Grant Douglas

The Commonwealth Scientific and Industrial Research Organisation | CSIRO · Division of Land and Water

This paper reviews the scientific knowledge on the use of a lanthanum modified bentonite (LMB) to manage eutrophication in surface water. The LMB has been applied in around 200 environments worldwide and it has undergone extensive testing at laboratory, mesocosm, and whole lake scales. The available data underline a high efficiency for phosphorus b...

Purpose of Review The unique properties of per- and polyfluoroalkyl substances (PFASs) have seen their widespread adoption, subsequent accumulation in the environment and concern regarding potential environmental effects. Globally, airfields and paved firefighting training surfaces are hotspots for accumulation of PFAS due to extensive use of aqueo...

Uncontrolled release of acid mine drainage (AMD) causes widespread detrimental impacts on the receiving environment. Thus, effective treatment to neutralise AMD effluent pH and capture a suite of metals is required. In-situ hydrotalcite (HTC) precipitation is an emerging technology for AMD remediation. HTC has an inherent capacity to accommodate a...

Per- and polyfluoroalkyl substances (PFAS) are now widespread in the environment. Globally, airfields and paved firefighting training surfaces are particularly affected due to extensive use of aqueous film forming foams (AFFF). This PFAS contamination in exposed concrete and asphalt has not been widely addressed. This review focusses on PFAS intera...

Historical use of aqueous film forming foams (AFFF) containing per- and poly-fluoroalkyl substances (PFAS) for fire-fighting activities has contributed to widespread contamination of infrastructure which can represent an ongoing source of PFAS to the surrounding environment. A concrete fire training pad with historical use of Ansulite and Lightwate...

Effective capture of fugitive actinides and daughter radionuclides constitutes a major remediation challenge at legacy or nuclear accident sites globally. The ability of double-layered, anionic clay minerals known as hydrotalcites (HTC) to contemporaneously sequester a range of contaminants from solution offers a unique remedy. However, HTC do not...

Processing uranium ores into transportable oxide powders produces a stream of wastewaters high in metals, acids, and predominantly nitrogenous nutrients. Conventional water treatment can remove metal ions and buffer acids, but nutrient removal is problematic as it entails both oxidative and reductive steps. Engineered wetlands can achieve nutrient...

In this study, we investigate the effects of excessive inputs of bioavailable phosphorus into a lake from agricultural fields and households on algal bloom formation, and its potential management by using the lanthanum-modified clay Phoslock as a bioavailable phosphorus adsorbent. We also investigate the impact of time delay involved in the process...

1. Coastal aquifers are vital water sources for humanity. Their quality and the ecosystem services they provide depend on the integrity of their subterranean biota. However, current anthropogenic impacts such as climate change effects and coastal population growth place enormous pressure on the sustainability of these environments. 2. Despite the...

Correction for ‘Method for extraction and analysis of per- and poly-fluoroalkyl substances in contaminated asphalt’ by Prashant Srivastava et al. , Anal. Methods , 2022, 14 , 1678–1689, https://doi.org/10.1039/D2AY00221C.

PFAS (per‐ and poly‐ fluoroalkyl substances) in water are typically present in their ionic (non‐volatile) forms, however, these can transition to their non‐ionic (volatile) forms when in contact with organic solvents and organic matrices. In particular, when PFAS is dissolved in organic solvents such as residues left from fire‐fighting foams, fuels...

The legacy use of aqueous film-forming foam (AFFF) has led to the generation of large volumes of per- and poly-fluoroalkyl substances (PFAS)-contaminated asphalt materials, especially at airports and fire training...

This study proposed and validated a method integrating in-situ hydrotalcite precipitation (Virtual Curtain™ (VC) technology) with bioprocess for treating a cyanide (CN)-augmented (ca. 5 mg-CN L⁻¹) sulfate-laden neutral mine drainage, from a waste rock dump (WD2) of an Australian gold mine. Efficacies of various carbon (C) sources (ethanol, lactate,...

Mineral dust particles from different source regions typically have distinct Pb isotope ratios. Theoretically, Pb isotopic composition of terrigenous minerals isolated from open‐ocean sediments should allow for dust provenance reconstructions. However, Pb isotopes of terrigenous fractions of sediments have frequently been inconsistent with expected...

Dredging and in situ adsorbent inactivation are two methods which are frequently used in eutrophic water bodies such as ponds, lakes and estuaries to control internal phosphorus (P) loading from sediments. However, their effects and modes on the control of sediment P loading has been seldom compared. In this study, a long-term sediment core incubat...

Sediments that are rich in organic matter (OM) can trap and accumulate metals, including uranium (U), and provide favourable conditions for the formation of minerals such as pyrite. In OM-sediments, pyrite may play an important role in sorption and reduction of U and other metals that are sensitive to redox change. Mulga Rock, located in Western Au...

Several years after decommissioning, a magnesium dross and mixed waste heap at a former industrial facility is still reactive, as evidenced by the emission of heat, Volatile Organic Carbon (VOCs), acetylene (C2H2), cyanide (HCN) and ammonia (NH3) from deep, discordant, epigenetic fissures. To evaluate the longer-term stability of the waste heap mat...

Several years after decommissioning, a magnesium dross and mixed waste heap at a former industrial facility is still reactive, as evidenced by the emission of heat, Volatile Organic Carbon (VOCs), acetylene (C2H2), cyanide (HCN) and ammonia (NH3) from deep, but discordant, epigenetic fissures. To evaluate the longer-term stability of the waste heap...

Hydrotalcite precipitation is a promising technology for the on-site treatment of acid mine drainage (AMD). This technology is underpinned by the synthesis of hydrotalcite that can effectively remove various contaminants. However, hydrotalcite precipitation has only limited capacity to facilitate sulfate removal from AMD. Therefore, the feasibility...

Lanthanum-modified bentonite (LMB, commercially called Phoslock®) has been widely applied in freshwater systems to manage eutrophication. Little is known, however, about its behaviour and efficiency in binding filterable reactive phosphorus (FRP) in saline environments. We assessed if LMB would adsorb phosphate over a range of salinities (0-32 ppth...

We report on rare earth element and neodymium isotopic compositions in a series of grain-size fractions separated from river suspended matter in the Murray-Darling Basin (MDB) and a nearby marine sediment core (MD03-2607) offshore south-eastern Australia. This source-to-sink approach was used to further investigate the extent to which sediment sort...

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Lanthanum Modified Bentonite (LMB; Phoslock®) is used to mitigate eutrophication by binding phosphate released from sediments. This study investigated the fate of lanthanum (La) from LMB in water, sediment, macrophytes, and chironomid larvae in Lake Rauwbraken (The Netherlands). Before the LMB application, water column filterable La (FLa) was 0.02...

The efficient removal of a range of anionic and cationic contaminants from acid mine waters to facilitate water reuse or for safe discharge constitutes a major environmental challenge. Recently, Layered Double Hydroxide (LDH)-type materials have shown considerable efficacy at experimental and full-scale for acid mine water treatment. In this study,...

Clay-based phosphorus (P) sorbents have been increasingly used as geoengineering materials for the management sediment-derived internal P loading in eutrophic lakes. However, the long-term behavior of these sorbents has remained elusive along with their response to burial under suspended particulate matter (SPM), and their effect on macroinvertebra...

The presence of organic matter (OM) has a profound impact on uranium (U) redox cycling, either limiting or promoting the mobility of U via binding, reduction, or complexation. To understand the interactions between OM and U, we characterised U oxidation state and speciation in nine OM-rich sediment cores (18 samples), plus a lignite sample from the...

The kinetics and mechanisms of the reduction of NO3⁻ in solution to NH3 by 1.5 μm diameter zero-valent iron (ZVI1.5) particles has been examined. The effects of initial pH, ZVI1.5 particle concentration and initial NO3⁻ concentration were also investigated. Results indicate that denitrification by ZVI1.5 is primarily a pH-dependent, surface-mediate...

Since the advent of large-scale U mining, processing, and enrichment for energy or weapons production, efficient capture and disposal of U, transuranics, and daughter radionuclides has constituted an omnipresent challenge. In this study, we investigated uranyl (UO2²⁺) sequestration by hydrotalcite (HTC) as a coprecipitation or surface adsorption re...

Whilst a diverse array of phosphorus (P)-adsorbent materials is currently available for application to freshwater aquatic systems, selection of the most appropriate P-adsorbents remains problematic. In particular, there has to be a close correspondence between attributes of the P-adsorbent, its field performance and the management goals for treatme...

Uranium (U) is of enormous global importance because of its use in energy generation, albeit with potential environmental legacies.Whilst naturally occurring U is widespread in the Earth's crust at concentrations of ~ 1 to 3 ppm, higher concentrations can be found, including within organic matter (OM)-rich sediments, leading to economic extraction...

Managed aquifer recharge of aerobic water into deep aquifers often induces the oxidation of pyrite, which can lead to groundwater acidification and metal mobilization. As circumneutral pH is often maintained by the dissolution of sedimentary calcite or high injectant alkalinity little attention is generally paid to potential alternative pH bufferin...

Purpose The purpose of this study is to define the relative contributions of fine (<10 μm) suspended sediment from tributaries within the Burdekin River catchment, NE Australia, and subsequent delivery to the Great Barrier Reef (GBR) lagoon. The temporal variability in these contributions was also investigated. Materials and methods Sediments in r...

With the advent of phosphorus (P)-adsorbent materials and techniques to address eutrophication in aquatic systems there is a need to develop interpretive techniques to rapidly assess changes in potential nutrient limitation. In a trial application of the P-adsorbent, lanthanum-modified bentonite (LMB) to an impounded section of the Canning River, W...

Many urban ponds experience detrimental algal blooms as the result of eutrophication. During a two year field experiment, the efficacy of five in situ treatments to mitigate eutrophication effects in urban ponds was studied. The treatments targeted the sediment phosphorus release and were intended to switch the ponds from a turbid phytoplankton-dom...

Eutrophication of Lake De Kuil (The Netherlands, 6.7 ha, maximum depth 9 m) has frequently caused cyanobacterial blooms resulting in swimming bans or the issue of water quality warnings during summer. The eutrophication was mainly driven by sediment phosphorus (P)-release. The external P-loading was in the range of the critical loading for phytopla...

Proportion of clay, fine silt and coarse sediment contributed by each sub-catchment tributary site (see Table 1 for site names). Circle size represents mean total suspended solids (TSS) concentration (mg L-1) over the study period. Major sub-catchment, reservoir and end-of-river sites are also included (represented by bold circle)

The CSIRO has designed and implemented a geothermal solution using ambient temperature groundwater to cool down the recently built Pawsey Supercomputer Centre in Kensington, Western Australia. The corresponding groundwater cooling (GWC) project has developed the system which runs by pumping cool water (21 °C) from the Mullaloo aquifer located appro...

A rapid biogeochemical assessment protocol has been developed to assess the potential effects of returning heated groundwater to the Mullaloo aquifer in Perth, Western Australia. A multi-disciplinary study encompassed geochemical analysis of the aquifer sediment, and microbiological, organic contaminant and major ion surveys of the groundwater. Geo...

Environmental context Australia's tropical marine estate is a biodiversity hotspot that is threatened by human activities. Analysis and interpretation of large physical and geochemistry data sets provides important information on processes occurring at the seafloor in this poorly known area. These processes help us to understand how the seafloor fu...

Remediation of 56 ML of acidic, contaminant-laden Baal Gammon mine pit water was undertaken using in situ hydrotalcite formation. The pit water composition was modified via the addition of MgCl2·6H2O to form a 2.5:1 M2+:M3+ metal ion ratio followed by the addition of NaOH to increase the pH 10 to induce spontaneous hydrotalcite precipitation. As a...

The fate of uranium (U) is strongly influenced by its oxidation state, i.e. U(IV, VI), where U(VI) has greater solubility and therefore mobility in groundwater. Reduction of the uranyl ion to U(IV) by bacteria or natural organic matter (NOM) can immobilise uranium into soils and sediments. The relationship between U and NOM is not well understood,...

Copper extractions from a low-grade, ground copper sulfide ore (0.7% Cu) leached in three media were freshwater < seawater > double-strength seawater and pH 1.5 ⩾ pH 2; 84% extraction was achieved in pH 1.5 seawater in 28 days at 23 °C. Cu-oxide and carbonate dissolved completely and chalcocite was altered to secondary covellite, some of which pers...

The use of geoengineering techniques for phosphorus management offers the promise of greater and quicker chemical and ecological recovery. It can be attractive when used with other restoration measures but should not be considered a panacea. The range of materials being proposed for use as well as the in-lake processes targeted for manipulation con...

An assessment of hydrotalcite (HT) formation as a method to neutralise acidity and remove trace elements was undertaken using barren lixiviant from Heathgate Resources’ Beverley North In-Situ Recovery (ISR) U mine in South Australia. This study demonstrated proof of concept in terms of the neutralisation of acidity and concomitant removal of a rang...

This study investigated the sorption-desorption behaviour of four pesticides by a by-product from mineral sand mining, commonly referred to as neutralised used acid (NUA). In batch studies the average amount of pesticide removed after 6h was 69% for atrazine, 89% for diuron, 61% for 2,4-D and 83% for chlorpyrifos. The lower sorption of 2,4-D to NUA...

Attenuation of excess nutrients in wastewater and stormwater is required to safeguard aquatic ecosystems. The use of low-cost, mineral-based industrial by-products with high Ca, Mg, Fe or Al content as a solid phase in constructed wetlands potentially offers a cost-effective wastewater treatment option in areas without centralised water treatment f...

This study investigates the use of a mineral processing by-product, neutralized used acid (NUA), primarily composed of gypsum and Fe-oxyhydroxide, as a soil amendment. A 1489-d turf farm field trial assessed nutrient, trace element, and radionuclide mobility of a soil amended with ∼5% by mass to a depth of 15 cm of NUA. Average PO-P fluxes collecte...

Geochemical and mineralogical characterisation of steel-making by-products is essential to understand their long-term behaviour and their potential use as environmental amendments or construction materials. A steel-making by-product generated in Western Australia from iron ore smelting, HIsmelt, has been extensively characterised in terms of its ma...

Excess nutrient input to water bodies frequently results in algal blooms and development of oxygen deficient conditions. Mining or metallurgical by-products can potentially be utilised as filtration media within water treatment systems such as constructed wetlands, permeable reactive barriers, or drain liners. These materials may offer a cost-effec...

An assessment of hydrotalcite formation to neutralize acidity and remove trace elements was undertaken using barren lixiviant from Heathgate Resources’ Beverley in situ recovery uranium mine in South Australia. Batchscale studies demonstrated proof of concept for neutralization of acidity using MgO + NaAlO2 with concomitant removal of a range of tr...

The Ambassador U and multi-element deposit occurs on the SW margin of the Gunbarrel Basin, Western Australia. Low-grade, flat-lying U mineralization averaging about 2m thick at 0.03% U occurs in lignites at the redox front at the base of the weathering profile within a laterally extensive palaeochannel network. Uranium is principally associated wit...

The deep (>10 km) Permian to present day Perth Basin in southwest Western Australia is composed of sedimentary successions of continental to shallow marine origin. This study examines the compositional variation, weathering and provenance of the early Cretaceous Leederville Formation within the Perth Basin. Over 200 sediment samples were retrieved...

This study presents new information on the regional geochemical characteristics of deep-sea floor sediments (1300–2423 m water depth) on the Lord Howe Rise (deep–sea plateau) and Gifford Guyot (seamount/tablemount), remote areas off eastern Australia. The aim was to provide a coherent synthesis for a suite of geochemical data that can be used to ma...

The four year joint project between CSIRO and the Western Australian Department of Water-based Water Foundation, investigated the characteristics of a range of mining industry by-products, which are currently unused, to determine whether they could instead be productively applied as high volume, low-cost environmental amendments. CSIRO project lead...

A series of analyses were conducted to characterise neutralized acid residue from the synthetic rutile industry. Column sorption experiments were conducted to investigate the attenuation of DOC and nutrients in wastewater using neutralized acid residue. After 145 days, DOC, TP, PO4-P, TN, NH3-N, NOx-N and DON in neutralized acid residue/sand column...

Process water from the Ranger Uranium Mine requires treatment to meet stringent environmental water quality criteria. The acidic water contains substantial SO4, metals, and U. One novel treatment method under consideration is the use of Na-aluminate to both neutralise the process water and precipitate hydrotalcites. Hydrotalcites are a class of Mg–...

Environmental context. Undisturbed sediments provide a record to past events in a catchment. In this study we examine changes in sources of sediment and their variation over the past century due to changes in climate and extensive modification of the catchment after European settlement. We also highlight how multiple lines of forensic evidence acqu...