Browsing by Author "Reichelt-Brushett, AJ"

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    The effect of dissolved nickel and copper on the adult coral Acropora muricata and its microbiome
    (Elsevier, 2019-04-03) Gissi, F; Reichelt-Brushett, AJ; Chariton, AA; Stauber, JL; Greenfield, P; Humphrey, C; Salmon, M; Stephenson, SA; Cresswell, T; Jolley, DF
    The potential impacts of mining activities on tropical coastal ecosystems are poorly understood. In particular, limited information is available on the effects of metals on scleractinian corals which are foundation species that form vital structural habitats supporting other biota. This study investigated the effects of dissolved nickel and copper on the coral Acropora muricata and its associated microbiota. Corals collected from the Great Barrier Reef were exposed to dissolved nickel (45, 90, 470, 900 and 9050 μg Ni/L) or copper (4, 11, 32 and 65 μg Cu/L) in flow through chambers at the National Sea Simulator, Townsville, Qld, Australia. After a 96-h exposure DNA metabarcoding (16S rDNA and 18S rDNA) was undertaken on all samples to detect changes in the structure of the coral microbiome. The controls remained healthy throughout the study period. After 36 h, bleaching was only observed in corals exposed to 32 and 65 μg Cu/L and very high nickel concentrations (9050 μg Ni/L). At 96 h, significant discolouration of corals was only observed in 470 and 900 μg Ni/L treatments, the highest concentrations tested. While high concentrations of nickel caused bleaching, no changes in the composition of their microbiome communities were observed. In contrast, exposure to copper not only resulted in bleaching, but altered the composition of both the eukaryote and bacterial communities of the coral's microbiomes. Our findings showed that these effects were only evident at relatively high concentrations of nickel and copper, reflecting concentrations observed only in extremely polluted environments. Elevated metal concentrations have the capacity to alter the microbiomes which are inherently linked to coral health. Crown Copyright ©2019. Published by Elsevier Ltd.
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    Electroacoustic isoelectric point determinations of bauxite refinery residues: different neutralisation techniques and minor mineral effects
    (American Chemical Society, 2012-08-14) Freire, TSS; Clark, MW; Comarmond, MJ; Payne, TE; Reichelt-Brushett, AJ; Thorogood, GJ
    5Bauxite refinery residue (BRR) is a highly caustic, iron hydroxide-rich byproduct from alumina production. Some chemical treatments of BRR reduce soluble alkalinity and lower residue pH (to values <10) and generate a modified BRR (MBRR). MBRR has excellent acid neutralizing (ANC) and trace-metal adsorption capacities, making it particularly useful in environmental remediation. However, soluble ANC makes standard acid-base isoelectric point (IEP) determination difficult. Consequently, the IEP of a BRR and five MBRR derivatives (sulfuric acid-, carbon dioxide-, seawater-, a hybrid neutralization, i.e, partial CO2 neutralization followed by seawater, and an activated-seawater-neutralized MBRR) were determined using electroacoustic techniques. Residues showed three significantly different groups of IEPs (p < 0.05) based around the neutralization used. Where the primary mineral assemblage is effectively unchanged, the IEPs were not significantly different from BRR (pH 6.6-6.9), However, neutralizations generating neoformational minerals (alkalinity precipitation) significantly increased the IEP to pH 8.1, whereas activation (a removal of some primary mineralogy) significantly lowered the IEP to pH 6.2. Moreover, surface charging curves show that surfaces remain in the +/-30 mV surface charge instability range, which provides an explanation as to why MBRRs remove trace metals and oxyanions over a broad pH range, often simultaneously. Importantly, this work shows that minor mineral components in complex mineral systems may have a disproportionate effect on the observable bulk IEP. Furthermore, this work shows the appropriateness of electroacoustic techniques in investigating samples with significant soluble mineral components (e.g., ANC). © 2012, American Chemical Society.
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    The response of corals and the coral microbiome to metal exposure
    (Society of Environmental Toxicology and Chemistry, 2017-11-12) Gissi, F; Reichelt-Brushett, AJ; Chariton, AA; Stauber, JL; Stephenson, SA; Cresswell, T; Greenfield, P; Severati, A; Humphrey, C; Jolley, DF
    The mining and production of Ni is increasing in tropical regions. The potential impacts of these activities on the valuable coastal ecosystems are poorly understood. Specifically, there is little information available on the effects of Ni to corals. Scleractinian corals are keystone species for coral reefs forming vital structural habitats that support other species, resulting in habitats with high species richness and diversity. For these reasons, it is important that future research provides data which can inform the sustainable development of Ni operations in tropical regions. This study aimed to investigate the effect of dissolved Ni exposure to the scleractinian coral Acropora muricata. Utilising the facilities at the National Sea Simulator (SeaSim), flow through chambers (2.5L) were used to test the effects of Ni and Cu on adult corals and its associated microbiota. Copper was tested alongside Ni to allow for comparisons with past studies. Four replicate chambers were used for; control, 50, 100, 500, 1000, 10000 µg/L Ni and 5, 20, 50, 100 µg/L Cu. Each replicate chamber contained 3 coral fragments (5-8cm in length). After a 96-h exposure, 1 fragment from each chamber was sacrificed for 3 different analytical purposes. One replicate was air blasted to remove tissues which were flash frozen and later used for DNA and RNA sequencing of the microbiota to observe if the bacterial community structure changed in response to metal exposure. A second fragment was air blasted to remove tissues, which were then acid digested and analysed by ICP-MS to determine metal concentrations in the coral tissues. A third replicate was frozen for subsequent metal uptake and distribution analyses using elemental mapping techniques including CT scanning and XRF-ITRAX. Control treatments remained healthy throughout the exposure. After 36 h, bleaching was observed in corals exposed to 50 and 100 µg Cu/L and 10000 µg Ni/L. At 96 h significant discolouration of corals was observed in Ni treatments 500 and 1000 µg Ni/L. The effects of Cu and Ni on adult corals and associated microbiota will be discussed.
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    Reversibility of uranium and thorium binding on a modified bauxite refinery residue: the effects of aging temperature
    (Elsevier, 2015-02) Clark, MW; Payne, TE; Harrison, JJ; Comarmond, MJ; Collins, RN; Reichelt-Brushett, AJ
    The effects of aging on the pH-dependence and reversibility of uranium and thorium binding by a modified bauxite refinery residue (MBRR) were studied in laboratory uptake/leaching experiments. Natural uranium and thorium isotopes (predominantly 238UVI and 232ThIV) of 0.4, and 0.2 mM were loaded for an 8-day period at the natural equilibrium pH of the MBRR (approximately 8.5) and were allowed to age for 6 months in humid sealed containers at 4, 23, and 65 °C. After aging, anthropogenic 232UVI and 229ThIV were added as exchange isotopes and the pH decreased stepwise from 8 to 3 over several hours in pH dependent experiments. The relative concentrations of the isotope pairs (i.e. 238UVI and 232UVI; 232ThIV and 229ThIV) indicated that irreversibility of UVI and ThIV binding by the MBRR increased with aging and was dependent on the aging temperature and surface actinide loading. Linear combination fitting of the EXAFS data for the uranium loaded materials indicated that at low uranium concentrations sorption to minerals (particularly hematite) was a prime uranium removal mechanism, but at higher concentrations precipitation dominated. The data suggest that increased irreversibility and incorporation of UVI during aging is associated with re-crystallisation of precipitates. © 2014 Elsevier Ltd.