David J. Chittleborough

Bio: David J. Chittleborough is an academic researcher from University of Adelaide. The author has contributed to research in topics: Soil water & Loam. The author has an hindex of 35, co-authored 102 publications receiving 4868 citations. Previous affiliations of David J. Chittleborough include University of Central Asia & University of the Sunshine Coast.

Solubility and batch retention of CeO2 nanoparticles in soils.

Abstract: There is a paucity of information on the environmental fate of cerium oxide nanoparticles (CeO2 NPs) for terrestrial systems that may be exposed to CeO2 NPs by the application of biosolids derived from wastewater treatment systems. Using ultrafiltration (UF), dissolution, and nonequilibrium retention (Kr) values of citrate-coated (8 nm diameter) CeO2 NPs and partitioning (Kd) values of dissolved CeIII and CeIV were obtained in suspensions of 16 soils with a diversity of physicochemical properties. Dissolution of CeO2 NPs studied in solutions was only significant at pH 4 and was less than 3.1%, whereas no dissolved Ce was detected in soils spiked with CeO2 NPs. Kr values of CeO2 NP were low (median Kr = 9.6 L kg−1) relative to Kd values of dissolved CeIII and CeIV (median Kd = 3763 and 1808 L kg−1, respectively), suggesting low CeO2 NP retention in soils. Surface adsorption of phosphate to CeO2 NP caused a negative zeta potential, which may explain the negative correlation of log Kr values with dissolved p...

Chemistry of chromium in soils with emphasis on tannery waste sites.

Abstract: Worldwide chromium contamination of soils has arisen predominantly from the common practice of land-based disposal of tannery wastes under the assumption that the dominant species in the tannery waste would be the thermodynamically stable Cr(III) species. However, significant levels of toxic Cr(VI) recently detected in surface water and groundwater in India, China, Australia, and elsewhere raise critical questions relating to current disposal criteria for Cr-containing wastes. It now appears that despite the thermodynamic stability of Cr(III), the presence of certain naturally occurring minerals, especially Mn oxides, can enhance oxidation of Cr(III) to Cr(VI) in the soil environment. This factor is of public concern because at high pH, Cr(VI) is bioavailable, and it is this form that is highly mobile and therefore poses the greatest risk of groundwater contamination.

Genes and salt tolerance: bringing them together.

Abstract: Salinity tolerance comes from genes that limit the rate of salt uptake from the soil and the transport of salt throughout the plant, adjust the ionic and osmotic balance of cells in roots and shoots, and regulate leaf development and the onset of senescence. This review lists some candidate genes for salinity tolerance, and draws together hypotheses about the functions of these genes and the specific tissues in which they might operate. Little has been revealed by gene expression studies so far, perhaps because the studies are not tissue-specific, and because the treatments are often traumatic and unnatural. Suggestions are made to increase the value of molecular studies in identifying genes that are important for salinity tolerance.

Nanomaterials in the environment: Behavior, fate, bioavailability, and effects

Abstract: The recent advances in nanotechnology and the corresponding increase in the use of nanomaterials in products in every sector of society have resulted in uncertainties regarding environmental impacts. The objectives of this review are to introduce the key aspects pertaining to nanomaterials in the environment and to discuss what is known concerning their fate, behavior, disposition, and toxicity, with a particular focus on those that make up manufactured nanomaterials. This review critiques existing nanomaterial research in freshwater, marine, and soil environments. It illustrates the paucity of existing research and demonstrates the need for additional research. Environmental scientists are encouraged to base this research on existing studies on colloidal behavior and toxicology. The need for standard reference and testing materials as well as methodology for suspension preparation and testing is also discussed.

World salinization with emphasis on Australia

Abstract: Salinization is the accumulation of water-soluble salts in the soil solum or regolith to a level that impacts on agricultural production, environmental health, and economic welfare. Salt-affected soils occur in more than 100 countries of the world with a variety of extents, nature, and properties. No climatic zone in the world is free from salinization, although the general perception is focused on arid and semi-arid regions. Salinization is a complex process involving the movement of salts and water in soils during seasonal cycles and interactions with groundwater. While rainfall, aeolian deposits, mineral weathering, and stored salts are the sources of salts, surface and groundwaters can redistribute the accumulated salts and may also provide additional sources. Sodium salts dominate in many saline soils of the world, but salts of other cations such as calcium, magnesium, and iron are also found in specific locations. Different types of salinization with a prevalence of sodium salts affect about 30% of the land area in Australia. While more attention is given to groundwater-associated salinity and irrigation salinity, which affects about 16% of the agricultural area, recent investigations suggest that 67% of the agricultural area has a potential for "transient salinity", a type of non-groundwater-associated salinity. Agricultural soils in Australia, being predominantly sodic, accumulate salts under seasonal fluctuations and have multiple subsoil constraints such as alkalinity, acidity, sodicity, and toxic ions. This paper examines soil processes that dictate the exact edaphic environment upon which root functions depend and can help in research on plant improvement.

Mycorrhizal ecology and evolution: the past, the present, and the future

Abstract: Almost all land plants form symbiotic associations with mycorrhizal fungi. These below-ground fungi play a key role in terrestrial ecosystems as they regulate nutrient and carbon cycles, and influence soil structure and ecosystem multifunctionality. Up to 80% of plant N and P is provided by mycorrhizal fungi and many plant species depend on these symbionts for growth and survival. Estimates suggest that there are c. 50 000 fungal species that form mycorrhizal associations with c. 250 000 plant species. The development of high-throughput molecular tools has helped us to better understand the biology, evolution, and biodiversity of mycorrhizal associations. Nuclear genome assemblies and gene annotations of 33 mycorrhizal fungal species are now available providing fascinating opportunities to deepen our understanding of the mycorrhizal lifestyle, the metabolic capabilities of these plant symbionts, the molecular dialogue between symbionts, and evolutionary adaptations across a range of mycorrhizal associations. Large-scale molecular surveys have provided novel insights into the diversity, spatial and temporal dynamics of mycorrhizal fungal communities. At the ecological level, network theory makes it possible to analyze interactions between plant-fungal partners as complex underground multi-species networks. Our analysis suggests that nestedness, modularity and specificity of mycorrhizal networks vary and depend on mycorrhizal type. Mechanistic models explaining partner choice, resource exchange, and coevolution in mycorrhizal associations have been developed and are being tested. This review ends with major frontiers for further research.