for producing clean water from mine wastewaters. The principle is that growing ice crystals reject impurities during freezing. As a result, pure water is separated from mine wastewaters as clean ice. Actually, there is a need for improved techniques to increase water yield and purity. Here we tested ice formation in complex synthetic solutions during cooling and addition of seed. Solutions included: pure distilled water, 50, 33 g/L NaCl and 17, 50 g/L Na₂SO₄, 50 g/L NaCl and 50 g/L Na₂SO₄. Results show that heat of crystallization was the highest with pure distilled water at 8859 J, whereas the lowest heat of crystallization, of 4608 J, was for the solution of 50 g/L NaCl and 50 g/L Na₂SO₄, indicating that the presence of the salt enhances ice formation. As an application, we designed a new flow diagram, which, in addition to heat exchanger and ice filter, now includes a fluidized bed reactor for salt crystallization and recovery, and a separate heat exchanger for ice crystallization.     

The behaviour of selected rare-earth elements during the conversion of phosphogypsum to calcium sulphide and residue

Phosphogypsum (PG) is a large hazardous waste from fertiliser and phosphoric acid industries from which useful products including rare-earth elements (REEs) can be recovered depending on the treatment process. Its conversion to calcium sulphide (CaS) which was achieved at 95% followed by the formation of S, CaCO₃ and residue is one of the plausible treatment processes leading to economic and environmental benefits. This study aimed at monitoring selected REEs behaviour during the conversion of (PG) to (CaS). The concentrations of REEs in the raw PG, the produced CaS and the obtained residue were determined after digestion (microwave and traditional acid leaching) using ICP-OES. The effect of CO₂ and H₂S used in the process of forming CaCO₃ and S from PG on the concentrations of REEs was also investigated. Microwave digestion proved to be more effective than traditional acid leaching in the recovery of REEs. Microwave digestion using 3 mL HNO₃ + 1 mL HCl was more effective than 1 mL HNO₃ + 3 mL in REEs recovery. CaS contained the highest amount of Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, La and Y with values of 2646, 476, 2255, 320, 60.5, 376, 79.8, 1.24, 476, 1185 and 318 µg/g respectively. Based on these findings, the residue could be further processed to recover REEs despite less than 40% decrease in concentration for the majority of REEs observed due to the use of H₂S and CO₂. CO₂ was found to be more suitable as fewer REEs were leached as compared to H₂S. All things considered, the obtained residue could be a good secondary source of REEs as it is easier to leach, retained good amount of REEs and lesser impurities.