Jock Churchman

University of Adelaide · School of Agriculture, Food and Wine

Allophanic tephra‑derived soils can sequester sizable quantities of soil organic matter (SOM). However, no studies have visualized the fine internal porous structure of allophanic soil microaggregates, nor studied the carbon structure preserved in such soils or paleosols. We used synchrotron radiation‑based transmission X‑ray microscopy (TXM) to pe...

Allophanic tephra-derived soils can sequester sizable quantities of soil organic matter (SOM). However, no studies have visualized the fine internal porous structure of allophanic soil microaggregates, nor studied the carbon structure preserved in such soils or paleosols. We used synchrotron radiation-based transmission X-ray microscopy (TXM) to pe...

Al-hydroxy intercalated vermiculitic phases have been widely observed in pedogenic environment, but soil organic intercalations have rarely been reported. In the present study, mixed-layer illite–vermiculite (I/V) with organic matter (OM) intercalation under hydromorphic conditions in the Xuancheng red earth sediments was investigated in order to b...

Results from earlier laboratory and field experiments were interrogated for the possibilities of sequestration, or long-term accumulation, of carbon from excess greenhouse gases in the atmosphere. In the laboratory study, samples of three (top) soils dominated by kaolinite and illite (together), smectite, and allophane were examined for the adsorpt...

This cover image can be cited as: Bhabananda Biswas, Ravi Naidu et al., 2019. Inside Cover Image. Chem Soc Rev. 48: 3678-3678. Doi: 10.1039/C9CS90062D. This cover image is linked to the feature article: https://doi.org/10.1039/C8CS01019F. Original article: "Biocompatible functionalisation of nanoclays for improved environmental remediation" by B...

Among the wide range of materials used for remediating environmental contaminants, modified and functionalised nanoclays show particular promise as advanced sorbents, improved dispersants, or biodegradation enhancers. However, many chemically modified nanoclay materials are incompatible with living organisms when they are used in natural systems wi...

Local topography and elevation gradients can exert important influences on soil formation processes such as elemental migration, mineral weathering, and soil organic matter (SOM) accumulation, yet these influences remain insufficiently investigated to date, particularly in surface soils of subtropical monsoonal regions. Here, we report on an invest...

In agricultural soils, subsoil clay addition to sand has the potential to improve carbon sequestration by increasing soil organic carbon (OC) concentration through adsorption and occlusion. However, the factors influencing increased OC in these engineered soils are poorly understood. The addition of subsoil clay creates clods of different sizes, fr...

Sandy soils cover large proportions of Australia’s cereal-cropping region and are wide-spread globally. Sandy soils often have low organic C (OC) content due to limited plant growth and rapid decomposition because of low clay concentration. The addition of subsoil clay to sandy soil has the potential to increase OC storage. This study aimed to (i)...

This book provides new and synthesized information on the dynamics of SOC in the terrestrial environment. In addition to rigorous state-of-the art on soil science, the book also provides strategies to avoid risks of soil carbon losses. Stabilization of C in soil is important for minimizing greenhouse gas emission into the atmosphere and for improvi...

Diffuse reflectance spectrophotometry (DRS) is a new, fast, and reliable method to characterize Fe-oxides in soils. The Fe-oxide mineralogy of the Jiujiang red earth sediments was investigated using DRS to investigate the climate evolution of southern China since the mid-Pleistocene. The DRS results show that hematite/(hematite + goethite) ratios [...

Halloysite concentration of core Omok-1

Remolded and undisturbed shear strength, sensitivity, halloysite morpholigies, and spheroidal grain sizes along core Omok-1

Using data from the literature, we pose the question of the extent to which a knowledge of soils is contributed by that of its clay fraction. In the past, soil characteristics have not related well to mineralogical analyses but we have redefined clays and also used a computer programme to more closely analyse X-ray diffraction (XRD) profiles. It wa...

Unfortunately, in the original publication of the article, Prof. Yong Sik Ok's affiliation was incorrectly published. The author's affiliation is as follows.

Defining soil clay minerals as all inorganic particles < 2 µm would enhance their predictive power for soil functions. The future task is to unravel the prominent functional role of clay associations in the “ultimate particles” in soils–microaggregates. High energy techniques and decomposition of XRD patterns offer the prospect of understanding ass...

2017 Elsevier Inc. There is a growing concern about climate change, and soils have attracted significant research attention as a sink for atmospheric CO 2 . Mechanisms of soil organic carbon (SOC) stabilization have received much focus recently due to its relevance in controlling the global C cycle. The purpose of this chapter is to review our exis...

Sensitive soils derived from weathered rhyolitic pyroclastic materials are associated with many landslides in the Bay of Plenty. Undrained, consolidated static triaxial tests show contractive p'-q' plots, strain-softening stress-strain behaviour coupled with rising pore water pressures, shear band formation after peak strength, and considerable str...

This study investigated the effects of surface functional groups, cation exchange capacity (CEC), surface charge, sesquioxides and specific surface area (SSA) of three soil clay fractions (SCFs) (kaolinite-illite, smectite and allophane) on the retention of dissolved organic carbon (DOC) in soils. Physico-chemical properties of the SCFs before and...

The mineralogy and chemical composition of the Jiujiang red earth sediments were investigated using X-ray diffraction (XRD), X-ray fluorescence (XRF), and inductively coupled plasma mass spectrometry (ICP-MS). Mixed-layer illite–vermiculite (I/V) was confirmed based on the conditions that a broad peak of 1.0 to 1.4 nm appeared in XRD after Mg-satur...

Environmental conditions like temperature and moisture could affect the carbon protection capacity of various clay types in soils. Using dominantly kaolinitic-illitic, smectitic and allophanic soils, we conducted systematic incubation experiments over 42 days at different temperatures (4, 22 and 37 °C) and moisture contents (30, 60 and 90% of water...

To understand climate changes recorded in the Luochuan loess-palaeosols, Shaanxi province, northwestern China, clay mineralogy was studied using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and scanning electron microscopy (SEM) methods. XRD results show that clay mineral compositions in the Luochuan loess-pala...

Altered pyroclastic (tephra) deposits are highly susceptible to landsliding, leading to fatalities and property damage every year. Halloysite, a low-activity clay mineral, is commonly associated with landslide-prone layers within altered tephra successions, especially in deposits with high sensitivity, which describes the post-failure strength loss...

There is a growing concern about climate change, and soils have attracted significant research attention as a sink for atmospheric CO2. Mechanisms of soil organic carbon (SOC) stabilization have received much focus recently due to its relevance in controlling the global C cycle. The purpose of this chapter is to review our existing knowledge of soi...

Altered tephras are highly susceptible to landsliding and account for fatalities and property damage every year. The clay mineral halloysite is often associated with landslide-prone layers within weathered tephra successions, especially in deposits with high sensitivity, which describes the post-failure strength loss. However, the precise role of h...

Despite being first described nearly 200 years ago, halloysite still has the capacity to surprise. We report here the remarkable discovery in New Zealand of two new morphologies for this 1:1 Si:Al layered aluminosilicate member of the kaolin subgroup. One discovery was entirely serendipitous, thus lending validity to the famous phrase attributed to...

Abstract

New insights from the recent literature are summarised and new data presented concerning the formation, structure and morphology of halloysite. Halloysite formation by weathering always requires the presence of water. Where substantial drying occurs, kaolinite is formed instead. Halloysite formation is favoured by a low pH. The octahedral sheet is...

Hydrated halloysite was discovered in books, a morphology previously associated exclusively with kaolinite. From ~1.5 μm to ~1500 μm in length, the books showed significantly greater mean Fe contents (Fe2O3 = 5.2 wt%) than tubes (Fe2O3 = 3.2 wt%), and expanded rapidly with formamide. They occurred, along with halloysite tubes, spheroids, and plates...

Potassium is common in a wide variety of wastewaters and in some wastewaters is present at several hundred to several thousand mg L–1. Potassium is taken up by expandable clays leading to its fixation and illitisation of smectitic and vermiculitic layers. Hence the addition of wastewaters to soils may lead to mineralogical changes in the soils that...

Andisols, developed from late-Quaternary tephra (volcanic ash) deposits and dominated by the nanocrystalline aluminosilicate, allophane, contain large stores of organic matter and are potential reservoirs for DNA. However, DNA recovery from Andisols and other allophane-bearing soils has been difficult and inefficient because of strong chemical bond...

Andisols, developed from late-Quaternary tephra (volcanic ash) deposits and dominated by the nanocrystalline aluminosilicate, allophane, contain large stores of organic matter and are potential reservoirs for DNA. However, DNA recovery from Andisols and other allophane-bearing soils has been difficult and inefficient because of strong chemical bond...

Andisols, developed from late-Quaternary tephra (volcanic ash) deposits and dominated by the nanocrystalline aluminosilicate, allophane, contain large stores of organic matter and are potential reservoirs for DNA. However, DNA recovery from Andisols and other allophane-bearing soils has been difficult and inefficient because of strong chemical bond...

The Mg-rich clay minerals, palygorskite, sepiolite and also Mg-smectites are generally rare in soils. When they occur they are usually concentrated in subsurface horizons and become replaced by other minerals, e.g., dioctahedral smectites in near-surface horizons. Salt-affected soils on limestone in a flat landscape in southern Australia showed pat...

Unlike smectite, the surface characteristics of palygorskite remain underexplored for its potential application in environmental remediation. In this study, palygorskite from Western Australia was activated through thermal (300 °C for 4 h), acid (4 M HCl for 2 h at 70 °C) and acid-thermal (acid treatment followed by heating at 300 °C for 4 h) treat...

There is increasing research interest in potential applications of halloysite as fillers for polymer composites, controlled drug delivery, carriers for the supply and sustained release of active agents for anticorrosion coatings, in nanoreactors or nanotemplates, and for the uptake of contaminants or pollutants and support for catalysts. In this re...

New insights from the recent literature are summarized and new data presented concerning the formation, structure and morphology of halloysite. Halloysite formation by weathering always requires the presence of water. Where substantial drying occurs, kaolinite is formed instead. Halloysite formation is favoured by a low pH. The octahedral sheet is...

Up until about 2005, the main application of halloysites had been as an alternative raw material to kaolinite for ceramics. Since then, however, there has been an exponential increase in studies aimed at applications of halloysite nanotubes, now widely referred to as HNTs (Fig. 1). The readily available and relatively cheap nanotubular forms of hal...

Ka Loko Dam, in Kauai, Hawaii, failed suddenly and catastrophically on March 14, 2006. The resulting breach was marked by three topographic benches, the lowest of which exposed native volcanic deposits once resident in the dam foundation. These deposits were found to contain outcrops of a waxy, gel-like material that appeared to result from in situ...

Tubular halloysite has many applications as a nanomaterial. Spheroidal halloysite (SPH) is the other most common form of halloysite. Its mode of formation has had different explanations, including association with allophane, or more generally, following weathering of volcanic glass. Some SPHs have formed from minerals in crystalline rocks, sometime...

Hydrated halloysite was discovered in books, a morphology previously associated exclusively with kaolinite. From ∼1.5 to ∼1500 μm in length, the books showed significantly greater mean Fe contents (Fe2O3 = 5.2 wt.%) than tubes (Fe2O3 = 3.2 wt.%), and expanded rapidly with formamide. They occurred, along with halloysite tubes, spheroids and plates,...

Clay delving in strongly texture-contrast soils brings up subsoil clay in clumps ranging from large clods to tiny aggregates depending on the equipment used and the extent of secondary cultivation. Clay delving usually increases crop yields but not universally; this has generated questions about best management practices. It was postulated that the...

In order to improve the understanding of factors influencing weathering in hydromorphic soils, the clay mineral and chemical compositions, iron (hydr)oxides, organic compounds, and Sr and Nd isotopic compositions, of hydromorphic soils on the banks of the Liangzi Lake, Hubei province, south China, were investigated. The B horizon in the lower profi...

This study provides fundamental knowledge about the interaction of allophane, deoxyribonucleic acid (DNA), and organic matter in soils, and how allophane sequesters DNA. The adsorption capacities of salmon-sperm DNA on pure synthetic allophane (characterised morphologically and chemically) and on humic-acid-rich synthetic allophane were determined,...

This study provides fundamental knowledge about the interaction of allophane, deoxyribonucleic acid (DNA), and organic matter in soils, and how allophane sequesters DNA. The adsorption capacities of salmon-sperm DNA on pure synthetic allophane (characterised morphologically and chemically) and on humic-acid-rich synthetic allophane were determined,...

Sensitive soils in the Bay of Plenty in North Island occur within weathered, rhyolitic pyroclastic and volcaniclastic deposits, with hydrated halloysite (not allophane) as the principal clay mineral. We evaluate the development of sensitivity and characteristic geomechnical behaviours for sequences of the silt-rich, halloysitic soils. Morphological...

To understand clay mineral transformations in hydromorphic conditions in the red earth sediments in Xuancheng, south China, clay mineralogy was investigated using X-ray diffraction (XRD) and highresolution transmission electron microscopy (HRTEM). The XRD results indicated that clay minerals in the hydromorphic soils were illite, kaolinite, smectit...

Mitigation of ruminant methane (CH 4) production remains a formidable challenge for both improving feed conversion efficiency and decreasing emissions of this potent greenhouse gas but no viable solutions are yet available. We have taken a novel approach to addressing this challenge, based on our understanding of soil microbial ecology and clay min...

Clay delving is becoming a popular practice to increase productivity of texture-contrast soils in southern Australia. The practice brings subsoil clay to the surface to be mixed with the sandy topsoil, and unlike clay spreading, it combines the addition of hydrophilic material with a ripping effect that disrupts the sharp boundary between the sandy...

Buried allophanic soils developed on sequences of well-dated tephras sequester organic matter over long time periods. Allophane in these paleosols also potentially enables DNA to be preserved, and this ancient DNA (aDNA) could provide a means for reconstructing past environments from terrestrial sequences comparable to, for example, phytolith analy...

Palaeoenvironmental DNA (PalEnDNA) is defined as ancient DNA (aDNA) originating from disseminated genetic material within palaeoenvironmental samples. Sources of PalEnDNA include marine and lake sediments, peat, loess, till, ice, permafrost, palaeosols, coprolites, preserved gut contents, dental calculus, tephras, and soils as well as deposits in c...