Curtin University

About: Curtin University is a education organization based out in Perth, Western Australia, Australia. It is known for research contribution in the topics: Population & Zircon. The organization has 14257 authors who have published 48997 publications receiving 1336531 citations. The organization is also known as: WAIT & Western Australian Institute of Technology.

Ion-Selective Electrode Potentiometry in Environmental Analysis

Abstract: This review will illustrate how it is possible to develop ion-selective electrode (ISE) methodologies that meet the stringent requirements (i.e., high selectivities and very low detection limits) for the analysis of important analytes in the environment, and will present a variety of examples on the application of ISEs in environmental analysis. Despite the experimental biases that have limited the analytical performance of ISEs through apparently high detection limits and modest selectivities, there has been a plethora of research in the application of ISEs in the monitoring of environmentally important trace metals and anions in natural waters and soils. Most popular has been the analysis of free metals in natural waters, as this parameter is known to be a master variable in the uptake and toxicology of trace metals on aquatic biota reflecting the bioavailability of trace metals in the environment. Furthermore, as copper is a major trace metal in coastal waters due to its extensive use in antifouling paints on sea vessels and structures, there are many reports in the literature on the use of the copper ISE in assays of either free copper or the copper complexing capacity of natural waters and soil peats. Moreover, there have been a variety of studies showing a strong correlation between free copper levels and the toxicity of copper on a variety of marine and fresh water organisms. Nevertheless, there are numerous reports in the literature that have used ISEs to monitor important anions such as fluoride, phosphate, sulfate, nitrate, nitrite, chloride, cyanide, etc., as well as other important cations such as ammonium and chromium(VI) in waste and natural waters. In conclusion, this review will present new and interesting perspectives on the application of ISEs in environmental analysis using approaches such as real-time remote monitoring of water quality, shipboard monitoring of environmentally important analytes using flow analysis instrumentation, the use of robust all-solid-state ISEs in submersible instruments for long-term deployment in the field, and innovative analytical approaches such as backside calibration and switchtrodes that avoid standard addition analysis and the concomitant perturbation in analyte speciation in natural samples.

Structure, ecology and physiology of root clusters - a review

Abstract: Hairy rootlets, aggregated in longitudinal rows to form distinct clusters, are a major part of the root system in some species. These root clusters are almost universal (1600 species) in the family Proteaceae (proteoid roots), with fewer species in another seven families. There may be 10–1000 rootlets per cm length of parent root in 2–7 rows. Proteoid roots may increase the surface area by over 140× and soil volume explored by 300× that per length of an equivalent non-proteoid root. This greatly enhances exudation of carboxylates, phenolics and water, solubilisation of mineral and organic nutrients and uptake of inorganic nutrients, amino acids and water per unit root mass. Root cluster production peaks at soil nutrient levels (P, N, Fe) suboptimal for growth of the rest of the root system, and may cease when shoot mass peaks. As with other root types, root cluster production is controlled by the interplay between external and internal nutrient levels, and mediated by auxin and other hormones to which the process is particularly sensitive. Proteoid roots are concentrated in the humus-rich surface soil horizons, by 800× in Banksia scrub-heath. Compared with an equal mass of the B horizon, the A1 horizon has much higher levels of N, P, K and Ca in soils where species with proteoid root clusters are prominent, and the concentration of root clusters in that region ensures that uptake is optimal where supply is maximal. Both proteoid and non-proteoid root growth are promoted wherever the humus-rich layer is located in the soil profile, with 4× more proteoid roots per root length in Hakea laurina. Proteoid root production near the soil surface is favoured among hakeas, even in uniform soil, but to a lesser extent, while addition of dilute N or P solutions in split-root system studies promotes non-proteoid, but inhibits proteoid, root production. Local or seasonal applications of water to hakeas initiate non-proteoid, then proteoid, root production, while waterlogging inhibits non-proteoid, but promotes proteoid, root production near the soil surface. A chemical stimulus, probably of bacterial origin, may be associated with root cluster initiation, but most experiments have alternative interpretations. It is possible that the bacterial component of soil pockets rich in organic matter, rather than their nutrient component, could be responsible for the proliferation of proteoid roots there, but much more research on root cluster microbiology is needed.

Derivation of an accurate force-field for simulating the growth of calcium carbonate from aqueous solution : a new model for the calcite-water interface

Abstract: The performance of existing force-field models for the calcium carbonate - water system has been critically assessed with particular reference to the thermodynamic consequences. It is demonstrated that all currently available parametrizations fail to describe the calcite-aragonite phase transition, and the free energies of solvation for the calcium cation are also considerably in error leading to a poor description of the dissolution enthalpy for calcite. A new force-field, based on rigid carbonate ions, has been developed that corrects these deficiencies and accurately describes the thermodynamics of the aqueous calcium carbonate system within molecular dynamics simulations. Not only does this new model lead to quantitative changes in the properties of the calcite (1014) surface in contact with water, but also significant qualitative differences. With this more accurate model it is found that calcium ions do not adsorb at the pristine basal plane of calcite, while carbonate ions only weakly bind. Carbon...